Sigma 30mm f/1.4 - how to test it?

[Bicko]

Hi,

I've just treated myself to a Sigma 30mm f/1.4, in Canon fitment. I have read that I might fall victim to Sigma's alleged poor QC and possibly have to return it, for replacement.

My question is; now that I have this in my hands, how should I test it? Or, rather, what are the issues I should be checking for right away?

I would normally spend quite a while getting to 'know' a new lens and take it from there, but the weather is shonky and the "7 day change your mind period" waits for no man.

Thanks, in anticipation
Mike.

 

[Gary Coyle]

Hi,

I've just treated myself to a Sigma 30mm f/1.4, in Canon fitment. I have read that I might fall victim to Sigma's alleged poor QC and possibly have to return it, for replacement.

My question is; now that I have this in my hands, how should I test it? Or, rather, what are the issues I should be checking for right away?

I would normally spend quite a while getting to 'know' a new lens and take it from there, but the weather is shonky and the "7 day change your mind period" waits for no man.

Thanks, in anticipation
Mike.

Just go and shoot with the damn thing.

 

[twist]

If your photos are out of focus you have a dodgy copy.

 

[mike_6480]

The battery test seems to be the usual one people use for focussing.

Stand up a few batteries in a diagonal line so that you can see the brand or other lettering on each one.

Use a high aperture (eg f1.4 or similar) and focus on a battery in the middle of the line if batteries. Should show whether it is focussing in the right place or not.

I'd also do some tests for sharpness across different apertures as well.

 

[LongLensPhotography]

The battery test seems to be the usual one people use for focussing.

Stand up a few batteries in a diagonal line so that you can see the brand or other lettering on each one.

Use a high aperture (eg f1.4 or similar) and focus on a battery in the middle of the line if batteries. Should show whether it is focussing in the right place or not.

I'd also do some tests for sharpness across different apertures as well.

This may tell a very obvious misfocusing, but will miss out any finer, but very annoying faults.

I always advocate testing far away targets too, unless the lens is a close up only lens. So you find something very detailed and fire a few shots at different apertures. Then recompose (don't refocus) and shoot the same thing in the corners and edges. If the centre is pretty sharp from beginning, and corners are not far behind AND equal to each other you probably have an OK copy and can do more testing until you eventually find some other flaw. If you find problems by this stage you get rid of the stupid thing as fast as you can.

 

[Bicko]

The battery test seems to be the usual one people use for focussing.

Stand up a few batteries in a diagonal line so that you can see the brand or other lettering on each one.

Use a high aperture (eg f1.4 or similar) and focus on a battery in the middle of the line if batteries. Should show whether it is focussing in the right place or not.

I'd also do some tests for sharpness across different apertures as well.

This sort of thing, then?

Cropped-in it looks like this (at f/1.4):

I was focussed on the 'L' of the eneloop, but it was quite hard to do since my focus point was pretty much as wide as the battery itself. I was also very close to the subject, so I don't know how useful this is as a test.

You'll see that it appears to be focussing a little behind the target, but I *have* microadjusted a little - and got it wrong! Without microadjust, it was focussing in front of the target by the roughly the same amount. It looked great on the camera's LCD!
I guess it's probably not wise to try to microadjust on a target so near to the camera itself but, as a quick "is this lens ok, focus-wise" test, it'll do. Right?

Thanks.

 

[Bicko]

This may tell a very obvious misfocusing, but will miss out any finer, but very annoying faults.

I always advocate testing far away targets too, unless the lens is a close up only lens. So you find something very detailed and fire a few shots at different apertures. Then recompose (don't refocus) and shoot the same thing in the corners and edges. If the centre is pretty sharp from beginning, and corners are not far behind AND equal to each other you probably have an OK copy and can do more testing until you eventually find some other flaw. If you find problems by this stage you get rid of the stupid thing as fast as you can.

Understood, but this will have to wait for better weather. A "far away" target, indoors, would only be about four metres away, in my house

Thanks though, I'm waiting for a break in the rain.

 

[HoppyUK]

This sort of thing, then?

Cropped-in it looks like this (at f/1.4):

I was focussed on the 'L' of the eneloop, but it was quite hard to do since my focus point was pretty much as wide as the battery itself. I was also very close to the subject, so I don't know how useful this is as a test.
You'll see that it appears to be focussing a little behind the target, but I *have* microadjusted a little - and got it wrong! Without microadjust, it was focussing in front of the target by the roughly the same amount. It looked great on the camera's LCD!
I guess it's probably not wise to try to microadjust on a target so near to the camera itself but, as a quick "is this lens ok, focus-wise" test, it'll do. Right?

Thanks.

It's completely useless as a test. No idea why this seems to have caught on. It's far too close and there's no way of telling what the camera has actually focused on.

Target must be flat, and taken at a realistic shooting distance. Lots of threads on AF microadjustment.

 

[SixToes]

Just go and shoot with the damn thing.