35mm Adapter Static Aldu35

[Joel Corkin]

Hi Brett, thanks for the response. But, perhaps one of us is missing something in this equation. I'm talking about less grain AND more electronic resolution.

My assumption is that, of the nikkor/canon/etc. lens's image circle, you will be using only the center 15.3x36mm (2.35:1) portion, as though you were shooting something with a stills camera and then cropped the resulting image.

That 2.35:1 image would be stretched only vertically, so that when it appears on the GG for the video camera to record, it will occupy a 27x36mm (1.33:1) area of the glass, allowing your video camera to shoot it using all of its CCD's pixels.

Are you trying to do something more complicated than this, because unless you need some different sort of functionality, what I have outlined seems to be relatively easy to do with good benefits on image quality (i.e. more benefits than shrinking the image on the GG)? Please tell me what specifically I'm missing about what you're trying to do.

Thanks a lot.

[Brett Erskine]

I see what your saying now and your right. It will give you less grain and more electronic resolution (full CCD). The reason why I wanted to squeeze the image horizontally (which is more of a traditional anamorphic technique) is because it allows you to do 16X9 enhanced DVD's with a image that is 2.35. In case your scratching your head I'll explain.

Most DVD players can unsqueeze a image on the fly but only by a factor of 1.78 (16X9) so what the pros usually do when they are encoding a film that was shoot in a 2.35 anamorphic ratio (ie Panavision) is create a DVD with a image that is only partially unsqueezed to 16X9. The DVD player then takes care of the rest of the unsqueeze when it palys the DVD. This brings the image back to 2.35 and makes the most of the resolution that NTSC DVD's allow.

Now is your idea better or not...Hmm thats a good question. I wonder now. I think if you have static GG I would say yes. But if you have moving GG I would go with a horizontal squeeze instead.

Hope that explains it all.

Great thinking by the way.

-Brett Erskine
www.CinematographerReels.com

[Joel Corkin]

Thanks for the response. I think the biggest obstacle either way is finding a quality cylindrical lens with the proper characteristics, and that sounds like a cutom job to me. I would love to have this in a static adapter, since it would be so much simpler to make and the tolerances would be relatively looser.

A while ago I asked a lensmaker about having them make a cylindrical lens to my specifications based on an explanation of my overall intended device. We didn't get into prices at that point, but they did say the major problem would be about 1-1.5 stops of light loss first because of the magnification of the image and second because of the added optical "roadblock" to the device. Every piece of glass you put into your system will contribute to a loss of light that at some point will become unacceptable for your needs. The light loss, hotspot and accumulating costs were the three reasons I halted my own work on this project over a year ago. Things will hopefully work out this time because of this community of people working together.

[Brett Erskine]

The perfect cylinder lens will project the desired squeezed image on the back side of itself. Meaning the plano (flat) side of the cylinder lens, which would be ground to create a GG surface, would be a the perfect focal length for the right magnification. This will help cut down on the amount of elements in you adapter and increase the optical quality.

[Bob Hart]

Joel.

Some time back, I shot a test into the AGUS35-PD150, through a Proskar Anamorphic projector lens into a 55mm Micro Nikkor. I can't remember the filename now but if you have a look at www.dvinfo.net/media/hart, and look for something like widescreen or cinemascope with .jpg after it on the list you'll find two 4:3 and 2.35:1 images composed together as single files.

There's also a couple of tests I did with the Century Optics 16:9 on front of the Micro-Nikkor.

Cinemascope was fine for MiniDV/DVCAM resolution in close to about 40ft but fell apart for sharp focus beyond that. I don't think it would hold up for HDCAM.

There's also a few early fixed groundlgass tests titled something like "fixed groundglass" or "agusday1" & "2" In those early tests I used a microscope slide dressed with aluminium oxide and enclosed in a Pringles can. The prime lens was retained in the can with a rolled up toeless woollen sock. (I suppose you could call that evolution the Pringlecam or SPUD35??)

[James Ball]

Quality Statement:
I have made gg numerous times with mechanical abrasives up to 1000 grit AO. I consider myself somewhat good at this. The Acid etched gg is far easier to produce, costs less for materials and I feel is of far superior quality to mechanically produced gg.

Needed:
Soft bristle toothbrush (throw away when finished)
Armour Etch Glass Etching Cream 3 oz. or larger (available online and at Hobby Lobby for those in larger US cities.)
UV (Haze Filter) of appropriate diameter. LEAVE in its mount.
Soft paper towels and or toilet tissue
Windex or other alcohol or ammonia based glass cleaner.

½ hour !!!!!!!!!!!!!!!!!!!

Access to running water. This material when diluted and treated in a modern waste treatment plant will not harm the environment.

Precautions:
Follow the mfg. safety precautions printed on the bottle label.

You’ll need:

Rubber Gloves
Goggles (not safety glasses as the material can get past)
Long Sleeve protective garment (that you don’t mind holes eaten in)

Good ventilation.

Hold the work at a distance from your face when applying cream, brushing, rinsing, or working with the piece.

Technique Discussion:
With this etching method you’ll find technique is everything! Please re-read the previous sentence. Others have tried this and found that the results are blotchy. The label itself says that the material is not meant to treat large areas.

What you’ll notice is that if you apply the paste in a blotchy pattern, the glass seems to be etched in a matching pattern. If you use a toothbrush to apply the paste applying it with horizontally aligned strokes then the pattern of blotches seems to be horizontally aligned. This observation and others lead to the technique I use to produce a surface that is free of blotches.

I would say that the grain is finer than anything I’ve been able to produce mechanically.

Procedure:
Rough etching. Always hold the glass horizontally.
1. Thoroughly clean the glass, front and back with alcohol or ammonia based glass cleaner and dry.
2. Apply a generous amount of etching paste to one side of your glass. Be sure to note the side you wish to etch so that subsequent treatments will be to this same side. Wait about 5 minutes.
3. Scrape the paste off the glass and back into the Armour Etch container.
4. Rinse thoroughly and dry.
5. Repeat steps 1 thru 4.
6. If any smooth glass remains spot treat them with paste until the entire surface has been etched and no smooth places remain.
Fine etching. Always hold the glass horizontally. At this point you’ll probably be very disappointed with the appearance of the gg. It’s all etched but hardly uniform in appearance.
7. Add a generous amount of paste (but don’t overflow the mount) to the glass surface.
8. Using short strokes (about ½ inch 13 cm) gently scrub the glass surface all over. Still with short strokes brush the glass horizontally all across the surface of the glass.
9. Now gently stroke with shorter strokes and at the end of each stroke pull the brush up away from the glass. Do this all over the glass. At the end of this step you’ll end up with a fairly uniform thickness of paste covering the glass (about 1/8 inch, 3 or 4 mm thick).
10. Let sit for 4 minutes, then repeat steps 8 and 9
11. Let sit for 3 minutes, then repeat steps 8 and 9
12. Let sit for 2 minutes, then repeat steps 8 and 9
13. Brush the excess paste back into your Armour Etch containerRinse thoroughly and dry.
14. Inspect the gg.

That should do it. If not try it one more time. Developing technique does require a little perseverance, experimentation, and practice.

James the Chemist

[Jaime Valles]

Thanks for the detailed procedure, James! I've been following this thread for a while now, and am very interested in starting up my own Aldu35. I've been extremely impressed with the samples on your website.

Have you tried the GG made with acid etching in your setup already? How do the images look? Let us know if it's better than your previous GG (which seemed to produce great results!).

[Dana Jan]

James, I know this is going to sound crazy...but since we do have these dv cameras...hehe..would it be possible for you to give us a video tutorial of your method with audio narration of the steps? You don't need to show the full 30 min. Just so we can see the toothbrush 'stroke' technique, and how we're supposed to do this?

I read your post twice now, and I still have a fuzzy mental image of how I should do this. I would love to see this done by you on video.

-Dana

[James Webb]

Very cool! Thanks James!!

[James Ball]

-Dana-
Love to but time and hosting situation will prevent me from doing a video tutorial. Also my camera (a DVCPro 25) doesn't have firewire out and it's a pain for me to get it out into my PC at present my deck is away for repairs.

It's easy though and fairly inexpensive. About $5 for the paste. It will become more self evident if you just try it. I figured it out in a few hours just playing around here and there. Plus if you don't get it right just add more paste and start over till you get it right.

If you have more specific questions I'll try to answer. The key to the whole thing is that if you just glob it on the paste the glass is etched in an uneven way; but it's not random the pattern matches the "globbiness". I soon found that if you applied the paste with horizontal strokes all oriented in a single direction that the pattern of etching nicely matched the brush strokes.

Last I found that if you did a short horizontal stroke and at the end of the stroke pulled the brush away from the glass it left a finer grain.

[James Ball]

I've only begun my Aldu35. So I have no means of final comparison. However it'll only be a few days off as I have a few 35mm cine primes and my Fujinon lens has a macro lens that will allow me to focus on the gg screwed onto the front of my video lens.

I have a microscope that I've been using for comparison purposes.

I can send 200X microscope pics of the grain from a 1000 grit AO and etched gg if someone will host them.

[Alex Raskin]

James, send the pics to me, one pic at the time.

Just reply to the email I sent you privately earlier today.

I'll gladly host them on my site, FancyFlix.com.

[Jaime Valles]

<<<-- Originally posted by James Ball : I've only begun my Aldu35. So I have no means of final comparison... -->>>

My mistake... I thought you were James WEBB, not James BALL. Sorry ;)

Anyways, the info was great! I can't wait to see pics once you put together an adapter!

[John Cabrera]

James (Ball),

Is the thoothbrushing simply done to even out the cream on the surface of the glass, or is the toothbrushing actually done to help the corosive process.

The reson I ask is that if it's only used to help create a uniform spread of the cream, then couldn't you also just put a bunch of cream on the surface of the glass and then lightly press another piece of glass (uv filter of the same size without the ring) over the top of that till the cream speads between them both evenly like a sandwich?

John

[Justin Burris]

Alex,

Thanks for offering to host James' pix. I'm really looking forward to seeing them.