Kx vs. K100

**psoo** · 03-09-2012, 02:00 PM

My first digital Pentax was a K100 which I used with a Tamron 28-300 mm f3.5-6.3 XRDi lens. I was reasonably pleased with the sharpness of my photos but was tempted to buy a Kx because I thought that going from 6.1 to 12.4 Mpixels would give me sharper images. However, I don't really see much difference between the two cameras in the sharpness department. I actually like the D100 body more because it is larger and heavier and seems to balance better with the zoom lens. Can anybody tell me if they have noticed sharper images with the Kx?

**paulh** · 03-09-2012, 02:16 PM

More megapixels doesn't necessarily mean sharper images when viewed at normal size. The lens has more to do with sharpness than the sensor. More mpx does give you more resolution - ability to crop without losing as much IQ as you would cropping from the smaller 6 mp images. You can also make larger, higher quality prints with more megapixels.

pxpaulx · 03-09-2012, 02:17 PM

I'm wondering if the lens might be a limiting factor for your scenario. It is a mega zoom that is a carry-over from the film era and might not be up to snuff for today's current crop of digital cameras, even the K-x which is a few years old. Have you tried with the Pentax 18-55mm kit lens? If you don't have it, that might be an inexpensive way to run a better test. Pentax has even updated that lens between release of the K100d and K-x due to more stringent sensor requirements with more megapixels (pointing out further that the 28-300 being a much older lens is likely the culprit).

AndrewShirley · 03-09-2012, 02:19 PM

Not to mention all the other great benefits of the KX's sensor... which is MILES past the K100D.

- Andrew

normhead · 03-09-2012, 03:10 PM

We had the opposite experience, my wife tessfully was using her Optio, she didn't like the K100d enough to take it with her most of the time... when we got the k-x it was hers within a couple of days. The two big things were, File size large enough for decent size prints (we have a 19x13 printer) and low noise high ISO shots. But I have to say, the K-x is broken after a drop... we're packing it to send it off to Pentax... and when inspecting it, we noticed the case is cracked. Tess thinks it happened screwing on the tripod plate. Now that's not good. ANother possibility is it was cracked by the weight of the DA*60-250 while on the tripod, also not good. We aren't sure that case is strong enough. I've never even seen a cracked camera shell before. That's not right.

**luftfluss** · 03-09-2012, 03:32 PM

I've had both the K100D & the K-x... take the K-x file, downsample it to 6mp and apply sharpening, you will see more detail.

VoiceOfReason · 03-09-2012, 04:44 PM

I have the Sigma 28-300 and I can tell you it is definitely the limiting factor. If you can get a Sigma 18-50 f/2.8-4.5 HSM lens and take shots with both you will see the difference.

**psoo** · 03-10-2012, 05:42 AM

Thanks for all the good advice everybody. I'll make a comparison with a better lens. Hope it justifies my purchase of the Kx.

GibbyTheMole · 03-10-2012, 07:43 AM

I had the K100D and upgraded to the K-x. After shooting with both for awhile, I gave the K100D to my wife & bought a second K-x. As good as the K100D is, the K-x is a BIG upgrade, just for the extra resolution & superb high ISO ability. I can easily shoot handheld with a tele lens in low light conditions with the K-x. You can't do that very well with the K100D.

After you hit a certain threshold, extra megapixels don't do much for sharpness. The main benefit you get from more MP is the ability to crop more aggressively and make larger prints. I don't make a lot of prints, but the cropping ability that the extra MP affords is a big benefit for me as a guy who shoots a lot of nature photos with tele lenses.

The K100D is a very nice camera, but if I had to choose one or the other, the K-x wins hands-down.

Marc Sabatella · 03-10-2012, 09:11 AM

Better lens or not, it is a mistake to think more pixels will lead to more sharpness in normal use. Consider that viewed on your screen or printed 4x6", you are already using no more than 2MP - the rest of the pixels are simply being thrown away. Only by blowing up the picture large enough that you are *not* throwing away pixels will you see any difference. Make a 16x20" print and you'll see the advantage of 12MP over 6MP. Or, take a picture, mentally divide it into a grid like a tic-tac-toe board, and crop out the center square, then print that at 8x10" - again, that would probably show a difference.

**psoo** · 03-12-2012, 03:07 PM

Thanks Mark, I'll give it a try.

twitch · 03-12-2012, 03:36 PM

I think it's a mistake thinking a camera has much at all to do with sharpness. Sharpness comes from the lens and the skill of the photographer before and after image capture, not from the camera.

**luftfluss** · 03-13-2012, 10:30 AM

Originally posted by twitch

I think it's a mistake thinking a camera has much at all to do with sharpness. Sharpness comes from the lens and the skill of the photographer before and after image capture, not from the camera.

The sensor does have somewhat to do with the sharpness, though, in particular the AA filter.

03-09-2012, 02:00 PM	#1
psoo Site Supporter Join Date: Jan 2012 Location: Long Island, NY Posts: 485	Kx vs. K100 My first digital Pentax was a K100 which I used with a Tamron 28-300 mm f3.5-6.3 XRDi lens. I was reasonably pleased with the sharpness of my photos but was tempted to buy a Kx because I thought that going from 6.1 to 12.4 Mpixels would give me sharper images. However, I don't really see much difference between the two cameras in the sharpness department. I actually like the D100 body more because it is larger and heavier and seems to balance better with the zoom lens. Can anybody tell me if they have noticed sharper images with the Kx?

03-09-2012, 02:16 PM	#2
paulh Site Supporter Join Date: Sep 2010 Location: DFW Texas/Ventura County, CA Photos: Gallery \| Albums Posts: 33,262	More megapixels doesn't necessarily mean sharper images when viewed at normal size. The lens has more to do with sharpness than the sensor. More mpx does give you more resolution - ability to crop without losing as much IQ as you would cropping from the smaller 6 mp images. You can also make larger, higher quality prints with more megapixels. Last edited by paulh; 03-09-2012 at 02:21 PM.

03-09-2012, 03:10 PM	#5
normhead Pentaxian Join Date: Jun 2007 Location: Near Algonquin Park Photos: Gallery \| Albums Posts: 40,451	We had the opposite experience, my wife tessfully was using her Optio, she didn't like the K100d enough to take it with her most of the time... when we got the k-x it was hers within a couple of days. The two big things were, File size large enough for decent size prints (we have a 19x13 printer) and low noise high ISO shots. But I have to say, the K-x is broken after a drop... we're packing it to send it off to Pentax... and when inspecting it, we noticed the case is cracked. Tess thinks it happened screwing on the tripod plate. Now that's not good. ANother possibility is it was cracked by the weight of the DA60-250 while on the tripod, also not good. We aren't sure that case is strong enough. I've never even seen a cracked camera shell before. That's not right. Last edited by normhead; 03-09-2012 at 03:20 PM.*

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03-09-2012, 02:17 PM	#3
pxpaulx Veteran Member Join Date: May 2009 Location: Twin Cities, MN Posts: 2,867	I'm wondering if the lens might be a limiting factor for your scenario. It is a mega zoom that is a carry-over from the film era and might not be up to snuff for today's current crop of digital cameras, even the K-x which is a few years old. Have you tried with the Pentax 18-55mm kit lens? If you don't have it, that might be an inexpensive way to run a better test. Pentax has even updated that lens between release of the K100d and K-x due to more stringent sensor requirements with more megapixels (pointing out further that the 28-300 being a much older lens is likely the culprit).

03-09-2012, 02:19 PM	#4
AndrewShirley Inactive Account Join Date: Mar 2007 Location: Barrie, Ontario, Canada Posts: 421	Not to mention all the other great benefits of the KX's sensor... which is MILES past the K100D. - Andrew

03-09-2012, 03:32 PM	#6
luftfluss Site Supporter Join Date: Jun 2011 Location: NJ Photos: Gallery \| Albums Posts: 11,619	I've had both the K100D & the K-x... take the K-x file, downsample it to 6mp and apply sharpening, you will see more detail.

03-09-2012, 04:44 PM	#7
VoiceOfReason Site Supporter Join Date: Jun 2010 Location: Mishawaka IN area Photos: Albums Posts: 6,124	I have the Sigma 28-300 and I can tell you it is definitely the limiting factor. If you can get a Sigma 18-50 f/2.8-4.5 HSM lens and take shots with both you will see the difference.

03-10-2012, 05:42 AM	#8
psoo Site Supporter Join Date: Jan 2012 Location: Long Island, NY Posts: 485 Original Poster	Thanks for all the good advice everybody. I'll make a comparison with a better lens. Hope it justifies my purchase of the Kx.

03-10-2012, 07:43 AM	#9
GibbyTheMole Veteran Member Join Date: Nov 2009 Location: Iowa Photos: Albums Posts: 2,275	I had the K100D and upgraded to the K-x. After shooting with both for awhile, I gave the K100D to my wife & bought a second K-x. As good as the K100D is, the K-x is a BIG upgrade, just for the extra resolution & superb high ISO ability. I can easily shoot handheld with a tele lens in low light conditions with the K-x. You can't do that very well with the K100D. After you hit a certain threshold, extra megapixels don't do much for sharpness. The main benefit you get from more MP is the ability to crop more aggressively and make larger prints. I don't make a lot of prints, but the cropping ability that the extra MP affords is a big benefit for me as a guy who shoots a lot of nature photos with tele lenses. The K100D is a very nice camera, but if I had to choose one or the other, the K-x wins hands-down.

03-10-2012, 09:11 AM	#10
Marc Sabatella Veteran Member Join Date: Sep 2006 Location: Denver, CO Photos: Gallery Posts: 10,685	Better lens or not, it is a mistake to think more pixels will lead to more sharpness in normal use. Consider that viewed on your screen or printed 4x6", you are already using no more than 2MP - the rest of the pixels are simply being thrown away. Only by blowing up the picture large enough that you are not throwing away pixels will you see any difference. Make a 16x20" print and you'll see the advantage of 12MP over 6MP. Or, take a picture, mentally divide it into a grid like a tic-tac-toe board, and crop out the center square, then print that at 8x10" - again, that would probably show a difference.

03-12-2012, 03:07 PM	#11
psoo Site Supporter Join Date: Jan 2012 Location: Long Island, NY Posts: 485 Original Poster	Thanks Mark, I'll give it a try.

03-12-2012, 03:36 PM	#12
twitch Veteran Member Join Date: Nov 2009 Posts: 4,571	I think it's a mistake thinking a camera has much at all to do with sharpness. Sharpness comes from the lens and the skill of the photographer before and after image capture, not from the camera.

03-13-2012, 10:30 AM	#13
luftfluss Site Supporter Join Date: Jun 2011 Location: NJ Photos: Gallery \| Albums Posts: 11,619	Originally posted by twitch I think it's a mistake thinking a camera has much at all to do with sharpness. Sharpness comes from the lens and the skill of the photographer before and after image capture, not from the camera. The sensor does have somewhat to do with the sharpness, though, in particular the AA filter.