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02-24-2015, 11:26 PM   #16
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QuoteOriginally posted by npc Quote
To put it in a different way - I know they are not going to be any worse, but is the resolution noticably better on k-3?
Put that way, no. The k-3 is a better camera, but I have both k-5IIs and k-3 and honestly have a hard time telling an image from one apart from the other after they are developed. If you want any of the other great features of the k-3 go for it. But if you are looking to upgrade to get noticeably better images don't bother. That said if I had a choice between getting a k-5IIs and a k-3 even with the price difference I would go k-3 without even thinking about it.

02-24-2015, 11:28 PM   #17
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QuoteOriginally posted by stevebrot Quote
To be honest, it is more likely that a digital sensor will limit a lens than the other way around.
QuoteOriginally posted by npc Quote
Well, if a lens outresolve a sensor across the frame, you won't be able to see any difference in sharpnes between the center and edges of the image.
That is not quite how it works. I would refer you to the lens resolution figures on photozone.de where values are available for different resolution sensors. For the lower resolution sensors, the lenses perform more poorly, both center and edges. In other words, the sensor limits the lens proportionally across the frame. My statement is a little tongue-in-cheek, but it is based on the observation that as better films and sensors are developed, the measured resolutions of many of the better primes (and many of the not so good) tends to improve.

As noted in several comments above, the lens is what it is. A higher resolution sensor will always result in the same or better lens performance than with a lower resolution sensor.


Steve

Last edited by stevebrot; 02-24-2015 at 11:43 PM.
02-25-2015, 02:24 AM   #18
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QuoteOriginally posted by npc Quote
Like if I take the same image with k-5 iis and k-3 and up-size the 16 mpix image to 24 - will I be able to really tell the difference?
Upsample? I don't have the K-5iis, so I can't try. But I would be very surprised if you couldn't tell the difference (at 100%) even with the kit lens.

I know that where my K-5 (classic) needs some sharpening my K-3 generally doesn't. That might be mainly the AA filter, though.
02-25-2015, 05:42 AM   #19
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QuoteOriginally posted by npc Quote
I have a K-5 IIs and I am definately ok with the performance of my 15/21/35 limiteds on it. But the 21 is not the sharpest lens ever and the 15 is known for its corner issues.
The 35 is fine on K-5 IIs but recently i saw some pictures taken with it mounted on sony a5100 via adapter and I was somewhat dissapointed with the results (the sony has a 24mpix sensor but I'm not sure if it has AA filter or not) ...

So I was wondering - what is your experience with these lenses on K-3 ? Are they up to the 24 mpix sensor?
The 15 mm is an excellent lens in combination with the K-3. Also the corners are sharp. But with my sample it is not possible to get both the center and the corners perfect sharp (because of field curvate). Stopping down did not solve the problem.

02-25-2015, 08:28 PM   #20
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When I saw the title of this thread I thought you were referring to the FA Limited lenses. All of them do just fine on the 24 MP sensor and can safely go higher, I'm sure. The FA 77 is sensational on the 24 MP sensor.
02-25-2015, 11:31 PM   #21
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I was not quite satisfied with the performance of my DA 21 Lim on K-3. Colours and contrast are great but corner / side sharpness is insufficient for my needs.
DA 35 Lim on the other hand performs perfectly fine. No complaints at all.
02-26-2015, 01:38 PM   #22
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QuoteOriginally posted by savoche Quote
Upsample? I don't have the K-5iis, so I can't try. But I would be very surprised if you couldn't tell the difference (at 100%) even with the kit lens.
I have my friend's K-50 for a couple of days and might make a couple comparison images between it and the K-3 with the FA 77/1.8 Limited.


Steve

Last edited by stevebrot; 02-26-2015 at 01:59 PM.
02-26-2015, 04:01 PM   #23
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QuoteOriginally posted by Stagnant Quote
I was not quite satisfied with the performance of my DA 21 Lim on K-3
It is rubbish on my K-5ii as well. Must try stopping it down ...

02-26-2015, 04:06 PM   #24
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It should be noted that diffraction kicks in a bit sooner with a bigger sensor as well, so if you're used to shooting at, say, f/11 on the K-5, f/11 on the K-3 is going to look (mildly) worse due to that as well.

I believe the low end of diffraction for the K-3 is around f/8 or so, and gets worse from there. It may even be a touch wider.
02-26-2015, 04:25 PM   #25
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QuoteOriginally posted by Sagitta Quote
It should be noted that diffraction kicks in a bit sooner with a bigger sensor as well
The sensors are the same size for both cameras, higher pixel density perhaps? Sorry could not resist


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02-26-2015, 05:19 PM - 1 Like   #26
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QuoteOriginally posted by npc Quote
Like if I take the same image with k-5 iis and k-3 and up-size the 16 mpix image to 24 - will I be able to really tell the difference?
QuoteOriginally posted by stevebrot Quote
I have my friend's K-50 for a couple of days and might make a couple comparison images between it and the K-3 with the FA 77/1.8 Limited.

Ok, because inquiring minds want to know, here is a head-to-head comparison of the K-50 with the K-3.
Sorry, I don't have access to a K5-IIs.

Methods:
  • Lens: Pentax FA 77/1.8 Limited
  • Aperture: f/5.6
  • Shutter: 1/6s, with two second timer, SR OFF
  • On tripod (Giottos 9360)
  • CDAF in live view at same focus point (lower eyelid), best of three focus attempts
  • Calculated DOF is ~1.2" at 36" distance
  • Anti-alias filter emulation on K-3 turned OFF
  • RAW
  • Default import into Lightroom
  • Normalized white balance and curves
  • +15 clarity, +15 vibrance (my standard practice)
  • No additional sharpening
  • No len correction
  • K-3 RAW exported to full-resolution TIFF
  • K-50 RAW exported to 4000x6016 TIFF (upsized to 24 Mpx)
  • Full resolution crops sampled from the same area of each 24 Mpx image and exported to JPEG with no resize, no compression

The subject:
The doll is about 20" tall and was photographed from 36" away.


K-3 converted from full resolution TIFF


Comparison at point of focus (lower eyelid):
Note that I need to dust more often.

K-3


K-50


For fairness, here is the non-upsampled section from the original K-50 DNG...



Comparison at collar:
Note hair at center.

K-3


K-50


Links to full-sized files

K-3 Full Size JPEG
https://farm9.staticflickr.com/8635/16657673815_71f0988a28_o.jpg

K-50 Upsized JPEG (4000x6016)
https://farm9.staticflickr.com/8571/16631762816_e2459a050b_o.jpg

Should anyone want the original DNG files, let me know and I will provide a drop-box URL for you.

Discussion:
As you can see, both cameras captured an admirable amount of detail. The K-3 did somewhat better overall with the difference being best appreciated when comparing various regions from the TIFFs. I would suggest downloading both and using a tool such as the Lightroom Library to do section-by-section comparison.

Some would argue that I should have used other than Lightroom's built in upsize algorithm. I might do that some time, but not today. Others might notice that the two photos don't look quite the same. I would respond that they were taken with different cameras at different bit-depths with different image processors. Someone else might notice that the K-3 TIFF file is several hundred KB larger than the K-50 TIFF. I may be running low on electrons.

Are the differences traceable to the K-3 not having an AA filter and the emulation being turned off for this test? Yes, that is possible.

All the tech aside, this test still leaves the question open as to whether the K-3 sensor out-resolves my copy of the FA 77 Limited. That would require an image taken with a higher resolution camera like the future FF Pentax or perhaps an adapted to a Sony A7R. What we can deduce is that the FA 77/1.8 Limited is not out-resolved by the sensor in the K-50.


Steve

Last edited by stevebrot; 02-26-2015 at 06:54 PM.
02-26-2015, 05:52 PM   #27
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QuoteOriginally posted by stevebrot Quote
Some would argue that I should have used other than Lightroom's built in upsize algorithm. I might do that some time, but not today.
Up/down scaling is always going to apparently degrade the image. Wouldn't you be better off moving the K-3 back a bit for such a comparison ?
02-26-2015, 06:12 PM   #28
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QuoteOriginally posted by npc Quote
ISo I was wondering - what is your experience with these lenses on K-3 ? Are they up to the 24 mpix sensor?
Stopped down? Definitely. I have found the 35mm macro and the 21mm to be very good. Even the kit 50mm f/1.8 stopped down is more than capable. Wide open is another matter...

YMMV

Michael
02-26-2015, 06:39 PM   #29
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QuoteOriginally posted by kh1234567890 Quote
Up/down scaling is always going to apparently degrade the image. Wouldn't you be better off moving the K-3 back a bit for such a comparison ?
No, I don't think so. I spent some time writing up why this is so, but decided to not post it since doing so would make me appear to be a total madman more than I actually am.

I will state, though, that an appropriate up-sampling is a dilution, not a degradation of data. The previous state can always be reproduced if the algorithm is known. Down-sampling, on-the-other-hand, is true degradation. The original state cannot be be determined beyond a very rough estimate and then only if similar non-perturbed systems are available for sampling.


Steve
02-26-2015, 08:11 PM   #30
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QuoteOriginally posted by Sagitta Quote
It should be noted that diffraction kicks in a bit sooner with a bigger sensor as well, so if you're used to shooting at, say, f/11 on the K-5, f/11 on the K-3 is going to look (mildly) worse due to that as well.

I believe the low end of diffraction for the K-3 is around f/8 or so, and gets worse from there. It may even be a touch wider.
Diffraction kicks in later with a larger sensor:
  • FF sensor, 24mp, diffraction limit f/11.3
  • 1.5X crop sensor, 24mp, diffraction limit f/7.4
  • 1.5X crop sensor, 16mp, diffraction limit f/9.1
For the same size sensor with more pixels (finer pixel pitch), diffraction presents itself at a larger aperture. But that doesn't mean that suddenly the resolution of the 24mp sensor plummets at f7.4. It simply means that the sensor's resolution is being gradually compromised. The 24mp sensor will still out-resolve the 16mp sensor from f/7.4 to f/9.1. At apertures smaller than f/9.1, both sensors will resolve the same amount of detail.

Check this Diffraction Limited Aperture Calculator for verification:
Digital Camera Diffraction – Resolution, Color & Micro-Contrast
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