OK, problem here - lens or camera? (or me?)

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Tim Crammond Contributing Member • Posts: 724
OK, problem here - lens or camera? (or me?)

I've run into a problem which I initially thought was something wrong with my Sony 55-300mm, but which, after running some tests today, I'm forced to admit may be my a57. Frankly I'm baffled. The evidence doesn't seem conclusively to support either theory to the exclusion of the other.

I can't think of a reason why either party should be at fault. They've both been carried in a backpack, and perhaps at worst lightly jostled, but nothing worse than the sort of treatment they've had since I owned them. They certainly haven't been dropped, or even knocked over.

Just to keep things consistent I've picked photos which are all jpegs with no processing except for the same degree of light sharpening.

None of these pics were chosen for aesthetic reasons - in fact some of them I was just shooting test pics at a certain aperture, focal length and approximate distance without much concern for what was in the viewfinder.

First, some baseline photos. This is the lens performing properly. This is late May:

105mm, f4.5, 1/400

And this was on a gloomy day as recently as August 4th

105mm, f7.1, 1/250

Just for comparison, here's one at 300mm

300mm, otherwise as above

The first time I noticed something not quite right was the next time I used it, just three days later

300mm, f8, 1/200

I'd shot at this location under near identical conditions only a week or so before, and not had this problem. All the photos from this shoot show this same problem. Nothing seems quite in focus, so it evidently wasn't a back or front focus problem. I thought I may have stopped down so far that I was getting diffraction, but it turned out only to be f8.

Next time out, i ended up with this:

300mm, f6.3, 1/160

And that was with some more aggressive sharpening applied. In case you think it was too slow a shutter speed, I did get this somewhat cleaner shot at a slower speed, just afterward

As above but 1/100

You're going to have to trust me that I usually don't get such inconsistent results. Although this shot is cleaner, it's still nowhere near as sharp as the lens routinely performed until recently, and this was the best of about a dozen shots.

Anyway I then decided to try the Sony against the Minolta Beercan on the same camera. Here are some crops from a series of photos I took the other day:

Sony 55-300 vs Minolta 70-210 at around 200mm

Now I was confused. This looked better than I expected, and - as I would have predicted - a bit better than the beercan. So when i tried the two in better light, and at greater distances this afternoon, and got THESE results, I was a bit dismayed

Sony at 300mm, f9, 1/125

And expecting the Beercan to perform properly, I got this:

Beercan at 200mm, otherwise same as above

Just to confound things, a few minutes later, the Beercan gave me this:

Beercan, as above, but 1/200

Ok, the really awful 300mm and 200mm shots were at 1/125 and 1/60 (f400 BTW), but I've had enough experience of this lens to have noticed it was behaving oddly at faster shutter speeds (note the cormorant photo at 1/200 - almost the same speed as in in-focus cockatoo photos at 1/250).

So far I haven't been able to do any further tests. I put the Sony on my a6000 and got similarly awful results, but this was inside, under artificial light, and using a cheap Minolta AF adapter which from the few times I've used it, I suspect of being overlength.

Anyone got any ideas? Next sunny day we get, I'll try the Sony at 300mm with as fast a shutter speed as I can manage, to eliminate the possibility that it really is just movement, but I have my doubts. If it is only that, I'll feel a total idiot. I must admit, in the process of uploading these images and noting the settings, the low shutter speed on the worst shots did raise suspicions, and perhaps I've found the problem in the process of discussing it. All the same it seems odd I haven't got a single good shot out of the Sony in over a fortnight.

NB I checked, and steady shot was still turned on.



 Tim Crammond's gear list:Tim Crammond's gear list
Sony SLT-A57 Sony a6000 Sony a77 II
Sony a6000 Sony SLT-A57
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