I hate to be the bringer of bad new this time but Filip your design wont do what you want it to do. In fact it ends up having the same effect as if you had done nothing at all. Do a test with a mirror, 35mm lens a white piece of paper. In fact even if it did you still would have a problem with having the whole image in focus top to bottom. You would have to have your camera at 45 degrees so that that image plane is flat to the camera's CCD.

The rest of the last few designs ideas only do a partial correction -leaving you rendering your footage in the end anyways.

One front projection idea I had was to use a 35mm lens > forward slainted 45 degree two way mirror > white grainless projection surface > directly below the first two way mirror theres another mirror. This one is a regular one way mirror mounted at a 45mm rearward slating position > video camera.

It has two problems though. It doesnt flip the image L to R and wastes too much light. It does however makes alot of other things possible (flips the image right side up, doesnt need a condenser or ground glass, is grainless, possibly no need for a diopter either)

Personally Im still going the GG/Condenser route and simply rotating the monitor and render in post. The reasons: making my adapter much shorter, Im shooting with anamorphics, easier for steadicam work, etc.

-Brett Erskine

<<<-- Originally posted by Brett Erskine:
In fact even if it did you still would have a problem with having the whole image in focus top to bottom. -->>>

i don't understand this. why image will be out of focus? isn't it just a periscope system? if two mirrors are parrarel to each other, in my opinion (i'm not a periscopist:))) the image will be in focus all the time. i will of course make a test with a mirror and white surface, but as i remember my games with a periscope, there is no need to correct anything, everything is in focus...

oupsss...

ok. now i can see what you wroted... you are talking that the image IN THE CAMERA will not be in focus if camera itself is looking on 45 angle white screen. you are right. i just thought about the first part - mirror--->white screen parallel system. sorry, i was too fast...

<<<-You would have to have your camera at 45 degrees so that that image plane is flat to the camera's CCD. ->>>

correct.

<<<- One front projection idea I had was to use a 35mm lens > forward slainted 45 degree two way mirror > white grainless projection surface > directly below the first two way mirror theres another mirror. This one is a regular one way mirror mounted at a 45mm rearward slating position > video camera. ->>>

can you ascii this? i have problems with understanding the whole construction.

THANK YOU

I just receive my roller bearing.
the hole is 50mm dia and the external ring is just 65mm dia.
the thickness is 7mm
I will use a 50mm dia. condenser lens mounted inside with the flat side grounded with 1000 grit alu. oxide (still waiting for it) so i should not need an additional GG.
Then i got the choice to rotate it or not.
the roller bearing cost 30$, so it doesn't add to much to the price of it.
I think i will make a flange on the roller in Delrin (kind of white plastic , easy to use, very used in mechanics)
The flange will be a kind of ring, to accept inside the gg-lens and outside the way have the motor rotating it (probably a simple plastic belt)
Ideally everything clips together so there should be no need for soldering or glueing anything

Francois,

is it possible to pass somehow (somewhere) some jpgs of your roller bearing etc.
it will be nice to see that!

thanks

filip

I've been following this and the agus topics very closely for past few weeks. And you may have noticed I'm new here. One major questions for you guys is, do any of you( and mainly to those of you that live in the UK) know where to buy aluminium oxide grit in the UK? I can only seem to find it attached to paper, and even then, it's not 1000. It's only about 250, which from what I have read , would be far to coarse.

Filip-
Send me your email and I'll send you the drawing of the design. In the mean time...
A B C
35mm Lens> // ||
// ||
\\ <video camera (E)
\\
D

One front projection idea I had was to use a 35mm lens (A) > forward slainted 45 degree two way mirror (B) > white grainless projection surface (C) > directly below the first two way mirror theres another mirror. This one is a regular one way mirror mounted at a 45mm rearward slating position (D) > video camera (E).

damn that didnt line up too good. Oh well. Send the email.

I found a place nearby that sells a Hoya 58mm Closeup Filter Set, that comes with 3 lenses. I think the lenses are +1, +2 & +4 or something. Anyhow, I have heard the hoya filters mentioned in some of you guys' mini35 devices, so I wanted to get some feedback before I purchase them. I well know that an achromatic/2 element filter would be better as far as the color separation goes, but (and maybe the guys out there with a Canon GL2 can tell me) would this kit be acceptable? Also, what about when they are stacked? Does this introduce vignetting or cause chromatic abbheration to really show up?

Thanks for your help!

code and /code
 

by the way - if you wrap up your ascii art in a
code tag (in square brackets) and end it with a /code tag in square brackets, things should line up as you expect. (testing now...)

See this page http://www.dvinfo.net/conf/misc.php?action=bbcode for some info on codes.

My optics knowledge comes from what little I remember of grade 10 science; Can't a dove prism be used to properly orient the image?
http://electron9.phys.utk.edu/optics421/modules/m2/prisms.htm

Yes you are right , there are many prism that could help to have the picture in the correct position.
Unfortunately we are not at the stage where we are looking on how we could do thing (theory), but more in a stage on how we can build it. and unfortunately prism you can find easily and affordably are usually to small for a 24x36mm picture.
If you know a good source for big cheap prism...

uhhh....people, a X/Y switchable LCD is only about $120, and its easier & better image quality, I dont know why you guys are trying so hard with prisms & mirrors for this magic trick when an LCD is the best answer.

gas

I agree
 

I use lcd monitor is just fine
Prism éand other hare to difficult to calibrate for homemade kit

ans light loss to

i think movietube
www.movietube.com/
dont use prisme but only aadiitional viewier

<<<-- Originally posted by John Gaspain : uhhh....people, a X/Y switchable LCD is only about $120, and its easier & better image quality, I dont know why you guys are trying so hard with prisms & mirrors for this magic trick when an LCD is the best answer.

gas -->>>


John,
Where can someone find this X/Y switchable LCD monitor for $120? Can you or someone provide a link to a source?

To all,

The LCD monitor is the best solution for dealing with the inverted image (for now) but I believe an optical solution is out there. Please don't stop the flow of creative ideas. It's my guess that many of them are untested and so they shouldn't be so quickly and easily dismissed. I agree that it would be fool hardy to run out and buy a $500 prism just to test a hunch. (my pockets aren't that deep) But there's bound to be someone out there who happens to have access to one. What we need is more testing and more sharing of results. It would be nice to know exactly how many functioning adapters are out there and what those builders did to correct the common issues with this type of adapter. Hotspotting, vignetting, inverted image etc. I'm new to this forum so I'm not too savy on what is possible but could we create a survey to see who's building what. It would be nice to know which cameras are being used.
WIBN, Joe

on another note:
Has anyone ordered 5 micron grit from www.gotgrit.com yet? I just ordered some two days ago. I now believe Frank was originally right about the gray 1000 grit AO from Rock Shed. I too am noticing some varient scratches that could only be caused by a large particle. (I was being careful, following my own sugestions posted here) I don't think it is anything against Rock Shed but I now understand that the blue AO (I think that is what they call the gray colored stuff) is not consistant enough for optical work and that you need white AO. Got Grit is entirely based on telescope making supplies and only deals in white AO. After thinking about it for a minute, it makes sense that someone wanting to polish stones in an agitator isn't going to be as picky about how refined their grit is. So from here on, I think we should advise all to use only white AO for glass grinding. I'm still looking for a source for 3 micron AO. anybody have a source?

lcd
 

the link
http://www.portablemp3playerstore.com/stuff_you_need/special/th-5688.htm

120$ 5"6 TFT monitor

I find in europe 7" monitor for 120€

I dont think stop creativiti
but for me te mini35 it to make movie is not for losing 2 year to bild up .
If some can do whit prism etc etc...
But me for now i already use for real.

PS i even use whit Super8 camera and videotap is fantastic....

Link for AO grit 1000 in canada (only french english page is not working
http://www.aei.ca/~astronat/equinox/listeprix.htm

I'll second that loudly -- care to show us a link John? Please make sure it isn't 7" -- I'm looking for something in the 3-4" range...

- jim

Paolo Rudelli
 

i think movietube
www.movietube.com/
dont use prisme but only aadiitional viewier

I have take a look at this movi tube, and I am almost shure that they use a 45 degre prism.

Alain

Alain,

I'm working on your adapter for HD cam (see here) and have a question:

- Have you tried to use Nikon focusing screen as Ground Glass?

I found that the focusing screen (I use type D, plain matte) has a very visible grain. Do you think the grain can be eliminated by further refining the matte with the aluminum oxide powder? (I do have some on order, but they haven't shipped it yet.)

Thanks!

Alex Raskin
 

I haven't seen this focusing screen but I am pretty shure you can.

All the focusing screen I have seen even Hassel blad are not fine enought for that.

Alain

Nikon
 

Alex ,

i work whit a Nikon type D focusing screen

http://www.sinedie.org/lickthetoad/p...ni35/index.htm

http://www.sinedie.org/lickthetoad/p...ni35/photo.htm

the grain is visible under DV camera so i think whil be even more under HD and also the screen is 36mmx24mm not 4/3 ratio

i think the materiel is plastic or somthing else so ginting whit AO i don't know if is working

Paolo

people who want the X-Y switchable LCD's, just do an eBay search for a brand called " lilliput ", make sure you buy a TFT and not an STN screen.

http://www.amazon.co.uk/exec/obidos/...704539-6752633


Its kinda funny how these are things we already discussed 2 month ago, but oh well...here we go again.

gas

Well...

It's not as if I'm about to strap a 6" LCD screen to my camera. Thanks for the links but they do me no good.

- jim

moniteur
 

4" tft

http://www.bullnet.co.uk/shops/test/tft.htm

John Gaspain
 

Please don't recomend or buy this, I have this model and this is real crap.

http://www.portablemp3playerstore.c...ial/th-5688.htm


Paolo Rudelli

the one you sugest has only
Resolution 383(H) * 234(V) DOTS
It's not good enought to be able to make focus whit this.


Alain

Re: moniteur
 

<<<-- Originally posted by Paolo Rudelli : 4" tft

http://www.bullnet.co.uk/shops/test/tft.htm -->>>

I guess you could just mount that one upside down.

AH HA! or Ureka...anyways, yea just mount a regular $50 4"LCD UPSIDE DOWN!

Don't know if this website is currently used by anyone in here. Thought it might be useful to someone:

http://www.einsteins-emporium.com/science/l-optics/sl215.htm

Hmmm....what if we all do this?
 

<-----Read----------Learn----------Progress----->




-Brett Erskine

TWO-LAYERED GROUNDGLASS.

For those who are following the fixed groundglass path, here is something which may be of use and someone might develop to a furthur stage than I have the time to do at present.

Whilst educating myself with microscope slides in the method of polishing glass before I turn myself loose on the real glass disks, I decided to see if I could replicate the partial polishing back of the plastic CD disks which seems to confer an improvement in the projected image.

I discovered after polishing back some of the frosted finish on glass slides to a semi-opaque condition, it would be of little use as a groundglass screen because of hot spot and some of the aerial image being apparent.

But with two such groundglasses mounted with polished-back frosted surfaces face-to-face, a more useful projection surface can be found with the finer texture remaining, therefore hopefully better resolution than with a single more opaque frosted surface of coarser texture.

The downside will likely be two internal reflective surfaces instead of one and anti-reflective coatings on the clear sides will likely be mandatory.

GotGrit.com
 

Yes, I did. The guy's name is Tom. Very helpful. I got WAO 5 Micron (white). I also wanted 3 Micron but he didn't have WAO 3 at the time. I did buy some 1 Micron he had (left over from a previous special order) but from what I can tell it's a little too fine and polishes more. He did suggest trying Cerium Oxide (CEO) as a substitute for Aluminum Oxide. He said CEO was soft like WAO and might work as well. Although I didn't order any so I don't know.

Anyway, his WAO seems extremely consistent and from what I can tell, made a beautiful GG. I hope to be testing it this weekend/early next week.

I just placed an order at gotgrit.com for the following items:

Aluminum Oxide
WAO5-025 WAO 5 Micron 1/4 LB $1.75USD
Cerium Oxide
CEO-025 CEO 1/4 LB $4.50USD


I don't know much about the Cerium Oxide, but I spoke over the phone with the owner (very friendly and helpful) and he suggested it, so I'll try it out on a piece of glass or something and let you guys know how it goes.

Its been mentioned that Cerium Oxide is similar in hardness, but did you get any information on how it compares to Aluminum Oxide in grain size?

Nicholi: I told him that I required something fine for making ground glass and he suggested the WAO 5 and CEO, so I took it that the CEO was comparable in size, since he mentioned them together.

However, I just called back and spoke with Tom and he said that the CEO is 2 micron. So...looks like that won't do me any good for the ground glass. However, I won't mind having it incase I decide to one day make a mirror. :-)
Also, he mentioned that the CEO creates some sort of chemical reaction with the glass when grinding.

Guess I should have ordered WAO 9 instead of CEO with the WAO 5, but hopefully the WAO 5 will be coarse enough to make a fine ground glass. (Thanks for the feedback, James.)

An amateur telescope making site I saw described making a mirror using Aluminum Oxide for the 'Fine Grinding' (down to about 3 micron) and then to use the Cerium Oxide for 'Polishing' - which goes much much finer.

Has anyone gone much finer than 1000 grit?

I've got my first adapter done with the 1000 grit and a big fat condenser (no hot spot). My only problem is that I want to be able to stop down the aperture of my SLR lens. Very very short Depth of Field is good sometimes, but not all the time.

I definitely see hotspotting at 22, but in the 11 range, I have a nice consistently bright image with a longer depth of field.

The downside - as you stop down the aperture, the grain just jumps right out. At F2.8 (my current lens' max ap), the grain is basically invisible - but at F11-- yuck.

Cool Clip, Paolo
 

Paolo Rudelli: I like chopping oranges and cups and saucers.

Nice clip :)

Grit vs Micron
 

Well unless this chart is inaccurate or I'm reading it wrong, 5 Micron = 4,500 Grit.

http://www.facetingmachines.com/grit-mesh-micron.shtml

Jonathon Wilson
 

I have done it whit 9 micro bryte capsule, that is just a bit smaller. after that there is something call I think metal oxyde ,it's a red stuff but this is for polishing and I haven't been able to get a even surface whit it , I start to have some transparent spot, so no good.

Alain

Adapter pics up
 

For anyone interested, I've got some pics and shots of my adapter available at:

http://home.austin.rr.com/aqua99/adapter/

First attempt, but given my hobbyist-only level at this point... it's enough to get me started :)

Jonathon, thanks for the very detailed photos and description!

Question: why is there a distance between your condenser and the ground glass? It seems that the other pointed that the condensor should be put directly next to the ground glass?..

Yeah - the only reason there's any distance is because I wanted everything to be 'removable' so that I could clean either side of the ground glass and condensor. There is only the necessary distance between the lens and the condensor to facilitate some threaded mounting. I think the total distance is maybe 1mm or less. I tried some different schemes and very quickly (like 3-5mm) I saw all kinds of spherical distortion in my image as the condensor moved too far from the GG. You want them as close as possible.

Jonathon, your setup looks good and the depth of field results are impressive. I'm curious to see the setup with a newer, higher resolution camera. It looks like the 45mm focal length diffuses well. The bottom pics of the white post show a little barrel distortion, but not too much... much less than I expected from such a short lens. My question is... how much did the condenser lens diffuse the image (how big is the diameter of the diffused image)? Does it seem to diffuse an image larger than 44mm (the minimum image diameter to record a 36x24mm frame) or does that seem to be the limit of the 35mm lens?