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Old Jan 2, 2005, 10:35 AM   #1
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hi all,

I've just gota 300D and used it with my old Tamron ( EF compatible )28-200mm ( 3.8 - 5.6 ) and found that when doing full zoom, the pictures turn out rather soft / not sharp ( not out of focus ).

Pictures taken with the kit lense looks fine and sharp.

I know that the default for the 300D not to sharpen the image but is there a method to improve the sharpness of images with this tamron lense.

Is the "softness"caused by the aperture too small at 200mm ( f5.6 ) ??

Is the reading 3.8 - 5.6 the aperture of the lense at 28mm- 200mm?

I reada lot of replies from canon DSLR forums something about doing full zoom at 200mm is not a good idea in the 300D. ( not idea why )

Andalso a lot of people recommend to use the canon 35-135 USM/IS lense. I mean the camera was suppose to be compatible with EF lense. For those people that purchase the 35-135 USM/IS lense, are those new Canon SLR users or people are selling off their 28-200 or 300mm for a smaller zoom at 135mm ??





Thanks



Stanley




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Old Jan 2, 2005, 10:59 AM   #2
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A lot of lenses have sweet spots that are somewhere in the middle of the zoom range, and that area is the sharpest you will get with that lens. Another reason is when you use a extreme zoom like that 28-200 or 28-300, you'll find that the extremes will be kind of soft. It could also be that it is a low quality lens, check out http://www.photozone.de/2Equipment/easytxt.htm#Zstd and find your lens there.
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Old Jan 2, 2005, 2:39 PM   #3
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You might want to consider the Tokina AT-X 24-200mm lens. If you're looking for a good walk-around zoom that has a long range, takes sharp photos, is built with lots of metal (like a tank), and can be bought at a bargain price, it may be the lens to suit your needs. It isn't "L" quality, but only "L" series lenses can make that claim. I've found many more positive remarks from users of this lens, than negative. I am one of the postive users. I have the Canon 18-55mm kit lens, and the Sigma 18-125mm lens (among others), it outperforms both of these lenses. With this lens I can travel much lighter, and leave my gadget bag behind a lot more.
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Old Jan 3, 2005, 7:11 PM   #4
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I had this same problem when I first started shooting with the drebel and the Canon 55-200 lens. I was getting really soft shots when I had the lens set at 200MM f5.6. However,remembering the 1.6 magnification factor, I set my camera to 135mm which equals a little over 200MM actual and increased shutter speed to 200-250 and aperture toF8 and got noticably sharper shots. However, to do this I needed much more light. I picked up a set of Alien Bees (AB800) studio strobes and breathed new life into my otherwise cheap lens. The Canon low end lens can not shoot at their extremes so I would suspect the tamron can't either. But I bet you main problem is 1.6 mag factor, at 200MM you are really at 320MM on a Digital Rebel.


PS

I have learned the hard way that although I can sometimesget great photos with my current lens it is sparatic. I will be upgrading to a 17-40 F4L and 70-200F4L to get more consistently great shots. I have also learned to stay away from variable aperture lenses.

This was shot with 300D, canon 55-200, and two AB800's.

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Old Jan 4, 2005, 2:22 AM   #5
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Dear all,

Thanks for the replies...

I think now I understand why those images were soft...

- too much zoom ( 1.6 X 200mm )

- aperture too small @ f5.6

- not enough lights into the CMOS

- low quality lense

What is the special "L" on the Canon lense means. ??



Stanley




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Old Jan 4, 2005, 4:17 PM   #6
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Quote:
What is the special "L" on the Canon lense means
I was told the "L" stands for Luxury as the are Luxury lenses with a Luxurious price..

I just got off the phone with Canon Technical Support. I was trying to get definitive answers to which would give me better images upgrading my digital rebel to the Canon 20D (8-megapixals) or upgrading 18-55 and 55-200 lenses to 17-40L and 70-200L. They confirmed the latter, L -series glass will give a greater impovement in image quality over a better camera.
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Old Jan 7, 2005, 1:43 PM   #7
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Dumb question perhaps: Did you use a tripod / very fast shutter speed?

What happens at large magnifications is that the camera / lens movement is also magnified. So what you may think is unsharpness might actually be a slight image blur. The general rule of thumb is 1/focal length should be the minimum shutter speed. Adding the 1.6x crop factor post-processing magnification, you might need to shoot at around 1/500'th of a second before you can rely on hand-held sharpness with a 200mm lens. At this point, however, unless you increase the ISO / have a lot of light, you might also have to use a wide aperture, which will limit the DoF / make focusing more critical, esp. so with objects that are close.

Bumping up the ISO to at least 400 and perhaps 800 with post-processing noise reduction, and usinghigh shutter speedswould be advised for sharper images at 200mm etc.

A tripod would be necessary for any critical sharpness evaluations.

Focus Magic is a good tool for correcting camera shake blurs after the fact -- it can help you recover some of your important images at the cost of the software itself and your time tweeking. Better to get the image right first of course, but when you can't..

Tamron 28-200's have changed over time, and the current one is regarded as one of the better consumer super zooms, but it is certainly not as good as even the budget L lenses, and isat its weakest at the focal length extreme.
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Old Jan 8, 2005, 1:18 AM   #8
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Quote:
What happens at large magnifications is that the camera / lens movement is also magnified. So what you may think is unsharpness might actually be a slight image blur.
his confirms one of the problems I was having with 55-200 which is equal to kit lens. It is variable aperture so past 100mm or so it switches to max f5.6 which oftens means dropping shutter speed. But I always kept iso at 100 for sharpness. Never tried 400 or 800, I went to studio strobes and powerful 580ex flash. Now I can get sharp pictures handheld at iso 100 @200mm (actual 135 -1.6). But outdoors I am going to adventure into the 400 iso range and chechout NeatImage for sharpness.
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Old Jan 11, 2005, 1:01 AM   #9
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I hope camera shake, as Madwand suggested, is the problem. Otherwise, what's the point of having a 24-200 mm zoom if you can't use it at 200 mm?



-Sci
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