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Forums > Back > Tamron 70-300 VC exposure issues
#25
[quote name='_sem_' timestamp='1287995098' post='3769']

>> Well, maybe they (finally) do. There have been reports of Di 60 lenses which no longer show underexposure, either purchased new just recently or repaired by Tamron. That's why I just sent mine in again.

> While we're at it, just a quick update on this one: the lens is back from Tamron, repair report says aperture has been adjusted, but it seems unchanged to me.



Have they adjusted metering perhaps?

My guess regarding the exposure issue with this lens is that the aperture works as designed, but that there is another rim in the lens blocking the light more than the aperture diaphragm at inf and intermediate focus (not at close focus, you get F/2 there). And that the autoexposure issue is due to the lens "thinking" it meters at F/1.8 (the metering aperture position is a bit wider than that of F/2), which in fact gives no more light than say F/2.5.

If this is so it should be possible to adjust the meter to the reality so +1EC would not be required anymore. Don't know if the underexposure in M is fixable because this is likely a construction thing.

Notice that the Nikkor 50/1.8D seems to have a similar issue but at the close-focus end (less likely to be noticed when testing MTF and such).

[/quote]

Actually many macro lenses have extra shades built into them, even normal ones. Some even have extra diaphragms. All this to prevent flare amongst others, especially when closing down the diaphragm.



Kind regards, Wim
Gear: Canon EOS R with 3 primes and 2 zooms, 4 EF-R adapters, Canon EOS 5 (analog), 9 Canon EF primes, a lone Canon EF zoom, 2 extenders, 2 converters, tubes; Olympus OM-D 1 Mk II & Pen F with 12 primes, 6 zooms, and 3 Metabones EF-MFT adapters ....
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Messages In This Thread
Tamron 70-300 VC exposure issues - by mst - 09-16-2010, 08:01 AM
Tamron 70-300 VC exposure issues - by Klaus - 09-16-2010, 08:11 AM
Tamron 70-300 VC exposure issues - by mst - 09-16-2010, 08:20 AM
Tamron 70-300 VC exposure issues - by wim - 09-16-2010, 09:05 AM
Tamron 70-300 VC exposure issues - by mst - 09-16-2010, 09:12 AM
Tamron 70-300 VC exposure issues - by joachim - 09-16-2010, 03:14 PM
Tamron 70-300 VC exposure issues - by mst - 09-16-2010, 03:33 PM
Tamron 70-300 VC exposure issues - by Bare - 09-16-2010, 06:49 PM
Tamron 70-300 VC exposure issues - by Klaus - 09-16-2010, 07:53 PM
Tamron 70-300 VC exposure issues - by koulang - 09-17-2010, 04:35 AM
Tamron 70-300 VC exposure issues - by Bare - 09-17-2010, 10:33 AM
Tamron 70-300 VC exposure issues - by sth - 09-21-2010, 10:57 PM
Tamron 70-300 VC exposure issues - by Steinar1 - 09-23-2010, 02:15 PM
Tamron 70-300 VC exposure issues - by Steinar1 - 09-24-2010, 10:58 AM
Tamron 70-300 VC exposure issues - by Guest - 09-26-2010, 06:31 AM
Tamron 70-300 VC exposure issues - by Steinar1 - 09-27-2010, 02:20 PM
Tamron 70-300 VC exposure issues - by william9 - 10-06-2010, 04:41 PM
Tamron 70-300 VC exposure issues - by mst - 10-19-2010, 10:43 AM
Tamron 70-300 VC exposure issues - by mst - 10-19-2010, 10:46 AM
Tamron 70-300 VC exposure issues - by samos1111 - 10-25-2010, 08:24 AM
Tamron 70-300 VC exposure issues - by hackmann - 10-27-2010, 12:47 PM
Tamron 70-300 VC exposure issues - by mst - 10-27-2010, 01:25 PM
Tamron 70-300 VC exposure issues - by mst - 10-27-2010, 01:30 PM
Tamron 70-300 VC exposure issues - by wim - 10-27-2010, 01:44 PM
Tamron 70-300 VC exposure issues - by wim - 10-27-2010, 01:46 PM
Tamron 70-300 VC exposure issues - by mst - 10-27-2010, 02:03 PM
Tamron 70-300 VC exposure issues - by hackmann - 10-27-2010, 10:14 PM
Tamron 70-300 VC exposure issues - by samos1111 - 11-08-2010, 03:19 PM
Tamron 70-300 VC exposure issues - by samos1111 - 11-08-2010, 03:35 PM
Tamron 70-300 VC exposure issues - by hackmann - 11-08-2010, 11:00 PM
Tamron 70-300 VC exposure issues - by mst - 11-10-2010, 10:52 PM
Tamron 70-300 VC exposure issues - by samos1111 - 11-12-2010, 01:26 PM
Tamron 70-300 VC exposure issues - by samos1111 - 11-12-2010, 01:48 PM
Tamron 70-300 VC exposure issues - by wim - 11-13-2010, 02:03 AM
Tamron 70-300 VC exposure issues - by mst - 11-13-2010, 12:12 PM
Tamron 70-300 VC exposure issues - by mannypr - 11-17-2010, 09:36 PM
Tamron 70-300 VC exposure issues - by mst - 11-18-2010, 10:26 AM
Tamron 70-300 VC exposure issues - by mannypr - 11-19-2010, 01:07 AM
Tamron 70-300 VC exposure issues - by mst - 11-19-2010, 08:16 AM
Tamron 70-300 VC exposure issues - by Guest - 11-19-2010, 10:21 AM
Tamron 70-300 VC exposure issues - by mst - 11-19-2010, 11:49 AM
Tamron 70-300 VC exposure issues - by mannypr - 11-19-2010, 05:30 PM
Tamron 70-300 VC exposure issues - by mst - 11-19-2010, 06:18 PM
Tamron 70-300 VC exposure issues - by grahamnp - 11-20-2010, 05:42 AM
Tamron 70-300 VC exposure issues - by lugui - 11-27-2010, 07:47 AM
Tamron 70-300 VC exposure issues - by woodsfortysix - 11-27-2010, 04:16 PM
Tamron 70-300 VC exposure issues - by woodsfortysix - 11-28-2010, 12:30 AM
Tamron 70-300 VC exposure issues - by vincent_photo - 12-17-2010, 04:46 PM
Tamron 70-300 VC exposure issues - by opiecat - 12-18-2010, 08:09 PM
Tamron 70-300 VC exposure issues - by vincent_photo - 12-19-2010, 02:59 PM
Tamron 70-300 VC exposure issues - by Steinar1 - 12-20-2010, 06:03 PM
Tamron 70-300 VC exposure issues - by Klaus - 02-06-2011, 01:09 PM
Tamron 70-300 VC exposure issues - by sth - 02-06-2011, 04:42 PM
Tamron 70-300 VC exposure issues - by Klaus - 02-07-2011, 09:13 AM
Tamron 70-300 VC exposure issues - by koulang - 02-08-2011, 06:59 AM
Tamron 70-300 VC exposure issues - by Klaus - 02-08-2011, 07:21 AM
Tamron 70-300 VC exposure issues - by miro - 02-08-2011, 08:59 AM
Tamron 70-300 VC exposure issues - by mst - 02-08-2011, 09:31 AM
Tamron 70-300 VC exposure issues - by IanCD - 02-08-2011, 10:47 PM
Tamron 70-300 VC exposure issues - by IanCD - 02-08-2011, 11:03 PM
Tamron 70-300 VC exposure issues - by Klaus - 02-09-2011, 10:39 AM
Tamron 70-300 VC exposure issues - by mst - 02-09-2011, 10:56 AM
Tamron 70-300 VC exposure issues - by mst - 02-09-2011, 11:26 AM
Tamron 70-300 VC exposure issues - by IanCD - 02-09-2011, 06:32 PM
Tamron 70-300 VC exposure issues - by samos1111 - 02-16-2011, 09:51 AM
Tamron 70-300 VC exposure issues - by janjhoi - 02-26-2011, 04:16 AM
Tamron 70-300 VC exposure issues - by miro - 02-05-2011, 02:42 PM

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