35mm Adapter Static Aldu35

[Jonathon Wilson]

People on these forums (myself included) tend to use the term 'ground glass' when what is really meant is 'imaging plane.' A 'ground glass' is a specific material treated in a certain way - and works as an imaging plane. Of course, so do frosted/scratched cds, strips of satiny magic tape...

In order for the depth-of-field characteristics to be captured, the imaging plane must have enough diffusion to actually become a projection screen for the 35mm lens. If you're actually seeing a flat image which is materially on the clear cd/uv filter, than you may have fingerprints, or some other material on the surface. If not, you may also be looking through the clear disc/filter and seeing the 'aerial' image from the lens. If this is the case, your imaging plane is serving no purpose. Unfortunately, this will not maintain the depth-of-field characteristics of the 35mm lens and will image to your CCD exactly as if you weren't using an adapter (except a little darker and upside down).

Jim - that's exciting. Definitely let us know what you find. My single-ply architectural mylar film secured to my clear cd works pretty well, but I'd love something with an even finer grain. (I'd rate it at about 9 micron gg size... okay for spinner which is what I have, but I still see a fairly noticeable grain-swirl which takes some massaging in post to remove).

[Rai Orz]

Brandon,

A GG must strew (not refeflect, and not only let through) the light.

The only way to do this is a structure of different translucent areas. One more, the other less, but both are translucent.

So the ideal GG is:

The structure, what ever it be, is smaller than the smallest pixel of the camera
The structure must be even
The structure is only on one side (or in the middle) of the glas (or plastic)
The structure is also more thinly than the smallest pixel

The GG lets light through, as much as possible and if you look by the glass, its a little like milk, not like glass, so you can not see any details.

[Wayne Morellini]

Rai, something that has come up here before is using microlense viewing screens (and also low angle hologrphic diffusers). People have said they cannot be made fine enough, but the sensor chips themselves are covered in smaller microlense arrays to maximise light to each pixel. What do you think of the possiblity of using one of these to straighten the light? I know your company works on cinematic optical stuff, so maybe you can advise us on this?

Thanks

Wayne.

[Rai Orz]

Wayne, you are everywhere, (smile)...

Yes you are right. Self-made-people cannot made it fine enough, but... I only say: nothing is impossible...

I will email you, but today i am very busy

[Wayne Morellini]

You wouldn't believe it, I think I was here before I was over at the hd threads (and yes, I am registered with every major forum, but only concentrate on this one ; ).

[Frank Ladner]

Filip: LOL!

Microcrystalline is the finest thing I've used for an intermediate image surface, but it is so hard to work with that I have thoughts about just shooting w/ open aperture and ND filters at telephoto to achieve the DOF I want. :-) Anyone else been thinking like this?

[Eric Ohman]

- Frank

I've heard the there is/was a company who made GG's using paraffin... I don't know what the company is called but they sure know how to get rid of the bubbles and uneven surface..

while writing here I wonder Frank if the wax-solution softens the image, like a soft filter? Looks like that on the test pictures

[Frank Ladner]

I'm not sure if anyone other than Bosscreen uses Paraffin wax to make viewing screens, but yeah...I wish I knew how they did it.
Not only are bubbles a problem, but little pieces of lint and dust can easily get into the mix and show up in the footage. My kitchen isn't the best workshop for this. :-)

About the diffusion:
According to the manufacturer, Microwax has a very low refraction index. Couple that with its small grain, and it gives a pretty sharp image. I have some new footage captured and will try to post something tonight or tomorrow. (Some stills and a small pan shot.)

[Eric Ohman]

- Frank

Do you think you could post a 10 frames clip with the setup you used on http://www.frankladner.com/testpics2.htm too? I would thank you forever!

You can export it as a jpg-animation if you want to save space.. btw, i have 400mb hosting so just tell me if someone of you guys want me to host something for you ;)

/ Eric

[Frank Ladner]

Eric: The images on ttp://www.frankladner.com/testpics2.htm are pretty grainy - especially noticeable in the moving footage. I deleted the original footage those framegrabs came from, and I have likely recorded over the footage on the DV tape. (Using the same tape for all my 35mm adapter tests.) However, if I can find it, I would be glad to put up a sequence of frames.

Also, while I'm here - I spoke with someone about getting some microcrystalline wax with a 170 degree melting point, which is above what I am currently experimenting with. Does anyone happen to know what the melting point is on the wax in a Bosscreen?

Thanks!

[Jim Lafferty]

If/when I move to experimenting with micro wax, my efforts would likely surround sandwiching the melted wax between glass extracted from two filters, and applying even pressure across their surfaces with a vice. This way, you'd force the bubbles to the edges, and also solve the lint problem by making both surfaces glass (much easier to remove lint from glass than wax.)

Of course the problem would be applying enough pressure and not too much, coupled with keeping the glass from being scratched in the process.

That's the theory anyway. In the meantime I'm waiting for my WAO 5, and if this proves to be a sufficient improvement over my current setup, I'll forgo the wax idea and just start shooting.

- jim

[Jim Lafferty]

As it turns out, dyeing PVC complicates things -- in order to get the color to set in the plastic properly, the dye bath must be near boiling and stay there for the duration (about 30 minutes). To my surprise, this actually shrinks the PVC by about 3mm, just enough to make previously tight fittings impossible.

My only recourse at the moment is switching to a 55mm filter for my GG (down from 58), and file down the interior edge of the piping so that it slides over my achromat.

In the future, I'll be dyeing both halves as a solid piece, with metal rings at either end to preserve the proper diameter.

I hate learning these sort of things the hard way :/

- jim

[Eric Ohman]

updated with some new movieclips and pics.

i'm still into the cd-adapter (agus). do you think there are any solutions to make a static adapter with no visible grain? i mean, the testpics i've seen from frank, why do you need it better?

- Frank
What's the bad thing with the wax GG you used for testpics3.htm? Cause what I see looks great. Sell me one ;)

[Eric Ohman]

www.de-interlaced.net/mini35

sorry, always forget to copy-paste the link

[Frank Ladner]

Eric: Thanks for the comment!

I don't think what I have would be suitable to sell, and I have no clue what it would sell for. I have yet to come up with a repeatable way to get a flawless wax layer.