Comments on: Sigma 120-400mm OS – Review http://brentpennington.com/2010/01/sigma-120-400mm-os-%e2%80%93-review/ Official website & blog Tue, 31 Aug 2010 01:56:34 +0000 hourly 1 By: Brent Pennington http://brentpennington.com/2010/01/sigma-120-400mm-os-%e2%80%93-review/comment-page-1/#comment-228 Brent Pennington Mon, 25 Jan 2010 23:37:04 +0000 http://brentpennington.com/?p=1719#comment-228 Hi Mike - Sorry to hear that you're having troubles with the Sigma! Based on what you said, I do have a few suggestions for you: first off, cloudy, gloomy weather does make things a little harder since the light is lower (although the fact that it diffuses the light helps, too). When I have the Sigma mounted, I'm at ISO 400, minimum - and often at 800. I keep the aperture between f/5.6 and f/8 depending on the day, and at those apertures, to get the needed shutter speeds, the ISO just has to go that high. From what I hear the XSi is a very capable camera and should be able to handle those ISOs - I know my old XTi would do okay there. Second, be sure to use good telephoto shooting posture (Google for details if you're not sure). Perhaps most importantly, remember the reciprocal shutter speed rule, ie: 400mm needs at least 1/400 sec. for stable shots. Then take into account the 1.6 crop factor of the camera, and the 400mm effectively becomes 640mm, so your shutter speed needs to match (ie: 1/640). The OS system will compensate for several stops: 2 safely, up to 4 if you've got a good, steady arm. So between the higher ISO and the OS, you should have good shutter speeds then. I'd see if that makes a difference first. Sadly, Sigma lenses are known to have focus issues from time to time. My copy of this lens is incredibly sharp, but soft copies are out there, and you may have gotten the unlucky one. If you find you still can't get sharp photos after reading my suggestion above, try turning off the OS and shooting a fixed object from a tripod. If the tripod shot STILL isn't quite sharp, then you know for sure that you've got a focus issue. If then lens is new enough, contact the store you bought it from and get them to take it back and give you another copy. Failing that, send it to Sigma and get them to fix it - if it's under warranty this shouldn't be an issue (if you complain loud enough, they may even pick up the shipping!). You'll be without your lens for a couple of weeks, but hopefully it will then come back and live up to its full potential. Hope this helps! Let me know how you manage. Best, Brent Hi Mike -
Sorry to hear that you’re having troubles with the Sigma! Based on what you said, I do have a few suggestions for you: first off, cloudy, gloomy weather does make things a little harder since the light is lower (although the fact that it diffuses the light helps, too). When I have the Sigma mounted, I’m at ISO 400, minimum – and often at 800. I keep the aperture between f/5.6 and f/8 depending on the day, and at those apertures, to get the needed shutter speeds, the ISO just has to go that high. From what I hear the XSi is a very capable camera and should be able to handle those ISOs – I know my old XTi would do okay there.

Second, be sure to use good telephoto shooting posture (Google for details if you’re not sure). Perhaps most importantly, remember the reciprocal shutter speed rule, ie: 400mm needs at least 1/400 sec. for stable shots. Then take into account the 1.6 crop factor of the camera, and the 400mm effectively becomes 640mm, so your shutter speed needs to match (ie: 1/640). The OS system will compensate for several stops: 2 safely, up to 4 if you’ve got a good, steady arm. So between the higher ISO and the OS, you should have good shutter speeds then. I’d see if that makes a difference first.

Sadly, Sigma lenses are known to have focus issues from time to time. My copy of this lens is incredibly sharp, but soft copies are out there, and you may have gotten the unlucky one. If you find you still can’t get sharp photos after reading my suggestion above, try turning off the OS and shooting a fixed object from a tripod. If the tripod shot STILL isn’t quite sharp, then you know for sure that you’ve got a focus issue. If then lens is new enough, contact the store you bought it from and get them to take it back and give you another copy. Failing that, send it to Sigma and get them to fix it – if it’s under warranty this shouldn’t be an issue (if you complain loud enough, they may even pick up the shipping!). You’ll be without your lens for a couple of weeks, but hopefully it will then come back and live up to its full potential.

Hope this helps! Let me know how you manage.
Best,
Brent

]]> By: Mike Murray http://brentpennington.com/2010/01/sigma-120-400mm-os-%e2%80%93-review/comment-page-1/#comment-226 Mike Murray Mon, 25 Jan 2010 13:37:10 +0000 http://brentpennington.com/?p=1719#comment-226 Hi Brent, I recently purchased the sigma 120-400mm lens. Although i want to be, i have not been very excited about this lens. It could be that most of my bird shots have been in cloudy, gloomy weather but i am still waiting to get that tack sharp picture that i have been waiting for. I am using a Canon XSI, shooting in AV mode. The birds that i have been shooting are probably around 25-35 feet away and i am setting my lens set at anywhere between 250-350mm. It seems like my pictures are right on the cusp of being clear but i have yet to get a tack sharp shot. I have also tried shooting at 200-400 ISO to see if it makes a difference. Any suggestions would be appreciated. Hi Brent,
I recently purchased the sigma 120-400mm lens. Although i want to be, i have not been very excited about this lens. It could be that most of my bird shots have been in cloudy, gloomy weather but i am still waiting to get that tack sharp picture that i have been waiting for. I am using a Canon XSI, shooting in AV mode. The birds that i have been shooting are probably around 25-35 feet away and i am setting my lens set at anywhere between 250-350mm. It seems like my pictures are right on the cusp of being clear but i have yet to get a tack sharp shot. I have also tried shooting at 200-400 ISO to see if it makes a difference. Any suggestions would be appreciated.

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