Odd Tamron Lens Behavior - Advice Please?

krs · 09-01-2009, 05:35 PM

I bought a used Tamron 70-200mm f/2.8 some time ago, but have not used it too much. On Saturday I took it to my son's soccer game, and found I was having difficulty getting the lighting right (it was at noon - not a good time - I know).

I then set it on manual, and found if I varied the aperture, taking pictures, that the exposure was not changing with the changing aperature, and then suddenly it would change a lot. It appeared that the lens was not getting the signal from the camera for several shots, and then for a shot it would.

Last night I took it out in the evening, and was seeing the same thing.

Other lenses are not showing this behavior - only this one.

Any insights?

wlachan · 09-01-2009, 05:43 PM

Clean the lens mounts with isopropyl alcohol and see if it helps.

snostorm · 09-01-2009, 05:59 PM

Hi krs,

in addition to cleaning the contacts, manually actuate the aperture blades to make sure they "snap". If they are sluggish, it would definitely effect the exposure.

Scott

krs · 09-01-2009, 06:09 PM

Originally Posted by snostorm

Hi krs,

in addition to cleaning the contacts, manually actuate the aperture blades to make sure they "snap". If they are sluggish, it would definitely effect the exposure.

Scott

Perhaps a silly question, but ... - this lens has no aperture ring - so how do you manually actuate the aperture blades?

wlachan · 09-01-2009, 06:14 PM

Originally Posted by krs

Perhaps a silly question, but ... - this lens has no aperture ring - so how do you manually actuate the aperture blades?

The aperture arm sticks out from the rear, just flip it.

*Ash* · 09-01-2009, 08:42 PM

Uh oh...
Sounds like a recurring theme.
This lens is unfortunately notorious for having a sticky aperture lever.
Have a look through the lens whilst it's in A mode on the aperture ring - it should leave a tiny opening (basically an aperture of f/22). If it's gaping open, then the lever's stuck at the wide open position, which it shouldn't be.

If that's the case, and you bought it new, I'd take it back for either an exchange or repair under warranty. It's such a great lens otherwise, though - I'm sore I had to give mine up for the same reason...

*pentaxman* · 09-02-2009, 12:23 AM

I bought 3 Tamron 70-200 F2.8 lenses. The first one I bought was decentered badly. I exchanged it for the second one which had a sticky aperture. The third one was also badly decentered. At this point, I gave up and returned it for a refund. The pity was that the second one was an astoundingly good lens when the aperture was not sticking. I really wish I had been able to keep that one.

I think Tamron has some severe quality issues to work out on this lens.

krs · 09-02-2009, 06:02 AM

I cleaned the lens mounts yesterday, and that seemed to make no difference. I will play with the aperture lever next and see what conclusions I can draw.

I bought the lens used - this might cause me to conclude to stay away from used lenses in the future...

*Ash* · 09-02-2009, 06:29 AM

Did you have a look at the lens diaphragm and aperture lever first?

I've written to Tamron expressing concern over the sticky aperture lever with no response yet.
Such a shame - I also really loved its performance.
krs, I wouldn't shy away from buying ALL lenses used, just THIS particular one - it seems to just keep coming back as a problem area for Tamron.

krs · 10-21-2009, 11:53 AM

Just an update to this issue. Some pictures might turn out fine, but then one will appear over-exposed. If I take the lens off the camera after an overexposed one, I will find the lens stuck wide open.

I called Tamron - they said it sounds like the diaphram needs to be replaced - cost $225.00 The warranty on that is 90 days. Since I am not the original owner (bought it on this forum), it is not under warranty. You would think they would warranty their work longer for something that is a quality issue in the first place..??!!

Insight/advice is welcome!

axl · 10-21-2009, 12:05 PM

Originally Posted by Ash

Uh oh...
Sounds like a recurring theme.
This lens is unfortunately notorious for having a sticky aperture lever.
Have a look through the lens whilst it's in A mode on the aperture ring - it should leave a tiny opening (basically an aperture of f/22). If it's gaping open, then the lever's stuck at the wide open position, which it shouldn't be.

If that's the case, and you bought it new, I'd take it back for either an exchange or repair under warranty. It's such a great lens otherwise, though - I'm sore I had to give mine up for the same reason...

Ufortunately Ash is right here annd OP confirms by saying he's getting lot of overexposed pics.
The appreture is stuck wide open and that's the reason. My copy did the same after month or so andd I know I wasn't only one it happened to. It's sad because otherwise it's a great lens.