Sigma 150-500mm soft focus

[Andy77]

ive had this lens for roughly 8mths now ans every time i use i feel as if my shots are soft compared to the ones i see that other people have taken with the same lens... is it my technique:shrug:, i use it on a canon 400d if that makes a difference im not sure, the lens is still under warranty from sigma so do i send it off to be checked, if so does the warranty cover all the costs???

Any help would be apprieciated :help::help:

[RichardtheSane]

Show us some images with exif and we will be able to help more...

[strax]

I would be interested in seeing some images too as I have the same lens only in a nikonfit and would like to compare sharpness of my images too.

[Andy77]

http://images-1.redbubble.net/img/art/size:xlarge/view:main/2374429-2-deer.jpg

focal lenth 500mm
f 5.6
iso 400
1/500 sec

[swag72]

Pretty sharp I think, but if you're not happy, here's my thoughts.

I would suggest that the shutter speed is at it's absolute limit for a 500mm lens and a 1.6 crop sensor? So perhaps some camera shake.

Also, perhaps you would find it sharper at f/8. Something about difraction that I don't understand, but it will be sharper at f/8

These are all things I have looked at when I looked into the softness of my 100-400.

[Andy77]

cheers for the info swag... Anybody else want to input there views....

[strax]

is this unsharpened and a 100% crop from a raw?

[Andy77]

anybody?????????????

[Andy77]

This is as it was taken apart from very slight sharpening in cs4, no cropping:)

[vmlopes]

We need a 100% crop if possible

[King of Groove]

I've got the Sigma 150-500 as well for my Nikon D300. Although you can hold it it can be difficult.

Do you use a tripod? Have you got the image stablisation switched on/off?

[RichardC27]

If it's anything like my Sigma 120-400mm it will be pretty soft wide open at 500mm. If you stop the lens down to about f7.1, f8 by either using a lower shutter speed or boosting the ISO you should get a much sharper shot. I try and avoid using my lens at f5.6 unless it's absolutely necessary. Unfortunately, with such a long focal length for a relatively low price there are always going to be optical compromises, especially at maximum focal length and maximum aperture.

[HoppyUK]

You can't possibly tell from that shot.

To draw any meaningful conclusions you really need to do side by side comparisons with another lens of similar focal length, of know quality, on the same camera. Anything less is frankly guessing. You must absolutely eliminate camera shake, nail focus perfectly, and post-process images exactly the same way.

It's not easy, but you're looking for a subtle difference, not a night and day change. It's the sort of difference that a bit of camera shake or mis-focusing can easily cause, and both these effects are common with long lenses.

BTW, defraction only affects small apertures (high f/numbers) and is very unlikely to be an issue with this lens.

[RichardtheSane]

OK, here is what I take from that image.

The lens was wide open at F6.3 (F5.6 at 500mm is not possible on this lens) so being wide open it will already be pefprming at it's worse.
Your shutter speed was 1/500 which is below the 'recommended' speed to ensure camera shake is not an issue. Were you tripod or monopod mounted?

Now, the shot you show looks fine to me, just not adequately sharpened for a web processed shot. Whenever you reduce the size of the image for web display you must sharpen quite aggressively otherwise it will look soft.

As Hoppy says, the only real way to check sharpness is using a 100% crop from the image - and only when shooting in ideal circumstances. Do you have anything shot with a shigher shutter speed you can post for us at 100%? This would be a better indicator.

Nice shot btw :thumbs:

[Andy77]

cheers for all your help guys, ill fire some more shots off and get them posted up for you asap, prob be weekend now though....:thumbs:

[fracster]

I use F8 on my Sigma lens,wide open at 5.6 it is pretty soft.Also you need to up the shutter speed if handholding.

[Andy77]

cheers fracster :thumbs::thumbs::thumbs:

[kalibre]

Bit late to this party but I too thought my 150-500 was a tad soft but in the end I just found that the learning curve was a big one for this lens. I find that the 'butter zone' is f8 @ 400mm.

I find that with my D300 a higher ISO with a long f-length still yields better results than low ISO short f-length and a big crop. Not sure if that stacks up for a 400d because I don't know enough about it's performance at high ISOs.

Needless to say for the first 6 months I was hoping to get away with 1/500 shooting wide open just like other lenses, but I really found that you do need the higher SSpeeds even with OS.

Hope that helps.

[arclight]

The edition of AP that appeared on the shelves yesterday has a lens test for the Sigma 150 - 500.
The results were not great.
Strangely, the reviewer remarked that the lens was worse with IS on. Perhaps he made the mistake of having it on when the lens was on a tripod - I don't know

Not always 100% convinced by magazine tests. However, generally long lenses are soft when wide open unless they cost mega bucks.