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Resolution Chart Comparison (JPEG and RAW)

Images on this page are of our standard resolution chart which provides for measurement of resolution up to 4000 LPH (Lines Per Picture Height). A value of 20 equates to 2000 lines per picture height. For each camera we use the relevant prime lens (the same one we use for all the other tests in a particular review). The chart is shot at a full range of apertures and the sharpest image selected. Studio light, cameras set to aperture priority (optimum aperture selected), image parameters default. Exposure compensation set to deliver approximately 80% luminance in the white areas.

What we want to show here is how well the camera is able to resolve the detail in our standard test chart compared to the theoretical maximum resolution of the sensor, which for the charts we shoot is easy to work out - it's simply the number of vertical pixels (the chart shows the number of single lines per picture height, the theoretical limit is 1 line per pixel). Beyond this limit (when talking about line pairs usually referred to as the Nyquist frequency) the sensor cannot faithfully record image detail and aliasing occurs.

This limit is rarely attained, because the majority of sensors are fitted with anti-aliasing filters. Anti-aliasing filters are designed to reduce unpleasant moiré effects, but in doing so, they also reduce resolution (the relative strength and quality of these filters varies from camera to camera). In theory though, a sensor without an AA filter, when coupled with a 'perfect' lens, will deliver resolution equal to its Nyquist limit. Therefore, even though it may be effectively unattainable with normal equipment in normal shooting situations, an understanding of a sensor's theoretical limit provides a useful benchmark for best possible performance. Nyquist is indicated in these crops with a red line.

On this page we're looking at both JPEG and Raw resolution. For a (more) level playing field we convert the latter using Adobe Camera Raw. Because Adobe Camera Raw applies different levels of sharpening to different cameras (this confirmed) we use the following workflow for these conversions:

  • Load RAW file into Adobe Camera RAW (Auto mode disabled)
  • Set Sharpness to 0 (all other settings default)
  • Open file to Photoshop
  • Apply a Unsharp mask tuned to the camera, in this case 100%, Radius 0.6, Threshold 0
  • Save as a TIFF (for cropping) and as a JPEG quality 11 for download
JPEG (4928 x 3264) 5.8MB RAW (4928 x 3264) 4.0MB

Vertical resolution

JPEG
RAW

Horizontal resolution

JPEG RAW

There is a visible difference between Raw and JPEG output from the K-30, with a lot more detail available from the camera's Raw files. As we've seen on previous Pentax DSLRs the K-30's default JPEG sharpening is quite conservative. The nine lines of our test chart can be discerned up to around 2400LPH both horizontally and vertically but on the converted Raw file detail is accurately described up to almost 3000LPH, with some line detail surviving up to, and even slightly beyond Nyquist.

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Comments

Total comments: 6
adrianconst
By adrianconst (5 months ago)

When I compare the dynamic range of K30 against D7000 and T5i, it looks like K30 under performs. However, that might be because the K30 default contrast in all modes is pretty high compared to the other two. Maybe dpreview should mention that when it presents dynamic range results.

0 upvotes
oldnoob
By oldnoob (6 months ago)

In the RAW Standard studio scene comparison, the k-30 appears to be back-focusing a bit. look at the small writing on the Kodak grey scale

0 upvotes
JustSomeOldDude
By JustSomeOldDude (3 months ago)

And the "Q" on the queen card is sharper than anything

0 upvotes
ebaker
By ebaker (7 months ago)

I called the corporate office myself and spoke with Joe Virgil, who was apologetic, but insisted he couldn’t do anything because the part was being shipped from the Phillipines and there were 65 other service orders suffering from the same problem. I explained that his supply problem was now a customer service problem as we had reached the 7th week of this ordeal. After ordering a part, if it has not arrived in 5 weeks, they are supposed to provide a replacement and this has yet to happen.
When you purchase a camera, you also purchase warranty and customer service with it. This has now past over two months since I initially sent off my camera for repair and the company is refusing to honor its warranty. I have bought a DSLR from one of their competitors and am completely disgusted with Pentax — DO NOT GIVE THEM YOUR BUSINESS. I’ve yet to receive my camera back (10 weeks and counting!) or any kind of a firm timeline of when that might happen.

0 upvotes
ebaker
By ebaker (7 months ago)

I actually liked the camera…. until it didn’t perform as promised. I bought this camera because I work at an aquarium and need to take photos for our marketing. A month after purchase, the telephoto lens drew humidity into the body and condensation formed, thus killing the LCD screen.
While it claims to be weather resistant, it couldn’t even handle humidity.
What is worse is that after sending the camera in on July 6 for repair under the warranty, I have yet to get any kind of a realistic timeline of when I would receive my camera back. After the fifth week of hearing, “Call back next week” I requested a replacement. This caused the customer service rep to become extremely rude and tell me that they were in the midst of a corporate merger so he couldn’t help me. I requested to speak with a manager, he refused to give me their name or number. He insisted he needed to call the corporate office and said he would call me back by the end of the week. Of course, that never happened.

0 upvotes
Take5
By Take5 (7 months ago)

“…the only major barrier to fast and efficient operation is the relegation of movie shooting to the exposure mode dial.” Seriously is the time difference between turning the mode dial and pressing a button to enter the movie function all that relevant – you are talking about an extra second at the most !

0 upvotes
Total comments: 6