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09-20-2008, 01:33 PM   #1
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K20D vs K100DS

I should keep my mouth shut. In a discussion yesterday I offered to post a shootout: K20D with kit lens, vs K100DS with 50mm f/1.4. My assertion was that upgrading from a K100 to a K20 provides a greater resolution boost than any lens upgrade. Some general notes:

- I absolutely hate doing these things, and I am horrible at them. I can remember two things at any given time. The third thing I have to remember causes me to forget the other two. You wouldn't believe how long I spent on this tiny test. OTOH I always learn something.

- I tried doing this under artificial light but Tungsten wb is different enough between the cameras that it messes things up. The down side of natural light is that it changes rapidly. It was an overcast day, but there was some variation. I don't think it's germane to what I was trying to show anyway.

- I initially did this test with a silk flower arrangement. It was a grand waste of time. The flowers looked pretty in every shot, and who's to know what the texture is supposed to be?

- My 18-55mm underexposes by about 2/3 stop. No wonder I was so thrilled when I replaced it. The 18-55mm imagess below are at +0.7 EV. An initial run with +0.5 and 1.0 had to be scrapped. More time wasted.

- I used Av mode, with an aperture of f/5.6 and ISO 200. Note that the 18-55mm was wide open and the 50mm was stopped down to its sweet spot.

- I decided to use AF because manual focus with the K100's viewfinder is dodgy.

- I set both cameras to factory defaults (tone, sharpness, etc) and shot jpegs. I did the test a couple of times using all manual settings and Raw, but there were so many things that turned into variables, I decided to start over and do it the simple way. I think that's fair.

- I used a tripod and 2s delay.

- All images were cropped in Windows (2000mp wide for K20D, 1300 wide for K100) and then resized to 1200 mp wide using Picasa.

K20D with 50mm f/1.4:



K20D with 18-55mm:



K100DS with 50mm f/1.4:



K100DS with 18-55mm:



Conclusions:

I thought there should be a bigger difference between the K100DS/18-55 vs K100DS/50mm, so I repeated the shot and got the same results. I have to conclude that a 6mp camera doesn't have enough resolution to show off all of the prime's advantage. Maybe I'll have to try again using MF.

I believe I proved that a K20DS with a kit lens provides more resolution than a K100DS with a sharp prime, so people should at least consider a body upgrade when LBA strikes. Of course there are other things a lens upgrade brings that a camera upgrade doesn't (and vice versa).

I am not for a minute suggesting that K100DS shooters need to upgrade. The advantages of a K20D only show up in a few circumstances where resolution is an advantage, i.e. for cropping or large prints, archiving, etc. Artistically there's no significant difference. We've all seen the stunning 6mp with kit lens photos.

If this test wasn't to your liking, feel free to post your own. No way I'm going to redo this one.


Last edited by audiobomber; 09-20-2008 at 02:12 PM.
09-20-2008, 02:11 PM   #2
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Audiobomber:

Thank you for all of your hard work. Your conclusions are interesting and are supported by the 4 pics. I have never done a test like this, so I am not qualified to judge. But your post has me thinking about things and I am benefiting from this.

I had always heard "it is all about the glass," but never committed to either side of the argument because I am not qualified. I started DSLRs with a K20 6 months ago and I love it.

I am interested to hear more on this from others who are qualified to respond--thanks.
09-20-2008, 02:21 PM   #3
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.

I have both the K100DS and the K20D, and I fully concur with audiobomber - the sensor makes lens quality differences more apparent.

I've been saying this for a while, but many people still do not believe me... Good job illustrating what I and others are seeing, audiobomber!


.
09-20-2008, 02:35 PM   #4
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I'm glad you liked it. I just set up the scene again, K100DS with 50mm, same conditions as before except used manual focus and single AF. I got exactly the same results with MF vs AF. Nothing wrong there, the original results are valid.


Last edited by audiobomber; 09-20-2008 at 02:45 PM.
09-20-2008, 04:10 PM   #5
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Yeah, I know these tests are always harder than you imagine they will be, so I appreciate the effort!

I'll just say that I have also tested the 18-55 against a 50 prime with a 6 MP camera (DS), and in my test, the sharpness difference was *painfully* obvious at f/5.6. By f/8, you had to look more closely, because the kit lens improved dramatically and the 50 was by then diffraction-limited. But at f/5.6, there was *no question*, no contest, not even close. Made me avoid using the kit lens entirely for a while. I've since come to my senses; the kit lens is still quite good at f/8, and a useful enough focal length range that I keep turning to it when I "should" know better.

In any case, no, I don't think one can say that 6MP is not enough resolution to show the advantages of a prime. I was similarly able to *easily* show the DA40 sharper than the kit lens at that aperture. And the 10MP K200D was more than enough resolution to show that the M28 was also better than the kit lens.

QuoteQuote:
I believe I proved that a K20DS with a kit lens provides more resolution than a K100DS with a sharp prime
Perhaps, although I think of the images you posted, the K100D with the 50 is the most suspect - in my experience it should have been *much* sharper.

But of course, resolution isn't everything. There are other advantages of the prime - the wider aperture being most obvious.

And in any case, really, the test *I* want to see is whether the K20D with 50/1.4 cropped to resemble 135mm can really hold its own against the K100D with 50-135.
09-20-2008, 06:41 PM   #6
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QuoteOriginally posted by Marc Sabatella Quote
I'll just say that I have also tested the 18-55 against a 50 prime with a 6 MP camera (DS), and in my test, the sharpness difference was *painfully* obvious at f/5.6. By f/8, you had to look more closely, because the kit lens improved dramatically and the 50 was by then diffraction-limited. But at f/5.6, there was *no question*, no contest, not even close.
Did you account for the 18-55's tendency to underexpose? I know from others' posts that this is a common failing (maybe universal?). Why do you think the 18-55 and 50mm ended up so close to the 50mm in my test?

QuoteOriginally posted by Marc Sabatella Quote
Perhaps, although I think of the images you posted, the K100D with the 50 is the most suspect - in my experience it should have been *much* sharper.

But of course, resolution isn't everything. There are other advantages of the prime - the wider aperture being most obvious.
I'd like to see that. Do you still have a 6mp camera? Do you have a Jumbo box of Cheerios?

I know that resolution isn't everything, and I alluded to that in my first post. Speed, bokeh and colour rendition are more than enough reason for someone with a 6mp camera to buy a fast prime. But before buying that second prime they should look at the possibility of a body upgrade instead. Primes bring good things to the table besides resolution, but a body lets you get shots you will miss cycling through menus. More buttons, faster fps, more flash options, increased adjustability, heavy cropping, large prints, lower noise, better colours and wb, MTF mode, Live View, interval shooting, one-push bracketing, improved battery life, etc etc.

QuoteOriginally posted by Marc Sabatella Quote
And in any case, really, the test *I* want to see is whether the K20D with 50/1.4 cropped to resemble 135mm can really hold its own against the K100D with 50-135.
I wish I could oblige, but I've never even seen a 50-135. Just between you and me, I suspect I went too far with that one.
09-20-2008, 09:17 PM   #7
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that is a serious difference in sharpness and color.

I wonder why the camera tests don't pick up on that.
09-20-2008, 10:51 PM   #8
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Is Picasa messing with the Metadata?

I'm making an assumption here because I don't know about the K20's typical EXIF, but it looks like the K20 has Sharpness and Contrast boosted (Image Tone: Bright maybe?), but the K100 doesn't? (Image Tone: Natural, +1 Sharpness maybe?)

EDIT: I'm wrong here, they are default settings - it looks like the K100 doesn't set the Contrast, Sharpness flags in Bright mode - my bad


Last edited by cpopham; 09-21-2008 at 05:21 PM.
09-21-2008, 05:37 AM   #9
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QuoteOriginally posted by cpopham Quote
Is Picasa messing with the Metadata?

I'm making an assumption here because I don't know about the K20's typical EXIF, but it looks like the K20 has Sharpness and Contrast boosted (Image Tone: Bright maybe?), but the K100 doesn't? (Image Tone: Natural, +1 Sharpness maybe?)
Just before doing this test, I went into the menu and selected "Reset" to restore the factory defaults on both cameras. Both cameras defaulted to Bright image tone with controls for Sharpness, Contrast and Saturation set to neutral. I believe Bright setting does boost some of these parameters on both cameras. It's academic anyway. There's no amount of contrast or sharpness dithering that will make up the difference in resolution.

Last edited by audiobomber; 09-21-2008 at 06:25 AM.
09-21-2008, 09:15 AM   #10
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QuoteOriginally posted by audiobomber Quote
Did you account for the 18-55's tendency to underexpose? I know from others' posts that this is a common failing (maybe universal?).
I don't have that problem with my original 18-55 or my 18-55 II or my wife's 18-55. So no, not universal. Of course, there are plenty of reports about underexposure in general, but those are mostly people from people not understanding how DSLR metering works, not from people doing controlled tests between lenses.

Of course, shooting at 50mm and f/5.6, that's wide open for the 18-55, and I do tend to get darker pictures at that apertures than when stopped down, suggesting that f/5.6 is probably a bit "optimistic" for maximum aperture. But I don't think I have *any* lenses that are not this way - they *all* shoot darker wide open than stopped down.

QuoteQuote:
I'd like to see that. Do you still have a 6mp camera? Do you have a Jumbo box of Cheerios?
My wife still has her K100D. But you know how much work it was for you to do this? I'm in no hurry to repeat my tests.

QuoteQuote:
Primes bring good things to the table besides resolution, but a body lets you get shots you will miss cycling through menus. More buttons, faster fps, more flash options, increased adjustability, heavy cropping, large prints, lower noise, better colours and wb, MTF mode, Live View, interval shooting, one-push bracketing, improved battery life, etc etc.
I still say those tradeoffs are going to be quite personal. the otentil advantages of a prime I think we both agree on. But the advantages of the upgraded body is another matter.

First, I think the jury is still out on the extent to which a K20D + 50/1.4 cropped would outperform a K100D + 50-135 at 135mm. I know, you say you may have gone a bit far - but actually, I liked your logic, and really *am* curious now. But anyhow, aside from that, most of the other things you list are also either non-issues or actually issues in favor of the K100D for some people.

For instance, the whole "menu diving" thing is a *total* non-issue for me. There is absolutely nothing in any menu on the K100D that holds the slightest interest to me on a daily basis. I have the camera permanently set on center point focus, center weighted metering, RAW capture, "M" exposure mode, "OK" button to cancel focus in AF mode. This works perfectly for me, and even if you gave me buttons to change any of these settings, I wouldn't use them. Quicker control over ISO, that one I will grant, but not worth spending a grand on.

I've taken about three flash pictures in the last year. More options hold no interest. And I haven't sued continuous shooting mode at all with my DS or K200D (except to test it), nor have I ever exceeded my buffer in real life on either camera. Color/wb not really much of an issue since I shoot RAW, although I admit do appreciate the K200D as an improvement over the DS here. I similarly have little or not interest in automatic bracketing or interval shooting.

As for battery life, I was under the impression the K20D gives around 500 shots per charge, depending on who's doing the measuring - which is to say, pretty much exactly the same as the DS, K100D, or K200D with Eneloops. And this is a whole other religious debate, but you'd have to drag me kicking and screaming back to proprietary batteries - I hate the whole idea of them.

So, I'm not saying the K20D doesn't have some wonderful qualities - of course it does. But that's an awful lot of money to pay for features I personally have little or no use for, especially knowing that the average lifespan of a digital camera is pretty short and I'd probably end up wanting/needing to upgrade again in a few years and the K20D would be worth next to nothing. Whereas a good lens will likely be with me forever.

Now, for someone who *does* like to keep changing his exposure mode, or focus point selection, or shoots JPEG and wants quicker access to relevant settings, or uses flash a lot, etc - then those advantages may seem more compelling. Like I said, it's going to be pretty personal.

Last edited by Marc Sabatella; 09-21-2008 at 12:10 PM.
09-21-2008, 10:08 AM   #11
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QuoteQuote:
First, I think the jury is still out on the extent to which a K20D + 50/1.4 cropped would outperform a K100D + 50-135 at 135mm. I know, you say you may have gone a bit far - but actually, I liked your logic, and really *am* curious now. But anyhow, aside from that, most of the other things you list are also either non-issues or actually issues in favor of the K100D for some people.
I just did a little crop test. I was wrong. It appears that a 50mm FL cropped to equal the FOV of a 135 mm only has about 3mp left. Still not too shabby, as long as you don't print too big. Certainly enough pixels for a computer screen.

Regarding upgrading the body, we clearly have different styles. I constantly cycle betwen metering modes, jpeg and RAW, AF modes and ISO's. For wildlife photography especially, speed is critical. I don't have much experience with my Sigma flash, but I played with wireless flash all morning and I'll definitely be using that. The cost of a new body is about equal to the cost of a new lens, if one sells the old body. I'm just saying it should be considered.

I couldn't bear to part with my K100DS, so my wife uses it with the 18-250 as a large p&s, and I still have it should I need it.
09-21-2008, 10:36 AM   #12
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QuoteOriginally posted by Marc Sabatella Quote
First, I think the jury is still out on the extent to which a K20D + 50/1.4 cropped would outperform a K100D + 50-135 at 135mm. I know, you say you may have gone a bit far - but actually, I liked your logic, and really *am* curious now. But anyhow, aside from that, most of the other things you list are also either non-issues or actually issues in favor of the K100D for some people.

For instance, the whole "menu diving" thing is a *total* non-issue for me. There is absolutely nothing in any menu on the K100D that holds the slightest interest to me on a daily basis. I have the camera permanently set on center point focus, center weighted metering, RAW capture, "M" exposure mode, "OK" button to cancel focus in AF mode. This works perfectly for me, and even if you gave me buttons to change any of these settings, I wouldn't use them. Quicker control over ISO, that one I will grant, but not worth spending a grand on.

Like I said, it's going to be pretty personal.
My 0.02 of a dollar (US).

I use both the K100D and K20D and am still on a steep learning curve with both.

Anyway, in a nutshell, daily real world experience has found me settling on the following broad "lens to body pairings" as part of my field prep routine:

K100D: Zooms preferred. I zoom to crop the live image in order to minimize bumping up against the limits of its sensor. Most primes can out resolve it making their advantage marginal. M mode preferred, but AV, sometimes.

K20D: Primes preferred. The K20D's sensor allows PP cropping of the image to simulate a zoom, if needed. It also tends to out resolve my zooms and brings out their weaknesses. OTOH, its sensor can make primes (old and new) sparkle. TAV mode (fixed speed and aperture w/variable iso) is preferred.

So... When someone speaks to the qualities of a certain lens, I now ask: "Paired to which camera body?" For me, the pairing makes a big difference. If it's a camera body I know, I'll consider the observation, or offer a response. If not, I move along.

Finally, as evidenced by tons of examples on this and other forums, both camera bodies can produce spectacular results (with skill and luck ), if paired with a lens that plays to its strengths.

FWIW... enjoy...

Last edited by Michaelina2; 09-21-2008 at 11:34 AM. Reason: typo and clarification
09-21-2008, 05:23 PM   #13
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QuoteOriginally posted by audiobomber Quote
Just before doing this test, I went into the menu and selected "Reset" to restore the factory defaults on both cameras. Both cameras defaulted to Bright image tone with controls for Sharpness, Contrast and Saturation set to neutral. I believe Bright setting does boost some of these parameters on both cameras. It's academic anyway. There's no amount of contrast or sharpness dithering that will make up the difference in resolution.
My apologies, I was wrong about this anyway. I thought I was inspecting a K100 jpeg, but it was actually from PPL, and the metadata isn't the same. I've edited my original post.

I'm not sure whether to thank you for doing this test though... you've helped fuel my desire for a K20!

(Just kidding, it's been enlightening - thanks for going to the trouble to do this)
09-21-2008, 06:40 PM   #14
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QuoteOriginally posted by cpopham Quote
My apologies, I was wrong about this anyway. I thought I was inspecting a K100 jpeg, but it was actually from PPL, and the metadata isn't the same. I've edited my original post.

I'm not sure whether to thank you for doing this test though... you've helped fuel my desire for a K20!

(Just kidding, it's been enlightening - thanks for going to the trouble to do this)
The settings for sharpness, contrast and saturation are weird, because in the Pentax Photo browser, sharpness for example reads -1 on K100DS in Natural mode when it's set to 0. It reads 0 in Bright mode when it's set to 0. The K20D reads +1 on sharpness in Bright mode when it's set to 0. These settings are interpreted differently by the camera, Photo Browser and Photo Lab. I thought defaulting everything would be the safest course.

I had no intention of buying a K20D when I went to a local shop for a lighting seminar. But playing around with it and comparing the results with a bunch of fine lenses was too much. I lasted a week then went back and bought it.
10-21-2008, 04:09 AM   #15
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Thanks for testing, but I don't think this test has much validity. Your tests contains too many variables. You are not only comparing sensor resolution but also AF precision (perhaps the K100D has a BF focusing problem that also extends to manual focusing), JPEG conversion (although the parameters are all at default values, I'm sure the RAW->JPEG conversion is vastly different between the two cameras), and Picasa's behaviour when downscaling from two different input resolutions.

I cannot believe either that the 50mm on the K100D cannot produce a sharper picture. My 18-250 zoom produces sharper pictures than this one on a K100D.
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