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Old Mar 26, 2008, 9:05 PM   #1
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I don't seem to have any problem shooting with the 500 until it comes to distance shots. Does focusing accuracy and sharpness drop off on the long distance shots?

Thanks

Jim

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Old Mar 26, 2008, 9:05 PM   #2
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crop

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Old Mar 26, 2008, 11:50 PM   #3
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can u also post the exif details....



this is hundred % crop with the 500L and 1.4X ...it was really far tooo...



this one is 100% too...

I just think the low shutter speed could be an issue...







and a similar shot lke urs but with the 70-200 lens


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Old Mar 27, 2008, 6:02 AM   #4
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In a word, yes!! As a camera reaches infinity the focus is less accurate and you will generally find images softer. This something I've experienced with all lenses and on all the different cameras I've used. When trying to shot something a long way out then stopping down can help but it's still not an ideal situation.
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Old Mar 27, 2008, 4:41 PM   #5
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Mark1616 wrote:
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In a word, yes!! As a camera reaches infinity the focus is less accurate and you will generally find images softer.
This is also a reason why the common misconception that a smaller image sensor "Gives you more reach" is incorrect. It really doesn't. What it does do is put more pixels on your image at a given focal length. The softness is as much a part of the lens limitations as the cameras. So, a lens that gets soft at 50 yards on a 5d isn't going to give sharper images at 75 yards on a 1.6 crop sensor. But, what will happen is that at 50 yards you'll get more pixels on your subject so you'll have more detail on a subject 50 yards out.
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Old Mar 27, 2008, 8:05 PM   #6
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killdeer0007 wrote:
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I don't seem to have any problem shooting with the 500 until it comes to distance shots. Does focusing accuracy and sharpness drop off on the long distance shots?
Absolutely not!!!
-> IMO you have a misfocus (i.e. the lens can focus past infinity)

This is a cropped shot also far out from the 500mm @ f/4:








A teleconverter also softens the lens especially a 2x so do close down the aperture a bit

This one is probably way too far out @ f/5.6 (wide open) with a x1.4 teleconverter (and low-light):


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Old Mar 28, 2008, 9:42 AM   #7
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Thanks everyone for your input.

I should have mentioned that I took the pictures at F 5.6. I'm going to experiment today with different apertures with and without the extender.

One last question - is it a lens or camera issue?

Jim
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Old Mar 28, 2008, 10:37 AM   #8
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In general its asking too much from the sensor..at 100% except if u fill the whole sensor with ur subject its going to be tough to ask for a clear image at 100%.

The current bird picture is about 10% of the actual sensor size and its not easy to get the same effect as 90% of sensor coverage.

also ur picture is a bit out of focus. Try increasing the contrast too. And keep the shutter speed over 250-300
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Old Mar 30, 2008, 5:56 AM   #9
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killdeer0007 wrote:
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One last question - is it a lens or camera issue?
I would think neither if you don't have problem at shorter distances...
The AF mechanism should work the same regardless of the distance - If the AF has any front or back AF offset at all then it would have maintained this error throughout the focusing range. Make sense right otherwise why have the fine-tuning AF feature at all if it changes when you vary the focusing distances?

-> IMO it could be one of two things:
1. The subject might be too small in which case the AF sensor area may straddle both the subject and the sky and the camera would pick the background (or sky) instead
2. When you're not in single-shot AF, the AI-servo may dither the AF back and forth on the subject to anticipate movements and you may have some shots front and back focus if you don't happen to press the shutter at the right time or squeeze out a series and pick the best AF
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Old Apr 3, 2008, 6:52 PM   #10
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Thanks everyone for your help. After talking with the service department, I've decided to take the lens and body in for a check-up. I'll let you know the results.

Jim
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