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11-09-2012, 12:12 PM   #1
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manually focuing lenses on a Kr

Hello,

Im getting some manually focusing lense soon, some of the following, 50, 35, 28mm. Just wondering if anyone had any tips for manually focusing on a kr?

Ive found the aids in the camera like the beep focus thing, but for quick focusing would it help if I got a split image focusing screen?

Any tips appreciated, thanks

11-09-2012, 01:16 PM   #2
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Check the two posts below in the K-r forum

https://www.pentaxforums.com/forums/pentax-k-r/202336-has-anyone-used-50mm-2.html#post2148616
https://www.pentaxforums.com/forums/pentax-k-r/202336-has-anyone-used-50mm-2.html#post2161564
11-09-2012, 01:21 PM   #3
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I really like the split-prism screens (but I grew up on film SLRs that used split-prism screens). You may have to play a little with shims to get the screen positioned just right. The K-r can use the same screen as the K-x or K100D, but not the K-5/K-7/K-30 screen. I personally prefer the screens from KatzEye or focusingscreen.com (both are cut-down Nikon K2/K3 screens, I think) to the cheap ones on eBay. Some say they don't see a difference, but the cheaper screen seemed dark and murky to me.
11-10-2012, 08:59 AM   #4
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Coming from an old Nikon FA rig I decided to installed a Katzeye split prism on my Kr. I've found that I can focus faster with this screen, which may be due to my past expirience with my Nikon. I have no desire to go back. The split screen works with the AF operation. My question is why the manufactures don't use split sreens as a standard feature.

11-10-2012, 10:28 AM   #5
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Never used a focusing screen, with my K-r, I just hit the shutter when it's sharp. I find it's quicker in most cases than the AF on my 18-55mm, the only modern day lens I own.

The focus indicator is handy though, especially with darker situations. I'd just have a go, and see how you do. All my friends find it nigh on impossible to focus an MF lens. It just takes practice.
11-10-2012, 11:28 AM   #6
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QuoteOriginally posted by pentaxinhouston Quote
My question is why the manufactures don't use split sreens as a standard feature.
Well, for one, most consumer-grade camera buyers are only going to use the kit lens (I first heard that said by Nikon, but it was supported by the recent lens stats here on PF) or maybe another AF lens and rarely manually focus. Secondly, the split prism can behave unpredictibly (half going black, depending on the lens and aperture), which can throw off the metering system. It's one of those "you have to know how to use it" features. Even among the MF lens crowd, there is debate as to which type of screen works better, split-prism or microprism.
11-10-2012, 12:48 PM   #7
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QuoteOriginally posted by THoog Quote
Well, for one, most consumer-grade camera buyers are only going to use the kit lens (I first heard that said by Nikon, but it was supported by the recent lens stats here on PF) or maybe another AF lens and rarely manually focus. Secondly, the split prism can behave unpredictibly (half going black, depending on the lens and aperture), which can throw off the metering system. It's one of those "you have to know how to use it" features. Even among the MF lens crowd, there is debate as to which type of screen works better, split-prism or microprism.
I haven't observed the half black problem unless my eye is mis-aligned with the center line of the eye peice. I don't use kit lenses which might explain why I've not encountered any AF problems.

You're spot on that a split screen is a learn to use technique. I've used one for over 30 years which explains my preference. The particular Katzeye that I installed is a split screen encircled by a mircoprism. I use both to focus.

At a recent air show I found that manual focus was faster than the AF could track.
11-10-2012, 01:26 PM   #8
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QuoteOriginally posted by pentaxinhouston Quote
My question is why the manufactures don't use split sreens as a standard feature.
Spot metering. By the early 90s it was expected on an AF SLR.

11-10-2012, 01:34 PM   #9
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The AF sensor is located below the mirror, so the split-focus screen won't affect AF. However, metering is done up in the "hump" above the screen, so it can be a factor - especially if the camera is set to spot-meter on the center (right in the middle of the split).

I grew up on an ME-Super, and thought split-screens were "normal". I really missed it on my first dSLR (and I didn't own any AF lenses!). When I got my first Katz-Eye, it was like a homecoming. I excitedly showed it to an older friend who, to my surprise, had never seen a split-prism - he learned on a K1000 with a microprism screen.

I was at a zoo recently, trying to shoot a sea otter as it swam back and forth, back and forth. AF was struggling, and I was really wishing I'd brought a crappy old one-touch manual focus zoom - with a little practice, I used to be able to track things no problem. But then, a brain is smarter than any autofocus program (I hope) . It's got more information to work with, anyway...
11-11-2012, 04:57 AM   #10
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QuoteOriginally posted by THoog Quote
But then, a brain is smarter than any autofocus program (I hope) . It's got more information to work with, anyway...
Almost certainly. I keep my kit lens solely for the 18mm department, because I haven't got anything wide other than that. I hate the AF, and the MF with the short throw ring does my head in. A veeery long way from my 270 degree turn heavily damped K 55mm f2

I'm not entirely sure what screen I have on my K1000… With the 18-55mm put on it, it's filthy, with a spot of slightly less filthyness in the middle around 1.5cm in diameter. With the K 55mm f2, it's clear, except when put out of focus, when the spot becomes more visible. Split screen or microprism?
11-11-2012, 08:44 AM   #11
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QuoteOriginally posted by gilsouthwood Quote
Almost certainly. I keep my kit lens solely for the 18mm department, because I haven't got anything wide other than that. I hate the AF, and the MF with the short throw ring does my head in. A veeery long way from my 270 degree turn heavily damped K 55mm f2
I'd hate to be a lens designer - a lens with a short throw is hard to manual-focus, and a lens with a long throw is slow to autofocus. They're going to get criticized either way. There's no winning!

QuoteOriginally posted by gilsouthwood Quote
I'm not entirely sure what screen I have on my K1000 With the 18-55mm put on it, it's filthy, with a spot of slightly less filthyness in the middle around 1.5cm in diameter. With the K 55mm f2, it's clear, except when put out of focus, when the spot becomes more visible. Split screen or microprism?
Sounds like a microprism to me (a very good description!). The 'Special Edition' K1000 SE and most later MF bodies had a split-prism, with an etched circle in the middle, divided in two. The images in the two halves align when you are in focus, so you hunt around for a branch or a sharp edge to line up.
11-11-2012, 09:25 AM   #12
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QuoteOriginally posted by THoog Quote
I'd hate to be a lens designer - a lens with a short throw is hard to manual-focus, and a lens with a long throw is slow to autofocus. They're going to get criticized either way. There's no winning!
I guess so It's only when they make a lens that's difficult to focus manually, yet doesn't actually AF effectively either

QuoteOriginally posted by THoog Quote
Sounds like a microprism to me (a very good description!). The 'Special Edition' K1000 SE and most later MF bodies had a split-prism, with an etched circle in the middle, divided in two. The images in the two halves align when you are in focus, so you hunt around for a branch or a sharp edge to line up.
This suddenly makes a lot more sense. Spot disappearing or straight branches equals focus. Aha! Thanks for the help
11-11-2012, 10:00 AM   #13
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QuoteOriginally posted by THoog Quote
I'd hate to be a lens designer - a lens with a short throw is hard to manual-focus, and a lens with a long throw is slow to autofocus. They're going to get criticized either way. There's no winning!
...
Not necessarily. The internal 'throw' of the lens movement is one thing while the barrel that you turn on the outside is another. You can have an internal mechanism with a very short throw and then have a focusing barrel with a very long throw and a gear reduction system.

The SIgma 150-500 that I have seems to be constructed that way. It focuses very fast compared to screw drive lenses but also has a nearly 180 degree travel of the focus barrel, making it very easy to manually focus accurately.

For it to work though it would need to also have a clutch so that the autofocus motor only turns the internal mechanism and not the focus barrel, otherwise the inertia of the focus barrel would slow down the autofocus motor.

For lenses with internal motors (SDM, DC USM etc) this is quite easy to do whereas for scew drive lenses it may be difficult if at all possible, and your remark applies.
11-11-2012, 10:38 AM   #14
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QuoteOriginally posted by lister6520 Quote
The internal 'throw' of the lens movement is one thing while the barrel that you turn on the outside is another. You can have an internal mechanism with a very short throw and then have a focusing barrel with a very long throw and a gear reduction system.
I thought about that, but didn't feel like going into it - and a multi-speed system means more cost, weight, complexity, and things that can break, and we're back to "criticized no matter what you do"...
11-11-2012, 11:55 AM   #15
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Aha. I guess it just comes down to whether you trust AF over your own eye then. I don't.
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