kaushik thank you for your help. I will try the changes.

The PCX lenses are fairly cheap:
http://www.surplusshed.com/pages/item/l2119.html

Now that I have a working assembly, I can do a good comparison between the bosscreen and the ground glass. I will post the results soon.

I also had an idea the other day about an alternative GG. I was reading the thread about microcrystalline wax, and I wondered if some other material could be sandwiched between filters to get that effect. My eyes fell upon a bottle of Elmer's glue, and I grabbed two "junk" 50mm sky filters and proceeded to put a glob between them and squeezed out any bubbles and as much glue as I could. The funny thing is that it works pretty well, with no apperance of grain. I lost several stops, though, but the glue on the outer rim appears to have sealed the glue between the filters to keep it from drying. I will add it to my comparison.

Nice idea on the glue Michael. I had an idea to use some of that non-reflective frame glass. The two I tried, however, were too transparant to work.

image size on GG ?
 

Are people using a 35mm movie camera image size on the GG, ( 4 perf 35mm size ) or a full 35mm still image size ( 35mm vista vision, 8 perf ) ?

I think the mini35 product does the movie camera size, but is that what guys using 35mm still lens's actually want?

I see a dilemma here.

-Les

I don´t use a stacic adapter, i use vibration (micro circulation), but 35mm movie frame size or 35mm still image size, that is the same question. If you have original movie camera lenses, you will use movie size. These lenses are very, very expensive and in addition, very bright (mostly 1:1,2 to 1:1,4). If you have the $ for movie lenses, you have it also for use a P+S Adapter. But DOF is not only a question of picture size. Remember: More bright (more open iris) = more DOF. But, more framesize = more DOF too. So if you use a still camera lense with and full size frame, for example 1:2,2 instead of a 1:1,2 lense with movie size, the DOF will the same. The other way is, you can still camera size zoom in, or you can use each size between them, so you can play with different DOF. (But if you zoom, you can see more grid on a STACIC GG and you have a problem with wide angle)

Thanks Rai,
I am going to build a micro circulation adapter for my JVC HD10, I don't think a static screen will ever work with my camera.
I think I'll make it big enough for an 8 perf frame.
-Les

Looking for some advice...

I'm building a static adapter out of 55mm filter rings. I'm looking for a condenser lens that will fit inside the the 55mm tube I've created. I'm curious to know what you guys think about any of the 50mm lenses listed on the link below. Or do you have another suggestion for where to find a 50-54mm condenser?


http://www.edmundoptics.com/onlineca...=2032&search=1

I've finally finished reading this HUGE thread, and I've started building an adapter for the Xl1s. I heard Dino was building an adapter, but he seems to have disappeared lately. Anyone else trying to figure this thing out for the xl1s? Id love to hear what others have had trouble with and solutions they have found.


I've made some progress, but I have a few problems/questions, maybe someone can give me some suggestions.

1. Condensor lenses:
Im having hot spot problems, and want to add a condensor to my setup to see if that will fix the problem. Where and what to buy? I dont know enough about optics to understand what exactly I need, or even where to get it. At the moment, Im working with 2" pvc pipe and all my filter rings are 52mm. The focal length of my 35mm lens is 50mm. suggestions? links? How are you mounting them on the inside of your adapter? Whatever happened to the idea of putting one on both sides of the gg, has anyone tried that yet?

2. Ground Glass:
At the moment, Im simply using Hollywood frost gel as a substitute ground glass element, as it is much cheaper and faster than actually grinding my own glass, and works pretty decently. although I will be upgrading to reall gg in a later version of my adapter. What is the latest consensus on best option for GG element? I've seen posts about buying ground glass already made, seen about DIY gg, and I've seen posts about alternatives. Whats the latest scoop?

3. Relay lens:
For those of you who own an xl1 or xl1s, you know that its simply not practical to try to add an adapter to the end of the any of the lenses. Their just too long. I currently own a manual 16x and a manual 14x and neither of them will to the job i need it to. So, ive decided to build some sort of relay lense to capture the correctly sized image on the GG (which I havent had much success with yet). I've tried a 1' 16mm motion lens, but it had a very strange effect. I could focus between 1 and 3 inches from the lense (not film plane) but that was it. no more range. even at infinity, it was 3 inches away. So, I was looking at a rectangle (roughly) about 2mm across. definately not big enough, although it was conveniant that it focused so close. I dont know enough about 16mm lenses to keep trying them, so i've decided to try a ultra wide 35mm still lens and see how that would do. The reason i think it would work is because even though it is going to have a major tele effect because of the 7x magnification, its an ultra wide, so I can focus relatively close, and it just might be wide enough to get the 36x24mm image. If anyone has any suggestions, feel free. i really want to get this adapter in a more advanced prototype stage, but im stuck on more than one issue, and dont know where to go.

Stephen Birdsong
by the way, since there are a few threads that have nearly 100 pages of posts, wouldnt it be beneficial to be able to search a single thread, rather than just a category? Who could we recommend that to?

Stephen,
jears ago, i made three kinds of working adapters. One of the camaras it works with, was the Canon L1 / L2. As you know, it is the model before XL1 and had similarly changeable lenses (the only optical diffents are focal length, because: L1/L2 = 1/2" CCD, XL1 = 1/3"CCD). So i think it work also with the XL1. Next week i will test it.
One of my adapters come with static GG (i tested 100s of them, some selfmade all the way are posted here, but no one was satisfyingly) . Finally i found a manufacturer and we developed together a high quality GG (See my posts on Microcrystalline Wax). But unfortunately, another company have a patent on this way. The next two models have moving GG (micro circulation). Moving GG improves the picture always, also if you use the best GG. All modells hase aspheric lenses on both sides of the gg (each with flat side face to the GG). My first and most inexpensive way to focus on the GG with the L1/L2 was that: Apart a old, not working camcorder with smal lenses (with macro) make a connector and took it in place of original Canon lenses.
All my models are supported with a cameraplate, so there is no load on the lenses. (Without this you can destroy your camara body.
Next days, i will post a link to detail informations, with parts, pictures and sources of supply, etc.

Has anyone acid-etched their glass successfully?

Based on James Ball's advice, I purchased acid etching cream. I've copied his directions and looked over them carefully, but haven't had the time to set them to use (I'm in the middle of a big move at the moment...)

I'm writing wondering if James or anyone for that matter has had success with his method, or if the lack of updates is evidence of an idea gone wrong?

Thanks,

- jim

Rai, have you considered microlens array focus screen as GG?

It is totally grainless even to my hi-res HDV camera.

Please see here for the detailed discussion and pitfalls:

microlens focus screen discussion

agus35
 

Hi everyone I would like to ask for some help

I am looking for a part for my agus 35. I would like to find a way
to adjust the distance between the slr lens and the ground glass the agus 35 is made with 52mm filter rings. I found some things on a telescope site that almost work this would also help with my anamorphic lens ------- thanks in advance

Alex,
>...have you considered microlens array focus screen as GG?
>It is totally grainless even to my hi-res HDV camera.

You say it is totally grainless. Did you really test that? That can not be. It does not exist any grainless GG. A GG must even have grain, but it is just a way you look at them. A GG for a still camera is make for human eyes, and not for HDTV. You cant see any grain, but the cam see it. And microlenses are a bad way, because they have a repetition stuktur, as a lattice, and with a videocam it will produce moree´. Test it out, you will see, but if you find it work nevertheless, let me know details...

Richard.

Your enquiry says Agus35 so I presume your device is a spinner. I used a plate in the enclosure with three holes arranged in a triangle layout. Three threaded pillars face backwards and fit these holes. On those pillars are small hard coil springs. On top of each is a washer. (I used brass because it is easier to turn the adjustment by hand.) The plate goes on top of the washers. More washers go on top of the plate. A nut pulls down onto each washer. This gives adjustment in two axes relative to the lens centerline and distance adjustment from the lens. The pillar layout looks thus ---

----O-----Disc Centre-----O----




---------------O---------------

If your device is the Aldu version made of stacks of adaptor rings leading to a fixed groundglass, then I don't have an answer except perhaps to keep taking rings out or adding them until your backfocus is close, then taking one out, then cheating a half turn on each segment to lengthen until backfocus is correct, measuring the total of the added length, then dressing the contact face of each ring including the ring you took out, shorter so they all together make that length.

The other option is to make thin shims out of food foil which fit the screw hole pattern of your SLR lens mount and spacing the mount away from the focal plane with them until the backfocus is correct. You may be able to get some adjustment of your fixed groundglass inside its holder by the same means.

aldu 35
 

thanks bob your right .I was talking about aldu 35 . the problem is the filter spacer won,t get me to the adjustment I need. close but not a sharp focus


something like this http://www.harlequinastronomics.com/otheradapters.html

Rai, regarding microlens GG you wrote:

> You say it is totally grainless. Did you really test that?

Tested and re-tested.

Seems that because there's about 2 million micro lenses in the 24x36mm field, each lens element is therefore too small for even HD cam to resolve - but yet they do the job as a great ground glass with very little loss of light, too.

See here:

http://www.dvinfo.net/conf/showthread.php?s=&threadid=22456&perpage=15&pagenumber=4

Alex,
>Seems that because there's about 2 million micro lenses in the 24x36mm field, each lens element is therefore too small for even HD cam to resolve...

This does not convince me yet, because 2 million micro lenses on 24x36mm. That´s 2315 lenses each mm², but only 48/mm (on a string).
24x36 is a 3:2 format. A camcorder works with 4:3 or 16:9. Therefore a 16:9 picture is max. 24x13,5mm. If your HD cam works with 720 lines, the cam "see" 53 lines/mm, but there only 48 mirco lenses/mm. That cannot be invisible.
In order to make it invisible, it would have 2 ore more lenses each line. With a 720 line HD cam your GG would have 106 or more lenses on a 1 mm string. That means 11236 each mm² or approx.. 10 million for the GG. With a 1080 line HD cam your GG would have 160 lenses on 1 mm = 25600 each mm² or approx.. 22 million for the GG.
I had tested many GG, also Minolta, also with micro lenses, but i never found a grainless one.
Tell me the part no and i will test your GG on a optical bank and with a HD Cam, because i am open for all working 35mm parts

Rai, part number and a link to the store that sells it is in the thread I referred you too. See my previous post.

Regarding your doubts: I see what I see. Every other GG produces grain. Minolta does not. Period.

Alex, I believe you, but i would also like to see it. In the thread, they talk about minolt GG Type G and Type C. Which exact you mean?

Could anyone post a sample pic of this ground glass from Minolta?
How do you manage the problem with the markings?

minolta screen
 

hi everyone this is a link from the other thread

http://www.bhphotovideo.com/bnh/con...=minolta+screen

Posting a still image from a GG setup proves little. A slow image pan with parts of the image out of focus is the test I'd want to see. You see, the grain will only show up as being static if there is motion.
A media9 video of 8mbps would let you see it.
-Les

Les is right.
Also the link is useless.

Richard.

Sorry I cannot be of any help. In setting up are you attempting to work both the camcorder to groundglass focus and groundglass to SLR lens backfocus at the same time.

The only other suggestion I can make is that you make up a target, whiteboard marker lines on the groundglass to intially get that focus at optimum, then direct your SLR lens to a cardboard target, (beer carton or whatever with sharp printing on it) at a measured distance from the groundglass, set your SLR lens by the focus numbers on the lens barrel to the same, then adjust the space between the SLR lens and the groundglass until you get your sharpest image. If you measure from your groundglass to the lens mount face, it should now be in the ballpark of 46.7mm for Nikon. What the others are I don't know.

You've probably done all this stuff already but there it is anyway. Good luck.

Rai, here's the link to the GG. It's Maxxum type G.

http://www.bhphotovideo.com/bnh/cont...=173377&is=REG

The picture does not show any markings but unfortunately they are there. Plus, there's a very faint but still visible small circle right in the middle. Markings appear carved on the flat side while, while circle is on the curved side. Makes this lens unusable.

GG Minolta Type G, Maxxum: I found a GG with the same smal grain, but without "circles" and without marks. Read this:

Alex, thanks, but it is so: I have tested this GG type last year. And it is, like i said it before, this GG is not grainless. Okay, it is one of the best, and you must exact focus on it to see the grain. But than most (PAL version) cams see the grain. There are also some circles on it (not only one, like you say) but this is because this GG has a fresnel lens inside.

My company work with 35mm solutions since many years, so we have tested every GG we found. For my requirements this Minolta GG with this grain was too bad. Maybe it work with NTSC. But i can say we have a GG with exact the same grain like this Minolta Type G. The different is, it is without fresnel(=circles) and without marks.

So, what are the results?
What GG is the correct one?
Do they have Fresnell or Microlens? They are not the same.

Juan, the Minota GG Type G is a sandwich Type: fresnel + GG + (one-side-flat)lens. The fresnel lens kill the hot spot, but produce also the circles. And that´s why it in not unusable.
If the GG itself came with microlens or not, i dont know.

We use a optical bank to test groundglasses. A (still photo) pojektor with a high def testpicture on one side, the GG in the middle, and a microscope on the other side. For a good GG, there are 4 importantly points: low light loss, small grid, hight scharpness, and very even (no clouds or shadows).

So you still recommend the Wax/Parafin compound way?

Brett.

Is your email address as posted still current. I have a comparison test pattern split-image .jpg of the Agus35 (5 micron oharadisk)into PD150 plus a .jpg of the 5 micron machine-finished oharadisk while stationary which might offer some comparison with the other hand-finished 5 micron Aldu35 versions. I'm still using the SW5042 lens set which is inferior to the setups others here are using.

ADDENDUM TO THIS POST:

The comparison image is at www.dvinfo.net/media/hart and titled "oharcomp.jpg" There is also another image with the 5 micron AO dressed disk stationary, ie., fixed groundglass titled "oharatp1.jpg".

New images
 

I finally got to test my adapter in the field, so to speak, as I helped a friend finish his installation of a spiral staircase. I used a bosscreen in my adapter that day. It seems to be the best solution so far, but I have a friend who works with glass who will see about grinding a finer grain in the 5 micron GG I have.

The images were captured directly from tape to memory stick on my video deck (so they were compressed), with a little gamma correction done in Photoshop.

I am seeing some color bleeding around the edges of bright objects (purple especially), but I'm not entirely sure what causes it. I am working to take care of the light leaks (there are some pretty big holes) and figuring out a design that will allow me to remove some of the glass elements from the optical path.

I will post a short video clip to accompany the shots soon.

http://www.edwardflinch.com/images/DSC00003.JPG
http://www.edwardflinch.com/images/DSC00004.JPG
http://www.edwardflinch.com/images/DSC00007.JPG
http://www.edwardflinch.com/images/DSC00011.JPG
http://www.edwardflinch.com/images/DSC00016.JPG
http://www.edwardflinch.com/images/DSC00017.JPG
http://www.edwardflinch.com/images/DSC00018.JPG
http://www.edwardflinch.com/images/DSC00019.JPG

Michael,

The images look really good.

The purple fringing may have less to do with the adapter's optics than with the DV imaging process itself. I may not be remembering this correctly; but I believe DV will sample luminance, red/cyan and blue/yellow and then calculate the values for green/magenta. It also samples the luminance spatially more frequently than the two colors. So when the luminance shifts markedly from one line to the next, and it's still pretending the sampled colors from the prior sampled line line are unchanged, the green/magenta value ends up being inaccurate. This leads to the fringing.

So you may be getting that fringing even without the adapter.

<<<-- Originally posted by Kaushik Shridharani : Michael,

The images look really good.

The purple fringing may have less to do with the adapter's optics than with the DV imaging process itself. I may not be remembering this correctly; but I believe DV will sample luminance, red/cyan and blue/yellow and then calculate the values for green/magenta. It also samples the luminance spatially more frequently than the two colors. So when the luminance shifts markedly from one line to the next, and it's still pretending the sampled colors from the prior sampled line line are unchanged, the green/magenta value ends up being inaccurate. This leads to the fringing.

So you may be getting that fringing even without the adapter. -->>>

I sure hope not, but I don't think that's the case at all. I've had the camera for over 2 years and I've never noticed fringing of any colors. It's also a GL2, which I believe samples the green CCD more than the red and blue CCDs.

Michael very good images. What lens are you using? And, can you list the steps of how your adapter is put together. Thanks.

9 out of 10 times color bleed problems like the ones in your pictures are due to "chroma aberation".

Your using some form of a diopter (ie. plano convex lens, close up lens, etc.) arent you. Most likely that diopter is a inexpensive/single element lens. These diopters will have color bleeding problems.

To varify if this is the problem look at your footage again. Watch the section in the video that you noticed the problem. When the camera pans over and the object moves from the corner of the frame to the center - does it still have the color bleeding problem. In other words chroma aberration is only noticeable at the edge of the frame.

To fix it get a two element (or more) diopter (also known as a achromatic diopter).

As always for more info on this subject and many others do a search on the key words, "Achromat", "aberation" etc because this has already been explained in detail.

-Brett Erskine
www.CinematographerReels.com

Ernest:
The lens I'm using is a Nikon 50mm 1.4. You can see the adapter on this page:
http://www.edwardflinch.com/images/mini35.htm

Brett:
The dipoter I'm using is a +7 Century Optics Acromatic Diopter. A $200 piece of glass, it's the most expensive part of the setup, so I certainly hope it's not the source of the trouble.

I believe that the problem lies in the internal reflections within the setup. On some occasions I noticed a ghosting effect because of it. I will do more tests.

Maybe it's the condenser lens doing the chromatic aberrations. I would paint all the non-glass in your setup matte black to minimize flare.
There are ways to correct some chromatic aberrations in software. Panavision does this.
-Les

Les-
Interesting. I didnt know Panavision did that. Send me a link if you have it.

Mike-
Yeah that Century its great glass. Im with you. I highly doubt its causing the problem. I agree with everything Les said. Check it out. Pull the condenser out of the system and try it again. Also you can hand hold the condenser over say a newspaper and look for chroma aberation at the edge of the condenser.

Brett Erskine

The mentioned it when they talked about the anamorphic lens, if I remember correctly. It may be just a channel resize, or maybe a bit more fancy, like an affine warp of selected chroma ranges.
Could be done as a post process.
-Les

that is very silly to put a processor to correct thing after you make them bad using poor elements.
At surplusshed you will find a 52mm achromat for 5$.
it works very well for my vx2000 and you can even use two of them (one for the condenser and one for the macro)