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02-24-2010, 09:36 AM   #1
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delay to preview

I got an FA50/1.4 and a DA* 16-50mm for my K7. Both are absolutely great so far. One difference is in the time the preview of the shot shows up. When I shoot with the prime, the preview is shown immediately on the LCD. When I shoot with the zoom, several seconds pass between the shot and the view. The same was happening on my K10D and the Tamron zoom. Is it the effect of some postprocessing of the image which depends on the lens?

02-24-2010, 09:50 AM   #2
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Have you turned on the distortion or ca correction? If so it takes time for the camera to process the picture with DA-lenses.
02-24-2010, 10:14 AM   #3
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Yes I did, clicking through the menus yesterday and thinking, "this wouldn't hurt." Yeah right! Now what I wonder is, is this correction for JPEG only, i.e., since I shoot in RAW, should I bother?
02-24-2010, 10:24 AM   #4
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QuoteOriginally posted by braver Quote
Yes I did, clicking through the menus yesterday and thinking, "this wouldn't hurt." Yeah right! Now what I wonder is, is this correction for JPEG only, i.e., since I shoot in RAW, should I bother?
Seems to be for both, RAW and JPG. If it were for JPG only, it would be disabled in RAW and RAW+. The only time I've seen it disabled is with a lens that isn't in whatever database they have set up. That is, pre v1.03 update, the option to correct for the FA Limited lenses was not available. I have to say that it's very nice to have, even with the correction delays. I spend a lot less time in post processing trying to figure out how to remove CA.



02-24-2010, 10:04 PM   #5
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Interesting idea: disable in camera and apply in Lightroom/Photoshop in a better way... Possible?
02-24-2010, 10:10 PM   #6
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QuoteOriginally posted by braver Quote
I got an FA50/1.4 and a DA* 16-50mm for my K7. Both are absolutely great so far. One difference is in the time the preview of the shot shows up. When I shoot with the prime, the preview is shown immediately on the LCD. When I shoot with the zoom, several seconds pass between the shot and the view. The same was happening on my K10D and the Tamron zoom. Is it the effect of some postprocessing of the image which depends on the lens?
There should only be a delay in saving jpeg or RAW+ on the K-x or K7 when the camera is correcting for CA etc with supported lenses. Correction is not applied to RAW files and the K10D does not have the correction facility.

What type of shutter speeds are we talking about, you might be experiencing the effect of dark field subtraction noise reduction during long exposures?
02-25-2010, 02:05 AM   #7
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Totally forgot about that and was experiencing the lag....again..
02-25-2010, 01:32 PM   #8
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Usually happens with the DA* all the time -- indoors and outdoors. I put it in DNG first thing -- having attended Peter Krogh's Santa Fe seminar I was always a fan of DNG. K10D also could do that, but PEFs were smaller; now that it's compressed, I'm preferring it. Didn't try PEFs instead. I'm not doing any RAW+, no need for JPEGs at all.

Now since the DNG has an embedded JPEG preview, this is what may be happening here. Must experiment with PEF vs DNG to see if it makes the lag go away.

Regardless, I'm curious how the correction actually works. If it's not applied to PEF, i.e. to the raw-est data, then it will be lost if I rerun Adobe DNG converter on the DNG, which I do in my workflow to make sure I get Adobe-approved DNG, with some corrections applied always (per "The DAM Book").

If the camera knows how to correct for a given lens, why wouldn't the same correction be available in Lightroom as a separate plugin? Or Pentax knows better to correct for its lenses, or the camera us using some information available only right after the shot and not embedded in the RAW/DNG?


Last edited by braver; 02-25-2010 at 02:52 PM.
02-25-2010, 03:20 PM   #9
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QuoteOriginally posted by braver Quote
Now since the DNG has an embedded JPEG preview, this is what may be happening here. Must experiment with PEF vs DNG to see if it makes the lag go away.
I very much doubt that the embedded jpeg is corrected (but I could be proved wrong), PEF files have always also contained an embedded jpeg.

QuoteOriginally posted by braver Quote
Regardless, I'm curious how the correction actually works. If it's not applied to PEF, i.e. to the raw-est data, then it will be lost if I rerun Adobe DNG converter on the DNG, which I do in my workflow to make sure I get Adobe-approved DNG, with some corrections applied always (per "The DAM Book").
Basically if the lens ID, FL, aperture and the approximate focus distance is known then the degree of compensation required to counter vignetting, CA and distortion can be applied based on tables generated by empirical testing of a set of reference lenses. Unless the DNG converter strips this basic EXIF data then any converter with the appropriate smarts should be able to compensate for the three main aberrations, but currently I think it's only the Pentax DCU4 lab converter and possibly DXO that does?
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