Softer than a soft thing.

kalibre

kalibre

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Doug
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Given that this weekend I've had an 'opportunity' to compare a different copy of my Sigma 150-500 (covered in a different thread), I thought I'd break it out of the box for a 5 minute test. Mainly because since getting my copy I've had some doubts over the sharpness, but hadn't ironed out my technique yet so hadn't sent it back to Sigma.

Here are the results (100% crops @ F9 1/200 ISO800). Excusing the poor subject matter. Mine is on the left, new one on the right:

150mm AF - OS On
150mm-AF.jpg


300mm AF - OS On
300mm-AF.jpg


500mm AF - OS On
500mm-AF.jpg


500mm MF - OS Off
500mm-MF.jpg


Not much between them @300mm but other than that my copy seems softer than a soft thing on national soft day. :shake:

So I've got to investigate sending it back to Sigma for a service under warranty. Does anyone have experience of doing this with Sigma, and was it quite painless to get a good result?

Cheers.
 
Can't really say what the problem is, it looks like either movement or something else, there doesn't appear to be a sharp bit.
I'd shoot a target at 45 degrees f/5.6 as close as the lens will allow, f9 has too much dof, its too gradual for it to show it to be an obvious a lens fault and not just movement.
 
It's definitely not movement as I've repeated these shots lots of times with the same result, plus my technique (tripod) was the same for both copies. Can't really be OS either as I've had some poor results with it switched off too.
 
Well at least two of the images on the left show clear signs of motion blur, so need to be discarded from the comparison.

I've never seen or used the lens, but I suspect that the 500mm f/9 samples are pretty decent results for a superzoom?

You need to test this lens at 1/1000 with OS off to be sure...
 
The subject matter leaves a heck of a lot to be desired, as there is so much at stake and possibly only a short space of time to compare the two, would it not be an idea to get a subject that is going to totaly test the two lenses.
 
looks to me, more like a movement issue than a sharpness issue, could it be a loose element? as you say you used the same tripod technique.

1 little query, did you use a timer or instant shutter?
 
Remote release with mirror lock-up, which is why I'm pretty sure it's not movement. To be honest when I used the better copy I took the snaps first time no probs. When I switched back to mine I took probably 2-3 of each before I feel like I got a postable one.

I will do some higher shutter speed stuff and post. But it won't be till Wednesday.
 
Did you manage to get your lens swapped/altered by Sigma?
I have just bought the 150-500, and yes it is very soft, so it looks like I am going down the same track as you...
 
Like others, I'm not convinced by these pics. There is definite camera shake in some. Get that shutter speed UP UP UP - 1/2000sec for preference.

A tripod is not really a guarantee of sharpness unless really sturdy and the camera is properly 'damped'. And if you've got the camera perched on top of an extended centre column it will wave about and be very susceptable to vibration from the mirror. At between 1/8sec to 1/30sec mirror slap is a real danger, and you are quite close to that. Of course, a long lens will magnify it a great deal. Dampen the release with a heavy bean-bag on top, or some people gently rest their hand on top to kill the vibes.

If there is a lens fault, it will be most obvious at maximum aperture (lowest f/number) in the corners of the image. Set the exposure on manual (so that it cannot change between shots) and shoot four pics of the same subject with the target in each corner. If the lens is duff, or has been knocked, one or more of the corners will be noticeably softer than the others. Don't expect any of the images to look very good - they won't - what you are looking for is a consistent level of sharpness all over the frame.

This is a severe test and you will probably be disapointed with the lens even though there may be nothing wrong with it. Shoot a fifth pic with the target in the centre and that will probably make you feel a bit better about it ;)
 
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