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09-20-2010, 11:27 AM   #1
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Newbie Question on Tamron 70-200mm F2.8

Lurker for awhile, just registered and have a couple of questions regarding my new Tamron 70-200 F2.8 lens.

My camera body is a Pentax K100D. I've probably shot 200 images a soccer game since I have purchased it. I've got 2 kids so I have 2 games every Saturday. The lens I was using for this prior was the Pentax 50-200 F4-5.6 lens. Very happy with the images.

So this Saturday we had our first game at 8am (one of the reasons I purchased the new lens. The pictures turned out great with the new Tamron lens.

The next game was at 11am. Full Texas sun. I noticed while shooting at 1/350 that my F-stop was only at 13 when usually with my Pentax lens it would be around 22. I would think the opposite would be true (smaller aperture for the faster glass).

Any ideas?

The other is a bit disheartening....

About halfway through the second soccer game the aperture stuck in the full open position. Of course since I turned off the display on the back to save battery I had no idea it had happened until got home The fine folks at B&H Photo have sent me an RMA # and have made the entire process VERY easy. I knew there was a problem with this but I was hoping I would avoid it.

How many with this experience had to return the 2nd lens for the same reason?

Sorry for the long first post

thanks,

lee

09-20-2010, 12:27 PM   #2
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Hmmm, it sounds like you are just unlucky

I have never heard about this before. I am considering the purchase of this very same lens, but I would not be put off by your experience.

From what I have read here on the internets and in the forums, the Tamron SP line are very nice optics with few QC problems, but I have also gathered that the build quality of the Tamrons is not really up to that of the other manufacturers (including Sigma), but I would generally prefer to save money on a nice optic and treat it with care than pay more for one that I can bump around a little more. Maybe something to think about?
09-20-2010, 12:31 PM   #3
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It sucks that my roll of the dice came up snake-eyes on this lens, but B&H has made the process of return so easy that I do not regret the purchase.
09-20-2010, 12:53 PM   #4
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QuoteOriginally posted by leefranke Quote
It sucks that my roll of the dice came up snake-eyes on this lens, but B&H has made the process of return so easy that I do not regret the purchase.
No doubt, B&H is great! Remember to click through the B&H link on the Forum homepage or in Adams signature when buying stuff to support our site!

Good luck with the next copy!

09-20-2010, 12:59 PM   #5
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Firstly, on your 70-200 sticking at the wide open position, this is a WELL established phenomenon with the lens. So well it should be in the instruction manual. Since you bought it from B&H, you'll have no problems, but I suggest you ask them to REPAIR the lens under the initial warranty period. That way they FIX the lens for you at no cost and you're assured of a working lens.

Returning this one and asking for another one brings you back to square one if (or should I say when) the new one exhibits the same problem. It really is that common. I exchanged 3 copies that all had the same sticky aperture lever when I decided to ask B&H to simply repair the lens the third time, and they did. I'm much happier now with a lens that performs brilliantly without the worry of this problem resurfacing.

Your first question on metering differences has variables out of our control that it is hard to compare. But it is expected that under the SAME conditions and for the very SAME scene, metering is not lens dependent and should give equivalent exposure values. So the difference you noted could be explained by the slight difference in scene used to meter the shot, and for the difference you note, which is just over one stop of light, it is certainly conceivable that this slight change in scene for metering can explain the different exposure value you obtained.
09-20-2010, 01:30 PM   #6
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Excellent advice. If the next lens has the same problem I'll make sure to have them fix it (I assume that would entail me sending it to Tamron instead of B&H).

It was approximately the same time as the previous game (an hour difference) and it was on the same field so with me on the same side of the field and distance from the field. The difference is small but I thought it was odd and that any difference (however slight) would have been in the other direction.

thanks,

lee
09-20-2010, 01:48 PM   #7
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QuoteOriginally posted by leefranke Quote
The next game was at 11am. Full Texas sun. I noticed while shooting at 1/350 that my F-stop was only at 13 when usually with my Pentax lens it would be around 22. I would think the opposite would be true (smaller aperture for the faster glass).
I have the same lens and love it. Never had the sticky aperture, so I can vouch for the fact that some of them work great.

A few thoughts on your exposure question. First, was the Sensitivity (ISO) the same in both instances? Second, did you have any filters on the Tamron? Finally, even though the Tamron is "faster glass", it should still meter to the same aperture for the same light, so is it possible that the day was hazy or dusty?

I would be interested if you could post these two examples with the exif data.
09-20-2010, 05:56 PM   #8
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QuoteOriginally posted by leefranke Quote
The next game was at 11am. Full Texas sun. I noticed while shooting at 1/350 that my F-stop was only at 13 when usually with my Pentax lens it would be around 22. I would think the opposite would be true (smaller aperture for the faster glass).
The maximum aperture of the lens has nothing to do with what aperture might be chosen in any given setting. sounds like either you had a different ISO set between the two days, or else the light was different. Nothing about the lenses themselves.

09-22-2010, 08:23 AM   #9
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QuoteOriginally posted by leefranke Quote
Full Texas sun. I noticed while shooting at 1/350 that my F-stop was only at 13 when usually with my Pentax lens it would be around 22. I would think the opposite would be true (smaller aperture for the faster glass).
Why are you shooting sports at f/13 and f/22?
09-23-2010, 08:04 AM   #10
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Sports pictures usually better with shallow depth of field if your focusing can keep up.
QuoteOriginally posted by egordon99 Quote
Why are you shooting sports at f/13 and f/22?
At these apertures you are not taking advantage of the new lens!
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