Reading mode: Light Dark

Sigma 30mm f/1.4 - Simple Test?

Go to last post
A

artlogical

Member
Messages
15
Reaction score
0
Location
Lansing, MI, US
I'm thinking about buying a Sigma 30mm f/1.4 from a local camera shop. I have read the threads about good copies vs. bad copies, and I'm concerned about the problems. I wondered if there's a simple test that I could perform to make sure it's not a bad copy? I was thinking that attempting to autofocus at infinity might be a start - are there any other suggestions?
 
I would take 4 shots at 1.4 (this is based on my experience). Two shots within 2 feet (minimum focus to subject, and then infinity to subject) and then two shots at over 10 feet (minimum focus to subject, and then infinity to subject).

That should do the trick. WHen I first got mine, I could tell by looking at the LCD review when I zoomed in. Of course, this isnt scientific, but if its a "terrible copy" you'll be able to see it right on the spot. I recommend going home and viewing on a monitor for a closer comparison.

Good luck
 
artlogical said:
I'm thinking about buying a Sigma 30mm f/1.4 from a local camera
shop. I have read the threads about good copies vs. bad copies,
and I'm concerned about the problems. I wondered if there's a
simple test that I could perform to make sure it's not a bad copy?
I was thinking that attempting to autofocus at infinity might be a
start - are there any other suggestions?
Click to expand...
I was very paranoid but mine is "ok" for focusing and slightly de-centered, it has more contrast and is sharper on the left side. But it's very slight, not sure I'll bother sending it in for repair, probably won't.

In my opinion, buy from B&H and you'll have 14 days to test and if it's defective you can exchange it for another or return it and they pay the postage. You can't beat that. In a store you'll pay $100 more and be pressured into testing in just a few minutes.

Worst case, if you don't like your sigma, you can exchange it for a 28 1.8 which I think is almost as good.

--
Michael Mattox
http://www.michaelmattox.com
 
any one having problems with any sigma product can contact me. I work for sigma corp. of america. I am here to help all you have to do is contact me. If you find that you are having problems with a 30mmf1.4 we can test and adjust it for you no charge.(US warranty only)
 
I like your test method. Basically, if it looks good on the screen then the lens is good. All my lenses must be good then because I use a 45 inch 1920X1080 lcd driven at that rez as my primary viewer. Not that all of my images look good by any means because of operator error.

Do you have any idea what fraction of factory new lenses would fail your simple screen test? I am wondering if it isn't way less than 10% and that a lot of the bad copy posts are just squeaky wheels.
 
I want to buy this lens also, but I am not sure that I understand this focus test. At 2 feet and 10 feet to the subject, how do you autofocus at infinity? Should I use autofocus or manual focus.

Please explain this test method me to a little bit. Thanks.
 
I'm wondering the same thing - I'm not quite sure if I understand how to autofocus to infinity when the subject is so close - should I choose an AF point that is actually at infinity when the frame is mostly filled with the subject?

What sort of results should I expect from a bad lens vs. a good lens?
 
I've thought about buying from B&H - I was concerned about their return policy and the time it would take me to get a good lens. As it stands, when you factor in shipping, the local shop here only is $10 above the B&H price - so I will probably try there first.
 
on this lens to know if it's misfocusing; just shoot 10 shots outside at f1.4 and ctrpt AF, and if most are off (usually front focused) it needs its AF data adjusted. sigma NY can do this easily. by and far those who have sent theirs in get it back perfect. once it's focusing right, it's a gem.

--
http://www.pbase.com/lightrules/lenstests
 
You must log in or register to reply here.

Keyboard shortcuts

f
Forum
m
My threads
Mobile site
About
Editorial content
Cameras & Lenses
Community
All content, design, and layout are Copyright © 1998–2025 Digital Photography Review All Rights Reserved.
Reproduction in whole or part in any form or medium without specific written permission is prohibited.
When you use DPReview links to buy products, the site may earn a commission.
©GPS Media - Guides, Products, Services.
Back
Top