I recently received my Pentax K-3 and have been eager to test its high resolution, 24 megapixel sensor. This morning I had a few spare minutes and mounted a Tokina ATX 400mm f5.6 lens onto the K-3, along with an AF360FGZ flash for fill light. Then it was off to the bird feeder to snap some test photos of house sparrows having their breakfast. Here are some of the results, with actual pixel images below the full frame shots (click on the smaller image for a larger view: )
I went into this exercise with several questions in mind. Here is what I learned:
How would the Tokina ATX 400 work on the Pentax K-3? I wondered if this older lens, designed for film cameras, had the resolution and edge sharpness to work well on the K-3s high resolution, 24 megapixel sensor. Judging from the images - detail and sharpness is quite good, IMO. The backlit shot of the bird on the peanut wreath showed a small bit of color fringing, but that was easily corrected in Photoshop.
I should comment that while I have always considered this lens to be very good, it falls short of being truly excellent. Not to bash it - the sample I am using now was purchased used for a few hundred dollars. (My original copy developed a bad case of fungus.) So - I am hopeful that many older lenses from the film era will do just fine on the the K-3. (Good news for those of use with many older lenses from the film era….)
Shake reduction: Seems to have worked exceptionally well. While shutter speeds were in the 1/750 to 1/1000 range, for the equivalent of a 600mm (full frame) lens, the percentage of sharp images in this hand held exercise was quite good.
How would the K-3’s auto focus perform? AF was quite fast and accurate. It even tracked the moving birds pretty well, with minimal hunting. Overall, it was quite an improvement over the K-5 and earlier models that I have used – BUT the cam driven AF was as loud as ever.
How well did the camera handle white balance? The camera was set to AWB mode. The morning sun was still quite reddish when I shot these images. In shots where the flash did not fire the white balance looks very good. When the flash did fire the images have a noticeable greenish cast. This was easily corrected but suggests that the AWB adjustment for the flash is a bit off. (No surprise but the AF360 FGZ was underpowered for fill flash use in this case.)
How did the K-3’s metering perform? The camera was set to the new evaluative metering process, and performed excellently. Many of the birds were splashed with sun with a background that was in shadow, and the K-3’s metering adjusted the exposure to avoid any blown out highlights in the bird. However, some of the birds in the backlit shots were a bit underexposed, though this was easily addressed in post.
And what about image noise? All of these shots were taken at ISO 800. In general, noise is minimal. However, in backlit shots where the exposure was adjusted in ACR, some noise emerges. (See the image of the bird on the green peanut holder above) Probably not as noise-free as the K-5, though a much larger image size.
And lastly – How many files fit on a 32 gig card? I shot 441 images in the 20 minutes or so that I worked on it. Based on how much they filled the card, I would expect to get 760 images on one 32 gig card.
Overall – I’m pretty happy with the results here, given that it was an unplanned test, hand held, with a relatively inexpensive and old lens. When used properly, the K-3 will probably shine even more.
(Since this is tagged as a review I should comment that I am not employed by or paid by Ricoh / Pentax in any manner and bought the camera retail.)