Katz Eye Focusing Screens

[Ben Winter]

http://www.katzeyeoptics.com/

Offer custom-made focusing screens for around $100. Expensive, yes, but for an additional $55 they apply what they call OptiBrite which apparently gives a brighter image at lower apertures. The cooler part? They manufacture focusing screens for dozens of cameras with or without any gridlines or markings. Pick the size you want, and bam--you've got a screen. If they diffuse properly, I think this may be an impressive way to go.

[Andrew Todd]

"By f6.3, it's good for about 1 full stop."

i wonder what the brightening "process" is

[Francois Poitras]

My guess is that it is a coating applied to the diffusing surface. Reflexite apply a brightness-enhancing coating on their Beattie’s, so that would make sense.

I really wonder about the effects of a coating on a diffuser surface, how it is applied, etc., as a drop of liquid on a diffusing surface tends to fill whatever causes the diffusion (scratches, holes, microlenses, etc.) and simply cancel or reduce it.

[Francois Poitras]

Post deleted.

[Jim Lafferty]

I think the "brightness enhancing coating" is actually a very very finely etched fresnel. Optical acrylic is already itself more transmissive than glass -- it offers something like 95-98% transmission, where glass is 90% at best.

[Francois Poitras]

In the case of the Reflexite, it seems to a coating, from the document below.

http://www.display-optics.com/pdf/Fo...nologyrev3.pdf

I inquired about OptiBrite, and apparently, it is not a coating.

[Ben Winter]

Wow,
Ok so I talked to the woman who owns Katz Optics, and she was a truly unbelievable fountain of information. She knows more about focusing screens than...Carter knows about liver pills. This is what I gleaned:

Katz Optics doesn't actually make any screens without markings. All of their screens have split-prisms at the very least. They've got one mold in the early stages of a plain matte, but that's months away and the design could change.

So, in the awesome spirit of helpfulness, she pointed me in these directions:

There's something out there called Satin Snow. It's for medium and large format cameras but from what she said it sounded like the guy would be willing to machine the stuff in 35mm format. It doesn't look like it's grainless, but for a focusing screen that's to be shaken or stirred, it might diffuse properly and at least have minimal, if still visible, grain.

BrightScreen (http://www.brightscreen.com/flash.html) manufactures very expensive screens. They also use brightening technology that makes the image brighter but doesn't properly diffuse. $200 a pop. I'm not ordering one.

She mentioned alternatives to the now-discontinued Nikon D screen:

The Fuji S2 and S3 have plain matte, if you can find them they are good diffusers.

The Contax RTS II is a plain matte, but obviously the Beattie screen does not diffuse properly. She told me the Reflexite coating fills in the pits/troughs of the ground glass, reducing grain but also it's diffusion properties. If there are other companies that make this focusing screen, they might be viable options.

The FU series (Contax?) are really good focusing screens. She said she doesn't know if there's a plain matte, but while the BFU 4 is split-prism there might be other ones that aren't. I haven't been able to find any information regarding these screens yet.

The Leica R8 is a clear matte, but they're on the expensive side. Think 60-80 bucks a pop. I'm ordering one.

The Canon EC diffuses the best, but she doesn't know if they're made in clear plain matte format. (EDIT: checked, they aren't)

Then she suggested something really neat. the Nikon D100 camera uses a plain matte focusing screen behind a laser etched glass with markings. It isn't supposed to be user replacable, but if you call up Nikon they might sell you a "replacement" for around 20 to 30 bucks. I found a site that sells it for $25 here: http://gallery.bcentral.com/GID20255...us-Screen.aspx
I ordered one of these as well.

So, some things to look into. Cheers!

Ben

[Jim Lafferty]

Good luck with all that. Satin Snow glass has long been known around here and does not meet required standards for a static glass.

[Frank Hool]

Yeah, i have to agree with Jim. I had a look into "zenith e" gg because of this thread and because of kilo35 thread. I could see grain with my naked eye. It's understandable anyway because slr application doesn't require nothing too good. Artifacts only appear in viewfinder.

[Ben Winter]

These are all for my Letus35 adapter. My top priority is bokeh, and that means proper diffusion, which probably means grain, which isn't a concern for me because it's being vibrated.

[Andy Gordon]

Well grain might be a poblem for you cos there's a limit to how much you can hide with oscillation. e.g. The POC20 is an excellent diffuser but the grain can't be hidden with oscillation (not by me anyway), what you end up with is a static grain pattern something akin to the grain on a stationary 1500 grit gg.

[Toenis Liivamaegi]

How many of all bokeh tests are carried out on a progressive camera?
By my little knowledge any deinterlaced and in-camera-fake-progressive footage show bokeh quality that is not comparable to real progressive footage as sharp edges of light discs in bokeh will be fuzzier.

My only point here is that real progressive cameras can maybe contribute to better bokeh.

I`ll do some extensive testing when our HVX arrives next week.

In the other hand maybe it`s possible to order Intenscreens without Reflexite`s special coating?
They do custom screens including oversized 35mm ones. Minimum order is 10 pieces and prices aren`t higher than for normal screens.
I have been in contact with Reflexite`s Donna Desmarais regarding custom screens. I`ll mail her and ask about skipping that special coating process.
I really don`t know any more what`s the point if it is possible to use frensel gg combo from D100 but I´ll ask anyway.

Regs,
T

[Mikko Parttimaa]

We have seen tons of good bokeh produced with cameras in frame mode or deinterlaced. MacGregor and Jim Lafferty have done this with FX1 and GL1. At least I can't see any differences in Go35 tests made with GL1 and DVX100 for example. Of course DVX with its higher resolution has some effect but I don't find it that dramatic.

Or are you confusing in-camera bokeh with adapter bokeh here?

Word 'bokeh' is starting to sound a bit dumb. I wonder when all japanese people start coming here.

[Toenis Liivamaegi]

OT: Can anyone say, in formal way, what kind of diffusion properties we need to get proper diffusion and better out of focus areas?

How can diffusion properties be specified?
By thickness, rear surface, parallelism and transmission?
Or can we relate it directly to GG`s grade as universal measurement?

BTW
Yes, Reflexite can manufacture beattie intenscreens without the "coating" and that doesn`t change the price.
Actually they can manufacture it in size of 44x25mm that translates to 15% wider than normal 35mm full flrame would be, vignetting with some (wide) lenses might be observed.

So, would we risk it?
I guess we shall see what news will D100 replacement sceen bring.

Until that I`ll put that development on the shelves.

Regs,
T

[Ben Winter]

Toenis,
If you can give me some information on how to order a screen without the coating I would be probably follow through. Thanks.