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Hey old guys! Which SLR's had fine matte screens w/o prism?
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PostPosted: Tue Aug 14, 2018 5:29 pm    Post subject: Hey old guys! Which SLR's had fine matte screens w/o prism? Reply with quote

1 - I'm 53, so I am allowed to yell "Hey old guys!" in the title? Smile

2 - I'm a noob, bought my first SLR one year ago: a used K5.

3 - After a few months, I drifted almost entirely to vintage primes.

4 - I changed the Focus Screen to a "terence_camera" feebay 45° split prism. It's pretty decent, but regardless of the prism, it cannot accurately resolve DoF at apertures larger than 2.8. It's hit or miss at 2.0, and random wider than 2.0. This screen is 1.45mm thick. I use foil tape for shim; it is 0.10mm thick per layer. I needed 1 layer to get accurate focus. The stock K5 screen is 1.35mm thick with 0.35mm shim. (Takeaway lesson: matching overall thickness of screen plus shim is not the route to achieving accurate focus during screen replacement. There are apparently other variables involved.)

5 - I did a lot of reading.

5a - A finer grind of matte is required to accurately resolve DoF at very large apertures.

5b - A finer matte is darker, especially smaller than 5.6.

5c - A fresnel etching on the opposite side of a focus screen focuses light from the entire surface of the screen to a central area of the VF. This improves the perceived brightness of a more finely ground matte, especially the darker corners commonly associated with finer matte screens.

5d - Laser etchings (grids, etc) and focus aids (prisms & donuts) on a focus screen affect the meter and therefore the metering algorithm. The software or firmware of a modern DSLR may compensate for the presence of a grid or other etchings on the stock screen, but the metering is almost always affected when the original screen is replaced with something different. Sometimes this effect will be somewhat linear, requiring only a baseline shift to Ev to retain fairly accurate metering across a range of apertures. Other times, the effect is not linear, especially when the replacement screen has a radically different grid or prism. In these latter situations, the meter is so whacked by the new screen that you often have to remember different Ev compensation settings for different apertures.

6 - I bought a Canon 5D Ee-s screen from a Japanese vendor on feebay, "jaipfe", $31. It arrived yesterday. I intend to cut it down to K5 size and give it a run. The version I bought is pure matte, no etchings, no prism.

Since 2010, various individuals have reported satisfactory performance from this Ee-S screen cut to fit Pentax DSLR's, even at f11 on bright days.

So I really don't have anything else to talk about. I should just slap the Ee-S in the camera and go. Which I will do soon.





But, I'm a tinkerer. And a cheapskate.
I like to mess with things, and I feel odd cutting up a perfectly good, brand new $31 focus screen. OCD? Smile

So I am somewhat compelled to consider other options.

As you all know, sometimes to get a lens you want, you have to buy an old camera bag with camera and flash and a few rolls of 30-year old film.

A couple of my purchases:
1976 Sears Auto TLS EE. The kit lens for this camera was a Sears Auto 50mm 1.4.
1970 Ricoh TLS 401, with kit lens Auto Rikenon 55mm 1.4.

The Ricoh body was very nice. Really excellent condition. Sold it on feebay for $28 plus shipping; felt good about that.
The Sears TLS EE body was less nice. I killed it to get the focus screen out. I feel mild guilt about this death.

The 1976 Sears TLS EE focus screen is acrylic plastic, 1.24m thick, matte on the prism side, fresnel on the mirror side. It is only 0.10mm thinner than the factory K5 screen. It has a donut focus aid with no other markings, except for two brutal scratches on the fresnel side. Ouch! These scratches indicate that someone once removed and ruined the screen for unknown reasons.
I may cut it to size and see how it performs in the K5, but I have not done so yet because it is so ugly, and also because I am somewhat obsessively fixated on the search for matte-only screens that have no central focus aid or prism.

My current long-term plan:
Buy another K5, so that I have a backup camera.
Designate one camera Fast, and the other camera Slow.
Use the chinese feebay split prism screen in the Slow camera, because it works great from 2.8 up.
Use a matte-only screen in the Fast camera, starting with the cut-down Canon Ee-S, but also trying other screens such as:

A - Homemade screens. A 12"x12" sheet of 1/16" (1.59mm) acrylic plexiglass costs $5. I have a large selection of sandpapers and polishing compounds.
I intend to try several different grits to create different mattes to see what I come up with. These screens will lack a fresnel, but if they are only for use with fast lenses, I suspect that may not matter much. I will also try this with glass plate.

B - Vintage screens! The two bodies I described above came with f/1.4 lenses as the kit lens.
Disregarding brightness issues (SLR MF opaque mirror vs DSLR AF semi-transparent mirror), the focus screens in these cameras surely must have had mattes suitable for fast lenses; ie capable of resolving very shallow DoF.
If I can find one without a central focus aid, I want to cut it down and try it in the K5.

Do any of you ladies or gents know of a vintage SLR that came with fast kit lens and had a matte only focus screen with no focus aid donut or prism?

Thanks!

Dave


PostPosted: Tue Aug 14, 2018 7:47 pm    Post subject: Reply with quote

Interchangeable focusing screens were available for Canon A-1, AE-1 Program and T90. An all matte variant among them but that was not the standard screen. The Canon F-1 has interchangeable focusing screens as well but those screens include a lens with a beam splitter and usually sell at a higher price point. 50mm f1.4 was the standard lens with all these cameras.

Don't know about other vendors.

A guy a decade younger than you Wink


PostPosted: Tue Aug 14, 2018 11:16 pm    Post subject: Reply with quote

Thanks fd, you whippersnapper!

I'll check out these Canon bodies.


PostPosted: Wed Aug 15, 2018 9:18 am    Post subject: Reply with quote

The Pentax LX has the facility to change focusing screens, one of which is a plain matte. You'd need to check, but I think it will fit the Pentax MX too, but you need to drop the box film speed by a stop or so on the camera to get a correct exposure reading as the LX screens are brighter than the MX's. There are dedicated plain matte with circle available for both the LX and MX. I use one on a MX.


PostPosted: Fri Aug 17, 2018 6:07 am    Post subject: Reply with quote

For years I shot with a Canon original F-1 and plain matte screen. I bought a plain matte screen for that camera because I used my Sigma 600mm f/8 mirror a lot and trying to focus with the focusing aids blacked out in the center of the screen was an annoying nuisance. It took a bit of practice, getting used to shooting with a plain matte screen, but I got to where I preferred it. And I still do, after all these years. I have plain matte screens in all my SLRs that take interchangeable focusing screens. Lessee, that would be about 10 of 'em at last count. So, when I finally moved up to AF cameras, I felt right at home looking through screens with no focusing aids.

And I'm definitely a graybeard-type old guy.


PostPosted: Fri Aug 17, 2018 10:15 am    Post subject: Reply with quote

cooltouch wrote:
... It took a bit of practice, getting used to shooting with a plain matte screen, but I got to where I preferred it...



Exactly my experience too, Cooltouch.


PostPosted: Fri Aug 17, 2018 7:43 pm    Post subject: Reply with quote

fdlenses wrote:
The Canon F-1 has interchangeable focusing screens as well but those screens include a lens with a beam splitter and usually sell at a higher price point.


This depends. I believe the F-1 screens with the beam splitter were intended for the original F-1. I don't recall if the New F-1 still uses this tech -- I don't think it does.

Nonetheless, here goes what I know of F-1 screens. The original ones can be found on places like eBay for $25-30, if you're patient. The later Laser Matte screens for the Old F-1 will usually sell for more, but they're worth it because they are substantially brighter. Still, if you're patient and you shop around, often you can find the Laser screens for a decent price.

Now as far as the New F-1 goes -- these screens work differently from the old F-1 screens. Not only does the screen have a given viewing area -- plain matte, split prism, or what have you, but screens also determine your metering pattern. Giving my New F-1's screen for example, I found a plain matte screen with a partial metering pattern, which comes closest to duplicating the pattern found in the original F-1, which I still prefer to this day. So New F-1 screens can get pricey depending on the type of screen and its metering pattern. Spot pattern screens are usually the most expensive, I believe. I've never found a need for a spot screen -- I'm more than happy with my screen's partial pattern. As for what I paid for it? I bought it from KEH for about $30 maybe five years ago or so. That ended up being a good deal compared to what some eBay sellers are asking for theirs.


PostPosted: Sat Aug 18, 2018 1:50 pm    Post subject: Reply with quote

Quote:
I believe the F-1 screens with the beam splitter were intended for the original F-1. I don't recall if the New F-1 still uses this tech -- I don't think it does.


New F-1 focusing screens have micro beam splitters which are not as visible as beam splitters in (old) F-1 screens.


PostPosted: Sat Aug 18, 2018 8:18 pm    Post subject: Reply with quote

FWIW the old Zenit 3m, B and E cameras had plain matte screens and came (optionally) with an f/2 Helios 58mm lens. I don't remember having any problem focussing with one, but my eyes were a lot younger then Wink


PostPosted: Mon Aug 20, 2018 8:13 pm    Post subject: Reply with quote

Thanks everyone for the feedback and suggestions!

It's interesting that Zenit was mentioned: my weekend reading included this thread

http://forum.mflenses.com/solved-focus-screen-installed-problems-with-fast-lenses-t31301.html

where Zippie used half of a Zenit TTL screen assembly. He apparently removed the matte, kept only the prism sheet, and had good results. See his photos at the bottom of the thread.

My plan:
1 - Cut and test the Canon Ee-S screen in my K5.
2 - Procrastinate.
3 - My local window shop said he would cut 4 pieces of 1/16" glass plate to my exact dimension (26x17.9mm) for $10. I'm interested in testing different mattes with these pieces by wet-sanding with different grits.
4 - Score and snap some pieces of 1/16" plexiglass (acrylic) and try same.
5 - Buy an old TTL or screen thereof and try Zippie's route.

If I ever get around to any of the latter tests, and if I find anything worth reporting, I will!

Thx!

Dave


PostPosted: Mon Aug 20, 2018 9:22 pm    Post subject: Reply with quote

DCS wrote:
Thanks everyone for the feedback and suggestions!

It's interesting that Zenit was mentioned: my weekend reading included this thread

http://forum.mflenses.com/solved-focus-screen-installed-problems-with-fast-lenses-t31301.html

where Zippie used half of a Zenit TTL screen assembly. He apparently removed the matte, kept only the prism sheet, and had good results.


I don't remember the earlier Zenits even having microprisms or fresnel, just plain ground glass, but I may be wrong - it was nearly 50 years ago when I bought my Zenit 3m ... down payment from my first weeks wages in my first "real" job. The camera, with the Industar 50 f/3.5 lens and no instant-return mirror, cost the equivalent of a whole weeks wages and took a couple of months to pay off!