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05-26-2008, 07:36 AM   #1
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Downside to K20D

I used a Tamron 18-200 zoom on my K100D and thought it was pretty good. Perfect walk around and travel lens. Prints seemed Ok from most focal lengths up to A4. Used a Sigma 28-70 f2.8 as an indoor lens and it impressed me.
But - these lenses are like chalk and cheese on my new K20D.
The large Sigma produces far superior images to the Tamron with no distortion or CA. It looks as if the K20D's resolution is too high for the Tamron zoom lense and the Sigma full frame glass really shines. If I may use your term, Lance, looks like LBA big time!

Two 100% crops from recent POTW entries follow illustrating the power of the K20D coupled with a great lens.

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05-26-2008, 07:46 AM   #2
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According to what you say, the downside of the K20D is that the sensor is too good. Is that it?
05-26-2008, 07:50 AM   #3
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No way!
The sensor is excellent. But you will need very good glass to get the most out of it.
Couldn't be happier with a digital camera that now exceeds the best film SLR I ever owned in the last 40 years.
05-26-2008, 09:07 AM   #4
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QuoteOriginally posted by garth1948 Quote
No way!
The sensor is excellent. But you will need very good glass to get the most out of it.
Couldn't be happier with a digital camera that now exceeds the best film SLR I ever owned in the last 40 years.
What a name to choose for a thread... Courageous! It will get all the daggers and swords out on you...Specially from those K20D owners who ordered theirs just minutes before the rebate was announced :-)

05-26-2008, 09:22 AM   #5
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Hi Garth

Re your observation:

QuoteQuote:
It looks as if the K20D's resolution is too high for the Tamron zoom lens and the Sigma full frame glass really shines.
I can't speak from actual experience as currently I still own a pair of K10D's, but it's a *truism that once the resolution of a sensor begins to exceed the resolving power of a lens attached to that DSLR body, something naturally has to give where image quality is concerned !!! Unfortunately it seems that you may have reached this type of limitation with your 14.6 MP sensor, so if I were you I'd simply take a deep breath and then make an appointment to see your friendly bank manager......lol ! This* will really come as no great surprise to anyone who has used either the full-frame C***n 1DS Mk11 / 5D or N***n D3 for any length of time ! It's also the main reason why somebody seriously intent on purchasing a full-frame DSLR should be aware that its invariably a false economy to employ anything less the highest quality glass available, in order to avoid such inevitable disappointments !

Best regards
Richard

Although

Last edited by Confused; 05-26-2008 at 09:30 AM.
05-26-2008, 10:57 AM   #6
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That bird is staring at me....

Stop it, bird! STOP IT!

c[_]
05-26-2008, 11:06 AM   #7
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Your post is intriguing Garth. I have the k10d and k20d as well as the Pentax 18-250. I am going to go out and shoot a couple of shots and see if I can see much difference between that lens used on both cameras.
05-26-2008, 12:23 PM   #8
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Hi PentaxPoke

I'm delighted to hear that:

QuoteQuote:
I have the k10d and k20d as well as the Pentax 18-250.
and

QuoteQuote:
I am going to go out and shoot a couple of shots and see if I can see much difference between that lens used on both cameras.
Well, seeing as you seem to have far too much gear to play with in the first place, when you've finished that last assignment I'll be round sharpish in order to collect/borrow your K20D, purely for scientific purposes you understand. Six months or so should be sufficient and I'm sure you won't miss it much.......

Best regards
Richard

05-26-2008, 02:22 PM   #9
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Thanks Richard!

Ok, here is the test:

k10d and Pentax 18-250 at 18mm, 50mm, 100mm, 250mm
k20d and Pentax 18-250 at 18mm, 50mm, 100mm, 250mm
k20d and DA* 50-135 50mm, 100mm

Not entirely scientific. Handheld (with 1/500 shutter speed and SR on however). k20d images are 20% "bigger" in dimension at 100% due to increased resolution.

All original files are here:
k10d and k20d DA 18-250 and DA* 50-135 - a set on Flickr

I am showing the crops since that is the only place I think you will see major differences. All were cropped from highest res images viewed at 100%. I think those with a k10d and/or an 18-250 lens will be pleasantly surprised.

18mm 100% crop, k10d, k20d



250mm 100% crop, k10d, k20d



50mm 100% crop, k10d 18-250, k20d 18-250, k20d DA* 50-135




100mm 100% crop, k10d 18-250, k20d 18-250, k20d DA* 50-135




It is clear that the DA* is a sharper lens, but the 18-250 is still great, and very versatile.

Last edited by PentaxPoke; 05-26-2008 at 02:38 PM.
05-26-2008, 02:33 PM   #10
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If you stop inspecting your photos at 100% (I know, it's hard) then your insecurities about your lenses will gradually diminish. The problem is that as you increase the pixel count, 100% starts to mean higher and higher effective magnifications which will inevitably reveal the limitations of your glass at some point.

Alternatively, go mad and buy all the Limited lenses to use instead of zooms. It'll take a lifetime for a sensor to make them look bad.

Matthew
05-26-2008, 02:37 PM   #11
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QuoteOriginally posted by Matthew Allen Quote
If you stop inspecting your photos at 100% (I know, it's hard) then your insecurities about your lenses will gradually diminish. The problem is that as you increase the pixel count, 100% starts to mean higher and higher effective magnifications which will inevitably reveal the limitations of your glass at some point.

Alternatively, go mad and buy all the Limited lenses to use instead of zooms. It'll take a lifetime for a sensor to make them look bad.

Matthew
Is this directed at me? I am one on this forum that argues against viewing 100% crops! I just demonstrated that you really need to go to 100% crop to even see the differences. I did this test as a service to those who have any of this equipment and would like to see how it compares.
05-26-2008, 03:52 PM   #12
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Hi again PentaxPoke

Re Matthew's unintentional misinterpretation:

QuoteQuote:
If you stop inspecting your photos at 100% (I know, it's hard) then your insecurities about your lenses will gradually diminish.
and your bruised reply:

QuoteQuote:
Is this directed at me ? I am one on this forum that argues against viewing 100% crops !
.....all I can say is OUCH !! It only goes to prove (as this 'slightly mangled' version of the famous adage goes) that:

QuoteQuote:
The path to photographic hell/nirvana (delete as required !) is paved with good intentions ?
Best regards
Richard

P.S. You clearly can't please ALL the people ALL of the time......good try though........lol !

Last edited by Confused; 05-26-2008 at 04:06 PM.
05-26-2008, 04:50 PM   #13
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Thanks again Richard,

Yes I guess some prefer to give advice through pithy posts. I prefer pictures.
05-26-2008, 07:33 PM   #14
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Hi PentaxPoke,

Thanks for posting those comparisons. I'm new to the K10 and have both lenses so this was nice to see.

Cindy
05-26-2008, 07:54 PM   #15
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Happy to do it. I think it just shows how good both these cameras and lenses are. You really need to look at the extreme crop to see the differences, and even then they are subtle.

That said, I personally think the real advantage of the DA* 50-135 is in lower light where I can get f2.8 from 50mm to 135mm. (I wish my DA* would have come in time for my daughter's dance recital!) The best the 18-250 can do is f4.5 @ 50mm and f5.6 at 135mm. Outdoors in good lighting, I can't tell them apart without 100% crops.
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