Lens Issue - Do I have a problem?

I have got the Sigma 100-300 F4. While this is a nice peice of glass I am wondering if I have a problem. I have done a couple of testes and it seems to me that the lens is soft at 100mm than it is at 300mm at the same apature vaule.

Now I have done a test by mounting the lens on to a very steedy tripod and using cable release for the shutter. The subject in question is some distance away. I have also tested it using the 1.4x adaptor. Which with these results produce a sharper image at 140mm than at 100mm. NB I have not done any post processing and these are all 100% crops.

@100mm

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Buy a canon

haha, smart ass it was either this lens or the 300 F4, perhaps I should have gone with that

nzl-g3user wrote in post #2090515
haha, smart ass it was either this lens or the 300 F4, perhaps I should have gone with that

There are couple on trademe. Ive decided that a 400mm F5.6 would be more used to me than a 300mm F4
I can do 280mm with my 70-200 and 1.4 TC

My 300 f4 is my least used lens. A 35-350 would suit me better. Now if it had IS...

I would expect your lens to be sharper on the short end too. I gotta admit that wide open your lens sucks AND blows.

According to photozone.de testing, that lens should perform quite nicely, peaking in performance at f/5.6. f/4 MTF is similar to f/11 MTF numbers.

cosworth wrote in post #2090532
My 300 f4 is my least used lens. A 35-350 would suit me better. Now if it had IS...

I would expect your lens to be sharper on the short end too. I gotta admit that wide open your lens sucks AND blows.

I know. it's not like it's just a tad soft, it way too soft. The thing is these were taken on a tripod with a cable release, grrrr.

send it to sigma....I would rather have that lens thats recalibrated then most other lens...reviews for it are usually VERY high

Wilt wrote in post #2090540
According to photozone.de testing, that lens should perform quite nicely, peaking in performance at f/5.6. f/4 MTF is similar to f/11 MTF numbers.

that's why I went out and got it with out testing. I got the lens from the states. Which enabled me to save about $400 off the rrp in NZ. Also people on FM have given a good review of this lens.

Sigma has a 7 year warranty in Canada. What is it there? Similar? They are quite keen on taking market share and they should fix this promptly if it IS an issue.

Thats the trouble with FF cameras they know if the lens is off. There is a place in Auckland C F Kenedy I think that can service them.

weka2000 wrote in post #2090566
Thats the trouble with FF cameras they know if the lens is off. There is a place in Auckland C F Kenedy I think that can service them.

I should say that this lens was tested on a 10D some of us can't afford FF cameras unlike some hmmm

I might as wazza where he got his one fixed. I think it's time that it got checked out.

nzl-g3user wrote in post #2090633
I should say that this lens was tested on a 10D some of us can't afford FF cameras unlike some hmmm

I might as wazza where he got his one fixed. I think it's time that it got checked out.

I can afford FF I live in Mangere

I'd say you likely have more of a focusing problem than anything. It needs a trip to your Sigma service center..because when this lens is on, it's on.

weka2000 wrote in post #2090511
Buy a canon

yep!