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10-20-2009, 10:25 PM   #1
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Pentax Screwmount on newer DSLR

Can the newer Pentax DSLR's use the older Pentax Screwmount lenses or are they restricted to just the k mount lenses?

If they can does it require some type of adapter?

Tjhanks

10-20-2009, 10:34 PM   #2
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Any Pentax dSLR can make use of any K-mount (natively) or screwmount (with adapter) lens.

Adapter can be found here.
10-20-2009, 11:25 PM   #3
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QuoteOriginally posted by deadwolfbones Quote
Any Pentax dSLR can make use of any K-mount (natively) or screwmount (with adapter) lens.

Adapter can be found here.
shhh, don't spread that rumor.
If no one wants them there's a chance that people will sell them to us, cheap
10-21-2009, 12:04 AM   #4
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Interesting thing is that M42 lenses have much more accurate metering as you change aperture yourself and no errors accuring due to stopping-down on old K lenses.

10-21-2009, 04:30 AM   #5
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Two questions for users of the genuine Pentax converter: a) how does it behave in Av mode? b) does it allow focus to infinity?

Thank you!
10-21-2009, 04:48 AM   #6
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You use M42 lenses in manual mode. There are no contacts to send signals to camera.
Yes, the Pentax adapter allows infinity focus.
10-21-2009, 05:41 AM   #7
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QuoteOriginally posted by stl09 Quote
Can the newer Pentax DSLR's use the older Pentax Screwmount lenses or are they restricted to just the k mount lenses?
2143 "yes" votes from the K20D

I use screwmount lenses on a Pentax DSLR on a daily basis. Absolutely positively definitely yes yes yes you can use them. I seldom find a reason to use a K-mount.
10-21-2009, 07:04 AM   #8
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M42 adapters

QuoteOriginally posted by causey Quote
Two questions for users of the genuine Pentax converter: a) how does it behave in Av mode? b) does it allow focus to infinity?

Thank you!

I have a third-party adapter that is similar to the genuine Pentax version. The only difference is that some report that the genuine article is easier to install and remove from the camera. However, I have had no problems with mine. There is a small spring clip on mine (or was, anyway), that is also on the genuine Pentax. This locks the adapter into place, since the screw-mount lenses have no hole for the lens lock pin. I removed the clip. Now, I simply screw the adapter onto the lens and use the lens as if it were a k-mount lens.

I use an old (but still great) Super Takumar 50mm, f/1.4 prime lens on my K10D. I usually use Av mode and it seems to work fine. I set the lens in manual mode and the camera in Av. Then I just adjust the aperture and let the camera pick the shutter speed. I learned on a Spotmatic (that's where I got the 50), so stop-down metering doesn't bother me in the least.

Yes, it allows infinity focus. The genuine Pentax adapter and the better third-party ones all fit entirely within the k-mount opening of the camera, leaving a flush mounting surface for the lens. The cheap adapters have a large flange that extends beyond the camera opening. This adds a mm or two to the camera thickness, which is what prevents infinity focus.

BTW, some non-Pentax screw-mount lenses do not have an auto/manual aperture switch. Since Pentax dslrs have no mechanism to operate the aperture of an M42 lens, this means that such lenses can only be used wide-open. If possible, try to avoid these lenses. Use only Pentax brand lenses or third-party lenses that have the A/M switch. Some have super-glued or jammed the aperture pin so that the aperture is always stopped down, but I've never tried that.

10-21-2009, 08:00 AM   #9
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QuoteOriginally posted by noblepa Quote
I learned on a Spotmatic (that's where I got the 50), so stop-down metering doesn't bother me in the least.
The difference when using screwmount lenses on DSLRs, just so the OP understands, being that the photo must also be taken at the chosen stopped down aperture setting, while on the Spotmatic, after metering stopped down, you could return to wide open aperture, via the stop down metering switch, for focusing & taking the shot.
10-21-2009, 10:33 AM   #10
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Thank you all for your very clarifying answers! Two more (and I'm done):
- is multi-segment metering possible with M42 lenses and converter?
- should I be concerned about exposing the sensor to dust while attaching/ removing the converter? (I like the solution which turns a M42 lens into a P/K lens, but I wouldn't spend $30--the cost of a genuine Pentax converter--for each such lens...)
10-21-2009, 10:49 AM   #11
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QuoteOriginally posted by causey Quote
Thank you all for your very clarifying answers! Two more (and I'm done):
- is multi-segment metering possible with M42 lenses and converter?
- should I be concerned about exposing the sensor to dust while attaching/ removing the converter? (I like the solution which turns a M42 lens into a P/K lens, but I wouldn't spend $30--the cost of a genuine Pentax converter--for each such lens...)
It takes maybe 5 seconds to put the adapter on, so I wouldn't worry too much about dust. Keep a rocket blower handy and there's no cause for concern even if dust does manage to get inside in that short window.
10-21-2009, 12:42 PM   #12
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Stop-down metering

QuoteOriginally posted by raymeedc Quote
The difference when using screwmount lenses on DSLRs, just so the OP understands, being that the photo must also be taken at the chosen stopped down aperture setting, while on the Spotmatic, after metering stopped down, you could return to wide open aperture, via the stop down metering switch, for focusing & taking the shot.

You're right of course. You can open up after metering, but I never did. The procedure that I learned and read about from most Spotmatic users was: compose, focus, meter, shoot. If I was shooting several shots in rapid succession, in unchanging light, I would not meter each shot. On a dslr, however, you don't even have that luxury. You must keep the lens stopped down for each shot.

My point was just that the "limitation" of having to use stop-down metering on my K10D is not really a limitation, IMHO. Even after forty years, its still second nature to me.
10-21-2009, 02:11 PM   #13
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QuoteOriginally posted by noblepa Quote

My point was just that the "limitation" of having to use stop-down metering on my K10D is not really a limitation, IMHO. Even after forty years, its still second nature to me.
Matching your forty years experience with an equal amount of my own, I wholeheartedly agree. The vast majority of my DSLR shooting to this day is still accomplished with my beloved M42s.
10-21-2009, 02:14 PM   #14
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QuoteOriginally posted by causey Quote
- is multi-segment metering possible with M42 lenses and converter?
-
No, it's not.
10-21-2009, 02:51 PM   #15
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screwmount vs. k mount

Everyone thank you for your insight. I knew that we could use any k mount lens.
Thanks to this site I ran across a reference page that broke the lenses down by model so you know exactly what to expect.
I couldn't imagine that we couldn't use the screwmount lenses as well but figured that something extra would be required.

Just another reason why I chose Pentax gotta love the backward compatability.

thanks again everyone....



QuoteOriginally posted by deadwolfbones Quote
Any Pentax dSLR can make use of any K-mount (natively) or screwmount (with adapter) lens.

Adapter can be found here.
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