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View Full Version : Canon 20D - Focus Problems with Sigma 2.8 - 24-60



Hcasa
04-02-2006, 11:00 PM
Has anyone experienced focus problems with their 20D while using aftermarket lenses such as sigma?

I recently shot some pics and relied on visual sharpness and the camera's "In-Focus" indicators to determine correct focus. Even though eveything looked fine during aquisition, focus and firing some of my shots still appear to be not as sharp as the appeared in my view finder. I am previewing my pics in the Digital Professional software that came with my camera. Has anyone had similar experiences?

Hcasa

jamison55
04-03-2006, 06:46 AM
My focus problems with Sigma lenses on my 20D are well documented here. I switched to all canon lenses and my problems disappeared. The only Sigma lens I currently own is the 10-20, and it does really well (though with a lens that wide it would have to try really hard to not be in focus)!

cdifoto
04-03-2006, 07:40 AM
As far as I can foresee, Bigma is the only Sigma lens I'll own, and the Tokina 12-24mm will probably be the only other third party in my bag.

Canon just works better with Canon.

DonSchap
04-03-2006, 08:09 AM
So you you are saying the ONLY lenses I can "count on" using using with my -changable lens- dSLR are only made by the company that makes the body? What kind of nonsense is that?

You had better tell Tamron, Sigma and Tokina... because they are betting the bulk of their lens manufacturing business on compatibility. Failure to produce a quality photo with their equipment would literally spell the end of their business, once word got out.

Personally, I would expect some serious quality improvement when going to the upper end of the Canon lens spectrum, but when it comes to the lower end of the line... third party should be equal or even better if they want to actually sell anything.

Also... if Canon has a "lock" on sharpness with only their lenses... prices will never come down, as they could dictate any price they choose... because you're implying that "third party" always produces such inferior results, no matter what you pay.

Personally, I am not buying it. My results with the Tamron set (18-200mm and 11-18mm) have been equal in quality and sharpness to what I have been able to acheive with the Canon 75-300mm and the infamous KIT lens (18-55mm). Obviously, the 50mm and 28mm primes produce a top quality shot... but they should. That's the reason I bought them: studio work.

In conclusion, it would be terribly disappointing if we (the photographic community) can NOT count on the big third-party manufacturers for decent and quality lensing. I know I would sincerely appreciate hearing some "quality assurance" from the big three to set aside some of these implcations.

Shaking head... :(

cdifoto
04-03-2006, 08:14 AM
So you you are saying the ONLY lenses I can "count on" using using with my -changable lens- dSLR are only made by the company that makes the body? What kind of nonsense is that?

You had better tell Tamron, Sigma and Tokina... because they are betting the bulk of their lens manufacturing business on compatibility. Failure to produce a quality photo with their equipment would literally spell the end of their business, once word got out.

Personally, I would expect some serious quality improvement when going to the upper end of the Canon lens spectrum, but when it comes to the lower end of the line... third party should be equal or even better if they want to actually sell anything.

Also... if Canon has a "lock" on sharpness with only their lenses... prices will never come down, as they could dictate any price they choose... because you're implying that "third party" always produces such inferior results, no matter what you pay.

Personally, I am not buying it. My results with the Tamron set (18-200mm and 11-18mm) have been equal in quality and sharpness to what I have been able to acheive with the Canon 75-300mm and the infamous KIT lens (18-55mm). Obviously, the 50mm and 28mm primes produce a top quality shot... but they should. That's the reason I bought them: studio work.

In conclusion, it would be terribly disappointing if we (the photographic community) can NOT count on the big third-party manufacturers for decent and quality lensing. I know I would sincerely appreciate hearing some "quality assurance" from the big three to set aside some of these implcations.

Shaking head... :(

It's not an optical quality issue at all. It's reliability of focus with narrow depth of field. Accurate focus and sharpness are NOT the same thing. If you can't expect your lens to let your camera lock an accurate focus for those important shots, it doesn't matter how good the optics are.

Use those 3rd party lenses in a critical situation that isn't in ideal conditions, then you'll see.

Canon doesn't share its technology with the 3rd party manufacturers. Why do you think those comparable lenses are so much cheaper? I'll give you one guess...


Oh and by the way...there are also a lot of Canon lenses that suck. It's when you compare the 24/28-70/75 f/2.8s and the 70-200s and 16/17/18-35/40/50 lenses that the issue comes into play the most. Consumer lenses are mostly mediocre at best regardless of the brand anyway, so of course your kit lens and cheaper 75-300 are going to be comparable to your Tamron 18-200 and 11-18mm. You aren't working with narrow DOF in lowlight conditions either, so focus isn't that hard to achieve. Try that Tamron 18-200 in a church for a wedding that you're being paid to shoot. I dare ya.

aparmley
04-03-2006, 02:37 PM
In conclusion, it would be terribly disappointing if we (the photographic community) can NOT count on the big third-party manufacturers for decent and quality lensing.

I think enough proof of 3rd party lens performance has been documented - if performance is near the top of your list - 3rd party just doesn't cut it. ;)

After all those 3rd party business exist for one reason - They want a slice of the pie Canon/Nikon baked! They don't exists for us Photographers.

I'll concede they are important to pricing - they provide competition which is always good for the consumer. But at best, this is their most important reasons for existing and the only one in which they perform as expected. The third party manufacturer's strengths certainly are not producing lenses that meets or exceed the Canon counter parts performance. There is plenty of evidence that supports that. There is a reason why top pros don't shoot with tamron, sigma, promaster, or quantary lenses. . .

I'll be the first to admit - in perfect photographic circumstances third party lens perform nearly as good as Canons. Just as soon as those perfect circumstances begin to fade, so does the performance of said third party lens. . . This is speaking on the average - ofcourse their are exceptions to most all of this - There are a hand full of Canon lenses that are not going to perform worth a hoot - just as their a hand full of third party glass that out performs the canon/nikon equivelant. But after those exceptions - I feel there is enough reportage on the lack of performance of third party.

My Sigma lens performed great for me while I was unaware that I could be getting much better images more consistently with the right tool; same can be said about the 50 1.8. But not once for any moment did I feel that either of those two lens were good enough to never replace.

I agree with you though Don, Third party needs to start stepping up their game a bit - I was so close so many times in purchasing an Tamron 28-75. I wanted to buy it, a few times it was as good as ordered - I could never pull the trigger on the purchase - Why, I knew I wanted something that focused faster and more accurate in the less than stellar shooting environments, because I knew I most often find myself shooting in those conditions. I wanted a lens that wasn't going to restrict when and where I could take photos like I have read that the Tamron does. I wanted something that would perform excellent when paired with a flash. I wanted something that would be compatible with my next Canon DSLR - the Tamron/Sigma lens would most likely need to be shipped back to them so they can rechip it if I were to upgrade cameras in the future. . . Those reasons are enough for me. . . I am in no way saying they should be enough for everyone. I am also in no way insulting those photographers who use the third party lens. Simply stating why I choose and will continue to choose Canon lens for my Canon bodies. . ;)

Bluedog
04-03-2006, 05:36 PM
I have to agree with Jamie _ the one Sigma I had was a very frustrating experience. I do have a Tamron that is accurate at focusing and sharp but most likely since my last three purchases have been Canon I'll probably stay that way from now on.