Bob Keefer
Is a writer and photographer who lives in rural Oregon. This is an informal blog with no particular purpose other than to give myself something to do with some of the welter of photographs I take each day.
For more considered work, see my hand-colored photography at BobKeeferPhoto.com.
You can email me at bob/at/bkpix.com.
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Tag Archives: Pentax
K20D and the Pentax 645 300/4 A* lens
Towhee: Pentax 645 300/4+1.4x, handheld, ISO 3200, f/4, 1/320
Towhee: Canon 100-400, handheld, ISO 1600, f/5.6, 1/250
I got a chance to shoot some long-lens pictures on the new Pentax body today with my 645 300mm. The short version is: the medium format Pentax lens is entirely the equal of my Canon 100-400 L zoom. I won’t bother posting 100% crops, but take my word for it that in a variety of handheld (is there any other kind?) shooting situations I was easily able to match the Canon quality with the Pentax.
For example, I shot a distant license plate with the 300 on the Pentax and the Canon zoom sent to 300 with both cameras at 800 ISO. Both cameras were handheld and both used image stabilization. The images from the Pentax offered slightly more detail and considerably better color; this might result from the camera’s higher resolution sensor (14.6 meg) compared to the Canon 20D (eight meg).
Then I put the Pentax 1.4x converter on the 300 and racked the Canon out to 400 and shot a cooperative Towhee on a blackberry bramble. Those are the pictures shown here. I jacked up the ISO on the Pentax to 3200, which has roughly equivalent noise to 1600 on the Canon.
Blown up to pixel-peeping size, the two images have very similar sharpness and resolution with a slight edge to the Pentax, while the color and depth award definitely goes to the Pentax.
Finally, manual focusing—while not as quick as Canon’s blink of an eye autofocus—is easy with the long throw focus ring on the 645 lens. Auto focus confirmation in the Pentax helps but in the end it’s still up to you to get it right by eye. Fortunately that’s not too difficult.
This is all great news! I don’t do so much long lens work that I really want to go out and spend a lot of money right now on Pentax glass. The 645 lens, along with converters, looks like it will work fine when I get the urge to photograph birds and wildlife.
Now I just need a sunny day so I can try the 2x converter. That basically makes the 300 a cool 600/8 monster.
Pentax 645 lenses on the K20D
I got an adapter today to mount Pentax 645 lenses on the K20D. A couple things I’ve read on the web indicate the medium format lenses don’t do well on APS-C cameras, but as I own several 645 lenses I wanted to give it a try myself.
I brought only the 645 150/3.5 to with me to the office, where the adapter was delivered, so I mounted it on the digital camera and took it out to a nearby wetlands.
To my surprise, the camera metered fine with the lens even in P mode, even though the adapter has no contacts to transmit information about aperture. I’ve got to say I don’t really understand the complexities of using older lenses on this camera. But basically, with the mechanical aperture set, the camera functioned as if in aperture-priority mode. There is no need to switch to M mode and use the green button.
But is it sharp?
Undoubtedly. One reason people may be reporting that 645 medium format lenses don’t work well is the challenge of focusing accurately. You can’t just rely on the autofocus light for focus confirmation, as the zone of actual sharp focus may be even narrower than the confirmation light shows, especially at a wide aperture.
And, of course, there is the question of camera shake. The only good frames I got were shot at a 500th or faster, even with shake reduction working.
The real reason I got the adapter was to use my 645 300/4 lens, along with 1.4x and 2x converters. This will obviously be a challenging combination but one I still believe I can make use of. We’ll see.
photo: Delta Ponds, 2009
The K20D is a keeper
After a couple days of hard thinking, I’ve decided to keep the Pentax K20D and the 16-50/2.8 zoom. The autofocus, after some practice, actually isn’t as bad as I first thought (though it’s a lot slower than Canon). But overall I love the camera, for its handling, quality feel, and great images.
I also spent some time today shooting with my old SMC-M 135/3.5 lens, which was fun. It’s a sharp piece of glass and very light in weight.
And the other news is on the software front: I’ve been playing with Adobe Lightroom on free trial. Very impressive. May have to buy it.
photo: Sunrise over the forest, 2009
More on the K20D
I took the new (used) Pentax K20D out for Eugene’s first Friday art walk to try some high ISO shots.
First the good news: the pictures came out pretty good. Shooting at ISO 3200, there’s a bit of noise, but not enough to make me crazy. In fact I like a certain amount of noise in photographs like this; it’s just like grain in black and white film shots.
This picture in downtown Eugene was shot at 3200 with high ISO noise suppression set in the camera at “weak.” The picture is a JPEG straight from the camera.
The bad news: The terrible auto focus on this camera is going to drive me crazy. It couldn’t grab on to anything. It could barely find the stop sign in this photograph and lost it repeatedly even after it attained focus.
Shooting pictures of people in a gallery, a location with extremely high contrast lighting, it was miserably hard to focus on anyone’s face.
I may have made a mistake here, hoping the K20D would be better than it is. I’ll keep trying over the weekend, though; I’d like this camera to work out for me and it’s still possible that I’m in the middle of a learning curve with a new piece of equipment.
We’ll see. But if I don’t like it by Sunday, the camera goes back to the store on Monday.
photo: Downtown Eugene, 2009
K20D: Trial by fire, er, rain
I spent 4 hours walking and shooting in the rain today with the K20D hanging around my neck—yes, outside the Gore-tex. Yes, a typical Oregon winter day. The camera was glistening wet the entire time but continued to function just fine and suffered no apparent ill effects. So Pentax isn’t kidding about the weather sealing.
All wasn’t perfect, however. While the camera and I are getting much better acquainted, the autofocus is frankly crappy for anyone coming from the world of Canon. It’s vague, it hunts, and I’m never quite sure what it’s trying to focus on. Another unfortunate surprise is how long the Shake Reduction takes to turn on. Sorry, but I’m spoiled by the instant-on 20D—and every other Canon EOS body I’ve ever used.
Is all this a deal breaker? I don’t think so. I like the camera quite a lot—it fits very well in my hand and operates very sensibly. And I love the image quality. Pictures just look better.
photo: Oregon woods in the rain, 2009