Sometimes, whether it’s setting up a Linux server, or a focus problem with my camera, or buying a new BBQ smoker, I run into problems that are hard to solve. This blog is simply a place to put that info for my own reference as well as helping others who might just have the same problems.
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Gary
/ Sep 20, 2013Mike,
I joyfully (sorta) found your article on back-focus problems with the Sony A55. I too am a lucky owner 🙁 of a A55. I also own a Panasonic LX -3 which I dearly love.
A few week ago, I was scrutinizing the same landscape shot with both camera. The A55 lens was a Tamron 10-24mm f3.5 set to 10mm, aperture pryarity mode and stopped down to f5.6, image quality: fine, image file: large, steady shot off, auto focus: automatic AF, AF area: wide, ISO 100, HDR off, files saved as jpgs, cameras were tripod mounted. The LX-3 was set to approximately the equivalent settings.
After making the photos, I opened them and looked at the two images. The LX-3 was tack sharp, in fact, it made hash out of the A55 in just about every respect: contrast, dynamic range, sharpness, etc. Here is a little camera, with a small chip costing 1/4 the price of my DSLR and pounding it into the ground. The A55 was soft except for the extreme right side of the image. The left was very soft, but there looked like more was going on. There as more chromatic aberration with the Tamron lens, which I expected, I also expected some softness in the corners, it’s a Tamron . . . and a 10mm. But this didn’t seem right. The camera has never been dropped, so I ruled out physical damage by me. I know that Sony cameras using a prism instead of a mirror can be prone to “ghosting” but I wasn’t about to let this slip by.
I began searching and found your article, then read Jeff Fridel’s article and printed his focus charts. I’m ready to begin your process of aligning the focus sensors, but before I start (a process I’m not looking forward to) I wanted to get your opinion. I tried my other lens, a Sony 18-55mm just to make sure it wasn’t the Tamron. It was a tad better, but still with all the same basic defects as the Tamron. I read the reviews in DPReview of the Tamron before I bought it and the comments were very favorable.
Given your experience, do you think I have a miss aligned focus sensor? I manually focussed the image using the focus magnifier and it looked go. I was a photo major at RIT so I know a bit about lens aberration, mirror misalignment, etc. But my training is 1980’s vintage. film cameras are gone, people don’t even know what view-cameras are. It’s a new photography world.
If you have time and are willing, could I send you some images to look at?
Thanks in advance for your help,
Gary
Mike
/ Sep 20, 2013A misaligned focus sensor module would not explain what I believe you are seeing, which if I can paraphrase is a difference in focus across the frame on a single exposure, i.e. sharp on one side, soft on the other. A crooked focus sensor would affect all parts of the frame the same way. I would have to assume that either your sensor is crooked, or the lens mounting is crooked, or the lens itself is crooked within the barrel.