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01-13-2010, 12:01 AM   #1
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reversing SMC PENTAX-M 50mm 1:1.7 and SMC PENTAX-M 28mm 1:2.8

which lens will give greater magnification with sharp picture. is it better to use x3 or x2 teleconverter plus reverse?

01-13-2010, 02:23 AM   #2
Damn Brit
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The wider the lens, the greater the magnification when reversed so in this case, 28mm will be the greater.
If you want to reverse I would suggest extension tubes over teleconverters, there is no IQ loss due to extra glass that way.
Sharpness would be mainly dependent on your focusing skills. A tripod should be considered a necessity and a macro focusing rail would also help. To focus with reversing rings you have to move the camera to focus.
01-13-2010, 02:37 AM   #3
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QuoteOriginally posted by Damn Brit Quote
The wider the lens, the greater the magnification when reversed so in this case, 28mm will be the greater.
If you want to reverse I would suggest extension tubes over teleconverters, there is no IQ loss due to extra glass that way.
Sharpness would be mainly dependent on your focusing skills. A tripod should be considered a necessity and a macro focusing rail would also help. To focus with reversing rings you have to move the camera to focus.
thank you very much! i will take your advice!
01-13-2010, 02:44 AM   #4
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You're welcome. Extension tubes are cheaper as well.

12-15-2010, 08:06 AM   #5
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I have not been able to use extension tubes or bellows with my Pentax K-x. It seems that I loose lots of light and cannot focus. I set the aperture in PERMITTED, but still do not see. Is there anything I can do? I have successfully used the converter 2x with my Pentax M 50mm f4 to get a nice macro, but with the 31 mm extension I cannot focus and it is dark. Can you comment please?
12-15-2010, 08:16 AM   #6
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Great! I got all my lenses packed up ready to move and this site is constantly inspiring me to play in photography. Damn you Pentax!
12-16-2010, 10:48 AM   #7
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QuoteOriginally posted by Pepe Guitarra Quote
I have not been able to use extension tubes or bellows with my Pentax K-x. It seems that I loose lots of light and cannot focus. I set the aperture in PERMITTED, but still do not see. Is there anything I can do? I have successfully used the converter 2x with my Pentax M 50mm f4 to get a nice macro, but with the 31 mm extension I cannot focus and it is dark. Can you comment please?
With an ordinary bellows or cheap macro tubes, your M-type lens should be uncoupled from aperture control, and the lens should act as a preset -- open the aperture to f/4 for most light. More expensive macro tubes have a mechanical linkage for the aperture, and you should be able to do stop-down metering and exposures in M(anual) mode.

A 31mm tube on a 50mm lens should only reduce light by a little over 1 f-stop -- it shouldn't be dark, so I can only suggest that you check that the aperture is wide open and your subject is well-lit.

As for focus: On any extension, the small throw of the lens focusing mechanism doesn't amount to much. With bellows, you use the bellows for focusing , not the lens. With tubes, you generally move the whole camera-lens system or the subject back and forth to achieve focus. So don't worry that the lens doesn't focus -- it doesn't matter.

Good luck!
12-21-2010, 03:41 PM   #8
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Thanks.

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