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05-12-2013, 12:50 PM   #1
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m42 lenses on k-01

Hi, I recently picked up a k-01 and I went to test it out in video using m42 lenses. I noticed while in m mode changing iso or shutter have no effect on the brightness of the image. Ive read the sticky on enable use of manual lenses and the green button. But I can be in almost dark room at f2 and iso 100 is the same as 3200. My second question is I thought the k01 was a manual camera but panning from from bright to a darker area it takes a second and auto exposes to the brighter area. Is there any way around these 2 problems using m42 lenses or do I need a different lenses with a different mount to avoid this things.
Thanka seth

05-12-2013, 04:47 PM   #2
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The K-01's LCD doesn't reflect the brightness of the subject or the EV setting of the camera. It gives you a bright picture to use to focus and compose, even in low ambient light. Changing the EV by changing ISO, aperture, or shutter doesn't affect the brightness of the LCD. There are other threads on this specific subject.

I'm not sure I understand the second part of your question. If you are using an M42 lens, there is no way for the camera to change the aperture to auto expose.

Last edited by nparsons13; 05-12-2013 at 05:07 PM. Reason: added info
05-12-2013, 05:20 PM   #3
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I tested it out today with m42 lenses. Jupiter 9, and helios 58mm and when going from a brighter area to a darker area the lcd showed an adjustment on the screen showing the image getting brighter. I was also using a fader nd.
05-13-2013, 04:46 AM   #4
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It's worse than that - with 'A' lenses or newer, the camera will also adjust the aperture (while you're composing) in addition to adjusting the brightness of the screen.

05-13-2013, 08:21 AM   #5
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QuoteOriginally posted by Seth Quote
I noticed while in m mode changing iso or shutter have no effect on the brightness of the image.
There's nothing that can be done about it, I'm afraid. I'm not sure I would want it this way though, because it would affect my ability to compose the image, but to add insult to injury, the histogram in M-mode is not reflecting the actual exposure either. This I consider a bug, because there is really no point to that. Somebody at Pentax didn't think this through.
05-13-2013, 08:25 AM   #6
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QuoteOriginally posted by Rob22315 Quote
It's worse than that - with 'A' lenses or newer, the camera will also adjust the aperture (while you're composing) in addition to adjusting the brightness of the screen.
One could argue this is a good thing, since it effectively prevents sensor burn. The aperture used when exposing the image is not affected by it.
05-13-2013, 09:36 AM   #7
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QuoteOriginally posted by Ikarus Quote
One could argue this is a good thing, since it effectively prevents sensor burn. The aperture used when exposing the image is not affected by it.
Where does the belief that the sensor will burn come from (source info please)? If open aperture is OK with M lenses, why isn't it OK with A lenses?

We might be a step closer to having the liveview histogram reflect the actual exposure without this feature.
05-13-2013, 09:53 AM   #8
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QuoteOriginally posted by Rob22315 Quote
If open aperture is OK with M lenses, why isn't it OK with A lenses?
It may not be OK with M lenses,
just that the poor camera has no way to protect itself
when those lenses are fitted.

Like when you walk out in the bright sun
just after having your pupils dilated for an eye test.

05-13-2013, 10:04 AM   #9
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QuoteOriginally posted by Rob22315 Quote
Where does the belief that the sensor will burn come from (source info please)?
From Sun burned sensor ... [Archive] - Rangefinderforum.com

"I've seen burned in sun spots in earlier video cameras, and quite a bit less in P&S."
--
EdwardKaraa

Also, see

GoPro User Forum • View topic - GoPro hero 2 sensor burn.

for sample damage on a Go-Pro.
05-13-2013, 11:50 AM   #10
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QuoteOriginally posted by Rob22315 Quote
Where does the belief that the sensor will burn come from (source info please)? If open aperture is OK with M lenses, why isn't it OK with A lenses?
The fact that camera manufacturers believe this to be necessary as a safeguard is already a good clue. Second, when using your favorite search engine you will find enough evidence of people learning the hard way when using their mirrorless cameras or SLRs in video mode in bright sunlight. I suspect the reason we don't hear about this more often is that folks using mirrorless cameras with old manual glass are part of a small minority that generally knows what it's doing.

QuoteOriginally posted by Rob22315 Quote
We might be a step closer to having the liveview histogram reflect the actual exposure without this feature.
I don't see what one has to do with the other.
05-14-2013, 12:53 PM   #11
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QuoteOriginally posted by Ikarus Quote
The fact that camera manufacturers believe this to be necessary as a safeguard is already a good clue. Second, when using your favorite search engine you will find enough evidence of people learning the hard way when using their mirrorless cameras or SLRs in video mode in bright sunlight. I suspect the reason we don't hear about this more often is that folks using mirrorless cameras with old manual glass are part of a small minority that generally knows what it's doing.



I don't see what one has to do with the other.
No, we're not talking about the common sense issue regarding not leaving boxes attached to lenses pointed at the sun for long periods of time. This situation results in overheating and melted plastic or burned cloth shutters. We're talking about short duration exposure (a couple of seconds) which might result in some type of sensor burn-in or reduced sensitivity. I found a few internet examples of the former, none of the latter.

For some yet unknown reason, Pentax set up the K-01 so it adjusts the shutter on 'A' and newer lenses during liveview but no one is quite sure why this was done. The speculation is that it was done to protect the sensor but there's nothing from the engineers and nothing in the manual to verify or substantiate this. From what I've observed, the camera changes the aperture at levels well below that at which any possible sensor damage could occur so it's still a mystery and there's been no documented damage to sensors or cameras at those levels either.

There are a couple of discussions of this elsewhere on the forum - the interest being that the liveview histogram isn't an estimate of the final exposure in part because the camera adjusts the lens aperture. Some folks reasonably want to be able to do exposure compensation then see an estimate of the final histogram, likely to help expose to the right or left and keep from blowing highlights or dropping shadow detail.

Note also that CDAF and focus peaking work better at larger aperture openings (smaller f stop number) so closing the lens down during liveview does affect ability to focus.

Apparently, some of the other manufacturers' cameras do have a liveview histogram that is a reasonable estimate of the final exposure, why can't we have that on the K-01/
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