Exakta focusing screen

Hello everybody,

What focusing screen do you recommend for use with long lenses?

I find microprism screen great for lenses up to 200 mm, marginal with CZJ Sonnar

4/300 and utterly useless with Enna 5,6/600. Standard ground glass somehow works

with the Sonnar, but not with the Ennalyt. Greased ground glass is way better

suited for the later, but focusing accuracy suffers, to no great surprise. I

have really bad experience with split image screen (significant focusing errors

with lenses longer than 50 mm, maybe just a bad copy, don't know), but it might

be worth a second try. Does anybody know whether split image turns black with

long telephotos? Is the old glass screen better than the newer plastic one?

Best regards,

Miha

Hi Miha , split screens require light to function. So these are largely unsuitable for even f4 lenses.As to the Enna 600 I would be surprised if you get a worthwile photo at all whatever screen you use.

I find with my Exakta the best is the older glass use it with the pop up loupe.But then the longest lens for me is 135mm.

Cheers Manfred

Hi Miha, my Exactas all have split images and I find them pretty useless for anything! Seriously, anything slower than F3.5 causes my split screen to black out so I can imagine how bad the 600 is. I have a 400mm Meyer lens that I find that I can still focus with the ground glass that surrounds the split image, still not easy though.

Cheers, Tony

The plain ground-glass is the most useful overall. I have used it up to 500mm w/o any problems other than it's natural dimness. The microprism and split-image each have their optimal focal lengths and can be useless outside of that range.

The plastic screens are prone to scratching. The plain ground-glass might exist only in glass. I have never seen a plastic one.

I have a completely clear screen that gives a phenomenally bright image, but is useless for focusing. It might be useable for shooting at infinity settings. I have never been able to figure out what its intended use was.

-Paul

Miha,

For most purposes, I very much like the plain ground-glass focusing resting in my Exakta: it's simple and ubiquitous, but absolutely wonderful. Although applying a thin layer of petroleum jelly ("Vaseline"), or some similar concoction, to the bottom of a plain screen might make things look brighter, as you said, doing so will likely make focusing rather unreliable.

Though plain ground-glass works all right with most of my lenses, unlike many, I do also love plain ground-glass with split-image center: it's somewhat difficult to find one the center of which is in good shape (no chipping or significant yellowing), but, if you do, hang on to it and cherish it. If you end up with one that's chipped, you'll find that the center turns black (and effectively useless) if you're not looking at it right through its center; if it's yellow, it will require more light to be useful, and might look, as you peer through it, to have a dark (annoying, maybe, but not really destructive to its function) "ring" separating it from the matte surface; and if, at some point, the glue softened and the two halves of split-image glass moved out of position, later re-settling and hardening in new ones, you might find the item very useless for accurate focusing. With the split-image center, glass vs. plastic isn't very important: glass is advantageous in that it won't be scratched so easily; with plastic, the split-image portion is molded into the material rather than glued in place, so you won't wind up with a screen that's inaccurate because of misalignment.

The two-piece plastic screens (focusing screen bonded to clear plastic condenser) -- with fresnel surface and microprism ring around split-image center -- work all right, but they seem to be a bit smaller than the glass screens, often falling out of finders (waist- or eye-level) unless the latter's pins are adjusted; they're also far more prone to being scratched. If you demand fresnel, however, you have no choice but plastic: I don't think anyone's ever bothered to carve fresnel rings into glass for something so paltry as a camera's focusing-screen. Fresnel will, indeed, brighten matters a little, but will also make focusing on the surface cumbersome, if not impossible. If you're using a rather slow lens, however -- perhaps such as your 5.6/600 Enna -- the extra brightness might be necessary; understand, though, that Exaktas seem always to go "black" toward the top of the frame when fitted to long, slow lenses; even my 4/300 Zeiss Sonnar, wide open -- neither terribly huge nor painfully slow -- shows a small black band at the top of the frame, an issue exacerbated by shooting in low light. This band won't show up in your pictures, but, while you're actually in the field, it might make framing and focusing somewhat onerous.

Using long-focus lenses with the Exakta is thrilling, but, undeniable, a pain in the ass: the lenses are large and heavy, and often a tad slow, and their lack of autofocus implies you'll need a hell of a lot of practice to get so good that the vast majority of your shots aren't destined for the trash-bin. As I said earlier, I love plain screens, and I have used them with my 4/300 Sonnar, but the split-image center really is a god-send when I want to be certain my subject is properly focused: eyes, at least mine, can play tricks when you've got a behemoth weighing down your arms for a few hours (yes, I sometimes become bold enough to leave my tripod at home when taking the 300mm out for a stroll).

Tony, if you find the split-image screens useless, why do you have them on all your Exaktas? :-D Want to sell a few this way?

Here's something I wonder: has anyone ever seen an old-style waist-level finder with anything but a plain ground-glass screen? Allegedly, such items existed; I've never seen one, myself, though...

Thank you for your answers!

Long lenses with Exakta are indeed royal pain in the a$$. Nevertheless, I've mastered CZJ Sonnar 4/300 and can produce stunning looking 30X45 cm (12x16") prints with it. Enna 5,6/600 is a very different beast. Can't focus it with standard focusing screens, the ground glass' grain seems to be incompatible with the lens. Same goes with microprisms (a different angle of the prisms would be needed, i guess). It's not just the lens speed. I have no problems whatsoever using microprism screen with Sonnars 4/135 and 2,8/180 stopped down to 5,6. On the other hand, also can't focus well with microprism screen and Biotar 1,5/75 (ground glass works well here).

Greased ground glass allows me to compose and focus with the Enna, but focusing accuracy suffers. A split image screen may work with some luck and careful eye placement, but as I've already said, I have a pretty bad experience with one. The other option IMHO would be a clear spot & crosshair screen. It should be painfully slow and highly demanding for eyes, but theoretically it should work. I guess i should go back to eFly shopping for some focusing screens. ;-) I'll keep you informed on my findings.

Best regards,

Miha

PS: black upper part of the viewfinder image when using long lenses with Exakta is caused by (too) small mirror.

Miha, yeah, I learned about that too-short mirror not very long ago, right in this forum.

How do the crosshair screens work? EBay's killer when it comes to cost of accessories: most focusing screens (for Exakta) that are in decent shape seem to go for more than twenty bucks. Of course, one doesn't have much choice, I suppose...