Something else I've noticed with my SLR is that in the center of the ground glass, there are two concentric circles. Of course, these areas aide in focusing, each providing a more detailed/precise focusing area. The inner most area is by far more detailed than the outside, but makes diagonal lines look jagged, much like the "stairstep" appearence of interlaced video on a computer monitor. This is due to some type of coating/film used as a substitute for the grind. After viewing the area with a magnifying glass, I can see that the film is made up of numerous tiny "cells" almost resembling honeycomb... hence the jagged/pixelized appearance. I don't think that would look good on a television.

The middle area provides slightly less detail for a slightly softer picture, yet the diagonal lines are very smooth and natural. This provides an acceptable image.
The outer area is by far the worst quality both in detail and brightness... unacceptable in my opinion.

Okay, so what does this lead to? Exactly what was pointed out earlier today considering fresnel vs. double condenser lens. The innermost circle is the only one that contains the honeycomb looking film that I spoke of. The other two areas have been ground identically (same grit). However, the fresnel is only existant in the outermost layer (I can see the concentric circles with the magnifying glass... they're tiny) where the detail is much worse. The catch is that the middle area contains a very small bubble in the glass... in other words, the very peak of a second (technically the first in series) condenser lens. This tells me that the only acceptable layout is a double condensor lens. This will get rid of the hotspot (if you set it flat side down on a piece of paper, you can actually see it working... there is a shadowed circle in the center of the lens) AND sustain the most accurate detail. Honestly, there is a huge difference between the quality of the two.

If everything works out right (considering I know nothing of mother nature) we should be able to derive the focal length for two identical, thin condensor lenses to be aligned in sequence after the ground glass.

Here's a drawing I threw together to illustrate that last post.
http://f1.pg.photos.yahoo.com/ph/nic...dnm=SLR_gg.jpg

no GG?
 

hello there,

when i read about the solution WITHOUT GG, i was very sceptical, but anyhow ...
i just checked the option WITHOUT moving parts and WITHOUT GG.
here is the list of things used:

- camera sony PD 100 (52mm front filter diameter)
- macro lens +10 (single lens) from Hama (52mm diameter)
- cake CD box (for 50psc)
- zenit PHOTO camera lens 58mm/f2.0

i zoomed into the zenit's lens picture to avoid vignieting and that's all. no prism, no nothing exept macro lens with 10x power, and cake box with zenit 58mm lens on it. so it looks really simple. i did the tests with the camera, but cake box was not so stabile, so i kept that in my hands which results in vignieting, but this is due to my shaky hand. focusing is in this case really difficult. i changed focus here and there to see how it looks.

for me it looks really good:
- it HAS proper DOF,
- for some reason, colors are bit different (read: subjectively better)

also, because of low light conditions (just one table lamp on the begining and two ceiling lamps (2x 75W) + christmas tree lamps) i used 18dB image gain BUT with -3dB offset in main menu settings).

these gives me interesting video (grain) noise, which probably helps to see everything more "filmic".

maybe i'm too subjective, so please tell me - do you see what i see - or this is just my illusion?

maybe i'm fascinated with it, but to me it has something common with proper film feeling.


i can send my "filmeo" (film+video) tests today to you via taylor (with his kind permission) if you want to see it. should i send them?

excuse my ignorance, but wouldn't just zooming into the back of another lens cause the 7.2 magnification we are trying to avoid?

Zac

I agree with you Zac, but just in case, I've posted an experiment on Agus's thread that hopefully others will participate in.

No shit now, im working already
 

I got my first Job with the COLONIA35MM

the adapter i just made myself.

go to the site www.bobflash.com.br

choose the city RECIFE-PE

on the site theres a session called BOBCAM, where i go to parties and film everything.

check out the two last clips from a xmas party. i made the two with the 35mm lens, 50mm, 1.4.

it is wonderful, altought i had some problems to focus, with the light of the place, etc. im still learning. and i was drunk too, etc...anyway, tell me what you think of it.

im just waiting your review.

thanks

ciao

all static is the way.!!!!!

ciao

Daniel Looks good. Please post pix of your setup and rig.

You BR have too much fun.

T

taylor
 

it isnt just great because of my cheap trv18...

ive said before all the setup...

look at the pic of the Colonia35mm

http://www.bobflash.com.br/franquias/recife/locais/barrozoclub/eventos/24-12-2003_3146/fotos/124170.jpg

another
 

http://www.bobflash.com.br/franquias/recife/locais/barrozoclub/eventos/24-12-2003_3147/fotos/124306.jpg

Re: no GG?
 

<<<-- Originally posted by Filip Kovcin : hello there,
i can send my "filmeo" (film+video) tests today to you via taylor (with his kind permission) if you want to see it. should i send them? -->>>

You can also send it to me. I'll post it in my yahoo briefcase.

What you described is possible, I think I know the underlying optical physics. The problems with it is not the image, but the way to use it. I'll try to come up with a diagram to explain why it works.

Re: another
 

<<<-- Originally posted by Daniel Moloko : http://www.bobflash.com.br/franquias/recife/locais/barrozoclub/eventos/24-12-2003_3147/fotos/124306.jpg -->>>

Daniel, it looks good. Could you post a full resolution still image without color correction? I'd like to have a reference to compare. Thanks.

i cant post it
 

i cant post it on the site

i dont have where to post also

anyway, i can send you a email.

tell me yours adress...

ciao

email: coppercapt at yahoo.com

Daniel's image is up at

http://f2.pg.photos.yahoo.com/ph/lou...o+Still+Images

Can we see some footage, too? I've got server space -- I'm willing to lend space for files 15mb and under.

Drop me an email here: jim@ideaspora.net

- jim

I have got my prisms (roof+penta combo) from the links posted earilier. It looks like they will work. I'm working on a draft design right now and once I have it done I'll post it. But it's probably going to be something a little bit more complex. But you can strip it down or simplify it to fit your need. Actually the static version can be very simple if producing upright image is not needed, you only need a ground glass and two condenser lens to remove the hot spot problem.

Since I'm producing a physically correct 3D model, it's possible to create actual product from it. I'm planning to send it out to make a prototype in plastic.

My new material has not arrived yet, but I was told that it has a feature size of around 1 micron, comparing to the finest GG I produced at 3 micron. Plus it transmits much more light than ground glass. This sounds very promising. It should arrive any day now.

1 micron and dove prism
 

vendible,

i just spoked yesterday with the guy who knows optics, and he will find also 1micron GG from some russian military equipment... not bad.

did you tryed to work WITHOUT PENTAPRISM? since dove prism already inverts the image? am i correct? or in dove prism case - image is upside down AND turned left to right?

IF... dove works just upside down - you don't need prentaprism.

just dove and GG, and that's all...

i mean if you have following situation:

35mm lens -> (image upside down) ->dove (image corrected) -> GG ->camera... it means that everything should be allright... or not?

you mentioned somewhere in the thread that dove should be at least 150mm long to acheive 24x36mm frame.
BUT!!!!
film (cinema) frame is just half of that!
so, does this means that shorter dove is possible?
just a thought...

please, correct me if (or where) i'm wrong

filip

Filip,
Actually the image produced by the 35mm lens is both upside down and left-right reversed.

So the image must be both inverted up-down and reverted left-right. A dove prism only inverts the image up-down, not left-right. So you do need a way to revert the image left-right in addition to the dove prism.

Considering a roof/penta combo costs much less than a dove prism alone and without the need of additional instruments to revert the image left-right, the combo is a better choice. Another even cheaper one is the roof penta/mirror combo (the origenal method used in SLR camera), which could be even better.

Also after playing with the roof and pentaprisms, I realize although the roof prism is smaller at 28x28mm compare to the pentaprism at 24x35mm, it's possible to "see" approximitly the full frame passed from the pentaprism of 24x35mm. I know this is not very easy to understand and I was concerned before actually see it.

This more or less confirms why the roof-penta prism in SLR camera allows you to see the full image even when it has one side larger and the other side much smaller.

Honestly I don't know much about the film/cinema frame spec. I only see the standard 35mm camera produces frames of 24x36mm. What kind of lens do you use for half of that frame?

How is that you create the 3 or 1 micron GG ? Seens like here in Guatemala getting alliminun oxide is almost imposible, but still looking. Want to give this a try or o will try making a round GG just like the CD to but made from glass and with really low grain.

Agus, I found this site and it's also posted by someone else in the Homemade adapter thread. http://www.phototechmag.com/previous...kas/dokas.html

I bought the 5 micron and 3 micron aluminum oxide dust from the company mentioned in the article, Willmann-Bell, Inc. (800-825-7827). I don't know if they will ship international, but it's a good possibility.

For those want to make their GG using these dusts, you are better off buying those 1/16 inch thick glass (the thinnest I can get from a glass shop) at larger piece. I have a 6 inch rotary palm polisher for polishing cars. I use one round piece as the sander and use super glue to glue it on the polisher. With that to sand a bigger piece of about 7x7 inch. After you finish sanding it, you can cut it to fit your need.

The 1 micron material is totally different. I can't produce such thing, it's not made of glass and is less than 1mm thick.

From what I understand, the 1 micron and smaller grain sizes are all diamond... at least that's all I've been able to find that small. In the article Vendible just mentioned, it says diamond is too hard on the glass and causes big gouges that are easily noticable in the image. I've been thinking about giving it a try anyway, just to see what happens.
http://www.facetingmachines.com/polishes.shtml has some very fine diamond compounds, sprays, and slurries (dust & lubricant). Appearently, these are used for polishing purposes. Basically we're trying to get as close as possible to polish without actually polishing the glass. So maybe 3 micron is the best option until Vendible finishes his experiments with the coating he bought.

Ideally, we'll be able to grind/coat the flat side of the first plano-convex condeser lens. That would eliminate the plain piece of glass but accomplish the same result (much like the SLR's ground fresnel lens).

upside or not?
 

<<<-- Originally posted by Vendible Book : Filip,
Actually the image produced by the 35mm lens is both upside down and left-right reversed.

>>>>---

i think you are wrong on this. maybe i do not understand something, but if you extract (in SLR cameras) mirror, and penta roof prism - what you get? just the image which is upside down. i just took the lens from my AGUS35 and looked thru it - yes, it's of course upside down, but when i turn my head upside down, i can read everything thru this lens. i also tested it with frosted CD (just to be sure everything is checked) - and the image is still upside down. but not reverted left-right.

>>>>>>-- (Vendible's quote)
right. A dove prism only inverts the image up-down, not left-right.
>>>>>>>

so if above is true for dove prism (i cannot check it right now, i beleive i will found it in next few days, when i receive dove for testing) - that means - no need for pentaprism, roof or no roof.

>>>>>>-- (Vendible's quote)
Honestly I don't know much about the film/cinema frame spec. I only see the standard 35mm camera produces frames of 24x36mm. What kind of lens do you use for half of that frame? -->>>

i didn't thought about any specific lens. i'm using "normal" 35mm still camera (read cheap) lens for testing etc.
i just said that film frame dimensions are:

1.33 Full Gate 24x18mm

(1.33 stands for proportion of the frame - 24:18)

that is two times smaller then normal 35mm still cameras frame, so this means that we can still zoom into it and to have proper image - compare to film (cinema) frame size. and if you are talking about roof prism and your experiment - even with the smaller frame - it is possible to reach film look... i hope.


filip

p.s.

happy new year

16 mm C-mount trials
 

The home-made ground glass instructions are interesting, and they've inspired me to return to an abandoned project. For a while I've been playing with a C-mount adapter - like a 16 mm version of the 35 mm adapters. The depth of field is, of course, greater with 16 mm than with 35 mm (especially full-frame) but you can get very fast 16 mm lenses - 25 mm f/0.95 and 16-44 mm f/1.1 for example.

The other advantage of 16 mm is that it is easier to avoid darkening around the edges of the frame. A 20 mm diameter plano-convex lens can be used as the condenser. I've got my system to work with an aerial image (ie no GG), but the penalty is great depth of field: the video lens can focus the 3D aerial image too well.

Apart from a shortage of spare time, I've been putting off grinding the plane surface of the condenser because I didn't think that I could do it well enough. Having read Vendible's posts, I now feel like risking it - testing on a piece of plain glass first.

My existing adapter works with an image about 10.5 mm x 8 mm - just larger than full-frame Standard 16 (most Standard 16 lenses will cover a little more than the full frame). If you divide the frame height and width by 3 microns, you get about 3500 x 2500. That seems to suggest that the grain should not be visible if there is no light shining on it other than from the image. I'll test first, because it seems to good to be true and I wonder why it was visible when Vendible tried it with a much larger frame.

The final part of the adapter is a Hoya 10 diopter 55 mm c/u lens. I got the standard C-mount parts, condenser lens and mount from Edmunds.

Best,
Helen

Helen, what focal length condenser lens will you be using? are you planning to use a fresnel and condenser, or two condensers?

Nicholi,
The current version has a single 20 mm focal length, 20 mm diameter plano-convex condenser.
Best,
Helen

I have posted my new design
http://f2.pg.photos.yahoo.com/ph/lou...=/35mm+Adapter

The cost of making these plastic parts for prototyping will cost over $250, ouch. I guess I'll make my hardboard version first.

colonia35 zenit
my footage from january 01.

look

http://www.moorefilms.com/dtest.htm

to me it looked GREAT.

the best i can get from a trv18 with the 35mm adaptor.

ciao

OK, it's finally here! This new material I have been talking about is the Holographic Diffusers.

Benefits:
- High diffuse transmission efficiency (over 90% light are transmitted)
- Very high diffusion quality, details are not blured! At the same time, the hot spot problem is gone, no fresnel or condensor lens needed. (Can you believe it?)
- Very thin (less than 1mm thick) and flexible

I was hesitate to tell people because it's not cheap to test them out and there are many varieties of it. I have a picture of it with my other parts here

http://f2.pg.photos.yahoo.com/ph/lou...m=DSC00142.jpg

It's certainly better than any of the ground glass I have seen or made, even the 3 micron ones. I don't have a footage yet. But I have seen what it can do and I'm very excited. People probably aren't willing to spend $100 for a 2x2in piece at this point, since you haven't seen anything made from this material.

Edmund sells this kind of diffuser (but I didn't get it from them). See http://www.edmundoptics.com/IOD/Disp...Productid=1363

It's going to take me at least a week (2 weeks more likely) to complete a prototype and shoot some videos. Another reason you might want to wait is if it's good enough, many people might want to buy it and I can get them at a much better price.

That's excellent. I will admit I've been a bit hesitant to buy everything for grinding glass just in case your diffuser idea worked. It sounds very hopeful, good luck with the prototype.

A note about Holographic Diffusers, they are very easy to scratch, must be handled VERY carefully. Try not to get your figure prints on it and don't try to wipe it with cloth even if it's soft cloth.

If anyone is interested to order this together, please let me know. I can get them at OEM price of $50 each 2x2 inch piece if there are over 25 orders.

You already got the stuff... what dispersion angle did you get? I have been in contact with the company for about a week and a half... so far it seems the best angle is 80 degrees for complete elimination of vignetting over the entire 35mm frame...

Anyway, I certainly would be interested in getting an OEM price, as I was considering getting the stuff anyway...

What are the prisms that you got there? Once you get it all together would we be able to bulk order them also for that OEM discount?

I'm really anxious to get this all started, especially as I got a short film to start shooting in about 2 weeks.

Louis,

How thick is the diffuser itself? You have said that the material is less than 1 mm thick - but is the diffuser a thin coating on that, or is the diffusion medium that thick (like opal glass)? I'm asking because I suspect that it is very important to have an extremely thin diffusion layer (ideally infinitesimally thin), otherwise the image will be soft. Is it a very thin layer of photopolymer on a thicker substrate? It sounds ideal.

I'm also surprised that you don't need a condenser - that baffles me a little, but it is late after a heavy day. Are off-axis rays diffused towards the axis? Magic indeed!

Best,
Helen

Helen,
The whole diffuser is 0.1 mm thick, the coating (diffusing) surface is much thinner. I mentioned before that the feature size of it is about 1 micron.

Nathan,
This Holographic Diffuser (HD) is very interesting, the one I have is the 80 degree version. After some test, I'm very happy with its diffusing ability, since it completely removes the hot spot problem by itself without any help from condensor lens. The quality of the image is superb and there is no visible grain.

The diffuser itself transmits over 90% of light, but this 80 degree version diffuse light to all directions within 80 degree, that's a lot of light going everywhere. So comparing with a fine ground glass I have, the camera actually see a darker image with HD.

I want to get one with 10 degree or 40 degree to see if they will direct more light into the camera. The only thing is, I was told that with the smaller degree, the feature size goes up (up to 10 micron). But I think it's worth a try before we decide which one to order.

Louis,

Given the nature of the 'features' I wouldn't be surprised if you could get away with them being 5 to 10 microns without them being visible to a miniDV camera (when the image is 24 x 36 mm). After all, 36 mm is 3,600 units of 10 microns - about five times the number of pixels across a DV frame.

This appears to be the magic bullet - well worth 100 dollars a sheet!

Best,
Helen

Louis Feng (vendible)
 

louis,

this is exelent news. so exiting!!!!

i feel that we all are kind of underground group and working in secrecy to show one day - ta-dammm - it's here!

i'm desperate to see the results, but from the other hand, now i have SO big need to do some tests - since my guy who knows optisc asked me by the way about holograms, and i IGNORED!!!! that part. now, i know that there is SOMETHING which can be used from holograms.

by coincidence or not the very first part of the world HOLOgram means:

PREFIX: Whole; entire; entirely
ETYMOLOGY: Greek, from holos, whole !!!!

so that HOLO means that you have all parts to build it! :)

so, good luck, and share the news!

filip

So maybe Vendible, or Louis (I can't figure out what to call you now) is designing the new Holo35 or 35mm Holodaptor ;).

this is exciting......
 

I've been following these developments with bated breath since the Agus 35 developments. I realize I'm waiting in the wings on making this 35mm adaptor but I've got a feeling Louis is going in the right direction with the holo-diaptor.
Good luck and keep it coming.
I kind of think Holo-mini 35 is a good name for the unit.

I think the holo35 is going to work. I will join in on a power buy
when we have a parts list .

I was really just kidding around with the name. This is Louis's idea, experiment, and money, so he should have the honor of naming the adaptor.