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05-21-2009, 02:21 AM   #1
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Is it bad that K-7 only corrects DFA and DA lenses?

Obviously it's not bad that it does correct those, that's good. But what about the FAs that are still being sold and FA*s? I have an FA35 and FA50, do they need any "correcting"?


Last edited by Arpe; 05-21-2009 at 03:07 AM.
05-21-2009, 04:21 AM   #2
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I think Pentax felt that they wanted to "encourage" users to buy newer lenses. Also, I am sure there is a limit to the lenses that you can put in your database. Their explanation is that the DA and DFA lenses are already "optimized for digital" and therefore it made sense to tweak their performance.
05-21-2009, 04:25 AM   #3
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Didn't like it.
I have some FA and FA* ....
05-21-2009, 04:41 AM   #4
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The correction applies only to jpegs, so why bother... I don't remember last time I shot jpeg.

05-21-2009, 06:30 AM   #5
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Doesn't Pentax Photo Laboratory already offer this feature (Distorion Correction)? Thus it would offer a workaround. But without any correction presets for any certain lens. You would just need to research the correct parameters for a certain lens.
05-21-2009, 06:46 AM   #6
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You mean it wont work with my M42 mount lenses?

Damn, Nikon here I come.
05-21-2009, 06:54 AM   #7
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QuoteOriginally posted by mut@NT Quote
The correction applies only to jpegs, so why bother... I don't remember last time I shot jpeg.

I'm confused.

Isn't that the feature to "correct lens" on body ? + 1 - 1 etc ?
What does this have to do with being raw or jpg ?

I would appreciate the education.

Edit: I mean the feature to correct b/f focusing.
05-21-2009, 07:06 AM   #8
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Corrects for chomatic aberration and distortion

QuoteOriginally posted by netuser Quote

Isn't that the feature to "correct lens" on body ? + 1 - 1 etc ?
What does this have to do with being raw or jpg ?

I would appreciate the education.

Edit: I mean the feature to correct b/f focusing.
This feature of the K-7 specifically "corrects for lens distortion and lateral chromatic aberration" from DA and DFA lenses. The front or back- focus correction is still there, but that is different for every body and every lens based on manufacturing tolerances. The distortion and aberrations are consistent with the lens design (hence DXO makes a mint selling "specific lens correction kits"), and can be put into a database and applied automatically when a lens of that design is mounted. Nice that it can be disabled as well, since I kinda like the distortion of my DA 10-17mm!

Note: "lateral chromatic aberrations" are those subtle pesky color shifts most noticeable in the detailed corners of images. "Purple fringies" that appear at high-contrast areas with some lenses are not lateral, so I assume they won't be corrected (but then they are pretty well controlled in the DA series).

05-21-2009, 07:11 AM   #9
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QuoteOriginally posted by panoguy Quote
This feature of the K-7 specifically "corrects for lens distortion and lateral chromatic aberration" from DA and DFA lenses. The front or back- focus correction is still there, but that is different fro every body and every lens. The distortion and aberrations are consistent with the lens design (hence DXO makes a mint selling "specific lens correction kits").

Note: "lateral chromatic aberrations" are those pesky color shifts most noticeable in the corners of images. "Purple fringies" that appear at high-contrast areas with some lenses are not lateral, so won't be corrected I assume.
I would also assume that CA in out of focus areas will not be addressed, but what about vignetting? that could be useful?

On the whole, I think the real issue is that pentax does not want to go back and develop software to account for the hundreds if not thousands of past pentax lens designs, and why should they? but perhaps, they could leave a menu open, just like for focus, for users to inoput their own correction, assuming they have the patience to work it out.

something people need to think about, however, is that this may be the new way forward in lens designs, specifically to apply corrections in software. I would imagine this would simplify the optical design and lens complexity moving forward.
05-21-2009, 07:12 AM   #10
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QuoteOriginally posted by netuser Quote



I'm confused.

Isn't that the feature to "correct lens" on body ? + 1 - 1 etc ?
What does this have to do with being raw or jpg ?

I would appreciate the education.

Edit: I mean the feature to correct b/f focusing.
Adjusting front/back focus is an electromechanical adjustment in the camera body. The lens aberrration adjustment is software only, as it is dependent on the scene shot. No lens produces purple fringing on every shot (no matter how cheap the lens), but if it back focuses or front focuses, it does do that on every shot, by the same amount. Therefore, the camera body can be adjusted to correct for it.

What's in the K7 is the same general software (I'm speculating) that's photo processing software. Not sure why it has to be limited to DA lenses, but the fact that it offers it at all is still a nice selling point.
05-21-2009, 07:31 AM   #11
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It does seem strange that the FA's were left out, since the FA's are known to be worse at the PF/CA than most of the DA lenses. How sad that my PF monster the Tammy 70-300 and my FA 50 are not gonna get a little help. (insert sad face here)

Are you sure the FA's are not getting the fix?
05-21-2009, 07:32 AM   #12
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QuoteOriginally posted by Mike.P Quote
You mean it wont work with my M42 mount lenses?

Damn, Nikon here I come.
Hey Mike, I hope you were joking. Nikon is the absolute worst system to use with M42 lenses. The adapters have a magnifying lens in them due to the expanded distance between the rear of lens and sensor. Thought you should know.
05-21-2009, 07:34 AM   #13
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QuoteOriginally posted by Lowell Goudge Quote
I would also assume that CA in out of focus areas will not be addressed, but what about vignetting? that could be useful?
Good point about aberrations in OOF areas. Maybe the aperture and focus distance are considered in the calculations? I really have no idea how "fancy" correction software like DXO does it, since I only use Adobe Camera Raw which does global corrections (but I control when it does this). No idea why vignetting isn't a part of the correction, except that it varies greatly with aperture.

QuoteQuote:
something people need to think about, however, is that this may be the new way forward in lens designs, specifically to apply corrections in software. I would imagine this would simplify the optical design and lens complexity moving forward.
That kinda worries me, though I don't doubt it is considered. I've used and corrected for some really bad Canon lenses in the past, and you can only "dress up a pig" so much! Plus, any distortion correction will inherently degrade your image sharpness no matter when it is done, simply because the field-captured image data is compressed or expanded "to fit."
05-21-2009, 07:39 AM   #14
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QuoteOriginally posted by jeffkpotter Quote
Hey Mike, I hope you were joking. Nikon is the absolute worst system to use with M42 lenses. The adapters have a magnifying lens in them due to the expanded distance between the rear of lens and sensor. Thought you should know.

Yes I was joking, British sense of humour again


I must admit I have been thinking of the D300 for a while now as my K10D is getting on a bit but the K-7 has sorted that problem out for me.
05-21-2009, 07:54 AM   #15
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Thanks all for explaining so well this feature.

Seems a great improvement.
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