Best GG Diffuser?
 

Since I'm living in the UK, it's a bit harder to find the parts needed for the static adaptor, and while I've got the spacers and CU lenses ready, I still don't know what the best GG to use is. I tried scrubbing a UV lens (rookie mistake) and it looked rather awful, and I tried pitting a clear CD with a screwdriver end (the soft bit) and that turned out better, but still nowhere near good enough.

Since Knight Optical seems to be the best distrubuter here for this kind of thing, what type of GG would you reccomend using from them?
They have regular ground glass, opals, plastics and anti-newtons (apparently), and I'm not sure what would give the best diffusion, and minimum grain. Any suggestions?

WAO5 ground glass or microcrystalline wax. Wax is better. I'm putting a tutorial up on microwax diffusers shortly -- should be up by the week's end.

- jim

That would be brilliant, I've heard of the wax ones being used alot. The only type of glass this company sell is LEGB, B270 or UV fused silica... out of those, which would be the best to use, do you think?

I'm not familiar with what you're mentioning. I'm fusing two UV filters together with a very thin layer of microcrystalline wax. You can get a low melting microwax from companies like Strahl and Pitch -- http://www.spwax.com/spparaff.htm

If you write them in a somewhat professional manner, explaining to them that you intend to experiment with their wax with the hopes of using it in a future product, they will likely send you a 1lb sample free of charge.

- jim

Yeah, you mentioned the WAO5 ground glass, but I was saying I couldn't see anything at Knight Opticals that resembled that type of GG... unfortunate that this place seems to be just about only GG distributer in the UK. I'm intrieged by the wax techinque, but must admit I hadn't considered it as a viable option before you mentioned it. Would using wax give a significant improve of diffion from glass? And are there any known internation microcrystalline distributors?

ground glass
 

after trying 5 different ground glass companies, this was by far the best. http://www.optosigma.com/miva/mercha...+%26+Apertures


the one I used was the 50mm 1500 grit

cheap ground glass
 

I found this company It has a super cheap ground glass $7
It is 500 grit .I have not tested this one yet . the thorlabs was $15 but so far opto sigma is the best . It is the most expensive though.http://www.catalognavigator.com/roly...ompanyid=64329

Thats for the links, the OptoSigma GGs look like they'd certainly give great diffusion - do you have any images taken with that glass, Richard?

The microwax glass diffusion is different, optically speaking, than that of the WAO5 glass. Diffusion on the ground glass is a series of pits and ridges across a surface, the pits catching the image. WAx, on the other hand, diffuses the light by bouncing it on (in?) pieces of crystal suspended in a clear medium. For this reason, it's more crisp where detail is concerned.

On the other hand, producing properly thin and error free wax glass is a bitch, as I'm finding out. On my fifth try today -- doing two at a time with the hopes that one will work out :(

- jim

From all my experimenting, microwax definately produces the best surface, in terms of grain (and brightness, if a thin enough layer is achieved). I will say that there is NO grain noticeable ( at least when used with an SD camera - I have no HD camera to test )

However, as Jim stated, it is really difficult to work with.

I find myself using larger sheets of glass and after the wax has cooled, pointing the camera at whatever part of the glass is bubble-free. LOL!

What kind of errors can one expect from using the wax? Would it give a rippled type image if incorrectly applied, and would flashed opal GGs give good diffusion in comparison?

Steve: My first attempts were with a layer of wax coating one side of a single piece of glass. You definately don't want to go this route. You can easily get ripples, the thing would be near impossible to keep clean, if it melts then that's that.

However, with wax sandwiched inbetween two pieces of glass (and then sealed after you get a good layer), you can clean it, don't have to worry about ripples, and if it ever melts, it won't really go anywhere (It would just be transparent until it cools.)

flashed opal would be interesting to try. It provides excellent diffusion but has very, very low transmittance so it's probably not a good idea for this sort of thing.

regarding using glass with wax adapters:

Since the glass is uncoated you are going to loose at least 15% of your light.

There is definately some noticeable light loss (I haven't calculated how many stops), but this is mainly due to the wax. I'm not sure how much light loss is caused by the glass alone.

The problem is I'm using a GS120 which has horrible low-light capabilities, or so it seems to me, I'm not entirely sure how it fares in compaired to other DV cams. This means that I'll need to use something that gives a very bright image, but I'm not sure how worse wax would be when compaired to other options such as regular ground UV filters. Thres also the silica-uv glasses, but again I'm not sure how bright an image I'd get in compaired to wax. On the other hand, if the wax gives a very sharp image and doesn't reguire high-level pitting like the GGs do, then I think it would be worth considering. Does wax give a drasticaly darker image than glass?

It depends on the thickness of the wax. If it's thin enough, you can get a very bright image. I just recently got a really thin layered wax adapter, but I want to do another and shoot for a completely bubble-free version. If I succeed, I will post some uncompressed framegrabs comparing it and my AO5 glass adapter.

ground glass test
 

I think this is a shot made with the opto sigma 1500

http://www.liisikoikson.com/ftp/noise_redux_ex.jpg


this also contains the chris rubin workflow
which looks to remove whats left of the grain in a static adapter

Richard,

that is not optosigma, but a 600 grit sandblasted glass. Optosigma gg grain is much finer and not really visible on a fine-detail image of that particular size.

Chris

So, there would be hardly any grain from a 1500 GG? I wonder, what is the difference between grinding your own glass, and buying one premade? Does it work out alot more cost effective D-I-Y, or do you get a better image with a bought glass?

ground glass
 

chris your first image ,did look like more grain then I am seeing
with the 1500 ,. and maybe a good indicator of what the royln 500 grit will look like.


and for all my efforts hand grinding, I was never able to make a piece of glass as good as the one I am using now.

the next idea is to see if we could get the company to cement the ground glass to the plcx in a dust free room .

dust is my biggest problem now

static adapter
 

chris I may be adding a second plcx to the adapter.
I just tested the system on a tv chart and I am seeing a slight barrel distortion. I think a matching plcx on the opposite side will correct this . this is a link to a german patent for the movie tube
it has a wax diffuser in between two plcx . If we could get opto sigma to make this as one piece we would be set .
I don,t think we have to worry about patent infringment
because we are mearly buying off the shelf lenses and arranging them in a specific order in the tube and sharing the order

http://v3.espacenet.com/textdoc?DB=E...QPN=DE10240076

Richard, do you have any idea if OptoSigma take international orders? I had a look at their international page, but it was more for a laser optics firm that stocked OS equiptment related to lasers. If not, have you seen any optics sites that may ship the UK?

Steve,

The Optosigma dealer in the UK is:

http://www.laser2000.co.uk/

Richard, I use this in my adapter:

http://www.surplusshed.com/pages/item/l2030.html

No barrel distortion, but difficult to position inside the adapter because it has no flat surfaces. I'm still working on it, but I'm sure I'll get it done.

Chris, thanks for the link, the trouble is it seems they don't stockground glasses there, just the laser side of OptoSigma. Now, I may be wrong, but I'll give them an e-mail to see if they do the ground glasses. Also, what camera were you using in your test, Chris?

Steve,

that was XL1 with stock lens

Richard Mellor-
Increase the distance between your GG and video camera a few inches and zoom in a bit more to reframe again.

You shouldnt have any more barrel distortion problems.

i got barrel distortion with my adapter.
condenser as GG and macro only.
Then i add a lens (looks like a huge contact lens) between the macro and the GG-condenser.
moving back and forth vary the barrel effect (positively and negatively) but a finally found a position where barrel disappear.
The best of all it is that it gives me the brightest picture i ever dream and totally remove the vignetting.

Giroud, you say your adaptor gives a bright image, could you perhaps divulge any more information about the type of lenses your using, ect?

static adapter
 

brett :I added a1/2 inch tube to the system as per your advice. and your right the barrel distortion is gone.

as many builder, i unfortunately work with refurbished elements wit very few (if none) data about them.
My GG is a lense 55mm diam very thin (1mm in the border and 6 mm in the center).
It has been taken off of a TV camera lense (Fujinon-TV Z 1:1.7/10-140), one of the front lens.
The macro is a 52mm achromat from surplus shed, but except diameter , i have no information (works well with my VX2000)
the "contact lens like) is another lens from the fujinon.
For the GG i used AL. oxyde 1000.
I is very fast to obtain the proper result (when the lens is flat!), because almost every lens i tested until now, is never really flat, so the first stage is to use abrasive paper (starting with 200 then 600 ) to make it flat.
fortunately, the result is almost perfect, with no grain visible in normal light. Low light with iris closed increase the grain visibility, but having filmed at night, i can say it still workable.
The real secret is to have a 35mm lens with big output.
Most of lenses have a rear lens with diam. ranging from 15mm to 20mm. So you get a small bright output just behing the GG.
So when the camera see the GG, if it is not really opaque, you can see the bright spot.
I use now a Nikkor 1:1.4 that has a 30mm rear lens.
if you compare to the diameter of the GG picture (about 47mm)
you can imagine that really make a difference.
additionally the angle of incoming light on the GG is a lot better.

35mm adapter parts list
 

Hi everyone:this is a link to the new thread with complete parts list and photohttp://www.dvinfo.net/conf/showthrea...threadid=37296

I found a web page put up by a guy in Germany who has built a static adapter using a glass and paraffin wax screen. He seems to be getting some really great results with no hotspot or grain problems.

The first link is to site and the second is to the screen manufacturer.

http://www.blindcat.de/commentcreate.php?page=dv35genglish&title=DV35g%20-%20A%2035mm%20Adapter&parent=dv35g

http://www.glasscreen.com/

not really impressed by the picture.
you can do the same with a homemade GG and alu ox. 1000 grit
http://www.giroud.com/minidv/c.jpg
http://www.giroud.com/minidv/b1.jpg
http://www.giroud.com/minidv/b2.jpg
http://www.giroud.com/minidv/d.jpg
http://www.giroud.com/minidv/e.jpg
http://www.giroud.com/minidv/a1.jpg
http://www.giroud.com/minidv/a2.jpg

Giroud, what's the details on the rest of your configuration? What video camera are you using?

Giroud's camera?
 

If it's what he has listed on his profile, it's a VX2000.

Well, that's some of the nicest footage I've seen anywhere on "Alternative Imaging Methods". Documentation would be awesome (what macros if any, what the gg was mounted in, what extention pieces were used, and how was the 35mm lens attached, photo of the adapter and adapter on camera).

Giroud,
 

What camera did you use in these frames, what are the other details of your setup, they look much better than others I've seen.

Old Post, Great Pictures, Any Answer?
 

Several people asked Giroud what camera / device setup he used, but no response that I see.

The pics look much higher res. than that of a VX2000, which is what is listed in his profile. So whats the secret???

We need one person to post that they can see grain, and another to post that his adapter must have much more grain, which should be visible in a panning-motion clip. This thread is just not the same without it.

My confusion is more about what camera he used to capture these stills, and less about the grain (or lack there of) from the adapter.

To me, the image shows no signs of interlacing, just wondering if the footage a progressive scan camcorder, or if he deinterlaced it in post.