Hello all,

Just wanted to say thanks again and great work to brett, james, jon, joel and everyone who is putting their minds to this project. I'm still in the baby stages, but I'll be grinding my ground glass this week and I'll be shooting tests with the 100A to see if I can really fill the 36x24 frame while in sharp focus without diopters. I'll fill you guys in as soon as I can.

Hopefully I will be able to achieve a nice frame in focus without any help from additional achromats. But even if its real close maybe just the 72mm +3.5 will do the trick, in which case I'll let you guys know how it works cause I'll most likely end up buying it.

Be back soon,

Nick

A physical mechanical shutter like the ones found in a cine camera and electronic shutter speeds in a digital video camera work towards the same basic end but a mechanical shutter creates a different look. Its slightly less jittery motion. I've talked to other people about this and have come to the conclusion that its due to how a mechanical shutter exposes film (in this case its a CCD) to light. For thoughs of us that dont shoot film a 180 degree mechanical shutter generally looks like a half circle that rotates. When it rotates it basically exposes the CCD half of the time and then blocks the light the other half of the time - 24 times a second. But if you slow down the process and think about it you'll realise that the whole CCD isn't being either all exposed or all not expose like someone switched on and off a light. Instead that half circle is progressively exposing the CCD to more then less light as it makes its circular path across the CCD. If you used the example of a light switch again the you could say its more like if someone dimmed up, held and then dimmed down the light. If Im right this should take the hard edge off of the motion blur on progessive digital cameras. On top of that your only one step away from having rotating GG which makes the whole idea much more attractive. Anyways I hope that answered your question.

-Brett Erskine
www.CinematographerReels.com

Shutter
 

Brett,

You shutter idea does sound interesting. Although I have a feeling that the instantaneous nature of progressive capture (basically the same as the electronic shutter in the sense that it just snaps a photo for an exact period of time, then instantly starts on to the next), versus the pricipal of a film strip moving across the lens contributes, at least partially, to the more natural fluid motion blur. But I don't doubt that having the light fade on an then off in that very rigid 1/24/second progressive scan will help out. It's a pretty simple experiment that can be done without the aldu35 or any adapter. Just take a dremmel and attach a 180 degree shutter to the front of it that 's exactly wide enough to cover the lens completely at the 0 degree mark. Set the DVX to 1/24 electronic shutter which is equivalent to no shutter or a completely open shutter and see what it does. You'll have to get just the right speed on the dremmel (1440rpm) and I'm not sure if there's a way to tell. But a Ground glass adapter shouldn't have anything to do with getting the smooth kind of blur you're talking about from the experiment. It would be a good starting place to test out this theory before combining it with the Aldu35 or Agus35. We should start another post about it.

If you glue a half circle of paper on a rotating AGUS groundglass you get some weird stuff. Interesting things might happen if the rotary groundglass could be driven by a syncable electric motor.

As to the image erector. With other committments and an AGUS arrangement which works well enough for the time being I haven't pushed the erector for much the same reasons - light loss and degraded image which will require a whole lot more time and effort in development to get right.
There's also a sort of white sheer with mirrors which is also a bit of a spoiler.

Brett as to creative effects, controlled artificial light onto the groundglass for a faked fogging effect might be worth examining.

Ah... that helps. Thanks.

CCDs work conceptually just like film - the photosensitive diodes measure an increase in voltage over a certain period of time (1/48th of a second, for example) before dumping that number out as its (the diodes) 'exposure.' If you were to 'wave' a moving shutter over the diode during this time period, it would have the same effect that putting a mechanical shutter over film has.

It would have to be either very-well secured, or very light (or both) to not introduce vibration. Remember that virtually all 'vibrating motors' work on this principle - spin a half-circle off-axis very very fast. You'd need to create a vibrating motor without the vibration :)

erect image
 

To erect image dont use mirror because you have a lose of light use 90° prism in a posso configurations..

Distance from GG to Macro
 

I was testing double-weave mylar architectural drafting film as a ground glass and I came across some interesting information.

I was specifically looking at the diffusion and grain characteristics of the mylar, so I removed my condensor for testing. My camcorder has a built-in macro feature, so I can focus on something that's very close to the lens (1.5 cm). I have always attached my adapter right onto the end of the camcorder because I could and hadn't built any additional tubing. This created a situation with the condensor where the ground glass is about 3.25 cm from the camcorder lens which acts as my macro. I had always had to zoom in a bit past the edges of the hotspot, but thought this was normal.

Once I removed the condensor, I had the ground glass right up against the camcorder lens - about 1.75 cm. With the camcorder zoomed all the way out, the image completely fills the frame, but there's a big fat hotspot with literally a hard-ringed edge the same size as the aperture of the 35. As I open and close the aperture I can see the hotspot change size.

I took the adapter off the camcorder and looked through it directly... zero hotpot - I mean none. Perfectly flat even image across the entire 52mm gg surface. (?!). What the heck?!

So I tried taking some of my leftover PVC tubing (I think we all have buckets full of the stuff), and built a short extension tube such that I could manually hold the adapter at a longer distance from the camcorder - in this case, the pvc was about 5.5 cm long.

This time, when viewing zoomed all the way out, I (of course) could see the tube. However - at the end of the tube was a circle of almost completely even hotspotless image. I zoomed in just past the edge of the circle of the tube and was left with a very very nice image with a slight darkening in the corners... remember though - there's no condensor!

So... I'm wondering if a bit of space (at least a few cm) between the GG/Condensor and Macro is actually mandatory to allow the diffusion to happen. If you're too close (like I was), I think you still get the hotspot because there's no room for any diffusing to happen.

Just thinking out loud - thought it was interesting. By the way, the Mylar is a pretty good ground glass substitute. I don't think it will be quite fine enough for final product but for those getting started who haven't ground a real glass - it's super cheap and works awfully well. It's better than the focusing screen that came on my Canon AE-1. It would be awesome for a spinning ground glass version.

Jonathon-
The reason that your getting a hotspot on your GG when its real close to your macro is because all of that stray/diffused light near the outter side of the frame isnt being redirected towards the lens. The closer you are to the GG the more the angle of the stray light will need to be corrected. This is why you need a condenser -particularly at short distances.


Mechanical shutter-
A simple/even weighted example would be to simple spray paint half of the CD if your using a design with a rotating CD. Use flat black paint. Also the motor would need to be synced. The camera already sends out a electronic pulse to do this automatically.


-Brett Erskine
www.CinematographerReels.com

MECHANICAL SHUTTER
 

"If Im right this should take the hard edge off of the motion blur on progessive digital cameras."

Brett, you should ask Dan Vance about this.
He built his 1/2" Progressive scan camera with a mechanical shutter, I'm sure he'd have some insights on it.

http://home.teleport.com/~gdi/vancecam.htm

Luis-
Already done. ;-)

I met Dan Vance at NAB. We talked briefly on the subject. He's a incredible guy. I mean jez the guy MADE his own progressive scan video camera before any of us knew what the DVX100 was. I hope hops in this thread and helps us out.

Damn I really have to slow down and proof read my post. Hope you guys can understand me.

Joel,

Your question about an anamorphic lens can probably best be answered by checking out this thread:

http://www.dvinfo.net/conf/showthrea...5&pagenumber=1

Check out the pictures. I think they make it pretty clear what the options are for an anamorphic lens within the adaptor.

Justin

Hi Justin, thanks for the link. I read through everything on that thread, but still don't understand why you wouldn't want to place a cylinder lens in front of your GG that expands your image vertically. The benefit of this is that you spread the same image out over a larger area of ground glass. This has two nice repurcussions for the final image since the weaknesses of the GG are limited resolving power and visible grain.

I haven't seen a real reason not to take advantage of a larger projection area.

Joel-
Heres why. When you stretch it out you create a image that may be 2.35 in aspect ratio but the image is also distorted as well. Correcting for this will only take you back to a 4:3 image. Now you are right about the fact that by using a larger area of the GG your going to have smaller/less noticeable grain in the picture which may be all that your looking for. What Im doing is squeezing a 2.35 image to fit into a 4:3 aspect ratio full frame on the GG so I can use ALL of my CCD. This will give you a higher res.

So to sum up your idea gives you less grain and my idea gives more electronic resolution.

-Brett

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.

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

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.

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.

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??)

Acid Etched Ground Glass
 

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

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!).

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

Very cool! Thanks James!!

Thanks for the comments
 

-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.

Jaime
 

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.

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.

Re: Jaime
 

<<<-- 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!

Smoothing
 

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

Alex,

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

John
 

Sounds like an idea squishing it between two pieces but I didn't try that. I left the filter glass in the housing. It kept the paste away from the side I wanted to remain smooth plus it was just easier.

The toothbrush was just a handy, non-scratching applicator that allowed me to apply the paste in a uniform manner. I'm sure you could use anything that evenly contacted the glass and made the application more uniform. It was the non-uniformity of application that resulted in blotchy unevenly etched glass.

For those who didn't catch it in the lengthy posting It only takes about 1/2 hour for the entire process. Not hours.

http://home.bellsouth.net/p/PWP-AcidGG

Is a pic of my Acid etched gg at 200X the block is a calibrated piece of paper .4mm across. The smaller object marked with a green dot is a hair.

I'll try to get some mechanically etched (1000 grit AO) tomorrow.

Hi James, is that a jpg? I think the image isn't linked to properly. I can't get to it.

me too

Justin et al, you are welcome... no pics received so far, though...

I'm working on vibro35 version (some call it alex35) for high-def camera JVC JY-HD10, and of course the roadblock is how to achieve oscillating/vibrating movement of the GG cheaply.

As everyone, I'd much prefer static GG, if at all possible; Jamess said that he did achieve the best results, so I'm extremely interested.

Thanks for posting offer Alex
 

but I couldn't find your email, my spam filter kills a lot of legit stuff.

Anyway the link should work now. it only shows the acid etched gg surface at high mag. I'll post a mechanically ground pic tonight.

the pics are .jpg

comparison of AO ground vs Acid etched
 

the pics of the two are up.

If someone has a WORKING Aldu35 with posted pictures, a spare UV filter, and a Self addressed stamped envelope. I'd be glad to etch it with acid.

James, regardless the pic hosting... could you please contact me by clicking here. Thanks!

I'm having some issues with my Aldu35
 

I've been putting together one of these setups based on all the information everyone has been working with on these boards and I set up a pretty rugged one and shot some test footage.

I ground a UV filter with 5 micron and then 3 micron aluminum oxide for my ground glass. I have to say it came out really well, I did about 5 filters and used the worst one for the testing so I didn't have to be very careful with it.

I have the Century Optics 72mm +3.5 achromat on my DVX-100A. With a 72-55mm step-down ring with the ground glass immediately after that I can fill the 35mm still frame at Z70 and MF00.

I first shot tests without any condenser piece and there was a huge hotspot in the middle of the frame which got much much darker towards the edges, but the image in the center was looking nice hehe.

I can't seem to find any condensers rated at the same flange focal length as my nikon lenses (46.5mm) so for testing I got the closest thing I could find which was a 50x50mm pcx condenser.

My later test shots with the condenser were much better in respect to the hotspot, but there seemed to be some warping occurring which I'm assuming is because my slr lens and the pcx lens are not in sync.

But in both test shots with and without the condenser, objects which were out of focus in the bacground tended to have some kind of brushed swirl look to it and I'm not sure how to correct that problem. The whole setup is still real raw, I don't even have the slr lens mounted onto the adapter, I'm just holding it on so I'm sure stray light is proving to be a problem as well.

I'v got some space to host pics and my test footage, so if I'm not working I'll be able to put that stuff up on Sunday cause I'd really like you guys to see it and give me any of your insight on as to what I may be able to do to get the image to be acceptable.

Thanks to everyone who is working so hard on this rig because if it wasn't for you guys I wouldn't be able to even think about this as a possibility for my projects. As soon as I have all of my stuff uploaded I'll post the links so you guys can check it out. Good luck to everyone. Thanks again.

Nick

James B., based on your posted pics, the etched GG seems to give nicer contrast (or at least more image contrast) than the AO GG pic you posted. I'm looking forward to seeing more samples when you get your cine lenses. Nice work.

Nick, I'm curious about seeing your distortion, so I'm looking forward to your image posts.