Why does my Tamron 70-300mm stop working above 200mm at apertures narrower than f/5.6?
Asked 11/27/2012
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My EF-mount Tamron 70-300mm f/4-5.6 works normally from 70mm to about 200mm. Above 200mm, if I set any aperture narrower than f/5.6 (such as f/6.3 or smaller), the aperture does not stop down when I press depth-of-field preview, and the camera hangs.
I tested it on both a Canon EOS 30D and an EOS 600D. The 30D shows Error 99, and the 600D reports a lens communication fault and suggests cleaning the contacts. I cleaned the lens and camera contacts, but the problem remains.
What is the likely cause, and is this something that can be fixed cheaply, or does the lens need professional service?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
13y ago
2 Answers
1
It sounds like there is some sort of issue with something in the lens. My best guess is that there is some sort of short or loose wire. My second, rather unlikely, guess is that there is something wrong with the blades themselves. Neither of these could be fixed by yourself. Judging from the price that you commented with, you would be better off just buying a new lens, as repairs could easily exceed $100. Sorry that I couldn't offer some miracle solution.
Originally by user13254. Source · Licensed CC BY-SA 4.0
user13254
13y ago
0
Generated from our catalog & community — verify before relying on it.
The most likely cause is an internal lens fault, not a camera-body issue, since it happens on two different cameras and cleaning the contacts didn’t help.
Based on the symptoms, likely possibilities are:
- a loose wire or electrical fault inside the lens that appears at the long end of the zoom range
- a problem with the aperture mechanism or blades
Because the failure only shows up above about 200mm, zooming may be stressing an internal connection or component. This is not likely to be a simple user fix.
In practice, the lens will probably need professional service if you want it repaired. For a consumer zoom like this, repair costs can easily make replacement the more sensible option, depending on the lens’s value and the service quote.
So: the issue is probably internal to the lens, and there’s no obvious cheap at-home fix suggested by these symptoms.
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AI13y ago
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