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07-15-2009, 05:57 PM   #1
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Moving from K100D to K7 - What practical performance differences can I expect?

I've had my K100D 6mp for three years now...shot over 5500 images.

I've been generally happy with it, except white balance and slow low light focusing. Also, don't know if its the lens (2 kit lenses, and the FA f1.4 50mm prime), but I do not achieve the resolution I would like - e.g. close ups of model trains (not necessarily macros) with tripod and mirror lock. Also, no dust removal/masking system. I also shoot panoramas, landscapes, and interiors.

What will be the gains and losses I will experience going from the K100D to the K7?

Here is a recent photo I took with the K100D...

The white roof edging doesn't show up in the RAW I took. Must be a bit over overprocessing in the jpg.

This is one of the train photos. The tiny lettering on the lower front of the engine should be clearer. This was shot using the f4 50mm at f22, with tripod.



Last edited by gfmucci; 07-15-2009 at 06:23 PM.
07-15-2009, 09:49 PM   #2
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I've kept my old K100D, so the comparisons are very obvious.

First, the FA 50 mm is not at its best at f/22. I never use it at that aperture, unless its unavoidable in very bright sunlight. To really test its sharpness, set f/8.
You may have a bit of focusing problem with your copy, but you need to try it out on a tripod and a focus chart. Good thing about the K-7 is you can adjust for Back/Front focus yourself.

The K-7 almost the same size as the K100D, so it will feel very familiar, but heavier.
You get 2.3 x the megapixels, so the actual linear resolution is 52% more - which is a lot, but you need a good quality lens to bring that out. The FA 50mm will look better, the Kit Lens only slightly better.

The AWB on the K-7 is almost "perfect". The yellowish cast of the K100D JPEG shots indoors is gone. I've shot under intensely Yellow halogen lights (even worse than tungsten bulbs)- no problems.

The low-light AF is fast and responsive. Items in dim light which the K100D with the FA50 will give up AF, the K-7 will focus.

Exposure is more accurate. I rarely need to reach for the E/V button.

Its just a very much more refined camera. The K100D had a very good sensor, though "only" 6 MP, so the differences are not that much in the final photo, more obvious if you use a DA/FA limited lens.
07-15-2009, 10:57 PM   #3
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QuoteOriginally posted by gfmucci Quote
I've had my K100D 6mp for three years now...shot over 5500 images.

I've been generally happy with it, except white balance and slow low light focusing. Also, don't know if its the lens (2 kit lenses, and the FA f1.4 50mm prime), but I do not achieve the resolution I would like - e.g. close ups of model trains (not necessarily macros) with tripod and mirror lock. Also, no dust removal/masking system. I also shoot panoramas, landscapes, and interiors.



This is one of the train photos. The tiny lettering on the lower front of the engine should be clearer. This was shot using the f4 50mm at f22, with tripod.
Great to hear that you think it is an worth upgrade! Can't wait til I get one. ENVYYYYY!!! Hisss****

and with the train with f/22? Won't it be even less sharp then at f/4? best range to use I thought was from f/5.6-f/14.
07-15-2009, 11:52 PM   #4
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At f/22 you are badly diffraction limited. I would expect the image to be a bit fuzzy or at least soft. Even so, it doesn't look bad. Here is a good discussion on diffraction including a simple calculator:

Diffraction Limited Photography: Pixel Size, Aperture and Airy Disks

Even the photozone tests show that the '50 starts losing resolution after f/4:

http://www.photozone.de/pentax/126-pentax-smc-fa-50mm-f14-review--lab-test-report?start=1

I have never used a 100D, but I have used a 10d and a 20d. I would be surprised if you didn't think the K-7 was better in every way.

07-16-2009, 10:06 AM   #5
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Thank you for the links to those lens tests.

After some additional testing with that same shot, and the f1.4 lens shot at various f settings, there is "slight" improvement in the f4.0 to f11 range. However, the text on that little sign is still not legible.

My conclusion is that the increase in sensor size will improve the clarity and legibility of that portion of the image to a greater extent than the change of f stop from f22 to f8. Of course, doing both - using the best mid-range f stop AND increasing sensor pixels by more than 2-fold - may very well achieve the results I'm after. What do you think?

Here is the link to additional photos and discussion on this topic...Moving from K100D to K7 - what differences can I expect in performance?: Pentax SLR Talk Forum: Digital Photography Review

Last edited by gfmucci; 07-16-2009 at 10:13 AM.
07-16-2009, 04:21 PM   #6
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You can expect a huge lead in the performance of the camera body. I have just done the same upgrade.

There are buttons or quick access menus for most commonly used functions.
AF is much quicker and more accurate.
Buffer is HUGE in comparison. Even in RAW it just shoots and shoots and shoots without slowing down.
Response to viewing images is very fast in comparison.
VF is bigger, brighter and 100%. (it is straight too unlike my k100d). A level horizon with my k100d was only possible in PP.

In all.... it is a huge upgrade in usability. Still enjoy low light shots with the k100d. Low noise, nice colors.

mike
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