Feb 27, 2010, 17:20
There I was with the best of intent: a really diagnostic comparison of the Tamron 90mm f2.8 macro and the Canon 70-200mm f4L(IS) at 90mm. I was thinking what a useful and thorough resource this would be....
After about 4 hours pp back at base I noticed a distinct "softening" at f8 and then f11 with both lenses. After playing off diffraction with fears of all sorts of front/back-focusing issues, the penny dropped that as I'd not locked the mirror up nor realised there was vibration along the lenses, er, things might have got a bit unstuck.
I then saw I'd also left a polariser on one of the lenses throughout
..
...followed by the realisation that in fact I'd set the Canon to 85mm, not 90mm
..
So, a gig and a half later of tiffs and a total washout!
I did, however, take a couple...handheld, both at f8...resulting in the mindbogglingly underwhelming discovery that both lenses are, er, very good :/
I could regale you with the unsubstantiated but quite correct observation that the Tamron is excellent across the frame from f4 to f8, with f5.6 outdoing the Canon at the same length;
I could tell you that the Canon hits the mark at full aperture(f4) with the same excellence as the Tamron, and that diffraction only becomes noticeable on a pixel-level barely at f11, and I could tell you that the Canon softens in the top right of the frame whereas the Tamron loses bottom left-corner detail from f8.
Sigh: but I've nowt to back it up with! :mad:
So, for those who can bear to read on, these 2 posts will cover a comparison of the 2 lenses in 3 areas of the frame, shot handheld in a "real" situation(!) at f8.
Go on: go to the number 2 and be entirely nonastounded...
This is the scene...go to part 2 to see the 100% crops.
![[Image: 980wholeTamronf8.jpg]](http://www.shuttertalk.com/forums/images/upload/980wholeTamronf8.jpg)
After about 4 hours pp back at base I noticed a distinct "softening" at f8 and then f11 with both lenses. After playing off diffraction with fears of all sorts of front/back-focusing issues, the penny dropped that as I'd not locked the mirror up nor realised there was vibration along the lenses, er, things might have got a bit unstuck.
I then saw I'd also left a polariser on one of the lenses throughout
.....followed by the realisation that in fact I'd set the Canon to 85mm, not 90mm
..So, a gig and a half later of tiffs and a total washout!
I did, however, take a couple...handheld, both at f8...resulting in the mindbogglingly underwhelming discovery that both lenses are, er, very good :/
I could regale you with the unsubstantiated but quite correct observation that the Tamron is excellent across the frame from f4 to f8, with f5.6 outdoing the Canon at the same length;
I could tell you that the Canon hits the mark at full aperture(f4) with the same excellence as the Tamron, and that diffraction only becomes noticeable on a pixel-level barely at f11, and I could tell you that the Canon softens in the top right of the frame whereas the Tamron loses bottom left-corner detail from f8.
Sigh: but I've nowt to back it up with! :mad:
So, for those who can bear to read on, these 2 posts will cover a comparison of the 2 lenses in 3 areas of the frame, shot handheld in a "real" situation(!) at f8.
Go on: go to the number 2 and be entirely nonastounded...
This is the scene...go to part 2 to see the 100% crops.
