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01-26-2013, 12:41 PM   #1
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Tamron 70-200 2.8 help

I just purchased a Tamron 70-200 2.8. Read the reviews here and online , sold the old LX on fleabay threw in the difference and purchased some "fast glass" . Invited some friends over for a few test shots . First shot at 2.8 looks soft maybe out of focus , second 5.6 looks sharp . Swicthed from select point to 11 point for the third at 2.8 seemed better . Is the lens soft at 2.8 or do I need to tune the auto focus for the lens . Many dissapointing shots at 2.8 , but 5.6 seems much better . Opinions and suggestions welcomed. Thanks

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01-26-2013, 01:05 PM   #2
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My wifes Tamron 70-200 is a bit soft at f/2,8
From f/4 its much better and between f/5,6 and f/8 its razor sharp
01-26-2013, 01:12 PM   #3
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Tail is in focus in the first shot, not the eye. Like most lenses, the Tammy sharpens up with a stop or two.
01-26-2013, 01:16 PM   #4
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Focusing needs to be dead accurate at f/2.8 for those images to be useful. There is a characteristic soft effect to the bokeh of that lens that is less prominent at f/4.

01-26-2013, 01:56 PM   #5
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My copy is slightly sharper at f/4 than 2.8, but a lot of the issue is that at 2.8, the depth of field is small and it is hard to nail the focus on the subject.

If you were 10 meters from that squirrel, your total depth of field is only about one foot, which is why the tail is in focus and the eyes are not.

Have you tried calibrating the lens with your camera's AF?
01-26-2013, 02:07 PM   #6
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QuoteOriginally posted by klh Quote
My copy is slightly sharper at f/4 than 2.8, but a lot of the issue is that at 2.8, the depth of field is small and it is hard to nail the focus on the subject.

If you were 10 meters from that squirrel, your total depth of field is only about one foot, which is why the tail is in focus and the eyes are not.

Have you tried calibrating the lens with your camera's AF?
Calibrating the lens would be my next step . Does the focus mode have any effect on the calibration ? I understand the shallow DOF but this seems to be misssing the focus point in select point focus mode . There is no crop or PP applied , I was 10 ft away from the subject in these examples. I have never done a calibration before . Any tips?
01-26-2013, 02:44 PM   #7
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QuoteOriginally posted by jeffw Quote
Calibrating the lens would be my next step . Does the focus mode have any effect on the calibration ? I understand the shallow DOF but this seems to be misssing the focus point in select point focus mode . There is no crop or PP applied , I was 10 ft away from the subject in these examples. I have never done a calibration before . Any tips?
I certainly wouldn't think it needed calibration based on 1 photo. Try shooting something like a series of cans arranged so that they are staggered at slightly different distances and see if its a DoF issue or a focus issue first.
01-26-2013, 02:52 PM   #8
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QuoteOriginally posted by jeffw Quote
Calibrating the lens would be my next step . Does the focus mode have any effect on the calibration ? I understand the shallow DOF but this seems to be misssing the focus point in select point focus mode . There is no crop or PP applied , I was 10 ft away from the subject in these examples. I have never done a calibration before . Any tips?
It's not hard to do. I simply put the camera on a stable surface, line up AA batteries in a diagonal, focus on the center, and shoot (with 2 second timer delay). Then I zoom in the LCD and check which battery is in the best focus, and adjust accordingly in the setup menu (If the camera is focused behind the focus point, then add plus correction, if it is focused in front, then subtract correction.

There are more sophisticated ways, but this works for me.

PENTAX DSLRs: PART-1. Autofocus Adjustment charts for front and back focusing problems. Good for Pentax, Canon and Nikon.

RiceHigh's Pentax Blog: Focus Adjust the K-5 and Pentax AF Lenses with Live View

http://michaeltapesdesign.com/lensalign.html

Also, you were asking a lot if you were really 10 feet away. Your depth of field at 200mm f/2.8 is only 0.03 meters, or less than two inches. Even with perfect calibration, it will be hard to hit that every time. You could have moved that much. I think your lens if probably fine.

P.S. You must have friendly squirrels!


Last edited by klh; 01-26-2013 at 02:57 PM.
01-26-2013, 03:07 PM   #9
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Docrwm, I took a series at different f stops . Here is one at a longer distance .
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01-26-2013, 03:34 PM   #10
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Select a 45-degree (or less angle on that picket fence an' you'll have a much better read on AF issues).

H2
01-26-2013, 04:07 PM   #11
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The first shot looks like a depth of field issue. The center of the body and tail look pretty good, the head is out of focus. The F/5.6 shot looks pretty good. I don't think there is as problem with the lens although a calibration adjustment might help. I don't know how far you were but consider that a 200mm lens has a DOF of about 8 inches at 30 feet at f/2.8 and if you were closer, it is even narrower. Your focus has to be perfect.
01-26-2013, 04:24 PM   #12
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At f/2.8 you have to be spot on.
What *is* in focus is tack sharp with that lens!!!
My Tam 70-200 f/2.8 is tack sharp at 2.8, but I have to take extra care to get what I want sharp!
Congrats on the lens!
01-26-2013, 04:57 PM   #13
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I have this lens as well and that behavior seems pretty normal. It doesn't seem to be an issue with sharpness, it seems to be an issue with dof. I imagine any 200mm lens would have that issue at 2.8.

The most common problems with sharpness when I use my Tamron 70-200 is usually due to dof, shutter speed is set to slow, or I just missed the target. I really am curious, are any lenses always incredibly accurate at 200mm 2.8? I don't see how they could be since it seems it would come down to the camera's AF system more than the lens itself.
01-26-2013, 04:58 PM   #14
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By the way, when you do the calibration, make sure you put the targets well beyond the minimum focus distance. I forgot to do this once, and was really bothered about the back focus until I realized my mistake!

Also, be aware that if you calibrate a zoom lens at one focal length, it may not be perfect at others. I calibrated my 70-200 at 135mm.
01-26-2013, 05:08 PM   #15
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I also agree that it is the depth of field.

Looking at the railing the squirrel is sitting on, it is angled away from the camera. The tail and rear leg are in perfect focus. Also look at the railing below the the tail and then below the front of the squirrel - it is sharp underneath the tail and out of focus under his front paws.

Depth of field at f2.8 - simple as that.
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