Snod35 DIY adapter info

[Noah Yuan-Vogel]

All I have left is grinding glass, and I've moved away from the plastic focusing screens and cut my own glass which I have been grinding using the wetordry 1500 grit sandpaper I have which should be about equivalent to 12 micron or less. Is there something about using the powdered abrasive that causes more diffusion in the ground glass? because im getting a focused image but way way too much hotspot and tons of aerial image. I guess I'll have to get my hands on some aluminum oxide powder. Anyone have suggestions of where to get small quantities quick? anything in new york? will using a powder definitely help? I know moving the camcorder back will help get rid of the hotspot but that is a last resort and there must be a way to get good diffusion and no hotspot at a close distance. any help would be greatly appreciated.

[Jake Danilchik]

Justin,

Yes, the 35mm lens I am using has a 35mm focal length ( sorry I hadn't posted a reply sooner ). Also, to answer your other question, no ND filters were addded (however the canon hv20 may have its own automatic ND.. but I believe that is not user adjustable :-( ). I received the 12 micron aluminum oxide powder just yesterday. Using your 12micron "process" I ground the F3 nikon screen , I housed it in Daniel Schweinert's Vibrating GG holder VH-72ND and the achromat lenses he offers. I am happy with the results so far. When time permits I'll send some clips with the aperture closed down. Also, I'll have to purchase some longer lenses to get rid of any vignetting, although it seems the use of 12micron aluminum oxide has reduced vignetting to an acceptable level. Thanks for the advice. I am tempted to go for the redrock micro 72mm achromat or the cinemate achromat. Any thoughts on one over the other, Anyone ??? I need approximately 10+ diopter ( the redrock micro doesn't have its strength listed. )

Noah, I hope the clips will further convince you to go with the 12micron Alum. Oxide. Try to call the people at willbell.com. Ask them to expidite it, as they are in Virginia so it shouldn't take too long to get there.

(The clips are raw hdv format ( with a quicktime .mov wrapper )).

remember to RIGHT CLICK and SAVE AS / LOCATION :

http://idisk.mac.com/jaked/Public/12...__F2_clip1.mov

http://idisk.mac.com/jaked/Public/12...__F2_clip2.mov

[Noah Yuan-Vogel]

I think I will first try a real focusing screen and then if that doesnt work as I'd like, I will find some 12u abrasive powder to grind with. Looks like the most readily available appropriate screen is a canon ee-a, will that fit in a nikon focusing screen holder? my adapter is all ready and built around a nikon f5 focusing screen holder, i imagine i an f3 type d screen or canon ee-a screen would fit in it with a little sanding or shimming? justin, looks like youve used both nikon and canon screens, how do they compare in shape and size?

[Noah Yuan-Vogel]

This adapter project sure is taking longer than expected. Justin, your webpage made it all look so easy and quick. I guess my problem is I'm in a rush to finish it and i end up having to make/find my own parts instead of ordering them online. (my motor broke so instead of ordering a new one online, i found pager at a fleamarket and took it apart for the motor). How did you make all your parts, Justin? Things like cutting nice plastic circles are so much harder without the right tools. I've been doing a lot of cutting and grinding with my new dremel which i ended up buying for this project. I'm juts about done, i just need to figure out how to mod my HV20 camera to flip the image...

[Lau Ho Ming]

I have grinded a glass using 9 micron Aluminium Oxide. But the image is much darker compared to EE-A and EE-S focusing screen, which I consider it is not feasible. Since I have shot a whole Project with my DIY adapter using EE-S screen. The brightness is barely enough in some indoor scene. So anything darker than canon screen is unacceptable.
But there is a problem from these canon screen. Is that these screen produce weird edge "ghosting problem" when in some very bright situation, look at 4.jpg, notice the windows frame on the bottom left corner. And the bokeh "radial blur" problem(6.jpg). Both of the EE-A and EE-S shows similar problem. So I guess that the problem is related to the fresnel field design of these screens. I'm thinking if there are any method to remove the fresnel field to prove my point. I really satisfied with the performance of these screens, really sharp and bright. But the ghosting artifact is really unacceptable. Is it possible to use some plastic scratch remover and polishing product to grind away and remove the fresnel field(The shiny face of EE-S screen)?

[Justin Snodgrass]

Originally Posted by Noah Yuan-Vogel

All I have left is grinding glass, and I've moved away from the plastic focusing screens and cut my own glass which I have been grinding using the wetordry 1500 grit sandpaper I have which should be about equivalent to 12 micron or less. Is there something about using the powdered abrasive that causes more diffusion in the ground glass? because im getting a focused image but way way too much hotspot and tons of aerial image. I guess I'll have to get my hands on some aluminum oxide powder. Anyone have suggestions of where to get small quantities quick? anything in new york? will using a powder definitely help? I know moving the camcorder back will help get rid of the hotspot but that is a last resort and there must be a way to get good diffusion and no hotspot at a close distance. any help would be greatly appreciated.

If the hot spot is that bad then the surface is most likely not rough enough. The more transparent it is the worse the hot spot will be. Willbell.com is the only place that I know of who sells small quantities, but there may be others.

Increasing the distance between the camera and the GG will help with vignetting some. It only helps a little though. If you are getting a nasty hot spot, then it is most likely from the GG not diffusing the light enough (being too transparent).

Jake,
I'm downloading the clips right now. I'm not sure which of the achromats would be better. I would guess that they are about the same quality. I've used the redrock micro 72mm achromat with my DVX and it worked as expected. I didn't notice any chromatic aberration or soft edges. Oh, the redrock 72mm achromat is + 10.

As for the EE-A and EE-S screens. They are much brighter then any screen I have tested. The image just didn't look that good in my tests though. From what I could tell, the ghosting issue is a result of the fresnel surface of the screens. They just weren't made to capture moving images. If you remove the fresnel surface (not sure that you can), the screens won't be bright anymore. I think the bottom line is that light loss is the price you have to pay. The Brevis is known to have very little light loss, but some would argue that the price is paid in the quality of the image. Honestly, I have never had issues with the light loss and I normally only use 500 - 1500W of light for a given set up. I slapped my first static adapter on the day that I pulled my DVX out of the box though, so maybe that is why I don't see it as a problem.

Noah,
about making the parts and the project taking a long time... I built an Ed35 (static adapter) way back in Feb. of 2006. It took over a year for me to have a working DIY adapter that I could actually use for things other than tests. I love to build and have enjoyed my time with 35mm adapters. Honestly though, with the money that I have spent in all of this, I could have easily paid for a pre-made adapter (almost two!). And the time that I spent working on the various adapters... I could have taken on a second job and bought 3 more. Of course there is much more DIY adapter info out there now. Just make sure that it doesn't suck you away from whatever your passion is.

[Justin Snodgrass]

Jake,

The clips look good. Clip two (with the white flowers at the bottom right) looks like it was a little blown out. Notice how the blown out areas get that fuzzy hazy look. I get the same thing when I use the camera's ND filters. This happens because the image on the focusing screen is blown out. Using a built in ND filter on the camera will darken the image so that it looks okay, but there is no image info in the blown out areas of the focusing screen, so they retain a weird blown out hazy look. Once I started using ND's on the 35mm lens (when needed) instead of the camera, I was amazed at the quality change. Anyway, not sure if that was the case with this clip, but just FYI.

[Bob Hart]

You may find it helpful to visit the P+S Technik website. The info to be found there is specific to the Mini35/Pro35 but valid for operating alternative adaptors.

[David Braund]

do you mind if i ask what mics you used and how you recorded the sound?

thanks