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03-18-2012, 03:34 PM   #1
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using old lens. what about the Stadimeter?

Hi everybody ! I was plannig to get a 50mm old lens but i am not sure how does it work with focusing: i understand it is manual but in the old cams it has these two semidisks to check the focusing in the center. Is that feature preserved??? I mean one of the cool things of the 50mm is the precise focus... I would be very greatful if sb explained it newbies words.

Thanks!

03-18-2012, 03:46 PM   #2
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If I understand your question, you are asking if a film-camera manual-focus lens with a semi-disc stop-down button will still work on modern cameras. Do I have this right? The only such lenses I know of are for Olympus OM mount; these need to be modified in order to fit on a Pentax camera. I'm not sure if the old Asahi (Pentax) Auto-Takumars have such buttons. It would help if you could post pictures of the lens so we can identify it -- then we could help more.
03-18-2012, 03:47 PM   #3
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What you are referring to I believe is the focusing screen in the viewfinder. Our digital SLRs dont have those as theyre made to be used with auto focus lenses. Have no fear though because you can switch the viewfinder fairly easily with an old style with the focus assist.
03-18-2012, 03:58 PM   #4
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thanks for the replies. I ment what thebigcat said. But thebigcat, i am really a newbie and the pentax is my first dlsr so i might sound silly and wanted to ask a concrete example: how do you make a protrait having the 50mm focus on the eyes at f2?

03-18-2012, 04:08 PM   #5
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I found more details googling the keywords given by thebigcat. Thanks! I will see how does it work in practice with the 50mm lens...
03-18-2012, 04:21 PM   #6
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Using google FTW!

Every forum across the entire internet people ask question after question forgetting that they are using a machine that has virtually the entire collection of human knowledge at their fingertips.
03-18-2012, 04:23 PM   #7
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But just in case the KatsEye focusing screens are popular and make screens specifically for Pentax cameras.

KatzEye
03-18-2012, 05:16 PM   #8
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QuoteOriginally posted by endir Quote
I found more details googling the keywords given by thebigcat. Thanks! I will see how does it work in practice with the 50mm lens...
...and if you are still confused, you can always come back here. If understand your question, you are asking about the split-image focus aid that was common in most film SLRs. As mentioned above, the focus screen that came with your camera is not optimized for manual focus, though it is interchangeable to allow aftermarket screens that do have that feature. I have the Katz Eye screen and can confirm that it makes manual focus much easier.


Steve

03-18-2012, 07:22 PM   #9
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There were two types of focussing (three if you include plain ground glass). The first as previously mentioned was the split image rangefinder. In this device, a center spot had a line through its center. When the image was out of focus, the top and bottom portions of the image in these areas did not line up, they were split. When the image was in focus, the image appeared normal. This focussing system was better for low light focussing but was problematic at longer focal lengths ( <250mm, approx.).

the second type was the microprism screen. In this the center portion/spot had a crystaline appearance when the image was out of focus and would appear clear when the image was in focus. The main drawback to this system was it did not do well in low light. Better systems used both, the split rangefinder in the center surrounded by the microprism.

I have found with my K7 the focus confirmation works quite well with the manual focus lenses. The green "focus good" dot blinks on and the audible beep both provide the necessary feedback to confirm focus. When I try to confirm focus visually the sensor system is dead on! You may need to get used to verfying focus on the ground glass, something I learned years ago with view cameras. I would experiment some to test manual focus to get confidence with the electronic verification system. It really is quite good, even with screw mount lenses!

regards,
03-18-2012, 10:20 PM   #10
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The green hexagon indication in my K5 is quite accurate. It however varies if one comes from nearby or from infinity while focusing as the green hexagon 'covers' a range.

Your success rate can vary.

I have split prism screens in my K100D and K10D (not in my K5). Both needed calibration (shimming) before hey were accurate.
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