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02-07-2010, 11:03 PM   #16
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Thanks Lowell for the reply. It is K mount 300/f4 and not Takumar. The tin foil is still left from my earlier work with Carl zeiss jena. Never mind about tin foil stuff. What I understand is, K mount lenses with 1.7 TC always works on Max aperture? i.e. f4 here? Hmm.... I might loosing some advantage of DOF while bird shooting here.

02-08-2010, 05:42 AM   #17
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QuoteOriginally posted by Sudhakar Quote
Thanks Lowell for the reply. It is K mount 300/f4 and not Takumar. The tin foil is still left from my earlier work with Carl zeiss jena. Never mind about tin foil stuff. What I understand is, K mount lenses with 1.7 TC always works on Max aperture? i.e. f4 here? Hmm.... I might loosing some advantage of DOF while bird shooting here.
In Av mode yes, K mount lenses only work at maxximum aperture.

BUT in M mode, set to any aperture, and press the green button and the camera stops the lens down, meters and sets the shutter to the correct speed. Also if you just want to read the exposure using the DOF preview activates the metering and you can see over/under exposure with the metering when the lens is stopped down.
02-09-2010, 12:13 PM   #18
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QuoteQuote:
From what I gathered, the metering with M42 lenses is best with K-7 and I hope those metering improvements also prevail in K-x and K-m. Someone who uses k-m can share their m42 experience.

Thanks,
Hin
Probably this should be another thread, but anyways...

I use a k-m/k2000 and i can say that it works fine (if not great) with takumars. Although, the exposure compensation varies with lens.

For example, I have a (fungal) 200mm f/3.5 and it needs more than +2 EV (around +2.5 EV) in Av mode, but stop-down metering works fine (wonder why). A tak 28mm f/3.5 works with a +0.5 EV but needs to be the straightest possible or the left side suffers from heavy under-exposure (around -1 EV compared to the right side) I suppose that comes from the small exit pupil? Don't really know. I have some more, but they seem to work fine in Av mode.

Curiously, my pentax-m 50 f/1,7 needs a +0.5 EV for the "right" exposure.
02-09-2010, 06:23 PM   #19
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I think a potential solution would be to use a bare flanged m42-k adapter on the TC. You avoid the flanged ones mounted directly because you lose infinity focus, but maybe the internal focusing of the 1.7x AF TC would make up for that?

Obviously it cannot be painted since that would defeat the intent of its use which is to short out the contacts. This is also why the K100D underexposes with m42 lenses unless you used a bare flanged adapter; the genuine one didn't short out the contacts.

In other words, the reason for K100D underexposure with m42 lenses is the same as the reason for m42 lenses not focusing with the Pentax 1.7x.

02-09-2010, 10:12 PM   #20
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QuoteOriginally posted by jslifoaw Quote
I think a potential solution would be to use a bare flanged m42-k adapter on the TC. You avoid the flanged ones mounted directly because you lose infinity focus, but maybe the internal focusing of the 1.7x AF TC would make up for that?

Obviously it cannot be painted since that would defeat the intent of its use which is to short out the contacts. This is also why the K100D underexposes with m42 lenses unless you used a bare flanged adapter; the genuine one didn't short out the contacts.

In other words, the reason for K100D underexposure with m42 lenses is the same as the reason for m42 lenses not focusing with the Pentax 1.7x.
With comments about this exposure issue - Change the focus screen to the screen from the *ist series. I replaced my stock screen with an LL-60, and the exposure, while not spot on, is close enough. This is not MY idea - I gambled $50 on it because I was getting a bit annoyed trying to get proper exposure with my two M series lenses, and others had done this trick. I won the gamble.
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