Soft lens or poor technique?
 

Hi all,
First post and all that!
I own a 40D and a Sigma 50-500 DG. I've begun to believe that the lens is too soft for me but I need some help. Is there a way of eliminating "poor technique" from a shoot so that it is possible to be sure that any softness in a final image is down to the lens as opposed to anything else? I've read numerous articles on long lens technique but despite this many of my shots at the long end appear too soft for large crops etc.

Also is it worth getting a body and lens combination correctly calibrated? I don't seem to have issues with other lenses and sharp images (for example my 100mm Canon Macro gives lovely shots).

Any helpful suggestions gratefully received...
DS

Hi & welcome & all that.

I'm not a big user of long lenses, and this lens is generally quite well regarded. That said its probably not going to be as sharp as your Canon maco but a couple of general things to consider:

1. Try some shots with the lens on a good quality tripod, preferably using a shutter realease. If you dont have a shutter realease, use the timer setting to eliminate camera shake when you press the button
2. Consider using mirror lock up to further reduce vibrations
3. What shutter speed are you using - when hand holding the general rule of thumb with 35mm film photography was to use a shutter speed at least 1/focal length. So for a 500mm lens you would need at least 1/500 sec. There is debate as to whether with the crop factor effectively increasing your focal lenght to 800mm you need to increase this to 1/800 sec
4. Try stopping the lens down. Most lenses work best at least one stop down from the maximum aperture, if not two stops down so than means f9 - f13 at maximum zoom

Let us know how you get on

My experience of 'soft shots' is with a Canon 100-400 at the long end. It will only perform well when there is plenty of light so that there is good edge contrast to sharpen on. The max opening of this lens is 5.6 at 400mm and I get the best results with F6.3 to 7.1. Basically the subject has to be sunlit for it to work well.
I have never used the Sigma but I imagine it may be similar. The only way to get consistent sharp wildlife is with a prime lens. None of the long zooms seem to be up to it.

Pete

I agree with Clive on how to test it, I also have a Sigma Bigma and I find it is soft at the extreme end - 450 - 500mm unless you have very good light and are well stopped down - f8 + and 1/750 or faster for me - also agree that unless it is on a tripod or beanbag you will struggle. Personally however I'm not too bothered about softness in an image. I find it great for landscape and am not too much into birds. I would agree with Pete that for consistent sharp wildlife you need a prime but I find my Nikon 80-400 better than the Bigma.

giders is quite right eliminate any vibration chances fix the lens to the tripod not the camera and make sure the tripod is a heavy one i use the 100 400 l lens and i have had no problems IS can be used on tripods if the lens ( canon)is new enough

As well as Clive's suggestions, make sure the subject matter is static, i.e. eliminate subject movement as a possible cause of blur.

I bought a Bigma as a demo from Adorama and thought it too soft also. I used it on my D-50 nikon for birds. I now have a D-300 and wish I didn't return it as a 12 mp will allow me less cropping for close-up shots. I look back at the shots I took with it and now they don't look too bad. Everybody's advice before this is so true. A good ballhead is $400.00.Yikes!

I've had 2 copies of this lens - the first, a non-DG version died eventually from sand getting into the focus mechanism and destroying it. I found that at 500mm it really needed to be stopped down to about f8. That seemed to be a good compromise between slowing things down too much and adequate sharpness. At this apeture, I have regularly had pin sharp results when printing out to A4 size. Obviously good light helps, good technique is essential, but I found it to be a good performer throughout its focal range when stopped down a bit.
Have a look at my gallery on birdforum (same user name) - the more recent shots were with a 500mm sigma prime, but the older ones are with the bigma.

I wanted to get a different perspective on cars using 400mm block. I bought one 400mm 5.6 and found it horribly slow for my choice of ISO. In typical Indian condition one wouldn’t get more than 1/10th to have a decent f stop like f16 @ 100ISO. So that lens didn’t work for me and now one of my friends is using that on his 350D. He’s very happy with his bird photographs.

At the same time I’ve tried 400mm f2.8L. With and without 2X. That lens with my camera body feels like made for each other!

Quality is stunning and so is the price. 4500£ in India including that 2X convertor. :eek: