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06-03-2009, 01:43 AM   #1
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Sigma 17-70 AND Tamron 28-75?

Hi all,

I have a question I would like your opinion on.

Currently I own and use the Sigma 17-70 lens as a general walkaround lens. And it's good for that.
Lately I started to do portraits as a parttime job. I don't have a studio, so I shoot kids, adults and animals in parks, gardens, on the street, etc. For this a zoom is a handy tool, because it gives me a lot of flexibility.

As a mid range zoom I now use the Sigma 17-70. Exposureplot tells me I use it quit a lot around the 70 mm focal range. The long range is covered by the Tamron 70-200 f2,8 (great lens btw).

Now my question: do you think it is sensible to buy the Tamron 28-75 2,8 for portait work?

In general I like a shallow DOF, but in portraits around 70mm, I mostly use F5,6 , so in that respect the Tamron has no added value since I don't think I'll be using it a lot wide open. All it comes down to is the question whether or not the image quality of the Tamron is visibly better.

Any thoughts are welcome.

Thanks for reading,
Roger.

06-03-2009, 01:57 AM   #2
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QuoteOriginally posted by drerka Quote
All it comes down to is the question whether or not the image quality of the Tamron is visibly better.
@F5.6 the quality IMHO isn't that much better. The bokeh might be a bit better also @F5.6, but my copies don't show that much difference that it would be relevant to purchase Tamron.

Haven't really compared them though, this is just a feeling I have after using and owning both of the lenses.

But if you would use the lens around F2.8-3.5 then it would a different case....
06-03-2009, 02:08 AM   #3
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Thanks for your info!

QuoteOriginally posted by solisti Quote
But if you would use the lens around F2.8-3.5 then it would a different case....
By that you mean that the IQ and bokeh are worth buying the Tamron?
06-03-2009, 02:16 AM   #4
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QuoteOriginally posted by drerka Quote
By that you mean that the IQ and bokeh are worth buying the Tamron?
Well, in my opinion it's a great lens when it's used around F3.2-F3.5 or even wide-open for potraiture. Bokeh and DOF are great. And of course it's even better @F5.6, but then there just isn't that much difference compared to the Sigma.

I can make you some comparison shots when I have time, this started to interest and I have to see for my self also .

06-03-2009, 02:21 AM   #5
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Comparison shots would be great

I really appreciate your comments and effort!
06-03-2009, 03:08 AM   #6
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Save your money and get the FA 77mm or DA 70mm prime instead...
06-03-2009, 03:46 AM   #7
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Hi Roger, I more or less agree with solisti above. I too own both and while I'm not a great fan of the Sigma (I tend to use it more as a travel lens) I don't think that there is a great deal of difference in the middle apertures (5.6 to about 13) above that and below that the Tamron is a better lens. However, if you are planning on doing portraiture at @70mm or so, I'd think seriously of creampuff's suggestion of a prime. As much as I love my Tamron, it's bokeh is nothing to write home about compared to any of my primes.

NaCl(just my two cents, and worth all of that)H2O
06-03-2009, 05:14 AM   #8
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hi I also am interested in samples between the two lenses.. since i just sold my sigma to buy a tamron.. I hope it's a better choice..
my experience is that sigma is very sharp in the center, but the color reproduction is not very pleasant somehow it's cold or smthng..

i hope tamron's colors will be warmer and better.. while keeping the same sharpness.

06-03-2009, 06:03 PM   #9
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QuoteOriginally posted by creampuff Quote
Save your money and get the FA 77mm or DA 70mm prime instead...
My thoughts exactly. I have the Pentax zoom and the FA 77, and the only step up in IQ from these zooms that makes real sense is to the prime.
06-04-2009, 06:32 AM   #10
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Not the best samples, but the best I could do last night. Defaults in ACR, the same white balance in each photo from the same set. Focusing with liveview.
K20d ISO200.

Bokeh:
Overall scene with Sigma @70mm F4.5. Flash bounced from the ceiling.


Tamron F2.8

Tamron F4.5

Tamron F5.6

Sigma F4.5

Sigma F5.6


Sharpness:
Overall image with Tamron @75mm F2.8


Tamron F2.8

Tamron F4.5

Tamron F5.6


Sigma F4.5

Sigma F5.6
06-05-2009, 03:12 AM   #11
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thanks solisti for your work, it's interesting and helpful,
however the same composition and direct comparisons would be even more helpful

like f/3.5, f/4.0 and on, on both lenses next to each other..
also demonstration of focal length like sigma 17mm and tamrons 28mm; and sigma's 70mm and tamron's 75mm would be interesting to see and compare.. of course if you have time..
06-05-2009, 04:29 AM   #12
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Thanks for your comparisons. Looks like I have to take a closer one of these days.

Roger.
06-05-2009, 05:27 AM   #13
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QuoteOriginally posted by Mystic Quote
thanks solisti for your work, it's interesting and helpful,
however the same composition and direct comparisons would be even more helpful

like f/3.5, f/4.0 and on, on both lenses next to each other..
also demonstration of focal length like sigma 17mm and tamrons 28mm; and sigma's 70mm and tamron's 75mm would be interesting to see and compare.. of course if you have time..
These comparisons are taken from a tripod. The idea was to demonstrate the difference in potrait use. Sigma @70mm and Tamron @75mm.

The 17mm and 28mm difference is quite dramatical
Pretty equal to these two 28mm and 50mm shots from wikipedia (in 35mm film terms the FOV is 25.5mm for 17mm and 42mm for 28mm):




I can try to make better comparison shots for you later.
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