Lens correction feature on K7


aliengrove

Link Posted 20/03/2010 - 09:35
Not being much of a tech wizard, I am a bit confused by some of the features on my K7. Recently I have been wondering how much difference the lens correction features (distortion and chromatic aberration) on the K7 make: more specifically, how much it reduces the difference between a kit lens (I have the two WR kit lenses) and a higher spec lens that the camera does not correct. Or is the camera not doing anything that can't be done with software? Is what is done in-camera in any way comparable to say, DXO Optics Pro software, which has a database of lenses, images from which can be corrected automatically? I have also wondered if using this feature in any way affects the quality of the image. I would be most grateful if someone could explain exactly what the lens correction function does, as I am a bit confused!
Flurble

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i-Berg

Link Posted 20/03/2010 - 11:59
My understanding is from a K10 perspective - it only has one, universal adjustment for all lenses. I also understand that it affects only the autofocus, and in the K7, the individual lens adjustments only work if you shoot in jpg mode.

Thus, there are likely two allied solutions: first, shoot in RAW anyway, and second, focus manually!
http://www.pbase.com/iberg

bforbes

Link Posted 20/03/2010 - 12:23
I think you are talking about different things.

"
An innovative in-camera Lens Correction function that electronically adjusts for Distortion and Lateral Chromatic Aberrations to maximize image quality with DA series lenses."

Read more: http://digital-photography-school.com/pentax-k7-dslr#ixzz0iiccGNdA

And front/rear focus adjustment.
Barrie
Too Old To Die Young

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Greytop

Link Posted 20/03/2010 - 12:35
aliengrove wrote:
Not being much of a tech wizard, I am a bit confused by some of the features on my K7. Recently I have been wondering how much difference the lens correction features (distortion and chromatic aberration) on the K7 make: more specifically, how much it reduces the difference between a kit lens (I have the two WR kit lenses) and a higher spec lens that the camera does not correct. Or is the camera not doing anything that can't be done with software? Is what is done in-camera in any way comparable to say, DXO Optics Pro software, which has a database of lenses, images from which can be corrected automatically? I have also wondered if using this feature in any way affects the quality of the image. I would be most grateful if someone could explain exactly what the lens correction function does, as I am a bit confused!

You are quite correct, both aspects of the inbuilt lens correction can be carried out in software externally to the camera. However the neat thing about with this K-7 feature is that it is optimised very carefully by Pentax for DA and now some of the FA lenses, it does slow down the camera operation a little but works very effectively.
The other point to note is that it cannot and doesn't improve the sharpness of the image, so you will not for example be magically able to improve a DA 18-55WR to a DA* 16-50s quality. One other point, it only actively corrects Jpeg output although if you PP the RAW file in the supplied Pentax RAW converter the information is retained for that software to implement the same changes as in camera.
Hope that helps.
Regards Huw

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aliengrove

Link Posted 20/03/2010 - 12:48
Thanks for the info. I do have one annoyance with the K7, and that is that so many features only work with jpeg files....seems like this is another one. Also, I didn't get any software with my camera, so I guess I will go and ask the shop I bought it from for a copy.
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Greytop

Link Posted 20/03/2010 - 12:56
The Pentax software disc should have been in the top of the K-7 box along with the instruction manual.
Regards Huw

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Anvh

Link Posted 20/03/2010 - 14:19
aliengrove wrote:
Thanks for the info. I do have one annoyance with the K7, and that is that so many features only work with jpeg files....seems like this is another one. Also, I didn't get any software with my camera, so I guess I will go and ask the shop I bought it from for a copy.

That's because you only need them with JPEG, every PP you do and resave your image you've quality loss. With RAW you can do as many PP as you want without losing any quality.

Also RAW is not an image how strange that might sound, it's only data from the sensor, the undeveloped film in your camera.... how do you want to put something you do as development in your undeveloped film?
I hope this make sense to you.
Stefan


K10D, K5
DA* 16-50, DA* 50-135, D-FA 100 Macro, DA 40 Ltd, DA 18-55
AF-540FGZ

aybee

Link Posted 20/03/2010 - 16:54
- However unless I'm missing something the supplied Pentax software DOES NOT apply the lens corrections. It does have manual correction adjustments but nothing that takes account of the embedded information.
(I'd read this on the dpr review and on elsewhere before I bought my K7 and was slightly miffed to find I'd been misled.)

If you are happy using jpg and don't mind the slowdown in continuous shooting then turn on those features, otherwise disable those options.
Alan B

Greytop

Link Posted 20/03/2010 - 17:17
aybee wrote:
- However unless I'm missing something the supplied Pentax software DOES NOT apply the lens corrections. It does have manual correction adjustments but nothing that takes account of the embedded information.
(I'd read this on the dpr review and on elsewhere before I bought my K7 and was slightly miffed to find I'd been misled.)

If you are happy using jpg and don't mind the slowdown in continuous shooting then turn on those features, otherwise disable those options.

Strange, I thought there was a button to apply the lens settings
Well to be honest I haven't used it much as I prefer CaptureOne Pro
Regards Huw

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aybee

Link Posted 20/03/2010 - 22:22
I'm still hoping to be wrong....
Alan B

aliengrove

Link Posted 22/03/2010 - 08:55
I a lways shoot Raw save a few hdr,s I have done in camera and one days shooting when I did not notice it was shooting jpeg. i thought it might save the lens correcctions as a sidecar file if its switched on and then apply these corrections in ACR or other software. have to say though I have not noticed any particular distortion or aberration from the WR kit lenses.
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JonSchick

Link Posted 22/03/2010 - 11:16
Can't answer your specific question as I prefer to leave the function switched off to speed up the camera operation, and then use the PTLens Plug In for Photoshop (Elements 7 in my case). This seems to do the job very well indeed. And then you don't need to use the Pentax software and can still do lens corrections very easily even from RAW files.
Jon

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bretbysteve

Link Posted 26/03/2010 - 15:47
"That's because you only need them with JPEG, every PP you do and resave your image you've quality loss"

This is an often quoted downside of JPEG...however can you actually see the so-called quality loss?

Suggest you read the JPEG v RAW article by Lee Frost in the March 2010 copy of Black + White photography magazine...it dispels some JPEG/RAW myths.

cheers..

johnriley

Link Posted 26/03/2010 - 16:46
bretbysteve wrote:
"That's because you only need them with JPEG, every PP you do and resave your image you've quality loss"

This is an often quoted downside of JPEG...however can you actually see the so-called quality loss?

Suggest you read the JPEG v RAW article by Lee Frost in the March 2010 copy of Black + White photography magazine...it dispels some JPEG/RAW myths.

cheers..

The quality loss only occurs if you continually resave a JPEG file as a new JPEG file - then the resampling will start to degrade the image.

In practice it's a very unlikely scenario and unlikely to be visible to our eyes when used more normally.

For those in doubt, I would suggest trying it. Shoot a RAW file, make the best you can of it and print it at A3. Then shoot an identical JPEG and make the most of that image before printing at A3. I've put it that way because the two approaches need different processing to optimise the image, so it's only the final output that we should judge.
Best regards, John

Anvh

Link Posted 26/03/2010 - 17:19
bretbysteve wrote:
This is an often quoted downside of JPEG...however can you actually see the so-called quality loss?

Look at these.
http://www.cywarp.com/faq_jpg_degradation.htm
http://www.prophotoshow.net/blog/2008/03/25/file-format-degradation-saving-destr...
http://www.andrewkelsall.com/how-shocking-can-a-jpeg-be/

5 high quality surely aren't a problem nothing to worry about for the normal user I believe.
However you can push a RAW file further in PP than a JPG because JPG throws away the data you can't see so if that's the data you try to recover you can't
Stefan


K10D, K5
DA* 16-50, DA* 50-135, D-FA 100 Macro, DA 40 Ltd, DA 18-55
AF-540FGZ
Last Edited by Anvh on 26/03/2010 - 17:24
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