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03-14-2010, 04:41 PM   #1
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lens comparison- fa50mm / tamron 17-50mm / tamron 28-75mm

crossover37 got me thinking in this thread- https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/93510-should-i...75-f2-8-a.html that I needed to do a comparison between my new Tamron 17-50 f/2.8 & my 6 year old Tamron 28-75 f/2.8.

Just for giggles I threw the FA50/1.4 in the mix too. These were shot in RAW, opened and saved in ACR (w/no adjustments/crops), resized an saved as jpegs. No post processing except the resize/save.

The focus point was the left edge of the bell of the left bloom. Apparently I need to calibrate the 17-50 since it doesn't seem to be focusing where it should. I knew I bought that Lens Align the other day for some reason. All shots taken @ 50mm, proving not all 50mm lens FOV are equal.

FA50 @ f/2.8


Tamron 17-50 @ f/2.8


Tamron 28-75 @ f/2.8


FA50 @ f/4.0


Tamron 17-50 @ f/4.0


Tamron 28-75 @ f/4.0


FA50 @ f/5.6


Tamron 17-50 @ f/5.6


Tamron 28-75 @ f/5.6


FA50 @ f/8.0


Tamron 17-50 @ f/8.0


Tamron 28-75 @ f/8.0


There didn't seem to be much point in stopping down any farther than f/8.0 for this subject. The 17-50 seems to have better contrast than the FA or the 28-75, though they all had a hood on for these shots.

03-14-2010, 06:14 PM   #2
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Thank you Bimjo, for taking the time to produce this test for all of us. It is interesting to look at the pics, though I am not so quick to jump to any serious conclusions. However, I do think you have made a big point here.

QuoteQuote:
Bimjo: All shots taken @ 50mm, proving not all 50mm lens FOV are equal.
Bimjo, the 17-50mm will not be @ 50mm until it is focused to infinity.

QuoteQuote:
Bimjo: There didn't seem to be much point in stopping down any farther than f/8.0 for this subject. The 17-50 seems to have better contrast than the FA or the 28-75, though they all had a hood on for these shots.
Bimjo:

The exposures with the 17-50 are slightly more to the left than are the Fa exposures. Outdoor tests are virtually impossible to control all variables.
03-14-2010, 06:29 PM   #3
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Need full crop, this post doesn't prove anything. I also see that the 28-75 f/2.8 is focused further to the left than the 17-50 f/2.8 on the first set, then on the second set, it is more focused to the center than the 17-50 f/2.8.
03-14-2010, 06:55 PM   #4
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QuoteOriginally posted by Jewelltrail Quote
Thank you Bimjo, for taking the time to produce this test for all of us. It is interesting to look at the pics, though I am not so quick to jump to any serious conclusions. However, I do think you have made a big point here.
I've been meaning to do it, just finally got around to it.

QuoteOriginally posted by Jewelltrail Quote
Bimjo, the 17-50mm will not be @ 50mm until it is focused to infinity.
Hmmm... didn't know that. ACR reports all three lenses were at 50mm, but in retrospect is seems pretty incredible that I could actually get the 28-75 at 50 along with the others.



QuoteOriginally posted by Jewelltrail Quote
Bimjo:

The exposures with the 17-50 are slightly more to the left than are the Fa exposures. Outdoor tests are virtually impossible to control all variables.
Very true. Shot these in the shade of the house, but there were a few clouds blowing around. I should probably redo these indoors with a constant light source. But it was such a nice day today shooting inside would have been criminal.

If anybody wants 100% crops of any of these let me know what section you want & I'll get them up.

03-14-2010, 08:13 PM   #5
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QuoteQuote:
Bimjo:
Very true. Shot these in the shade of the house, but there were a few clouds blowing around. I should probably redo these indoors with a constant light source. But it was such a nice day today shooting inside would have been criminal.

If anybody wants 100% crops of any of these let me know what section you want & I'll get them up.
Indoor shooting is okay and easier to control the variables. No matter what test you make, someone will have some issue with it--it is the nature of the forum. This test is good, and it sure does level playing fields for Bokeh. It also shows that the lenses are "in the same ballpark"-- as they say.

It is just that you would expect more contrast in a scene which is more underexposed. I would love to see the %100 crops--they should prove interesting.
03-14-2010, 08:57 PM   #6
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QuoteOriginally posted by Jewelltrail Quote
Indoor shooting is okay and easier to control the variables. No matter what test you make, someone will have some issue with it--it is the nature of the forum. This test is good, and it sure does level playing fields for Bokeh. It also shows that the lenses are "in the same ballpark"-- as they say.

It is just that you would expect more contrast in a scene which is more underexposed. I would love to see the %100 crops--they should prove interesting.
Could be the black background messed with the meter & the contrast is off. [shrug] A little PP & these spiff up pretty good.

I did crops of the right bloom, as that was the most consistently sharply focused area of the pics. I only did f/2.8 & f/8.0 though.

FA50/2.8


Tamron 17-50/2.8


Tamron 28-75/2.8


FA50/8.0


Tamron 17-50/8.0


Tamron 28-75/8.0


Given these were shot outdoors I'd have to say these are all pretty close to one another. Slightly different timing could have shown any one of these shots to be sharper than any of the others. Only thing I proved is that these are three very good lenses, which isn't all bad.

Last edited by bimjo; 03-15-2010 at 05:56 AM. Reason: shot, not shout... stupid keyboard
03-15-2010, 01:30 AM   #7
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QuoteQuote:
bimjo: Given these were shout outdoors I'd have to say these are all pretty close to one another. Slightly different timing could have shown any one of these shots to be sharper than any of the others. Only thing I proved is that these are three very good lenses, which isn't all bad.
I agree, they are very close to one another, especially when one considers the margin for error. I agree with what you have proven here. Thanks again Bimjo!

03-15-2010, 01:39 AM   #8
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Where do you buy your Tamron 17-50?

03-15-2010, 05:57 AM   #9
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QuoteOriginally posted by rustynail925 Quote
Where do you buy your Tamron 17-50?
Bought it in the Marketplace here.
03-15-2010, 06:36 AM   #10
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Lucky you. I always check the market place but cant find that lens.
03-15-2010, 01:24 PM   #11
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QuoteOriginally posted by rustynail925 Quote
Lucky you. I always check the market place but cant find that lens.
Got to check periodically, some lenses sell very quick when they are first put up in the marketplace, ie. DA 35 Macro, Tamron 17-50.
03-16-2010, 01:10 AM   #12
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QuoteOriginally posted by LeDave Quote
Got to check periodically, some lenses sell very quick when they are first put up in the marketplace, ie. DA 35 Macro, Tamron 17-50.
Thx for the idea. Yeah i notice the DA 35 sells fast in the marketplace..
I post on the wanted section too but got nothing..
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