Homemade 35mm Adapter

[Nicholi Brossia]

It looks like the MOVIEtube holds the camcorder at a 45 degree angle. That makes me think that they're using a Schmidt roof prism which rotates an image 180 degrees (invert and revert), but is deviated 45 degrees http://www.edmundoptics.com/IOD/Disp...Productid=2430. If that's the case, once Vendible comes up with his static "ground glass," a MOVIEtube clone wouldn't be too hard to make. Although selling it may be a different issue.

[Daniel Moloko]

Spencer. thats right. NO BALL INSIDE THE GG.

no nothing. just the GG and the Fresnel on the back of it.

ive opened 46 photo cams to get this GG.

it was a Zenith. dont know the model. but i will return to the store and get a few more.

some of them GG has holes of degradation cause they are old. but i found out that it was like a fungus that eats the glass. i just found out that this fungus can be taken off, and the GG was clean (it was hard for clean).

anyway, i put the camera directly to the GG so i dont loose the light by re-inverting the image.

I will have to re-work when i get mine HD10.

tomorrow i will post everything needed, the video and the full res pics.

today i will rest, its xmas.

thanks

ciao

[Bob Hart]

If anyone in Australia is into roll-your-own groundglass, there's an outfit in Victoria named Abasco Trading Pty Ltd Unit 19/12 Edina Road, Ferntree Gully VIC. 3156. They have Aluminium Oxide grits which are mentioned in another website mentioned here. I actually thought they were here because they were listed in the city metro directory yellow pages under 1800 809 228. They have local phone 03 9752 2816 and a fax number 03 9752 2808.

Nevertheless the rep was very helpful on the phone and happy to send a small order of 500gms across Australia for $10-00 item, $10-00 mailbag and GST $2-00, all up $22-00. He apparently normally sells to industry in bigger lots but was good enough to hunt for a broken bag to send a smaller amount and got it here in 1.5 days which is not bad.

[Bob Hart]

Some components and optical engineering principles incorporated in the Mini35 and Pro35 might not in themselves be furthur patentable individually.

The method and order in which all can be combined to produce a deliberate and new unique outcome is another matter. (I think the legal-speak word used in court the other day was "synergy").

A case alleging such an intellectual property is being used by a defendent without consent or licence, might be pressed by an aggrieved party as an enforcable right if that method is sufficiently unique as to not be a commonplace practice of combination of those components for any other purpose.

So be careful out there relating to patent rights as wisely suggested in preceding posts. There seems to be potential risk of liability both under national patent laws and under common law.

There are references being made to case law in the UK and Canada in a current matter in Australia so be aware the issue is very far from dead.

I am not a lawyer and am paraphasing from recollection some things I have stumbled across recently.

[Rob Hester]

Hey guys, sitting at the computer I looked over at an empty glass I had egg nog in...and by golly there was a film layer coating the glass! Very smooth, not nearly as grainy as something like a CD.

So anyone out there wanna give glass dipped in Egg Nog and set to dry a go? I don't have time; leaving for a cruise down south tomorrow...by the time i come back this thread will be ~80pages! And i've been keeping up!

Anyways, egg nog it up!
Cheers,
Rob

[Peter Sciretta]

I'm lost in the past few pages of posts... we've gotten so far distracted from the original simplicity of this thread.

Some of these posts take someone with a lot of college science courses to figure out.

What happened to keep it simple???

[Bob Hart]

Another lowlight test with groundglass CD dressed on a glass sheet with loose 600 aluminium oxide grit in water. - Much nicer uniform finish. No flicker. Image seems slightly softer, maybe due to denser opacity. Light transmissability appeared to be not as good as the pressed version. Quality across image was uniform with screen stopped or spinning. Spinning removed any faults in the groundglass finish.

Has anyone done any tests with test patterns? Mine don't look too good so far with merging in different places in the image at between 400 to 450 TV lines. DVCAM normally gives about 500.

[Louis Feng]

<<<-- Originally posted by Peter Sciretta : I'm lost in the past few pages of posts... we've gotten so far distracted from the original simplicity of this thread.

Some of these posts take someone with a lot of college science courses to figure out.

What happened to keep it simple??? -->>>

The principle has been the same, static GG or spinning CD. The simple version of the adapter is done, Agus has given everything you need to make one yourself. What Agus and some are working on is to improve the quality of the image and make it more useable, such as producing correct upright image, and hopefully will bring the result on par with mini35 or even better.

Technical problems:

1. Ground Glass. Quality is everything here, you need something not only fine, but also transmit more light.
2. Hot spot. Without solving this problem, you are limited to what kind of ground glass you can use and the image quality won't be good.
3. Producing upright image.

Let me state the progress so far (as far as I am concerned):

1. The 3 micron ground glass is at the border line of suiteable for the static solution. It's certainly suiteable for the spinning solution as well and using in the spinning solution will give you much better result. There is a good possibility that a material better than the 3 micron GG will be discovered in a few days, in that case this problem is resolved for static solution as well.

2. Hot spot problem. I consider this problem resolved. Refer to the static solution thread.

3. producing upright image. This one is solved in a few ways and the most efficient/economic way needs to be decided.

I think it's going well, and in a few weeks you should have something layed out with everything you need.

[Bob Hart]

There is another solution to inverting the image. Some night-vision intensifier tubes have a very compact inverter built in to a tube measuring about one and a half inches long by about one and a quarter inches in diameter with a display screen of 18mm (about 2/3 of an inch).

It is military tech so they are not exactly going to tell how its done in detail. The principle is they use fine optical fibres. These are packed accurately together so that along the entire length of the path, each fibre remains in its correct relationship with its neighbor.

Both ends of the piece terminate as a pick-up screen at one end and a display screen at the other. At the eyeball end, as I can work out there is a form of opaque projection surface superior to anything we have been evolving, or it may just be the polished face of all the fibres themselves.

To erect the diplayed image, it is pure simplicity. They just twist the mass of fires through 180 degrees. The doing of it probably creates incredible challenges in just keeping those fibres from shifting about. If an intensifier tube gets a strong (for an intensifier) light into it and goes into clear display, you can sometimes see little imperfections where a clump of fibres has moved slightly in relation to the rest. It shows like an earthquake fault line.

The CP16RA motion picture camera viewfinder uses a little projection groundglass screen - not quite true. The screen is about the thickness of a circuit board. It is actually a sheet of packed optical fibres, stablilsed I guess with some sort of tough adhesive, thinly sliced and then polished on both surfaces. The light transmissabilily of the viewfinder is excellent on wide-open lens aperture. Detail and contrast is crisp. (After getting accustomed to one of these, tube or LCD video viewfinders comprehensively suck to extremity.) With the lens stopped down, there is a weird diffraction rainbow effect. As we are after a wide-open lens aperture for best depth-of-field effect, this would not be an issue for us.

Optical fibres have come a long-long way since the early seventies when the CP16 became the king of news gathering.

If sufficiently fine optical fibres could be accurately packed in a wide round, glued, sliced and polished flat on both surfaces, it would be the ultimate groundglass. Maybe that's what the Mini35 uses.

I doubt a full CD sized panel would be workable for spinning. A more compact arrangement like a Sarich orbital piston, which works something like an orbital sander, to move a smaller screen might be possible.

If the fibre screen could be made with sufficient resolution that it would not have to be spun, then a pack of fibres twisted 180 degrees like inside an intensifier tube might provide a solution.

As a custom job it might be horrendously expensive however there may be somebody here who messes with fibre-optics who could put us right. Even better, maybe somebody here works for Electrophysics Company in the US, Photonis in France and Delft in the Netherlands and might ask some questions on our behalf.

[Taylor Moore]

Here is a work around to inverting.
A monitor that will flip the image on all axis.

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=3065860805&category=14946&rd=1

[Filip Kovcin]

<<<-- Originally posted by Spencer Houck : ... So here's a design featuring literally no GG at all, just zoomed through the +10 macro's vignettes, and the 50mm lens' vignettes, and voila no grain, no fuss.
...and then bring me back to Earth as to why this won't work for some probably obvious reason.

Happily,
Spencer Houck -->>>

spencer,

i did yesterday the very same thing as you. i also didn't see any differences. i zoomed into attached lens, i used +10 macro lens etc. it WORKS for me. i don't know about others, but for me is completelly acceptable.

(please check my full explanation on Static 35mm Adapter Solution thread - there is a detailed list which lens and macro is used etc.)

i was sceptical before test, but... what can i say - i WILL do more test to find where is the secret, since then - i do not need any GG and spining CD. maybe i'm wrong, but... for now - i'm happy with this.
filip

[Bryan Mitchell]

Wow, several hours later, I have finally finished reading through this entire subject. Close to 600 posts. I'm glad to finally join this subject. I read through every single post because I wanted to be sure that no one else had done what I had immediatly thought of. As soon as the parts I ordered arrive, and I get this thing set up (hopefully as soon as possible) I'll post video and pictures of it. It's a really simple method of spinning GG(with no hole in the middle) from the outside (like I hear the mini35 uses). I'd like to thank Agus and everyone else that contributed to this project for all of their ideas and help they have given me that I will apply in my attempt.

[Anhar Miah]

Taylor Moore man, i've already suggested that idea!

not specificially that monitor in question but about using an external monitor flipped upside down OR using an optical device that will flip the view finder of the camcorder

Either way at least you do not disturb the incoming image.

I also suggested using a "project box" someones seems to have imlemented that to.

I think the race is on to make a pro version that does not need flipping in post and a static GG version may well be nearing reality.

One more idea for you guys :

If you wnat to vibrate as opposed to spinning try connecting the GG to a small speaker and apply a sine high frequency signal to the speaker. My guess is that a very high frequency will be needed in order to minimise the grain, and aslo if you use 2 speakers one in the x axis and one in the y axis then you will have the grain movement in total random fashion thus remaoving any "streakes" which appear from either spinning of vibrating in one direction

[Bob Hart]

Groundglass disks. Been doing some homework and have found there are two types of precision glass disk made in numbers for industrial applications, a third if you count CD mastering disks but these are too big at about the size of an old 45rpm vinyl record.

Some advanced computer hard drives now use a glass disk which has an outer diameter of about 3 and a bit inches and an internal hole of about 3/4" Its thin stuff at 0.6mm. It is supplied as blanks ( hard disk substrates )to the industry. They offer toom small an image target between the inner and outer diameters for our purposes.

There is another product which is probably most promising to us if we could get our hands on it. It is a glass disk made for testing computer hard drive read heads. It is available in varying outer diamaters with varying internal diameter centre holes. It is a bit thick at 2mm. (You could probably get something made up as 2mm glass is fairly common.) This stuff however is made to spin.

If there were such items as rejected disks which don't meet the surface standards but would suit us to make our groundglasses, or worn out disks, buyable cheap???

Otherwise it might be necessary to form some sort of group to buy in a batch at economic prices.

This product is called a glass disk for flying height tester "GD-FHT". made by ohara of Japan. There is a US website www.oharacorp.com The Japan website is www.ohara-inc.co.jp

Anybody here involved in R & D or product quality control at IBM???

[Nicholi Brossia]

A couple of people have experimented with zooming straight into the rear of a 35mm camera lens. I've watched Spencer's video and think it looks like video, and accomplishes the same as attaching a telephoto/wide angle lens to the camcorder. Others feel that it is acceptable. Either way, if you like it, you like it. But, for experiment's sake, maybe it would be a good idea to get a controlled group of shots from both Spencer's setup and Agus's setup. Spencer's keyboard/note shot and the guy at the door could be easily reproduced with a ground glass adaptor for comparison. Unfortunately I don't have my adaptor completed to do a controlled experiment here, but if Agus or any of the other guys that have completed their adaptor want to try this, then it might help clear something up.

here's something to try...

1) Find out your camera's 35mm focal length equivalent. You can usually find this information on the internet. GL2's are 39.5mm, PC-101s are 42mm, PD150s are 43.2mm equivalent at their widest settings.

2) Use a 35mm lens with a close focal length. The lens that most people have been using on their adaptors have been 50mm focal length (35mm refers to the size of the film frame, not the properties of the lens). 50mm lenses should be close enough to the 42mm of the camcorders to work for this experiment.

3) Record identical shots with each of the two setups as well as the stock camera lens. Keep the camera lens front at the same distance from the subject with both versions. Depending on the length of the adaptor, you may have to move the camera back or forward a little to keep the 35mm lens front at the same distance from the subject. The shots should be framed the same. For test purposes, if you have access to both setups (that would be most controlled) get a shot with the 35mm ground glass adaptor, 35mm non-ground glass adaptor, and the camcorder's normal lens (you may try zooming in just a tad to match the other shots... but be precise).

4) Keep track of which shot is which and compare, taking note of the distance between objects that are "in focus" relative to "out of focus"

5) Post still frames (with no post production) of the different setups with descriptions of what the shot was. That way others can see your findings.

Unfortunately, not everyone has access to everything, and not everyone has identical camcorders. However, this can still be done in a convincing manner... if you have an adaptor, you can contribute. Just be sure to mention which adaptor, 35mm lens, distance from subject, and camcorder model.