cheers anyone have comments on the sigma 150
I've only had a few but so far... Sigma 150mm f2.8. It's a bit big and the focus isn't lightening quick but for macro / pseudo macro stuff it is IMVHO just great.
Tokina 100mm 2.8 - Mainly because it is still sharp a few stops lower ( f16 ) than any other macro lens I know, allowing a larger depth of field. CA is a bit of a bugger though at times.
cheers anyone have comments on the sigma 150
Not true. Also impossible, due to diffraction.
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My own tests, and DXO Mark, disagree. I will show you the DXO Mark data, From the lenses tested on the Nikon D810 :
Nikon - borderline unacceptable at F22 and F16 sharpness is starting to become an issue <snip>
The 105mm might be more useful if you wanted to double it up as a portrait lens? I find the 150mm a touch too long for that.cheers guys looks like a hunt for a 150 is going to start
DXO mark talk utter cobblers.My own tests, and DXO Mark, disagree. I will show you the DXO Mark data, From the lenses tested on the Nikon D810 :
Nikon - borderline unacceptable at F22 and F16 sharpness is starting to become an issue
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Tokina - Still acceptable at F22 and at F16 sharpness is only just starting to be an issue.
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Sigma : totally unacceptable at F22, very borderline at F16 and also note the low sharpness at f2.8, making it less useful as a portrait lens than the other two above.
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This picture was taken at F22, it is a picture of a flying queen ant that landed on a rival nest and being pulled apart by workers. I would rather take a little theoretical sharpness loss over a great depth of field for this type of picture anyday.
Ant_attack2 by Nature Ist, on Flickr
DXO mark talk utter cobblers.
I agree that DXO Mark tests don't tell you the whole story about a lens, how it handles, if it suffers from zoom creep, if the autofocus is inaccurate or slow or other issues that effect lenses. However I buy a lot of second hand lenses, and always shoot them against an iso 12233 pattern to check for autofocus problems and decentering, and I have found a 100% matchup in DXO mark data and my own tests. If they say a lens is soft at f4 and sharp at 5.6, I find the same. If they say there is Cromatic Abberation at a certain aperture, I find the same. If they say one lens is soft at the edges, and sharp in the centre, I find the same. The empirical data they present is very useful and very reliable, and you can easily cross check it yourself.
Hoppy may be right, that the Tokina 100mm is not really F16 when you stop it down, and this results in the variation in the graphs above. I may run another test to see if changing from F8 to 16 really does quarter the available light, so I know if the aperture is accurate. I do know that setting the Tokina to F16 and even F22 results in acceptable sharpness, as I have tested it myself.
Don't beWow thanks for all input from everyone,im now confused more than before thanks![]()
Whatever the reason, the fact is that diffraction at f/16 knocks everything down to the same level. That's not me or DxO or whoever saying that, it's physics.
Here are some numbers I just dug out for interest. They are my own Imatest MTF test data that I do for various photo magazines. They are all tested on the same camera, in the same way, to the same standard, and are all directly comparable (you can't say that about many other published tests, so beware when making comparisons). These are all % MTF at 24-lines-per-mm, at f/5.6 (Sigma 180 at f/4) and f/16, field centre. A difference of less than 5% is very hard to detect visually, yet here they're all within 2% at f/16.
Canon 100/2.8 L, 85% @ f/5.6, 71% @ f/16
Sigma 105/2.8 OS, 88% @ f/5.6, 72% @ f/16
Sigma 150/2.8 OS, 87% @ f/5.6, 70% @ f/16
Sigma 180/2.8 OS, 89% @ f/4, 72% @ f/16
Tamron 90/2.8 VC, 80% @ 5.6, 70% @ f/16
Tokina 100/2.8 AT-X, 83% @ 5.6, 71% @ f/16