Hey,

I remember someone here claiming they'd used microcrystalline wax (henceforth mcw) in their adapter design, and I'm posting this here to push the idea a bit further, see what others have found, help perfect application techniques, consolidate info on materials and resources.

If memory serves, the idea was that mcw should provide the ideal optical qualities -- less lightloss than GG, with no visible grain.

I see that mcw is readily available online and at Perl. A few links that I've bookmarked, harvested from a google search, are these:

http://www.artstuf.com/waxes.html

http://www.spwax.com/spparaff.htm

this one (http://www.paramelt.com/markets.and.products.Waxes-Cosmetic.+.Pharmaceutical-Microcrystalline.wax.htm),

and this one (http://candles.genwax.com/do_not_index/___0___Z40M75W.htm).

I'm thinking about application techniques, spurned on by comments from a user on another forum:

You mention "the wax idea." I remember for rearscreen stop-motion, we made a wax screen by dissolving beeswax in solvent, and dipping glass in it. Is "the wax idea" like that? Beeswax is a microcrystalline wax that works very well for a screen.

Does anyone know offhand what sort of solvent would be used in this application, and how, once the wax is dissolved, it would be applied to the surface in an even fashion? I've asked the guy quoted above to respond, and hopefully he'll lend his insights to the project.

Meanwhile -- I've got an idea of using a small amount of wax spread out over the surface of a UV filter, and sitting the filter inside the interior pot of a double boiler -- the idea would be that you lightly coat the glass by shaving the wax with the pinhole side of a cheese-grater, the sprinklings falling to coat one side of the filter, and with the melitng point at 120, a double boiler should do the trick of getting it to create a thin surface. Take it out, sit it on a level surface while the wax is still hot, and let it set. Then screw another filter ontop of it so as to keep it clean/dustfree/free from scratches.

I've extended this discussion out to the users at The Wax Emulsions Forum (http://www.waxemulsions.com/forum/display_topic_threads.asp?ForumID=7&TopicID=37&PagePosition=1) for their ideas as well -- hopefully they'll kindly respond.

- jim

Hi Jim
I did try it a while back and after hours of trying different dipping techiques between two pieces of glass I gave up. I may have needed clamps or something more than the tongs I was using but I couldn't avoid the glass slipping out of place and tiny bubbles forming inside the wax.

However as I was cleaning up I filled one of the pots that I was using to melt the wax with boiling water. And as the water cooled a beauitiful thin sheet of wax formed on top of the water. Figures huh. It was perfect!!! but as I was pulling it from the water it tore in too many spots to press on a lens. I tried the same thing a couple of times after but could replicate it.

But I did work with it enough to see that it does project a very nice bright grainfree image and would be the way to go if you could find a way to get rid of the bubbles.

I'm now thinking of going for the oscillating glass kit the Les Dit has but if someone can come up with a solution for the wax I think it would be best and most compact solution.

Jon

I'm going to get this one down.

I've been looking over directions for applying mcw to glass bulbs, found here (http://www.fao.org/docrep/W6355E/w6355e0m.htm) -- no doubt it's more complicated than I have the resources for, but it points the way to some feasible techniques. I'm in talks with others who've done this sort of thing as well -- perhaps I can get someone with appropriate expertise here in NYC to make my waxed glass.

Any way you cut it I'm determined to get it done.

- jim

For the glass composite disk two x glass with wax layer, I used the 10% beeswax/paraffin wax mix, dip technique and spun the disks on a CD-R spindle under the wax to get the air out. Getting the spindle off after the wax sets without breaking glass is a bitch.

Don't remelt the wax to get parts of it off otherwise stresses get set up which will break your glass.

My problem with variable density due to varying wax layer thickness was related more to my imperfect finishing of the disks than the wax itself.

Temp must not be too high otherwise the beeswax will discolour. You also need bleached beeswax. I tried bleaching with peroxide. Didn't work as I could not get concentrated peroxide. I tried chlorine based bleach. Forget it.

Your pharmacist can order in sufficient bleached wax for optical applications.

I melted my wax in a small electric deep fryer/boiler which had temp control from below boiling point of water. Worked excellently and didn't burn the wax provided I was patient.

Thanks for the advice. Any reason you went with bees wax and not a true (synthetic) microcrystalline wax?

Jim.

It was a simple matter of what I could easiest get my hands on here in W.A.. I've since found out that fruit-packers here use microcrystalline wax on apples so I will look into that sometime.

The 10% formulation was one mentioned by Rai Orz I think so I just went with it. The image through the spinning disk seemed to have deeper contrast and was slightly sharper than the 5 micron but the flicker was totally unacceptable. Just how sharp it is I don't know.

It resolves up to the practical limit of the PD150 at just over 500 TV lines however it must still be soft as the digital image does not yield sharp vertical lines along the pixel edges. blow up a .jpg until the pixels show and the sharpness seems to be about two or three pixel resolution so I guess it falls over at about 600 TV lines.

Now that you mention it, I do remember your work in this area. OK, so we've got consistency issues to deal with...

Last night I emailed a lot of microwax companies, inquiring about their free samples -- many offer up to a pound to try out. I wrote describing our device vaguely and asked about ideal wax types, and their application. Hopefully I'll hear something back by early next week -- I'll let ya know.

- jim

movitube have a patent for her high res wax GG. I found it on:

http://v3.espacenet.com/textdoc?DB=EPODOC&IDX=DE10240076&F=0&QPN=DE10240076&CY=ep&LG=en

Seems a lot different than the device I'm building ;)

Looks like a unit comprising a sort of condenser both sides of the groundglass stuck together by the wax itself.

There's a few from here been down that route by grinding the flat side of the condenser then putting another on back to back. Then to erect the image, a schmidt? prism is added between the cam and groundglass/condenser unit.

In the (german) patent text are realy ALL details for making the GG. incl. mixture, lens diop. and also the way to bring the wax between the lenses

Could you translate and post it for non-germans?

I have no time, because it will cost me one or two days (my english is very "slow") . Maybe a translate software can do this.

Post a link to the patent and we'll babelfish it :D

<<<-- Originally posted by Jim Lafferty : Post a link to the patent and we'll babelfish it : -->>>

??? Sorry, but i had post it. Just read...

The drawings:

http://v3.espacenet.com/textdraw?DB=EPODOC&IDX=DE10240076&F=0&QPN=DE10240076&CY=ep&LG=en

The Description:

http://v3.espacenet.com/textdes?DB=EPODOC&IDX=DE10240076&F=0&QPN=DE10240076&CY=ep&LG=en

...and some more informations, all on th same side...

It looks like the wax is sandwiched between two plano-convex lenses. Then they send the picture through a "field lens", then a schmidt prism and finally a diopter. hmmm... this is interesting.

What does the field lens do?

<<<-- Originally posted by Anders Floe : Could you translate and post it for non-germans? -->>>

Why can't patent application published in English?

Here it is babel'ed:

Description OF DE10240076 [ 0001 ] the invention concerns an optical resolution adapter for a photographic camera such as photoapparat, film or video camera in the generic term of the patent claim 1 indicated kind, a projektionsoptik for such an adapter in accordance with patent claim 22 as well as a procedure for the production of a projektionsoptik after patent claim 24. [ 0002 ] During the view of picture the viewer can differentiate easily pictures from a photograph from the pictures of a video camera, whereby the optical impression of the photographs is usually felt as more pleasant. It is well-known that this effect apart from a smaller dissolution of the video picture and an unsatisfactory contrast behavior in the comparison to the film picture is essentially based on the large sharpness depth of the video picture. When taking up objects in a certain distance to the image plane a being fixed sharpness depth in the case of certain focal length and blendenoeffnung, which is independent first of the zerstreuungskreis of the respective photograph format, results. In principle with the fact the rule applies that with increase of the size the sharpness depth decreases. So has large 35 mm cinema format opposite the 1/3' ' video format one approximately around the factor 5 smaller sharpness depth with same screen stage and picture angle. With the digital picture recording of a video camera the picture on a chip is taken up, which is small in the comparison to the film gate of a movie camera - with 35 mm photograph format -, so that the taken up video picture exhibits a clearly higher sharpness depth than the comparable film picture. This characteristic is easily perceptible by the viewer of the picture. [ 0003 ] In order to achieve during same picture angle and blendenoeffnung as with 35 mm of movie cameras, video cameras and photoapparaten of arbitrary photograph format the same conditions of the sharpness depth, is well-known, to set an optical adapter before the camera. Such an optical adapter is not into December "small 3ër, but..., Film & TV cameraman 12/2001 from 20 December 2001, pages 18 to 20"described. The well-known optical adapter covers an objective and a ground-glass plate as projektionsoptik, on whose transparent projektionsflaeche the real picture is made visible. This intermediate picture is made available in an image output at the end of the optical way in the well-known adapter to the admission. A digital camera films so the intermediate picture off, whereby the the same focal length and sharpness depth conditions in the kleinformatigen digital camera result as with large sized 35 mm movie cameras. [ 0004 ] The ground-glass plate of the well-known adapter is shifted with an electric motor in rotations, so that the standing grain of the ground-glass plate does not become visible for example with Kameraschwenks. By the fast rotation the granulation is no longer locatable, however is not eliminated. On the taken up picture a soft draughtsman film in the size of the granulation, which is unwanted with back light photographs in particular, puts. The well-known ground-glass plate must exhibit also a certain layer thickness and grain size, in order to prevent a Durchfokussierung of the picture by the ground-glass plate. With this as "Hot Spot" becomes recognizable a bright mark in the center of the picture marked feature. [ 0005 ] During the rendition of photographs with the well-known adapter the operating noise of the driving motor for the rotary ground-glass plate becomes disturbing audibly, which can be eliminated only - if at all - at enormous retouching expenditure. Also the granulation of the ground-glass plate in the picture center can become visible in particular with an admission with more closed screens due to the larger sharpness depth. Such photographs with decreased quality are often not usable. Beyond that the well-known projektionsoptik is very faint because of the necessary thickness of the ground-glass plate, whereby many screen stages are not usable and in faint film situations such as interior photographs not for the order. [ 0006 ] The moreover back projection mechanisms are well-known for projector screens, with which to one or plates from transparent material light-faithful-end a layer to substance between two flat-parallel foils is arranged. The EP 0,027,287 B1 describes such a back projection screen for the view of microfilms, with which due to the relationship of the view distance from the size of the projected picture the contours under a larger picture angle are regarded than the picture center and so the Hot Spot effect arise. In order to meet the problem of the bright picture mark, the EP 0,027,287 B1 the thought is entnehmbar to arrange between the flat-parallel plates from glass or other transparent material a wax mixture from low light faithful ability such as paraffin and a wax with high streuvermoegen such as bienenwachs. The wax mixture is to be applied thereby in melted condition on a transparent carrier and be brought the layer after solidifying the wax mixture on the desired homogeneous thickness with the help of a scraping off device. The well-known principle of a favourably thick layer of wax between flat-parallel plates is intended for a bright projector. The enormous light losses of the thick layer of wax let a transmission of this well-known arrangement for bright projectors separate on photographic cameras. [ 0007 ] The available invention is the basis the task in such a manner to train an optical adapter further for a photographic camera in the generic term of the patent claim 1 indicated kind that with as small structural a measures as possible an improvement of the receptible image quality is reached. [ 0008 ] Beyond that it is task of the invention to create a projektionsoptik for such an adapter which promotes the improvement of the image quality. [ 0009 ] This task is solved according to invention by an adapter with the characteristics of the patent claim 1 and a projektionsoptik with the characteristics of the requirement 22. Beyond that a procedure with the characteristics of the patent claim 24 for the production of a projektionsoptik for such an resolution adapter is suggested. [ 0010 ] According to invention a back projection lens arrangement is intended with two transparent carrier bodies, which also flat lying surfaces limit a gap, in which a layer of one light-faithful-ends substance is taken up as projektionsoptik in an optical resolution adapter for a camera. The back projection lens arrangement covers at least one lens body, which light-faithful-ends layer with a surface curved outward covered, whereby the bundling effect of the lens increases the luminous intensity of the back projection picture abzufilmenden of the strewing layer. The back projection lens promotes besides light scattering, so that by the combination of the back projection lens with the transparent layer, which their light-faithful-end to characteristics also their layer thickness owed, a small layer thickness can be selected. With the thin layer thickness a bright picture is produced and so the luminous intensity of the entire adapter is increased. [ 0011 ] In compact building method at least one of the transparent carrier bodies is trained as flat-convex lens bodies in a back projection lens, whereby without an arrangement of separate lens bodies can be done. With a thin layer to one light-faithful-end substance can with the back projection lens according to invention a qualitatively high-quality picture to the collection by the camera be made available and without complex and cost-intensive constructions like the arrangement of an electrical driving motor be done. [ 0012 ] The back projection lens has favourably a focal length of several diopters, preferably 6 to 11 diopters. Thereby a focal length of approximately 9 diopters is preferred, whereby in the Gesamabstimmung of all construction units of the adapter a small size results. With such a focal length the object which can be illustrated is not in the focus of the back projection lens, thus not in the distance of 111.11 mm of the projektionsflaeche of the strewing layer, whereby a very good light distribution into the corners of the picture is reached also without enlargements. [ 0013 ] Both carrier bodies of the back projection lens are designed favourably as flat-convex lens bodies and specify together the desired focal length of the back projection lens. A simplification of the structure of the back projection lens is given, if the back projection lens is compound from two equal flat-convex bodies. By the integration according to invention layer into the back projection lens unwanted refractions of light, falsifications and light losses are avoided, light-faithful-end how they arise with flat-parallel carrier bodies. [ 0014 ] As if light-faithful-end substance as grainless a substance as possible into the gap between the carrier bodies of the back projection lens one brings, favourably a wax. Mixture from paraffin and white bienenwachs preferentially, whereby the taken up picture is provided with a warm radiant emittance pleasant for the viewer in relation to a digital picture recording, in which the picture appears often with cold and not film requirements corresponding colors, as it admits 35 mm from photographs in the large cinema format is. This Filmlook of a similar picture with warm, responding radiant emittance will preferably receive 5 % white bienenwachs with a wax mixture from approximately 2 to 60 bienenwachs. The half-value angle of the layer of wax with the layer thickness and the focal length of the flat-convex lens of the back projection lens following in the optical way can be co-ordinated by variation of the mixing ratios.

cont'd:

[ 0015 ] With grainless the according to invention back projection lens can without supply of energy of any kind and therefore economically and besides loudless a picture with high contrast and very good detailed solution is taken up, whereby the soft draughtsman effect of the ground-glass plates after the conditions of the technology is substantially reduced and is mostly not visible. [ 0016 ] For collecting the picture seized by the objective of the adapter a field lens is arranged in the optical way in the adapter, whereby the length of the adapter is shortened. In order to put to the camera an upright standing picture at the disposal, a prism arrangement is intended in the optical way, in that the picture around 180[deg. behind the back projection lens ] one rotates and one sets up thereby. The prism arrangement is favourably arranged behind the field lens thereby. For putting the picture up two Poro prisms with triangle cross section can be used, whereby the picture penetrates in each case by the surface area of the Poro prism and is totally reflected at the two sides. The optical way in the adapter is extended by several total reflexions, so that the adapter can be arranged altogether compact. Preferred roof edge or also Schmidt or Amici prism behind the back projection lens is planned, whereby in an individual prism body several reflections for the extension of the optical way to occur and the picture is put spent up. [ 0017 ] In preferential arrangement the prism is trained so that the image output direction takes place in relation to the picture idea angularly employed, for example by a 45[deg.]-Schmidt-Prisma. The adapter can be attached in such a way with a tubusfoermigen housing before the assigned camera, whereby on the one hand a compact gesamtanordnung of the adapter with the camera results and in addition a simple Schulterung is given to the arrangement. Employed the lying camera can be carried with the adapter ergonomically on the shoulder of a cameraman, whereby besides the emphasis of the system lies more deeply and so that a more stable camera guidance is possible. With the back projection lens according to invention and their focal length can in combination with an objective of the adapter as well as the field lens, which following prism and an eyepiece at the exit of the optical way of the adapter a very short total overall length are reached, since the individual optical components can be arranged also closely beabstandet in the housing of the adapter. [ 0018 ] The back projection lens is arranged favourably in a container from badly heat conducting material within housings of the adapter, so that the back projection lens is protected against larger thermal effect in the adapter inside. The container can thereby a ring from non-metallic material, preferably plastic e.g. PP or polystyrene be. The life span of the back projection lens is substantially increased by the isolation. The back projection lens is favourably solvable in the container taken up thereby and/or the containers themselves from the adapter solvable, whereby a replacement of a worn out back projection lens or a withdrawal of the back projection lens for cleaning purposes is relieved. Also back projection lenses with different characteristic know e.g. different layer thicknesses, mixing proportion of the wax mixture for changing are held ready and the characteristics of the adapter after the requirements of the available film situation are adapted. Also an aerial photograph illustration can be made by removing the back projection lens from the optical way, whereby the picture seized by the objective over the field lens, the prism and eyepiece to the reproducing equipment like a video camera or the photoapparat are passed on, whereby will receive a very bright picture can. The aerial photograph is taken up thereby with the same favourable picture angle as with the combination of the optical construction units with the back projection lens according to invention, whereby it can be appropriate to store the field lens mobile. [ 0019 ] During the production of the back projection lens light-faithful-end substance in hot condition into the gap between the flat-parallel surfaces of the carrying bodies filled and afterwards a cooling air flow on the vertex of the curved surface of a lens body blown. In this way the vertex range of the lens body preferentially consisting of transparent glass is cooled, where the largest material accumulation of the lens body results. Air warmed up at the vertex range diverts over the thinner edges of the lens, whereby the boundary region of the lens body is less strongly cooled than the vertex. In this way an even cooling of the even surface of the lens body is reached, at which the lying close layer light-faithful-end to substance homogeneous to cooling can. A wax as if light-faithful-end substance forms in such a way with an even cooling within approximately five minutes a very fine grain and it a practically grainless and therefore very bright back projection lens one creates. The grain size is influenceable thereby also by suitable variation of the mixing proportion in the layer of wax. The wax mixture should contain 2 % to 60 % white bienenwachs and paraffin, whereby a portion of 5 % bienenwachs turned out as favourable. [ 0020 ] With a back projection lens with two flat-convex lens bodies on the vertices of both lens bodies cooling air is blown favourably. Before filling the liquid wax into the gap between the flat-parallel surfaces of the carrier bodies the gap is fixed on the necessary width. The layer thickness amounts to with the back projection lens according to invention less than 0.15 mm. A layer thickness of 0.08 mm is favourable thereby whereby also layer thicknesses from 2 to 3 hundredth millimeters or thin application find. Such a thin gap can be fixed before filling the liquid wax into the gap with india rubber threads. [ 0021 ] A remark example of the invention is below described on the basis the design more near. Show: [ 0022 ] Fig. 1 a schematic opinion of a resolution adapter at a camera, [ 0023 ] Fig. 2 the optical way in the adapter and the optical construction units arranged therein, [ 0024 ] Fig. 3 an opinion of a portable camera with resolution adapter and adjusting device for the adapter. [ 0025 ] Fig. 1 shows a video camera 2 with small photograph format, before whose objective 23 an optical adapter 1 is set forward, in order the sharpness depth and thus similar image quality of a movie camera working with large photograph formats to receive. The adapter 1 covers a Tubuskoerper milled from aluminum as housing 4 with a pit left blank therein 9 for the admission of the optically effective components. Into the pit 9 the picture breaks in by an objective 3 and meets a back projection lens 10. The objective 3 is replaceable held 1 trained change bayonet 28 thereby in at the housing 4 of the adapter, which is out-arranged as objective adapters for all usual film and photo objectives. On the basis back projection lens 10 which can be described more near from Fig. 2 consists later of two flat-convex lens bodies, between which one light-faithful-ends layer for the visible making of the picture is arranged. The picture of the back projection lens is removed with the help of in the optical way of the adapter the 1 following field lens 5 and sent by a 45[deg.]-Schmidt-Prisma 6, in that the picture by repeated reflection around 180[deg. ] one puts up. The image output 24 of the adapter 1 forms an eyepiece 7, in which the picture of the back projection lens 10 is made available to the camera 2 to the Abfilmen finally. [ 0026 ] By the angular bypass of the optical way in relation to the direction of arrival the camera 2 can be held according to the angle direction of the prism 6, thus in the available case 45[deg. ], employed to the adapter 1, so that the gesamtanordnung, consisting of camera 2 with put on adapter 1, is distinguished by a very short building method. [ 0027 ] The gesamtanordnung from adapter and camera is carried by a control person with a shoulder mounting plate 31 on the shoulder, represented in Fig. 3, whereby by the angular arrangement of the adapter 1 opposite the camera 2 an ergonomic carrying way is refunded and in addition by the deep position of the center of gravity stable leading is made possible for the entire arrangement.

and finally:

[ 0028 ] The housing 4 of the adapter 1 is connected with an attachment mechanism 20 for the camera 2 firmly. The attachment mechanism 20 covers several cross-shaped according to kind of a coordinate system arranged rails 21, 22, in those the camera 2 by means of carriages 25, 26 adjustably stored is to each other. The carriage guide permits thereby a shift to the camera 2 in three space axes and an adjustment of the objective 23 of the camera 2 regarding the eyepiece 7 of the adapter 1. The attachment mechanism ensures thereby also a use of the adapter 1 at different cameras, which with the help of the attachment mechanism 22 is easily adjustable. The carriages 25, 26 know with the help of a fine thread impulse, whose set screw 29 cooperates with a thread admission, on which intended final position for the camera 2 are driven. The thread impulse has a high-speed shifting mechanism in order to start the intended final position roughly however fast and to finely adjust afterwards the camera position with the set screw 29. The main guidance of the carriage are manufactured from 12 mm up to 16 mm thick carbon pipes, the rail guidance preferably consist of light alloy. After the adjustment the camera 2 can be fixed by establishment of the carriages 25, 26 by means of elbow levers 30. [ 0029 ] The adapter 1 can be attached in such a way before each camera 2 with focal lengths within the middle Tele range easily. The sharpness of the camera is placed thereby on infinite whereby without further optical aids such as close lenses or such a fast connection of the adapter and photographic photographs with Filmlook are possible. The back projection lens 10 is taken up in a container 16, which consists of a badly heat conducting plastic material. Also the container 16kann thereby a ring its, which covers at least the layer of wax between the two flat-convex lens parts, or as in the available remark example shown with larger axial overall length manufactured its and also the field lens 5 to itself take up. The container 16 with the back projection lens 10 is solvable in the pit 9 of the Tubus housing 4 taken up, whereby the back projection lens is if necessary exchangeable 10. In this way on the one hand a thermic protection for the back projection lens 10 in the housing 4 heat sensitive due to their wax content is created and made possible on the other hand an exchangeability to cleaning purposes of the projection lens or for removing damaged lenses. For the change other lenses can to the back projection lens with different characteristics due to deviating layer thickness light-faithful-end of the layer of wax or the wax mixtures of the operator in a magazine carry. [ 0030 ] Between the projection lens 10 and/or the container and the field lens 5 a magazine for filter 8 is neighbouring the objective 3 intended 16 with the projection lens taken up to it 10 in the pit 9 of the Tubus housing 4, which are applicable as required into the optical way. [ 0031 ] Fig. 2 shows the optical way 17 in the adapter 1, whereby one behind the other the back projection lens 10, which field lens 5, a 45[deg.]-Schmidt-Prisma 6 and an eyepiece 7 are arranged, which represent the end of the optical way to the image output 24 of the adapter 1. The back projection lens 10 consists of two equal flat-convex lens bodies 11, 11', which exhibit a diameter from 30 to 50 mm, in the remark example 40 mm. The lens bodies 11, 11' lie with their even surfaces 12, 12' parallel and limit a gap 14, in which a wax mixture 15 as if light-faithful-end substance with a layer thickness is taken up of less than 0.15 mm. During the production of the back projection lens the two flat-convex lens bodies 11, 11' in one are held the necessary layer thickness for corresponding distance to each other and the gap width with threads from india rubber or elastan is fixed. After filling in the paraffin/bee wax mixture on the vertices 27 of the curved exterior surfaces 13 of both lens bodies 11, 11' a cooling air flow is blown, which diverts over the edges of the lens bodies 11, 11'. In addition, the lens bodies 11, 11' consist in the remark example of clear glass can of plastic or other clear materials be manufactured. By intensified cooling of the lens centers 27 an even cooling of the even surfaces is made possible for 12, 12' of the lens bodies 11, 11' with the layer of wax 15 in the gap 14. In this way within five minutes an evenly cooled down and grainless layer of wax is received. This proceeding permits the training of also very thin even layers of wax, whereby the curvature of the lens and the focal length of the back projection lens 10 reached thereby can be adapted to the layer thickness, around the desired Streuungzu received. For the production of thin layers also aluminum foils can be expedient as aids. [ 0032 ] The picture of the back projection lens 10 is collected in the field lens 5 and led into the Schmidt prism 6. The Schmidt prism 6 is trained as 45[deg.]-Prisma, whereby the picture loss direction is employed in the angle [ alpha ] in relation to the direction of arrival in the optical way 17. According to the training of the prism 6 the angle of incidence 45[deg. amounts to ], in which the picture of the back projection lens 10 by the eyepiece 7 is adjusted spent opposite the image plane of the back projection lens. In the 45[deg.]-Schmidt-Prisma the picture of the back projection lens 10 at both thigh surfaces 18, and between them at the surface area 19 of the prism 6, is totally reflected 18' whereby with altogether three reflections an extension of the optical way is reached. With a focal length of the back projection lens 10 from 7 to 11 diopters, preferably 9 diopters, the lenses and the prism can be arranged very closely beabstandet by the extension of the optical way, so that altogether a very compact building method of the adapter results. DATA supplied from the DATA cousin esp@cenet - Worldwide

An interesting link (http://www.largeformatphotography.info/gg.html) discussing the various screens: Beattie, Boss, Linhof Super Screen.

Another link discussing wax types and application (http://www.greenspun.com/com/qtluong/photography/lf/gg.html).

<<<-- Originally posted by Jim Lafferty : An interesting link (http://www.largeformatphotography.info/gg.html) discussing the various screens: Beattie, Boss, Linhof Super Screen.

Another link discussing wax types and application (http://www.greenspun.com/com/qtluong/photography/lf/gg.html). -->>>

Dear Jim,

Excellent. Thank you very much.

May I ask which translation software you used to translate German? I am very keen to read some article in German.

Regards
Leigh

Will the Boss screen then make better results than an oscillirating GG???? Better contrast and no-grain!!!

http://www.stabitech.nl/Bosscreen.htm#top

What would the advantages be with an osc. GG compared to the grainless GG????

For experiment, I tried 10% beeswax in paraffin wax blend between two glass disks on a spinner. I think the image is better than the groundglass but for a spinner there needs to be a uniform thickness btween the two disks which I found impossible in my low tech home build environment to achieve.

Some of the waxdisk.jpg test images are near the bottom of the list at www.dvinfo.net/media/hart.

(Frame grabs from the waxdisk images print up nicely on an inkjet on photopaper. They look more like photographic prints.)

One image I did which is not on the list was with the disk stationary. There was a visible grain structure but it was softer and less defined than on the glass disk.

With the wax disk there were no sparkles or pinpoint highlights which under certain lighting conditions can look like film grain with the spinning glass disk.

May I ask which translation software you used to translate German?

I Babel Fished (http://www.google.com/language_tools?hl=en) it, at Google.

Will the Boss screen then make better results than an oscillirating GG???? Better contrast and no-grain!!!

That's the theory. A Bosscreen type glass is more difficult to produce, however :/

I'm starting to find material on how it's done now, and will endeavor a glass sometime in the coming week or two.

- jim

Bob,

Can you take us through the steps of your wax application process in detail? If you already have in another thread, my apologies -- just provide a link to your original post.

- jim

Renaissance Wax (http://www.tools-for-woodworking.com/index.asp?PageAction=VIEWPROD&ProdID=1304) looks like it has potential for saving time, cutting corners in the application process. It's a semi-firm micro-wax polish. I do not understand how it will hold up in the long-run, however.

I'm looking over sites that use heat guns to apply micro-wax to glass surfaces for painting -- the trick is getting it sandwiched between two pieces of glass without trapping air bubles in-between. I'm wondering: can you just C-clamp or vice the two pieces of glass together to force the air pockets to the glass's edge?

I know the production mode of Bosscreen:

The secret is a physical trick, which everyone knows.

First two glass plates are installed into the desired distance (e.g. narrow strips from aluminum foil on the left and on the right). Then the whole thing is heated up and dives perpendicularly into hot, liquid wax . The Wax sucks itself through the capillary effect upward.

Its easily with rectangular glasses. To make a round GG (like movietube) is more difficulty

Then the whole thing is heated up and dives perpendicularly into hot, liquid wax . The Wax sucks itself through the capillary effect upward.

So, you're saying you'd need the following:

1) A container which can be heated and which has a depth that exceeds the length/width of your glass

2) A heat source to melt the wax

3) A set of spacers that keep the two sheets of glass apart when dipped into the wax

To induce the capillary effect, you just dip the glass into the wax perpendicular to the wax surface? Do you submerge it entirely or just enough so that the wax begins to move up through the two sheets of glass?

Thanks for the info!

- jim

Jim that Renaissance wax stuff looks interesting. Has anyone tried this yet? Seems like it would be simple to spray, say, a UVFilter with this stuff to make a great "GG."

<<<-- Originally posted by Jim Lafferty : Do you submerge it entirely or just enough so that the wax begins to move up through the two sheets of glass? -->>>

Just enough so that the wax begins to move up.

I got this information from a former Bosscreen coworker.

He said, the glasses should be a little bit hotter than the the wax
(made with hot air) . And if the wax is between the glasses, you should leave it cooling as slowly as possible.

BTW: Bosscreen GG have many thicker wax layer than the Movietube.

Ok just curious:

For those of you who have used a bosscreen before, can you see through the screen? I'm just curious because I'm interested in the "Renaissance wax" but do not know, since it is clear apparently, if it will work. Help?

Look for Bosscreen images on eBay -- they're frosted in appearance.

I picked up some cheap, low temp micro-wax today -- normally used to enhance the longevity of paints -- at a Utrecht art supply shop in NYC. I'll be experimenting with it soon.

Aside from the convection/capillary application, I'm going to try using a hairdryer (basically a cheap heat gun) to apply this wax and see how far I can get.

Next on the shopping list is a glass cutter :)

- jim

Aron,
No, you can not see through the bosscreen. You see only lights, not details. Is look like sand blow glass or milk glass

Here is a good wai to test the GG grain:

Use a still camera 50mm lens, or better 35mm (i think everyone have those). Hold the GG to the sky (or a lamp) and look through the lens (lens camera mount side in a distance ~ 30mm to the GG).

Now you can see all the details your camera also will see.

Aaron and Jim
I have something similar to that Renaissance wax called Conservators Wax that I picked up from a wood working store here in toronto. It comes in a semi-solidified form. Its about the consistancy of mayonaise or shortening.
While this made it easy to squeeze between two sheets of glass separated by something thin like tin foil or something, my concern was that any kind of heat inside the casing would cause the wax to melt and drip away.
But I did find it easier to work with than the melted solid MC wax.

Jon

Yeah, this is the trade-off/area of worry -- what may be easier to apply may not hold up to the test of time and production wear. That said, people seem to worry about their Bosscreens, but I can't imagine leaving my camera in frigid cold or blitering heat for any extensive period of time - wax or no.

I'm in need of more UV filters -- all mine are in various stages of experimental grind, or broken :D When I get over to B&H this week, I'll start experimenting with the glass and post my results if they prove favorable. If not, I'll be ordering MC wax in solid form and take it from there.

The capillary idea is tempting, but sounds to be quite the elaborate trick to reproduce in a conventional kitchen. I'm thinking of reaching out to a senior student or TA at a local university -- someone in the physics or chemistry dep't who I can quiz about fluid dynamics and any ideas they my have...

Anyone heard from Agus lately? To think, he kicked this off with a glue gun and sandpaper, and look how far we've come!

- jim

Sound interesting Johnny. I think I'm going to go down to the store and get myself a filter and some similar wax to experiment with today. I'll have to see if I can find something similar to what you found.

I'm personally not very worried about the Rennaisance Wax melting and/or loosing its form. The description seems to suggest that this is some pretty darn intense stuff (museum coating after all). Problem is I don't have any.

Hey guys!

Been a while since I last posted anything.

I'm glad to see there's still some experimenting with wax going on.

I just wanted to mention that my last few wax sandwiches were made from very cheap glass from picture frames. I picked up some square ones and some round ones (99 cents each, and they were a good diameter - 52mm) at a nearby Hobby Lobby.

What Rai mentioned about submerging the whole sandwich (2 pieces of glass w/ spacers inbetween) is exactly how I made mine. Keep the heat going long enough while it is submerged to give the little bubbles time to squeeze up and out from between the glass. Also, if you are using tape, try to stay away from any paper type stuff like scotch tape because bubbles will come from it and go between the glass.

One more thing: I never let the wax harden _completely_ before removing the glass. I let it get to the soft/mushy state and then take it out. At this point you don't have to worry about bubbles, and it is a whole lot easier than trying to cut it from completely hardened wax, at which point you'd have to worry about cracking the glass.

Hope this helps! Thanks for letting the rest of us know your progress, guys!

WB Frank. Care to share some footage with your adapter for others here to see? Also, what wax type did you use and which source did you use to purchase it?

Thanks,

- jim

Thanks Jim!

I got my microcrystalline wax sample from Strahl & Pitsch:
http://www.spwax.com

I posted some still frames a while back, but it is now sortof a requirement (and understandably) to post uncompressed motion footage.

Within the next week or so I will get some footage and host it here from my work computer. We're on a T1. Not the fastest thing in the world, but it should work fairly well if my computer and web server (free from analogx.com) can handle it.

Great! Thanks, Frank!

Questions for Frank, or anyone with good wax experience:

1) How close are the two plates of glass to be placed? 1a) Did you just run aluminum foil at its edges in one layer density for a spacer, or...?

2) How did you keep your setup level, and the glass consequently perpendicular? Could you be very detailed in your setup process, please?

3) How long do you let the wax heat up? In other words, once it has melted and moves up to the top of the glass, do you keep the oven on and let it sit for some time, and if so -- what's the approximate time for doing so?

4) Cooling -- just let it cool on its own slowly, or do you chill it/blow it with cool air?

I got my S&P wax recently and am playing with it today -- playing in a very non-committed fashion. I'm shaving wax into small bits with a cheese grater, placing these bits ontop of a UV filter, and then placing this inside an aluminum foil take-out container from a local restaurant.

Heating it in a toaster oven to 200 degrees, the wax melts to a clear liquid in about 3 minutes.

The first run of this had some solids (salt/grit/hair) that I used a pencil tip to remove from the wax -- it also had some spots where the wax didn't take to the glass' surface. I'm now re-applying more wax and letting it cool on its own time.

This go is just to experiment quickly to see what sort of tolerances there are (and aren't) with the wax, the glass (Hoya UV filters), and other random variables. All told it's a far less forgiving endeavor than aluminum oxide :D

- jim

Hi Jim!

Sorry about the lack of video footage, but I have not forgotten!

Anyhow, to answer your questions:


1) I used two thin strips of standard aluminum foil (not the heavy-duty stuff) folded over, making sure there were no creases/wrinkles in them.

2) I wasn't too precise in this area. As far as keeping the glass sandwich vertical (so bubbles would escape), I just propped the glass against a makeshift aluminum foil arm that was attached to the top of the aluminum cup.

3) Here I didn't really use any specific time. I just watched the surface of the wax above the glass (which should be completely submerged in the wax) and waited until there were no more little bubbles floating up. Then I gave it some more time after that to be sure before turning the heat off.

4) I just let the wax cool on its own. However, I didn't let it harden completely. Once it was in a soft/mushy state, I began to clean the wax away from the outside.

Hope this helps!

Tried my first somewhat serious attampt at making a wax glass yesterday, with mixed results. The oven still works, at least :D

The glass I've got as a result has a few bubbles, but the most notable problem with it is that I used a pair of tongs to dip the glass into the wax -- where the pressure of the tongs was placed on the glass' surface is a perceptible ring in the wax. So...

Tomorrow I'm going to change the setup and have another go at this. I plan on covering the exterior of the glass with Scotch tape, leaving tabs of tape running past the edge of the glass, so that when the wax hardens, I'll merely need to pull the tape of the glass and the wax will come with it.

Also, instead of using tongs, I'll be making a small wire device similar to the egg dippers you'd use as a kid for dying eggs -- this way I plan on submerging the entire glass, hanging the "dipper" over the edge of the melting pot, and waiting until I feel the bubbles have all risen to the top.

I can't seem to induce the capillary action. I'm using round pieces of glass because the few glass companies I've called have said they will not cut circular glass to my required dimensions (49mm). Resorting to submerging the glass entirely seems to be my best bet.

Tip on using aluminum foil spacers -- fold the aluminum over twice, and use a rolling pin to flatten it perfectly.

Tip on cleaning the glass -- use a razor blade and de-natured alcohol.

- jim

Excellent tips, Jim! Thanks for sharing your experience with us!

Good idea about the tape. Make sure you keep the glass submerged for a while, though. I found that when using scotch tape, tiny bubbles would come out of it and seep through the glass. So it may need to sit for a while.

Also, I tried electrical tape, and although it didn't melt, it didn't adhere very well to the glass when submerged.

Good idea about the egg-dipper device!

A thought came to mind. Maybe someone can think of a way to execute it.

It may be possible to place the groundglass in a shallow holder in a larger disk which is itself on a speed controllable drive, rotate the assembly, heat it up with a gluegun or hairdrier, spray or simply melt shaved wax onto the glass, then spin the excess off with higher rpm, blowing the wax runs across the radius paths with the gluegun, then withdraw the gluegun slowly enough allow the thing to cool gently.

This might yield a wax coat of even thickness without need of coverplate.

That's a good idea, Bob! Seems like that would help with the bubble problem we run into.

However, one of the reasons I am wanting to keep the wax inbetween two pieces of glass is to keep the wax clean. That would be a problem if it where just a wax coating on glass. Just something to consider.

But maybe you can have the second glass cover be non-contact (ie. raised from the wax surface).

Hrm... wonder what I could use for a slow rpm drive...

It's a good idea, but it seems a bit too complex for the homegrown stuff.

I may have time later today or tomorrow to give my microwax another go -- I'll let you know how things went.

- jim

I got the best wax/glass sandwich a couple of days ago - no bubbles in the view at all! However, the next day when I wanted to go out and shoot some stuff it had done something funny. The wax looked as if it pulled away from one side of the glass. It wasn't stored in a hot location or anything. Not sure at all why it did that. It didn't effect the image that much, until you pointed it at something bright.

Has this happened to anyone else?