Sigma 100-300f/4 EX

Hi! I'm pretty confused about the test of Sigma 100-300f/4 EX DG. The testshots that where taken on rhe "clocktower" was allright i think, both at100 and 300mm. However the shots that where taken on the stonewall where rather unsharp/smooth. Why is that?I'm planning on buying a Canon Xti and this lens has been my first choice so far.I've been checking on many forums for opinions and it seems to be a very good lens,therefore i'm a bit confused by these results.I'm also planning to use a 1x4TC on this lens, and what i understand it produces good quality pictures with the TC mounted. I've also been considering th Canon 70-300f4-5.6 IS USM but what i can undrestand by the rewievs and tests it's not in the same league, even whitout TC. So please if anyone could give me a kick in the right direction here i would be wer pleased.

Just posted a comment in the 100-300 review. I think that it was a mess with photos of other lens... Sigma is really great: I don't have the Canon 70-300 but I own the Sigma and, weight apart, it's really a great lens, also with a 1.4TC on the par - or better! - of fixed lenses of 135 and 300mm focal.

Thanks stefanOn it really feels much better now since i been rather mixed up about these photos. The photos that i've been looking at taken with this lens are "quite good" i must say, so thanks for the reply.

If you like to see some full size samples, jpeg as shot, without any software work, I've some on the web here: http://stefan0n.com/photo/forum/ ... look at the exif data, as comments are in italian.

Hi again stefanOn. I've been looking at your photosamples and they looked very good, except from the picture 9,10,11, that seemed very soft and unsharp to me.On shorter focals it's stunningly sharp,the portraits even so,very crispy! Is there any possibilty to download these 3 pictures so that i can look at them in photoshop. Thanks for showing interest.

Hi olympus

you're right about some photo looking worse... the ones you've listed are with the lens mounted on a 400D, instead of a 10D. I'm not sure if I've a problem with it when focusing distant subjects: several photos one after another looks really different for sharpness. I've already tried all kind of AF system and using only one, only central or all focus points, ever with unreliable results. I'm reading that the tolerance accepted for the AF should be 1 DOF unit, so focusing a building 400m far away, at 300mm f4 I can have more than 80m of error in focus, and also in a random way, so every photo can be appreciably different from the others I think. If you can help me understandig this, I'll be really happy.

For the photo download: sorry, I've used a gallery project that disables download, but I'll fix so that you can download all the photos you like. Thank you.

Hi again stefanOn. It seems to me that your problem is in the camera(400D)otherwise you should have the same problems with your 10D, dont you think.I've been studying several photos taken with Sigma 100-300 since i read your latest message, and they are just avesome. even photos taken with 1x4TC are "Spot on" and they where taken with different cameras, Minolta 5D, Canon 350 D Etc.Etc.The thing you wrote about "AF should be 1 DOF unit" is beyond my competence so i cant answer you on this, what if you focus manually? Is there still the same problems? If it works better vith manual focus then it must be in your camera. I dont want to call me an expert, cause i'm not.Maybe someone else on this thread knows about this and could give you the answer. Bye for now "O".

Hi it's me again. maybe this link will help you in some way.www.luminous-landscape.com/tutorials/dep.shtml
"O"

Hi "O"! I think the same of you, about problem in the camera, but results are too much different and seems to happen only when focusing very far subjects, so not yet found a way to describe to Canon service and show them the probable defect. Manual focus isn't so simple, and looks better or worse depending on the case... Thank you for reading and for your hints. Bye!