IQ of Tamron 28-75mm f2.8 mounted on a 5D or equiv?

mr peas · September 20, 2006

How is the IQ on the Tamron AF 28-75mm f2.8 XR Di Zoom when mounted on a 35mm size sensor, such as the 5D?

With more emphasis on the edges than the center: Maybe more CA? More Blur? ..at the edges?

Can anyone with both the lens and the body put out a sample/test image?

Thanks, I'm wondering if I get this lens (on an XT) and upgrade later on to the 5D, would the lens still be usable (IQ wise).

mr peas · September 21, 2006

I know someone is out there with both lens and body! Come on!! :ivar

Scott_Quier · September 21, 2006

I would help you but I can't - don't have the requisite FF body.

pathfinder · September 21, 2006

This is a good question, I am interested also so be patient -

Maybe I can get to it this week end:D

mr peas · September 21, 2006

hah, will do. pls let us know!

pathfinder · September 24, 2006

So.....I finally got a little free time to play with the Tamron SP28-75f2.8 XR Di lens on a Canon 5D.

You asked about image quality, and I am freely interpreting this to relate to resolution. I do not expect this lens to be as sharp in the corners as it is on the smaller image circle of an APS sensored camera like a 20D.

I do not own any Air Force resolution targets, so I decided to use a 2 page spread from the Wall Street Journal as my target. I loosely taped this to a sheet of poster board and set it up vertical. It was not exactly flat, but close enough for government work. I decide to light it with flash figuring this will help eliminate camera movement as a factor in the sharpness of the images. (I should have used two flashes as the lighting was rather uneven.) I mounted the 5D on a good tripod, set the mirror to lockup, and tripped the shutter with the 10 second delay timer.

I will not post the images here as they are very large - but the files links will be posted below.

As I expected, the lens performs much better at 75mm than at 28mm. It suffers from some barrel distortion as do most normal range zooms at the wide end. This disappears as the lens zooms out. There is some vignetting at the wide end that causes the corners to be darker than the center. Some vingetting is seen in Canon 16-35f2.8 L also.

I also shot a couple of bricks walls and some night shots and some grain fields. All of the images were shot in RAW and processed through ARC. The images have had no sharpening whatsoever, zero , nada. They have had some color correction if there was color in the image. The shots of the newspaper were shot in manual mode with 2 stops of + FEC to increase the contrast on the page and force the page closer to white than gray. I increased the contrast in ARC but did not sharpen the image in RAW or as a jpg. They were then stored as level 9 or 10 jpgs and loaded unchanged to smugmug. All were shot at ISO 100 I believe.

The first file was shot at 28mm at f2.8 1/160th with flash It is noticeabely soft in the corners, but the text is easily readable even in the corners. The center is fine. The vingetting is quite apparent, as is the barrel distortion

http://Pathfinder.smugmug.com/photos/97449771-O.jpg

F4 1/160th 28mm is a bit better than f2.8

http://Pathfinder.smugmug.com/photos/97449582-O.jpg

F4 1/160th 42mm Is rather sharp with crisp letters and good contrast

http://Pathfinder.smugmug.com/photos/97449892-O.jpg

F11 1/160th 42mm seems fine

http://Pathfinder.smugmug.com/photos/97443935-O.jpg

F4 1/160th 75mm

http://Pathfinder.smugmug.com/photos/97444248-M.jpg

The requisite brick wall shot f2.8 1/100th 28mm - looks better to my eye than the shot of the newpaper would suggest.

Real world shots include the taillight of my truck f8 1/100 75mm

So, is the Tamron SP28-75f2.8 XR Di as good as a 24-70f2.8 L?? I don't think that it is, but it certainly can be used on a 5D without fear of creating fuzzy, low quality images.

This has not been an attempt to evaluate critically the optics in the 28-75 DI, but to discuss its use in the real world of day to day shooting. I do not have an optical bench, nor do I desire one. Day to day shooting is enough to evaluate a lens for my purposes.

mr peas · September 24, 2006

Thank you for your input!

I really needed to see if IQ would be degraded when and if I'd like to use the lens for a FF sensor body. And it looks like the lens is usable with the FF bodies, its not bad at all.

Now, the next question is, whats the comparison between the 24or28-70L 2.8 with the Tamron 28-75 2.8.

Is the quality on the L glass that much better than the Tamron? Is it worth spending double the price from the Tamron for the L glass?

Btw I really appreciate your help, I think I will pick up the Tamron for my XT, but now I'm tempted in seeing how the 24- or 28-70mm L 2.8 shoots against the Tamron. That test will have to go on another day.

pathfinder · September 24, 2006

My answer, My Peas, is that I own both the Tamron 28-75 which I purchased for my 10D shortly as my first lens after the 10D was introduced, and I obviously still own and use it.

That said, I did purchase a 24-70f2.8 L as my first purchase after I bought the 1DsMKll that Andy divested the first time. The major difference, I think, is better sharpness wide open at f2.8. And slightly faster AF. The 24-70 f2.8 L is also much larger and weighs at least twice as much, and is too large for a 20D in my eyes, whereas the Tammy feels just right on a 20D.

The mass and size of the 24-70 L matches the 1 Series bodies better in my hands.

This is a very subjective report, of course, but that is how I tend to think of these two lenses. They both have their advantages and disadvantages. For carrying around all day, the Tammy is much nicer.

For critical images shot in low light, the Canon L will do much better in a full frame camera. In an APS sensor camera, the Tammy does a very nice job.

If I could have only one, I would probably choose the 24-105 IS L today, but I would really miss the brighter viewfinder the f2.8 lenses deliver.

mr peas · September 26, 2006

pathfinder wrote:

My answer, My Peas, is that I own both the Tamron 28-75 which I purchased for my 10D shortly as my first lens after the 10D was introduced, and I obviously still own and use it.

That said, I did purchase a 24-70f2.8 L as my first purchase after I bought the 1DsMKll that Andy divested the first time. The major difference, I think, is better sharpness wide open at f2.8. And slightly faster AF. The 24-70 f2.8 L is also much larger and weighs at least twice as much, and is too large for a 20D in my eyes, whereas the Tammy feels just right on a 20D.

The mass and size of the 24-70 L matches the 1 Series bodies better in my hands.

This is a very subjective report, of course, but that is how I tend to think of these two lenses. They both have their advantages and disadvantages. For carrying around all day, the Tammy is much nicer. For critical images shot in low light, the Canon L will do much better in a full frame camera. In an APS sensor camera, the Tammy does a very nice job.

If I could have only one, I would probably choose the 24-105 IS L today, but I would really miss the brighter viewfinder the f2.8 lenses deliver.

Hmm. I want at least a f2.8 semi-wide short-range lens and I think the Tamron will do me right. I'm just afraid that when I upgrade (within the next year) to my first L glass, I wont be putting away the Tamron for good. But for the price, I think its a good investment. At least I know it will work on a FF body when and if I buy a 5D.

So you still continue to use it? Does it work really well on your 10D and 20D? I'm just about ready to pick one up.

pathfinder · September 26, 2006

Sure I still use the Tamron lens - this was shot with it 2 years ago

And this was shot with a 20D August while travelling by motorcycle and the only lens I had was the Tamron 28-75.

cmason · September 26, 2006

Mr Peas: you should read these:

http://www.the-digital-picture.com/Reviews/Tamron-28-75mm-f-2.8-XR-Di-Lens-Review.aspx
http://www.pbase.com/lightrules/2470exl
http://www.pbase.com/lightrules/exvdi

a great resource of many lens tests is Lightrules website:
http://www.pbase.com/lightrules/lenstests

SpeshulEd · September 26, 2006

cmason wrote:

Mr Peas: you should read these:

http://www.the-digital-picture.com/Reviews/Tamron-28-75mm-f-2.8-XR-Di-Lens-Review.aspx
http://www.pbase.com/lightrules/2470exl
http://www.pbase.com/lightrules/exvdi

a great resource of many lens tests is Lightrules website:
http://www.pbase.com/lightrules/lenstests

never knew of the lightrules site before, thats nice.

mr peas · September 26, 2006

yeah ive never seen it before either. sweet.

ill be doing some reading today thats for sure.

thanks to both of you.

hmm.. i really want something wide to mid-range for around or less than $500.
i need to use it at night as well as daytime.

ill do more reading before i buy anything. ill keep you posted.

Also:

what does it mean when they say its bad when the lens 'back focuses' and 'front focuses'?

cmason · September 26, 2006

mr peas wrote:

what does it mean when they say its bad when the lens 'back focuses' and 'front focuses'?

This is when a lens focuses other than where you think it is: front focus is when you get focus lock on your target, but instead a spot slightly in front of your target is more in focus than your target. Back focus is the opposite.

I have tested my lenses with this: http://www.focustestchart.com/chart.html
but never found a problem.

IQ of Tamron 28-75mm f2.8 mounted on a 5D or equiv?

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