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08-10-2010, 08:56 PM   #1
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Some Advanced K-7 Questions

Hey guys, I'm loving my K-7, but had some questions that I couldn't figure out from the manual:

1) When and why should SR be turned OFF? The manual mentions turning it off for several scenarios, but never explains why. For example, if I don't wait for the SR logo when shooting sports, will my picture be more blurred than with SR turned off (due to transients in the control system)?

2) So far I haven't noticed bad pixels with my K-7, but I have noticed some wide purple column bands when shooting in high-iso. Would pixel mapping help with this? I guess I just want to know what all pixel mapping does (i.e. does it create non-uniformity and bias values for each pixel as well as mask obviously faulty ones)? I've upgraded to firmware 1.10.

3) For AF adjustment, the manual states that if I use an "Apply to All" setting that it replaces my individual lens's AF adjustment. This makes absolutely no sense, as I'd like to have an apply all that will get my focus indicator correct for old MF lenses, and an individual setting for each of my AF lenses. Is that not possible?

Thanks for the help!

08-10-2010, 10:00 PM   #2
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1) At the high shutter speeds usually associated with sports, SR usually won't be needed.
It can introduce blurring if you shoot while panning.

2) Pixel mapping works by ignoring the signal from the particular faulty pixel, and replacing with the average of pixels surrounding it. Essentially you will get a slight (usually hardly unnoticeable) reduction in Image Quality at that point. If won't affect other pixels.

3) The good news is, Setting AF adjust for All does not wipe out the previous individual lens settings you have made. It just overrides it. The previous individual settings you have made will still be there if you revert back. Only a Custom settings Reset will wipe out all the settings.

Individual lens AF adjustment won't work for MF lenses, because it is dependent on the camera electronically recognising the Lens ID (its in the lens circuitry somewhere) , which old MF lenses do not have.
08-10-2010, 10:05 PM   #3
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For number 1 you should definitely turn it off when using a tripod

If there's no vibration, then it's going to look for vibration and be correcting vibration that isn't there, causing vibration. It sounds crazy but it's true, I accidentally left SR on while making a time lapse video on a tripod and the vibration and jitters were terrible because I left SR on
08-10-2010, 11:04 PM   #4
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QuoteOriginally posted by jeffshaddix Quote
1) When and why should SR be turned OFF? The manual mentions turning it off for several scenarios, but never explains why. For example, if I don't wait for the SR logo when shooting sports, will my picture be more blurred than with SR turned off (due to transients in the control system)?
You already got some good advice. For SR, I would leave SR on anytime but on tripod (as suggested by future_retro). During sport shooting, I use SR on: I found that it does not add much as suggested by kittykat46, but I did not get blur because of SR during action shots.

Good shooting...

08-11-2010, 01:47 AM   #5
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QuoteOriginally posted by jeffshaddix Quote
2) So far I haven't noticed bad pixels with my K-7, but I have noticed some wide purple column bands when shooting in high-iso. Would pixel mapping help with this? I guess I just want to know what all pixel mapping does (i.e. does it create non-uniformity and bias values for each pixel as well as mask obviously faulty ones)? I've upgraded to firmware 1.10.
If your wide purple bands are really huge (1/4th to 1/3rd of the pic, usually on the left), then, from memory, it's a sensor defect, and you'll have to send it back to have it replaced...
If they are just some pixels large, then it's usual banding, and you'll have to live with it, by properly exposing your high-iso shots to avoid pulling them in PP.

Pixel mapping does only one thing : it detects pixels that are burnt-out (and that will produce white dots), and map them out (don't know how, maybe the camera average the neighbors...).
08-11-2010, 02:27 AM   #6
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I don't think it is necessary to do an AF adjustment for MF lenses.
08-11-2010, 08:43 PM   #7
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QuoteOriginally posted by MPrince Quote
I don't think it is necessary to do an AF adjustment for MF lenses.
Actually, adjusting the AF changes when the focus indicator shows up...thus helping MF. Furthermore, catch-in-focus mode would be useless without this being setup properly.
QuoteQuote:
1) At the high shutter speeds usually associated with sports, SR usually won't be needed.
It can introduce blurring if you shoot while panning.

2) Pixel mapping works by ignoring the signal from the particular faulty pixel, and replacing with the average of pixels surrounding it. Essentially you will get a slight (usually hardly unnoticeable) reduction in Image Quality at that point. If won't affect other pixels.

3) The good news is, Setting AF adjust for All does not wipe out the previous individual lens settings you have made. It just overrides it. The previous individual settings you have made will still be there if you revert back. Only a Custom settings Reset will wipe out all the settings.

Individual lens AF adjustment won't work for MF lenses, because it is dependent on the camera electronically recognising the Lens ID (its in the lens circuitry somewhere) , which old MF lenses do not have.
So if I set my overall to -5, then alter each of my lenses individual settings, does that mean all of my MF lenses will have a -5 adjustment, and all of my AF (with ID) lenses will have JUST the individual setting applied? Or do they stack...i.e. if I have -5 for all lenses and a +3 for an AF lens, does that mean AF is being adjusted by -2 or +3?

Thanks all for the SR tips...hard to believe SR causes blurring on a tripod, but I'll take your word for it.

Last edited by jeffshaddix; 08-11-2010 at 08:50 PM.
08-11-2010, 11:19 PM   #8
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The lens AF corrections for All and Individual lens corrections are independent - they don't stack.

If you set -5 for All lenses, it will apply to all lenses for as long as All Lenses is set.
It will ignore any Individual lens setting you earlier set.
If you revert back to individual lens setting, it will "recall" your previous setting, say e.g. + 3.

For manual lenses, too bad, if different lenses have different AF adjust requirements, you have to keep changing your AF adjust for All lenses each time you change lenses.
The system just doesn't cater well for Manual lenses, because of the lack of electronic lens Id.

08-11-2010, 11:29 PM   #9
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Does the purple banding looking something like in my case, as seen here ? https://www.pentaxforums.com/forums/pentax-dslr-discussion/109612-please-help...ing-issue.html

If so, I am afraid you could have a faulty sensor, I have sent my K7 back for service.

Regarding the SR off that would be advisable whenever your shutter speed is above 1/250 sec and/or you shoot from a fixed position or in specific situations where multiple exposures are taken (for in-camera HDR the body switches the SR off by default for example)
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