Nov 172009

I am chasing a black cat in a pitch black room, and so far I can’t rule out that it’s metaphysical.

Fact is, that I have the feeling that the new Tamron SP AF 17-50mm 2.8 XR Di II VC LD Asp IF performs not as well as it could, at least in the autofocus department. The only hard fact is, that the lens sometimes does not focus. Turn the camera off, turn it back on, everything is OK. It does not happen all the time it does not happen every second, third, or whatever-th time, but it sure happens every now and then.

So far Earl has contributed that his Tamron 28-300 behaves just as my 17-50. This may be a Tamron problem after all. On the other hand, it may be not. We are still far from having a statistically relevant sample.

I have an idea. I will compare this lens set to 35mm with the Nikon 35/1.8. I will make the comparison at f2.8, an aperture that both lenses are capable of. I will test different AF points, focusing from infinity to a certain target, the same from very near to that target, making the images without checking, just as one would in action, repeat 10 times for every lens and point and focusing way. Then I’ll count the perfectly focused vs slightly focused vs unfocused images and compare by lens. This is pretty tedious and I’ll need good light, thus it needs to wait for the weekend, but it will give me a clue about the general AF performance and accuracy of this lens.

I expect though, that my the results will support my current feeling: When it focuses, it focuses very accurately, at least that’s what I can say about the center AF point, the one that I use most often.

The other problem is, that when you’re trying to track down such a problem, you quickly begin to see ghosts. Take yesterday: I suddenly found that it did not focus at all. Oh dear, now it’s broken, I thought, but in reality I had accidentally set the camera to manual focus 🙂

The Song of the Day is “Light Nights” from Paul Weller’s recent album “22 Dreams”. See him perform live on YouTube.

  9 Responses to “1130 – Light Nights”

  1. Wonderful colored lights and nightfeelings!

  2. Andreas, all technical info aside, this image you created is wonderful. The lights, the colours, it’s all so embracing.

  3. the background is so very special
    it’s like a gigantic painting
    and in such a way that you can’t figure out
    where reality ends and
    the fake background starts.
    i like it 🙂

    have a nice day, andreas 🙂

  4. Exactly the reasons I’ve never pursued this 28-300 AF lens issue with Tamron, except to mention it in relationship to the VC problem I was having. The issue, while very real in the fact that I know firsthand it sometimes doesn’t autofocus, is also very elusive in that I haven’t been able to find a way to cause it to happen or even to predict when it may happen. Perhaps it is occurring only on a small subset of later generation Tamron lens with VC…some tolerance our lens are slightly beyond. My lens now mainly sits on the shelf, unused. Good luck in your testing…I’ll be following your results closely. I’m hoping you may find an answer for both of us. 😉

    Wonderful photo with this post!

  5. I had very bad auto-focus on a prime lens from Sigma too. Especially in low light it’s go haywire. I know, it’s not even the same manufacturer and far from similar lens characteristics to your 17-50. Plus it’s a Canon mount. But the one thing they have in common is having to reverse engineer the lens mounts, including the AF drive on both Nikon and Canon cameras. It could very well be some quirk in the Nikon or Canon firmware on a particular camera that the lens manufacturers didn’t account for; a new, weird response from the camera that causes things to go haywire. Turn it off and back on, and voila, things are resolved. It’s akin to the blue screen of death and the infamous “try rebooting” as a first measure of fixing problems on a Windows box.

    I concur with others that this is a very good photo. And I remember the church/cathedral in the background from my visit to Vienna.

  6. Thanks all. Glad you like the image. Actually it was not perfectly focused, so I thought I apply a healthy dose of Alien Skin SnapArt 🙂

  7. I’ve had the problem with my Tamron 18-270, where it will periodically refuse to focus, but then a simple off/on transition and it’s working again. I didn’t think much of it. None of my other lenses do it. When it happened a few weeks ago, I did the old switch-a-roo and it didn’t work. The camera had gone haywire. Hopefully it’s not a D300 thing! My D300 was repaired for $225 and is in tip-top shape now.

    The image is a very inviting night image, almost a dream scape. I see you managed to work in a bicycle, too. 🙂

    • Well, ya know, a bicycle a day …

      But that’s interesting. It really seems like a lot of Tamron users have this problem. I found a few on Google, actually with the 28-300 VC, it really seems to be a Tamron problem. Funny, I wouldn’t have thought that 🙂

  8. sobriety of this colour street so harmonious

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