Measurbating the Sigma 30/1.4

[GroovyGeek]

OK, so I usually don't spend (a lot of) time measurbating, but with Sigma lenses you kinda have to do it, because you never know what you are going to get :biggrin:.

I recently purchased a Sigma 30/1.4 for my D40. While you don't buy a lens like that for sharpness, my copy seems to drop off rather sharply below f/2.8. The whole purpose of this lens is to use it down there, so I am wondering... What do Sigma 30 owners think --- par for the course or send to New York for tweaking? I don't want to play the Sigma lottery and exchange for a different copy.

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[evokel]

wow

 

[Nuteshack]

got one for my wife's d40 ..it's SHARP at 1.4...if u have any doubts by all means send it in....;-)

 

[Tyke Tyler]

Indeed. It does appear that you have a bad copy there, did you do the test shots with a tripod? It does look like you have.
If not I would recommend doing so before sending it in.
I had the same lens but for Canon, it was very usable at f/1.4 if you were steady and precise.
T.

 

[GroovyGeek]

All shots were on a tripod with a wireless trigger

 

[Tyke Tyler]

All shots were on a tripod with a wireless trigger

Confirmed.
Send it in mate. The results should be so much better.

 

[mycom]

Don't confuse sharpness with contrast ! I think even at f1.4 your copy seems sharp to me - howver the contrast is lower - which is expected !

 

[weiran]

mycom is right, it looks perfectly sharp at f/1.4, but with a lack of contrast. I'm not sure what you're expecting, but it's impossible to make a lens that's as sharp at f/1.4 as it is at f/8.

To test the lens better, try taking a shot of something like textured paper so you can really see the resolution rather than contrast.

 

[mycom]

There is an ever so slightly backfocus -assuming you had the cam focus at the red line - but that need to be verified with other lenses - could be the cam as well.

Have a look at tests of the 85/1.4 - you will also see a tad lower contrast until you reach 2.0.

My 30/1.4 behaves excatly the same why as does my 50/1.4 and 50/1.2 and....

 

[GroovyGeek]

There is an ever so slightly backfocus -assuming you had the cam focus at the red line - but that need to be verified with other lenses - could be the cam as well.

Yes, I noticed the backfocus. It is the cam, it does it with the 70-200 also, it is particularly noticeable when shooting it wide-open with a somewhat distant object. I need to get around to tweaking it a bit some day, did it on my D70 several years ago.

Have a look at tests of the 85/1.4 - you will also see a tad lower contrast until you reach 2.0. My 30/1.4 behaves excatly the same why as does my 50/1.4 and 50/1.2 and....

Will do. Thanks for the suggestion...