View Single Post
Old Nov 5, 2006, 8:41 PM   #8
JimC
Administrator
 
Join Date: Jun 2003
Location: Savannah, GA (USA)
Posts: 22,378
Default

The Minolta 20mm f/2.8 probably is as sharp as it's competition.

The Tamron 20-40mm f/2.7-3.5 just tests much better than most wide zooms. So, according to the MTF Charts, it's actually slightly sharper than the Minolta 20mm f/2.8 (although they're very close). This Tamron also tests sharper than the Minolta 24mm f/2.8

I don't own a Minolta 20mm f/2.8, and MTF Charts never tell the entire story. It may be a pretty decent lens and may do a better job compared to my Tamron. There are more qualities to a lens compared to what an MTF chart is going to tell you.

I just didn't feel like I needed one, since my Tamron seems to do a pretty good job for when I need a wider lens.

So, if I were going to buy a wider prime, I'd get one that offers an advantage in an area like brightness over my Tamron. I often find that f/2.8 is not quite as bright as I need. For that matter, my 28mm f/2 is sometimes not as bright as I need. lol

You can find the MTF Charts for them at http://old.photodo.com

Minolta 20mm f/2.8
------------------------
Photodo test result: 3,5
Effective focal length: 20
Weighted MTF for 20 mm: f2,8 0,70, f4 0,75, f8 0,79
Average Weighted MTF: 0,77 Grade: 3,5
Weighted MTF 10 lp/mm: 0,88
Weighted MTF 20 lp/mm: 0,72
Weighted MTF 40 lp/mm: 0,44
Distortion: -3,95%

Tamron 20-40mm f/2.7-3.5
----------------------------------
Photodo test result: 3,7
Effective focal length: 20 - 39 mm
Weighted MTF for 20 mm: f2,7 0,71, f4 0,77, f8 0,79
Weighted MTF for 28 mm: f2,8 0,70, f4 0,76, f8 0,81
Weighted MTF for 40 mm: f3,5 0,71, f8 0,82
Average Weighted MTF: 0,78 Grade: 3,7
Weighted MTF 10 lp/mm: 0,88
Weighted MTF 20 lp/mm: 0,73
Weighted MTF 40 lp/mm: 0,50
Distortion: -3,7% - 3,2%

JimC is offline   Reply With Quote