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Forum: Pentax SLR Lens Discussion
02-24-2011, 08:37 PM
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It's funny that you bring up a focus issue - that was my first thought. The moon shot definitely shows the foreground in focus and the distant mountains blurry. And one of the Scotty's Castle is definitely front focused, the EV of the picture puts it solidly in the K5 front focus range but that's what I expected and it's pretty sharp where it IS in focus. And I've had some weird focus issue with a different lens, where for no reason at all the camera would wildly front focus for no apparent reason (I do have the camera set for focus priority, it shouldn't take a picture if the camera doesn't think it's in focus).
However, I took comparison shots of the construction site and the K7 pictures didn't look any better than the K5. I think I'll take both cameras and the lens tomorrow and take pictures of high-rise buildings, to see if there's any difference with objects that can't possibly move (I don't remember it being windy but it might have been breezy without me noticing).
Can a lens that might have minor mis-alignment problems originally become much worse all of a sudden? I thought the distant mountains in the first two pictures looked reasonable and one was taken with the K7 last fall while the other was taken with the K5 right after I got it in January. Even Oceanside's pier looks reasonable. It's the Death Valley pictures, taken 2 days later, that all of a sudden look really bad for distant objects but reasonable for something that was close (the vertical picture). But the horizontal shots do show quite a bit of distortion on both sides in all pictures so perhaps the lens finally got rattled enough to lose it's ability to focus at infinity? I didn't drop it, but it did ride around in the back of a Wrangler (in a camera case).
Or perhaps I'm back to the possibility that my K5 has problems, but what would cause the camera not to focus to infinity, other than front focus issues? And at f8, even if the camera was focusing at something 10 feet away (while I was trying to focus on a distant object) still have distant objects in focus?
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Forum: Pentax SLR Lens Discussion
02-21-2011, 07:39 AM
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I wondered about SR creating problems - the last picture was taken on a tripod with SR turned off to see if that would make a difference, I forgot to mention that in the original post. The first picture posted here was taken with the K7. I've looked at pictures from this particular lens for a couple of weeks now. One day I look at them and they all look dreadful. The next day I look at them some look quite good while others look bad. Then I try to convince myself that if I just don't look at them at 100% they all look reasonable. Last night I thought the first ones looked reasonably all right, compared to the later shots. Do other people think that, or am I just dreaming it?
Can a lens become misaligned due to some sort of damage?
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Forum: Pentax SLR Lens Discussion
02-20-2011, 11:47 PM
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We went to Death Valley recently and I was pretty dissatisfied with a number of pictures I took with the DA 12-24. I'm still not sure if the lens has a problem, the camera isn't adjusted to the lens right, LR does weird things to K5 files, my eyes are going bad or if there's something I'm doing that's causing problems. I seem to be having problems with objects that are half a block away or more, objects close up look fine.
I've uploaded some full sized pictures to a zenfolio album ( Zenfolio | Mtngal's Photos | Samples from DA 12-24 ) - all are either jpg straight from the camera or else dng and uploaded directly from Lightroom using whatever LR's default settings are. For the low-light pictures I didn't do any noise reduction. I didn't straighten horizon lines (simply dreadful in several) or adjust exposure. I readily admit that these need work. There's more examples in the album than what I've linked to here.
The first three pictures in the album were taken with the K7.
K7 picture from August:
Full sized version here: http://mtngal.zenfolio.com/img/s1/v19/p111340222.jpg
Here's an early K5 picture, taken from not far away from the one above:
Full sized version here: http://mtngal.zenfolio.com/img/s1/v21/p496715882.jpg
Right before we went to Death Valley I took this picture:
Full sized version here: http://mtngal.zenfolio.com/img/s1/v21/p289391699.jpg
I took the next two pictures within a minute of each other, looking in two different direction so very different light values:
Full sized version: http://mtngal.zenfolio.com/img/s3/v26/p37984673.jpg
full sized version: http://mtngal.zenfolio.com/img/s5/v4/p120703902.jpg
The shutter speed of this second one was 1/100 sec.
Several hours later:
Full size here: http://mtngal.zenfolio.com/img/s3/v23/p67252228.jpg
Same day:
Full sized version: http://mtngal.zenfolio.com/img/s3/v24/p218109188.jpg
Same day, Scotty's Castle is kept very dark. The subjects were sharp, though the second one shows some front focus, which the first one does not.
Full sized: http://mtngal.zenfolio.com/img/s3/v25/p423734452.jpg
Full sized: http://mtngal.zenfolio.com/img/s1/v19/p275329066.jpg
When I got back I took some sample shots. Here the focus point was on the rebar. At 24mm and f8, both the rebar and the trees beyond in the next lot should both be in focus, considering how far away the construction is from where I'm sitting:
Full sized: http://mtngal.zenfolio.com/img/s10/v16/p267896001.jpg
Do these K5 shots look like other people's shots with the 12-24?
In previewing this post, I notice that zenfolio has struggled a bit to reduce the full-sized pictures down to the smaller sized pictures I posted here. The imbedded images seem to be over-all softer than the originals, I think.
I'm trying to decide whether I should send the 12-24 (which isn't under warranty) back for repair. Or if the problem isn't so much with the lens as with the K5 (there's something else that's intermittent going on with the AF, I suspect). That's why I posted both the K7 and the early K5 pictures - I wondered if they look like other people's pictures taken with the same lens, regardless of what camera it might have been taken with. I'm really interested in what someone else thinks as I've gotten to the point where I've lost all perspective when it comes to this lens (and potentially the K5).
Thanks very much for looking at the album and the pictures and giving me your feedback.
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