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09-12-2008, 06:15 AM   #1
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In praise of viewfinder Bokeh

Most of the time we pay attention to the size and brightness of a view finder. These are good things, too.

However, recently I've been using my KX a bit, with the 50/1.7 lens. I am struck by the beauty of the focus screen, and how well it works. The KX doesn't have the largest or brightest screen. It doesn't have a split prism. What it does have is an excellent ground glass, a real joy to look through (and wish the lens had that bokeh!)

The image pops into focus and fades into smooth bokeh when past focus. I like microprisms, this one shimmers beautifully and thus is a good aid as well. The viewfinder is large and bright enough, though these aren't the main advantages of the KX.

I'll have to double check with my Program Plus screen using the same lens to verify my impression: the KX screen ground glass is better.

The KX screen is better than any on my screw mount bodies.

Also, I should note that in reading a '69 book on Pentax by Robert Fuhring, he makes the point that the Spotmatic viewfinder is designed to show a life-size image with the 'standard' 55mm lens. In other words, a design goal re. size and maginification of the viewfinder image is to provide approximate life-size via the standard lens. This may explain some of the decisions around this particular issue.

09-12-2008, 07:20 AM   #2
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These are interesting observations, Nesster. I had a KX briefly, and I noticed the aspects you mention. It is an excellent viewfinder (0.88x or 0.89x magnification, I believe), and the quality of its image is superb. The listed magnification is based on a 50mm standard (focused at infinity), and so what you say in regard to the 55mm lens seems plausible.

As I recall, the Spotmatic F and KX viewfinders are quite similar. The KX's could be a tad better, but I would have to compare them to determine this (I never performed a side-by-side comparison). Of course, the viewfinder is one of the main flaws of contemporary cameras. Viewfinders are not what they once were.

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09-12-2008, 07:39 AM   #3
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I can't find the reference at the moment, but I recall reading that most (all?) DSLR focusing screens do not "resolve" DOF at apertures larger than about f/2.8. Something about being optimized (brighter) for the f/3.5-5.6 lense commonly used on them, as opposed to the f/1.8 or the 50mm kit lenses of the past.
09-12-2008, 07:43 AM   #4
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Have you tried the viewfinder of a Russian SLR? Particularly that of the Zenit-E?

It's a far cry from the marvel of Japanese engineering, but have a flair of their own that no other camera can reproduce.

The Zenit-E's viewfinder presents heavy vignetting and insane barrel distortion; plus a yellow tint reminiscent of 50-60s colour photographs. It takes you back. It really takes you back...

09-12-2008, 08:00 AM   #5
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no, and after that description im not sure id want to try one.
09-12-2008, 05:29 PM   #6
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QuoteOriginally posted by Nesster Quote
I like microprisms, this one shimmers beautifully and thus is a good aid as well.
I am with you. The early pentaprism model starting with the '58 "K" have micro-prisms, and from that time on they had increasingly better and better viewfinders.

It is interesting to note that while the H2/S2 (1959) spec states "micro-prism" ** grid **, it is not so much a grid as it is a series of lines at about 45 degrees that end up behaving similarly to a grid, but not exactly like one. I wish I could illustrate it.

By the time they got to the S3/H3 (1961) they had it. Those cameras when stopped down very clearly show it to be a grid of opposing 45 degree lines, the space between the intersections of course forming the microprisms.

My favorite cameras for daily shooters are the later S3/H3 (1961) and the SV/H3v
(1962) precisely because by this time they had rather perfected the whole thing and it is a very sensitive and exacting piece of optics.

For a while I thought my sight was completely failing. As my optometrist loves to tell me, your 40's will not be kind to your eyes. It is true and to some extent they are failing. I was getting a lot of blurry shots with my '57 AP. Well, since all that camera has is a the fresnel without a micro-prism grid, it was no wonder.

Then I picked up my H2, S3, and SV and found that I CAN still focus. I think the S3/H3 SV/H3v were definitely the pinnacle of their focus screens BEFORE the Spotmatic. Indeed, I think I prefer them over my Spotmatic and Spotmatic F because the microprism portion of the focus screen is ** significantly ** larger than on the Spotties.

Hmmm... I wonder if I could swap them out to the Spottie. ... get some beat S3 body and transfer the focus screen from an S3. I kind of doubt it, but I might run it by Eric.

woof!
11-26-2012, 06:07 AM   #7
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Yes really..

K series viewfinder has concentric circles that make it easier to focus.
Spotmatics don't have it apparently, but earlier SV, oddly had it.
11-26-2012, 08:00 AM   #8
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Agree completely. Plain groundglass is the best screen for critical focusing, as you can judge the sharpness directly instead of relying on prism-type aids that are desiged for a particular lens. There's nothing like working with a large-format view camera, watching the image come into focus "live" on the big groundglass.
My first SLR was an H1a (diagonal line prism), and of course have used the other models through the years. The shimmering prisms only work when there is enough coarse high-contrast detail in the area desired, while a ground-glass does better on finer detail. I preferred the models with the smallest microprism spot when I couldn't get a plain groundglass screen, as I usually focused on the glass around the spot.
I think the Leicaflex SL (I bought one in 1969) was the first camera to use and all-microprism screen, with a normal microprism spot in the center, and very fine prisms over the rest of the screen. It was very bright (the mirror only reflected part of the light so it had to be), but it focused better with an f2.0 lens than an f1.4 because of the way the prisms were cut. I changed my later cameras to groundglass for that reason.
dSLR screens in general are not designed for focusing, but to give a clear view for composing while the camera autofocuses, and I find the K-5 very poor for manual focus. (and when the autofocus misses, there isn't much option...)
I put an SA23 screen in my LX, which is made for fast lenses, with a smaller center spot, and it's a better compromize between brightness and focus ability. But the original 1957 Pentax, before the prism spot, is my favorite SLR screen.

11-26-2012, 09:44 AM   #9
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QuoteOriginally posted by Nesster Quote
However, recently I've been using my KX a bit, with the 50/1.7 lens. I am struck by the beauty of the focus screen, and how well it works. The KX doesn't have the largest or brightest screen. It doesn't have a split prism. What it does have is an excellent ground glass, a real joy to look through (and wish the lens had that bokeh!)

Also, I should note that in reading a '69 book on Pentax by Robert Fuhring, he makes the point that the Spotmatic viewfinder is designed to show a life-size image with the 'standard' 55mm lens. In other words, a design goal re. size and maginification of the viewfinder image is to provide approximate life-size via the standard lens. This may explain some of the decisions around this particular issue.
I always assumed the KX has a split prism since mine does. However, the KX manual does not show a split prism. Never really considered the bokeh quality of the VF but always appreciated that Pentax took this approach to lifesize view which I understand is mutually exclusive for those who wear glasses.

Of course the lifesize VF is a continuation of the original Asahi Pentax release as shown in their ad.

11-26-2012, 11:42 AM   #10
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QuoteOriginally posted by LesDMess Quote
I always assumed the KX has a split prism since mine does. However, the KX manual does not show a split prism. Never really considered the bokeh quality of the VF but always appreciated that Pentax took this approach to lifesize view which I understand is mutually exclusive for those who wear glasses.

Of course the lifesize VF is a continuation of the original Asahi Pentax release as shown in their ad.
The KX came with two screen options, the "cross-microprism" or the "split-image". There was a different part number when ordering the body. The more common of the two is the "cross-microprism".

Phil.
11-26-2012, 12:49 PM   #11
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QuoteOriginally posted by LesDMess Quote
always appreciated that Pentax took this approach to lifesize view
Of course for the K-5 they also claim lifesize - but still with a 50mm lens; but they should state it for more like a 35mm lens for a "normal" field of view
11-26-2012, 06:23 PM   #12
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I suppose since the inception of AF, companies probably don't spend much time and resources on viewfinders.

However, in the manual focus world of film cameras, viewfinders must have been a main consideration. From all that I have seen, they seem to have favored design for use by people who wear eyeglasses or those who don't. And being of the latter, I really appreciate it. For instance, there were Nikons that had 100% viewfinders but I put more value in a higher magnification then VF coverage.
11-27-2012, 03:28 PM   #13
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Need I interject why I prefer cameras with interchangable screens?
12-04-2012, 02:33 AM   #14
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QuoteOriginally posted by TomB_tx Quote
Plain groundglass is the best screen for critical focusing, as you can judge the sharpness directly instead of relying on prism-type aids that are desiged for a particular lens
When I shoot an MX or ME super, I used to use the focus aid and then recompose. Now I tend to use the groundglass areas of the viewfinder, then do a quick check with the focus aid to see if it agrees with me
09-28-2013, 01:56 PM   #15
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I'll resurrect this thread, as my daughter had an interesting observation. She's used to the SP1000 and a Nikon FE. Her SP1000 ran out of battery, and I didn't have any replacements, so thinking quickly I put my MX in her hand. She loved the small size (I'd thought of putting the KX in her hand, but in the past she's thought it was too butch or something, compared to the SP1000 which she thinks is the prettiest SLR ever).

Anyway, while she was shooting in full daylight, she commented that she was having to adjust as she had to rely on the center spot more than she's used to.

In other words, for her the MX ground glass isn't as good to focus on, at least in bright light, as the SP1000 and FE. Kind of what I was getting at as well.
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