Quick Lens Question

Hi all, am just getting to grips with my new 50d in conjunction with sigma 50-500. Does anyone have an opinion as to if this lens is sharp at 500mm? After a few goes shooting on a bean bag I'm coming to the conclusion it probably isn't.

Thanks

Scott

HI Scott,

I have used and use my 50-500mm on a regular basis and don't have any real problems with it. I think it needs to be on a tripod or bean-bag and in good light conditions for it to be at it's best. A good, general, all round lens for it's class and quality. I took this image with a 50-500mm at the 500mm end, I know it's only at a small res on the web but it is sharp in the RAW..

http://i273.photobucket.com/albums/jj237/Commonseal/BL_Dragonfly--Exuvier_1575.jpg

Cheers,

Brett

Have you checked the lens calibration on the 50D , my one is out on my 300 F4 but fine on the 600 F4. The set up is to long to go into here but there are a few good teach ins on the web. The instructions in the manual start to make sense after the third time of reading . To calibrate the 500mm lens you may need a fence or long building , viewed at 45 degrees at about 30 to 50 yards, this will make more sense after you have read the book or seen the film .

Bob.

I also use a 50-500 Sigma, and when I can keep it steady or rest it on a rock-hard surface I find it sharp, even at the top end. I agree with what Brett says, if you are not using it on a tripod it probably won't perform all that well at the top end. There is, however, also an issue of quality checking by the manufacturer. Although my lens is superb, I have read reports of others who have had to send lenses back to Sigma for rebuilds, so maybe there is some variation between individual examples.

David

Sigma Ultra zooms have a reputation for being softish wide open at maximum zoom, are you stopping down to F8, or shooting wide open?

Hi, thanks for your replies.

Brett, that looks stunningly sharp to me even at low res!

Bob which calibration instructions are we talking about? Is this in the 50d manual?

Mike, I was shooting wide open, I will have a go over the weekend, shooting from a tripod and cable release at different apertures to see which gives me the best result.

Thanks

Scott

Hi Scott, page 180 of the manual or download from the Canon website.

Bob.

Thanks again Bob

Scott

Scott, it depends what you mean by sharp. No lens with a zoom ratio of 10 (50 to 500) is going to be critically sharp throughout its range. There are just too many compromises in the design. A zoom ratio of about 3 (eg 70 to 200) is the limit to obtain a good sharpness, although even then, images captured at the extreme ends of the range and at wider apertures are likely to be less so. Your strategy to test the lens and see what works best in terms of what is sharp to you is definitely the way go.

I'm not sure that using the AF micro-adjustment feature is going to change the inherent softness associated with the lens design. Sure you will be able to optimise the autofocus, but for one focal length only, not for the entire zoom range.

I found with mine, that if you put the lens on 500mm and set the camera on time release and take a shot whilst looking through the viewfinder you will be amazed at the wobble after the shutter has fired.!! ( Don't want to frighten you but its terrible. ) So sharpness may not be the problem but in herent camera shake.
I solved part of this by making a brace between the lens and the top of the tripod mount arm. Thats where one of the weaknesses is! It made a heck of a difference to mine.
JR