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Old Jun 11, 2005, 7:42 PM   #11
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the lenses you have listed are JUNK

for your 'long' goat shots:

minolta AF reflex 500mm f8 ( 35mm equivusing 7D is 750mm f8 )

RAZOR SHARP AND EXCELLENT AUTOFOCUS

use iso 400 for lowest noise !

$559 brand new at B&H Photo

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Old Jun 13, 2005, 2:55 PM   #12
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JimC, I did get some feed back from the Canon and Nikon, they did have some good information. Awaiting your word on the Sigma. I will be placing an order for one lens or another here ASAP in order to get it in time to take up to the Canadian Rockies on vacation!
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Old Jun 13, 2005, 3:51 PM   #13
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Well, I did some more digging, and did find multiple 7D users with the Sigma 18-125 f/3.5-5.6 DC lens.

Reports of how well it works at wider focal lengths are mixed. About half the 7D users of this lens are reporting some backfocus or softness at the 18mm end, with more than one user indicating backfocus problems using the center AF point until getting to around 35mm with it.

Some users are reporting no focus problems at wider focal lengths, and I found one user reporting that a second copy of this lens workedmuch better (apparently, there is some QC variation between samples that may be more critical on the 7D).

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Old Jun 13, 2005, 4:56 PM   #14
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JimC wrote:
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Well, I did some more digging, and did find multiple 7D users with the Sigma 18-125 f/3.5-5.6 DC lens.

Reports of how well it works at wider focal lengths are mixed. About half the 7D users of this lens are reporting some backfocus or softness at the 18mm end, with more than one user indicating backfocus problems using the center AF point until getting to around 35mm with it.

Some users are reporting no focus problems at wider focal lengths, and I found one user reporting that a second copy of this lens workedmuch better (apparently, there is some QC variation between samples that may be more critical on the 7D).
Well, unfortunately, it is the wider angles that I will be using it most for. I have read similar problems with the Sigma 18-50, and had read that the 18-125 was better, but perhaps it isn't. Then I read that the Vivitar 19-35 is an excellent lens, and then I read from a couple of Canon users that they are junk. I suppose that is to be expected. The backfocus of the Sigma's is something I could work around by using manual focus, but for the cost of the 18-125, that is a lot to spend for a lens I have to tweak all the time. I may end up getting a used Vivitar 19-35 or Promaster 19-35 from B&H. Very cheap and if it isn't any good, I can save up for something better. Thanks for all your help, Jim. -Dick Lane
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Old Jun 13, 2005, 5:12 PM   #15
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You may want to give the Sigmaa try (as some users were reporting no problems with it). B&H would be a good place, because of their more liberal return policy compared to some dealers. You could try it for a day or two, and if it doesn't work as expected, you could send it right back.

As for the Vivitar 17-35, most comments I found from Maxxum film camera users said that this particular lens was worth the money (with a few gripesthat may not be a factor on a digital camera with a crop factor, since the lens was design for 35 film requiring a larger image circle).

If you've got a dealer nearby that has these lenses in stock, I'd bring your camera down to 'em and see if they'd let youtry 'em at different focal lengths, focus distances and apertures to see how they work.

Then, compare the photos before making a decision. If you're going to be using 'em in better light, there may not be much of a difference between these lenses with the aperture stopped down some.


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Old Jun 18, 2005, 8:28 PM   #16
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Got the Sigma 18-50 3.5-5.6. Backfocus is awful.
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Old Jun 22, 2005, 6:42 PM   #17
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Got replacement for Sigma 18-50 3.5-5.6. Backfocus just as bad.

I do not see backfocus with my 28-80 or 70-300 Quantarays.

Now what?
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Old Jun 23, 2005, 7:32 AM   #18
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I'd takeyour camera down to a store and try some different lenses, including a KM lens starting out this wide.

If other lenses this wide don't work, perhaps the body is the problem (it may needcalibration by KM).

Are you sure it's backfocusing (i.e., you have focus lock on your subject and your subject is not in focus, but what is behindyour subjectis in focus)?




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Old Jun 23, 2005, 8:01 AM   #19
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Jim, yes, I am pretty sure it is backfocus. I focus on an object and it comes out blurred, while the object behind it is sharp. I switch to manual focus and am able to get a sharper picture of the object. I have plans to go to a camera shop this afternoon and try a few different lenses, as you suggested. Perhaps it is the lens, not the camera. I know that I have no problems with my Quantaray 28-80 at 28mm or 70-300. Of course, on the Sigma 18-50 3.4-5.6, it seems ok at 28 as well. It is the 18-28 ranges that shows the most problems with BF.

I leave for vacaction in 10 days, I hope I can get SOMETHING to use for wide angle. Obviously I will not have time to send in the camera for repairs if it turns out to be the camera.
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Old Jun 23, 2005, 8:13 PM   #20
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Took my 7D to Wolf Camera's main shop here in Dallas this evening, along with the Sigma 18-50 3.5-5.6 which has given me so much trouble. After extensive testing, where the gurus there put the 7D on a tripod, used their own macro lens (Minolta) as well as a Quantaray 19-35, and my Sigma, test results seem to indicate it is the lens, not the camera. (Details available if anyone is interested). So, after getting TWO of the Sigmas from B&H, I am now going to get another. Surely THREE of them won't be bad.
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