Yes I'm afraid I have another adaptor.

Hi guys, been busy at work and research on our project, I think I have news that could help all of you understanding a bit more about the problem we are seeing.

First marlene, I love your AOL case footage, if you have one too many case feel free to send one in UK to me :)

Now I thought it was time for me to return to basic, and make a bit of research and development on our project.

A long time ago when I was studying for my dregree in electronic I did a bit of opto_electronic, it's not quite what we are dealing with but it does help me understanding a bit more about light propagation, frequency, and clear aperture.

SO I will keep it as simple as I can.

First Problem is color seperation: This is due to the fact that when you use a lens, in this case the +10 macro, not all the surface is usable. you have aperture, and you have clear aperture. because of the shape of the lens only a certain diameter can be used. so without going into any scientific calculation, les say you have a 49mm close up lens, then only approx. 35 mm of this diameter can be used to have the effect required without distortion and light seperation. when you get to close to the side you have a king rainbow effect where each frequency used to create a white light are diverging and you of course get the light primary colors.
If you want to fix that then you will need to you a bigger diameter lens. for example a 72 mm +4 whould allow you to zoom onto the gg with no aberation.

Now second problem that seems to bug a lot of you is the hot spot.
Well this one is a funny one. you all know by now that creating the perfect ground glass is not that easy.D-screen, wax,plastic, all ahve their share of problem. the hot spot is due the material transaparency factor.

simple test, if you take a UV filter and replace you GG with it, what's happening? the light goes through with nothing (or very little) to catch the light. so what do you see? Only the hot spot which is in fact the light going through your lens. Now more opage you GG is then the less you will see the hot spot but then again the less light will go through, so you are loosing stops.

A bit of science: whan you look at UV filter, it looks perfect, well it's not..if you have a powerfull microscope you will see that it's chaos on the surface of it.

now by polishing with certain product, we make this chaos even more chaotic. that's the D-screen. but the light still go through quite a lot, so a condenser is used to correct the problem which is not perfectly corrected, but it doesn't matter because the d-screen was created for SLR, and you just use to look at what you are going to shoot, when you take the picture, the light to the film directly. the D-screen surface is altered with micro scrathes for you to resolve the image. now one funny test, if you put the d-screen under water it will become transaparent, it's bicause the micro scratched are filled with the water particles.

Now marlene may have found the solution to have problem. the AOL box is made of plastic, that is chemically altered, so all the paticle are heted together and create this compound full of micro particles. now the light goes through alright and it's also being retained just enough by the particles.

in a way it does exactly what wax will do but it's not messy:)

so I think you now all want to concentrate on finding the right plastic with the right balance of particle to achive you goal, and stick with a 72 mm macro lens if needed, the 49mm will always give you the problem...

Anthony
 
moochy said:
First Problem is color seperation: This is due to the fact that when you use a lens, in this case the +10 macro, not all the surface is usable. you have aperture, and you have clear aperture. because of the shape of the lens only a certain diameter can be used. so without going into any scientific calculation, les say you have a 49mm close up lens, then only approx. 35 mm of this diameter can be used to have the effect required without distortion and light seperation. when you get to close to the side you have a king rainbow effect where each frequency used to create a white light are diverging and you of course get the light primary colors.
If you want to fix that then you will need to you a bigger diameter lens. for example a 72 mm +4 whould allow you to zoom onto the gg with no aberation.
Click to expand...

I think I understand what you are saying moochy. I was doing some tests with different macros and combinations of macros today and noticed that the chromatic aberration showed up the most around the edges of the image. I think that this relates to what you are talking about. So are you saying to use a 72mm +4 without the smaller mm +10?

I have an achromatic 50mm + 10 on the way from an ebay seller. I will let you all know how it works out.
 
snodart said:
I think I understand what you are saying moochy. I was doing some tests with different macros and combinations of macros today and noticed that the chromatic aberration showed up the most around the edges of the image. I think that this relates to what you are talking about. So are you saying to use a 72mm +4 without the smaller mm +10?

I have an achromatic 50mm + 10 on the way from an ebay seller. I will let you all know how it works out.
Click to expand...

well you are right, what I'm saying is that you need a bigger diameter that what you gg is to resolve the image without aberation.

I not sure that only +4 will be enough for everyone, depending on how far away the gg is from the camera. in an ideal world we would use only the zoom of the camera but the gg would have to be quite far away. I tried to use 72mm +3 and +4 together by my GG is still to close to the camera. but I don't aberation, because I'm in the limit of the clear aperture.

of course they don't do +10 on 72mm and even if it exist it must cost a fortune....
 
Along with the AOL CD Case Screen I am using the 72mm +10 Macro next to the DVX lens and on top of that is a 72mm +4 Closeup filter. With that combo I am able to avoid the hotspot and not have to zoom in so much, but in my "lots o movement" test I do pick up a little blue fringe in a little of the footage which could be from a cheap +4 Close up. I totally agree with Moochy's advice to stick with 72mm, I never considered using a smaller size for the reasons Moochy mentions.

When I first picked up the AOL case my thoughts were how much it resembled the wax screens I had been making, in fact, I put one of my wax screens next to it to compare. The plastic does have some stress marks running through it when you look at it in the light at a certain angle but those aren't showing up on the image since it's straight on.

There was an earlier post in this thread after I posted my AOL Case screen findings that had a link to a place where you could buy them in bulk. These could be even better since they haven't been through the mail system. I had 6 cases sitting in my inventory and of those 6 only 2 had enough usable area.

I'm sure that there are other rigid plastic products out there that will work. Let's find them!
 
Try finding a custom plastics manufacturer, see if they let you customize your surface... if you have a place locally, go and check their stock. I checked Canal Plastics here in NYC, along with a bunch of other places when I started my adapter, but to no avail. There might even be a general term for the finish the AOL case has -- I know with glass there's, for instance, "opal" which is smoked, and all sorts of manufacturers make it and give it a proprietary name.
 
Also, if you can Marlene, post higher res footage. I'm seeing a lot of grain in that video and I think if you posted higher res footage (be sure to pan) then people here would have a better sense if this is worth pursuing or not.
 
Super8, good job w/ the testimonial and fire escape, worth the download.

Thanks also for posting your tests. That velum has an interesing 8mm projected look that would work well for a human interest type spot. The nikon D had some CA but worked well in the context of the (again very well done) music video.

I wish I could see a comaprison w/ an optisigma 1500grit GG.
 
bklyndv said:
Also, if you can Marlene, post higher res footage. I'm seeing a lot of grain in that video and I think if you posted higher res footage (be sure to pan) then people here would have a better sense if this is worth pursuing or not.
Click to expand...

I'm not seeing any objectionable grain on my bigscreen tv except for the underexposure in the shop (where the vid ends) which is just a result of the underexposure. I like a small amount of grain as it goes well with the 24pa, film-like quality that I'm trying to simulate.

As for people pursuing using an aol cd case as a screen, I'm not really saying anyone should pursue this as the great alternative screen. What I think is that the world is full of materials that can make focus screens and, just like effects filters, screens can be swapped for different creative effects.

Personally.......of the 3 screens I have (Nikon Type D, Wax, and AOL CD Case) right now I prefer the cd case screen.

I could post higher res footage but I still don't think that there is any true test of the quality of an adapter better than your TV. To truely judge the quality you must burn a DVD and play it. Since this is a DIY forum then I would think that the readers will be trying out different screens and making their own judgements based on the quality of the final output.

I plan on trying out different designs with my next adapters, such as a larger screen in a bigger tube. And I will probably keep creating adapters and comparing with previous adapters, and in the end (if there is an end) I may have gained the knowledge to really know what makes one static adapter better than another.

As I've said before.......it's fun, so it's easy to do :)
 
marlenedegrood said:
There was an earlier post in this thread after I posted my AOL Case screen findings that had a link to a place where you could buy them in bulk. These could be even better since they haven't been through the mail system. I had 6 cases sitting in my inventory and of those 6 only 2 had enough usable area.
Click to expand...

I've looked at that link. Looks like you buy them in packs of 100, and they get cheaper the more you order. If only we could find something of the same material but readily available. The original footage of the AOL case in the garage looked really good. I that adding the +4 made it look much worse.

On a related note, J said he'd like to see this compared to an optosigma. From the three different adapters that I've seen which have used optosigma glass I'd say none of them were quite up to par. They all seem to exhibit a certain 'look' to their footage. One which I don't like. It really seems to muddy up the footage, which is useful in some situations but not in all. It is interesting to see the differences though.
 
Well, there you have it.....in the pudding as they say! :)

"a shame to have them so close to each other, but.." -DERP!!!

We have a CO achro/diopter +4 at work and it runs circles around my Asian +4, so last week I purchased a CO +7 like in Dan's comparison. Makes the project much more expensive but I think it will be worth it. Should get here by the end of the week. I have totally gutted my original adapter and rebuilt it in hopes that the Achro/diopter will improve the image. My color smearing was never really that bad and only reared its ugly head on certain white objects, but now I want to take it to the next level.

Oh, and my Linhof focusing screen will be here tomorrow, but I might have to turn around and trade it in for an AOL case! DERPITY DERP-A-DERP!! :undecided
 
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snodart said:
Ed, what size (mm) is the CO achro/diopter +7 that you are waiting for?
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58mm. CO does not make a +7 for 72mm threads. The highest for 72mm is +3.5 and thats not high enough.
 
My question is this. Obviously the Asian glass is inferior to the CO glass. You get what you pay for. But for those of us who are cheapskates, wouldn't it be possible to take a +10 and a +4 and turn the +4 around? What I mean is take out the retaining ring and switch the +4 so that it is facing the +10? That should cut down on the chroma aberration but do so in a cheaper manner. I have no doubt that the CO glass that Ed just ordered will work better than the Asian glass. I have an achromat that I got off eBay that I am working on incorporating into my design. If that works then I won't worry about the +4-turned-around idea. But I just thought I would throw that out there as Ed has mentioned he got better results with this configuration. If the achromat fails I'll get a cheap +4 and try it the way I just mentioned.
 
I've been able to use my adapter just fine without the +4 and with no aberrations. The only time I used the +4 was to use less zoom when hand holding the DVX. So my point is......if you're going to keep your camera on tripod or well stablized then don't why add the extra glass at all?
 
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