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04-20-2012, 01:02 PM   #16
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QuoteOriginally posted by newarts Quote
I made an easy, reversible modification of my camera's mount so it thinks all lenses are "A" type
That's cool Dave! You should post this in the DIY thread.

04-20-2012, 02:58 PM   #17
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QuoteOriginally posted by newarts Quote
I made an easy, reversible modification of my camera's mount so it thinks all lenses are "A" type. This lets P-TTL flash work properly with all lenses and allows me to set the proper lens f-number to be recorded in EXIF (adjusting the viewfinder's report of f-number has no effect on an m42 lens). I have found no downside to this mod.
I've seen this before and finally decided to try it on my K20D. Implementation isn't quite as simple as purported: getting the ring|plate straight up is slightly tricky, and when replacing it, be sure to get the lens-lock pin in its hole first. But I managed to avoid losing screws, and it's back together and functioning.

Results... I'm not sure what to expect. So far I've just tried some test shots with K, M, A, M42, T2, and N/AI (modded) lenses. The camera does think the K and M glass are A-type. It doesn't recognize the others, even though the bases short all other mount pins. Onboard pTTL flash *does* work but not very well, and metering is way off in all modes.

Conclusion: I don't really see this as useful, not for me anyway. I'm going to pull the foil.
04-20-2012, 03:22 PM   #18
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QuoteOriginally posted by RioRico Quote
I've seen this before and finally decided to try it on my K20D. Implementation isn't quite as simple as purported: getting the ring|plate straight up is slightly tricky, and when replacing it, be sure to get the lens-lock pin in its hole first. But I managed to avoid losing screws, and it's back together and functioning.

Results... I'm not sure what to expect. So far I've just tried some test shots with K, M, A, M42, T2, and N/AI (modded) lenses. The camera does think the K and M glass are A-type. It doesn't recognize the others, even though the bases short all other mount pins. Onboard pTTL flash *does* work but not very well, and metering is way off in all modes.

Conclusion: I don't really see this as useful, not for me anyway. I'm going to pull the foil.
Be sure the DATA pin (near the bottom most pin) is shorted. It should recognize all those lenses as A type - if you short the A pin and a few others it should behave like there's an A lens there even with no lens at all. The proof is an f-number appearing in the viewfinder.

With an M42 lens preset it to whatever you want but tell the camera (with the e-wheel) the f-stop is as low as it'll go. Then the camera does not try to move the aperture lever. Adjust shutter speed or ISO so exposure deviation shown in the viewfinder is +/- 0.0

Metering in M mode should be ok with all lenses & green button (if your camera will stop down the lens for preview using the green button - it may vary with camera type.)

I
04-20-2012, 03:39 PM   #19
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Yes, the K20D stops-down lenses in M mode. OK, I'll check things over and try some more. Thanks.

04-20-2012, 04:14 PM   #20
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QuoteOriginally posted by RioRico Quote
Yes, the K20D stops-down lenses in M mode. OK, I'll check things over and try some more. Thanks.
I have a K lens on order to try it with the foil. My previous experience had all been with presets of various makes (no aperture lever).

I just checked P-ttl out again with an M42 lens - flash exposure was good no matter what aperture I preset on the lens (with the viewfinder aperture set at the minimum.)

Dave
04-20-2012, 05:36 PM   #21
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QuoteOriginally posted by newarts Quote
I made an easy, reversible modification of my camera's mount so it thinks all lenses are "A" type. This lets P-TTL flash work properly with all lenses and allows me to set the proper lens f-number to be recorded in EXIF (adjusting the viewfinder's report of f-number has no effect on an m42 lens). I have found no downside to this mod.
This looks like an excellent mod! Does the foil ever peel or rip?—do you have to adjust it a bunch?
04-21-2012, 02:17 AM   #22
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I feel the same as you do about zooms but there are still times that I wish I had a nice set of zooms (the whole Tamron set would be nice). If it was me I would try to add to it instead of selling it. the A28/2.8 and A100/2.8 are a nice start. those would cost about $300+ but you could get the M versions for $150+. these are exactly the same optics the only difference is that with A's you can control aperture from the camera and you don't have to use the green button. There are a few times that I wish the lens was constantly metering but the biggest issue I have is when I'm swapping back and forth between M and A lenses and forget which process to use to take photos.

Or you could get the A28f2.8 ($80-100) and find a $50 M135f3.5 as your telephoto. I prefer 100mm on digital but the M135 could be a placeholder until you later get the A100f2.8.

If you want the best Pentax legacy lenses then my suggestion is to check out the K series. The convenience of K mount but the quality of the takumars. They do lack the awesome styling of the taks though. My dream is to own a complete set of K's from 20/28f3.5/35f3.5/50/55/85/105. Possibly a few others but these are the ones that are at the top of my list although the 85 isn't as necessary (currently) on digital with the 105 so close.
04-25-2012, 10:01 AM   #23
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QuoteOriginally posted by abacus07 Quote
I feel the same as you do about zooms but there are still times that I wish I had a nice set of zooms (the whole Tamron set would be nice). If it was me I would try to add to it instead of selling it. the A28/2.8 and A100/2.8 are a nice start. those would cost about $300+ but you could get the M versions for $150+. these are exactly the same optics the only difference is that with A's you can control aperture from the camera and you don't have to use the green button. There are a few times that I wish the lens was constantly metering but the biggest issue I have is when I'm swapping back and forth between M and A lenses and forget which process to use to take photos.
I think I've found an A100/2.8 for pretty cheap. Hopefully $120 when everything is said and done.

I imagine the M and K series would give me problems for the same reasons you've mentioned: I rely heavily on the in-camera metering, I rely heavily on the two knobs for setting aperture and shutter speed, and I rely heavily on the green button to give me a quick shutter speed setting. —I find it's quicker (and simpler) than flipping through all the speeds myself. I just push point, hit the green button, and adjust from there.

These are the reasons I shy away from the K, M, and M42 lenses. Perhaps these things shouldn't worry me. (;

Here's a question… does the in-camera meter rely on the lens' aperture information? That's the real "make it or break it" for me.

04-25-2012, 10:11 AM   #24
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QuoteQuote:
I just push point, hit the green button, and adjust from there.
That's how the M,K,M42 lenses work. it's all green button. A lenses give you the option of constantly metering w/o pressing the green button. And the aperture info is saved in the exif and can be controlled by the camera.

edit - If you can get a good condition A100f2.8 for $120 then that is a great deal. Probably about the same price as an M100f2.8.

Last edited by abacus07; 04-25-2012 at 10:17 AM.
04-25-2012, 10:11 AM   #25
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QuoteOriginally posted by keyofnight Quote
Here's a question… does the in-camera meter rely on the lens' aperture information? That's the real "make it or break it" for me.
With a non-A lens you set the aperture using the aperture ring. The camera doesn't know what the aperture is at all. The green button stops down the lens and takes a meter reading.
04-25-2012, 10:21 AM   #26
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QuoteOriginally posted by abacus07 Quote
That's how the M,K,M42 lenses work. it's all green button. A lenses give you the option of constantly metering w/o pressing the green button. And the aperture info is saved in the exif and can be controlled by the camera.
QuoteOriginally posted by boriscleto Quote
With a non-A lens you set the aperture using the aperture ring. The camera doesn't know what the aperture is at all. The green button stops down the lens and takes a meter reading.
Perhaps I could deal with that, but I certainly rely on the constant metering. It would take a lot of getting used to, so I'll have to think on it more.
04-25-2012, 10:44 AM   #27
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QuoteOriginally posted by keyofnight Quote
This looks like an excellent mod! Does the foil ever peel or rip?—do you have to adjust it a bunch?
I just tried the mod. Doubled-over the foil and everything. I mentioned my problems above. And metering for non-A lenses was totally screwed. So I pulled the camera apart again and removed the foil fragments -- yes, it had ripped. I'll write that off as a failed try. And I'm nervous about repeatedly dismantling the mount (I'm very good at losing irreplaceable screws) so I may not try it again.

Meanwhile, I'm pretty sure my Arizona sojourn is near it's end. I should be back at my home base in a couple weeks. Then I can start sorting through my M-types to decide what to sell so I can buy a few more A-types. Let's see, maybe the Hanimex and Rokinon 28/2.8's, and a Sears-Cosina and a couple SMC-M 50/2's, and the Rokinon 135/2.8, and the Vivitar-Kiron 80-200/4.5... hmmm, those probably won't raise enough cash to get anything good. Would anyone like to buy a hyperactive grandson?
04-25-2012, 11:04 AM   #28
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tbh even with my A50/1.7 I typically use M mode and the green button. the light isn't changing that much so once I've found a reading that I like I don't want it to be changing depending on how much grass/sky or background shadow I have in a shot. The exposure bracketing feature is pretty slick also. It makes it so easy that it's almost like cheating.
04-25-2012, 11:18 PM   #29
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QuoteOriginally posted by RioRico Quote
I just tried the mod. Doubled-over the foil and everything. I mentioned my problems above. And metering for non-A lenses was totally screwed. So I pulled the camera apart again and removed the foil fragments -- yes, it had ripped. I'll write that off as a failed try. And I'm nervous about repeatedly dismantling the mount (I'm very good at losing irreplaceable screws) so I may not try it again.
Damn. Maybe an extra thin piece of sheet metal would last longer? I don't have any lenses to test the mod with. ;D
04-26-2012, 03:37 PM   #30
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QuoteOriginally posted by RioRico Quote
....
Results... I'm not sure what to expect. So far I've just tried some test shots with K, M, A, M42, T2, and N/AI (modded) lenses. The camera does think the K and M glass are A-type. It doesn't recognize the others, even though the bases short all other mount pins. Onboard pTTL flash *does* work but not very well, and metering is way off in all modes.

Conclusion: I don't really see this as useful, not for me anyway. I'm going to pull the foil.
-The camera does think the K and M glass are A-type. It doesn't recognize the others, even though the bases short all other mount pins

Something is wrong. All lenses should be recognized as A type; if a lens is not recognized (ie. an F-Number does not appear in the viewfinder) then data pins are not being short circuited.

Onboard pTTL flash *does* work but not very well, and metering is way off in all modes.

This most likely has to do with how you've set aperture in the viewfinder. For m42 lenses the viewfinder f-stop should be set to a minimum in the viewfinder - then the camera does not expect to be closing the aperture - if anything other than the minimum is entered with the e-wheel the camera calculates what the exposure should be when the lens is stopped down - but it cannot be stopped down because there is no aperture lever, therefore the exposure is incorrect (only correct when the camera does not anticipate or attempt to close the aperture.)

P-TTL works fine for me when the viewfinder f-stop is set to minimum and slow-synch is used.

I am waiting for an M type lens to arrive so I can tell you how to best set the exposure with the foil in place.

Dave
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