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05-05-2009, 09:51 AM   #1
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Blur possible at 1/3000th?

I was test shooting a 500mm Tamron the otherday in poor conditions. Nevertheless, I cranked the shutter to 1/3000th and was surprised to see blur

I understand you can get any speed to blur if you tried, but I was shooting this normally. Panning slowly to follow the relatively slow commercial jet, hand propped on a window sill. Focus is OK, as evident in the 100% crop. Other images obtained at 1/180, 1/500 were sharper than this.

Any input?

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05-05-2009, 09:55 AM   #2
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did you wait for the SR icon to go on?

and honestly that just looks out of focus more than motion blurred.

and were you shooting through a window?
05-05-2009, 10:18 AM   #3
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Looks like focus error plus shake to me. You can see the shift of the text, cockpit and tail, all in the same direction in the middle of frame (focus tends to do shifts in all dirrections from center). On the other hand i've heard that speeds like this is when you actually need a mirror lockup.

Like if the main virbation after the slap travels trough camera body in 1/2000s, then the camera would be "shaking" during whole 1/3000 exposure time whereas with 1/180s exposure you'd exposed much longer so the shake would make up an invisible fraction of the exposure. At this focal lenght it may become apparent.
Have you done any other testing of this blur other than this shot. If not it could be anything.

I see no focal length (=0mm) in exif but aperture is shown. Can this fool the SR?
05-05-2009, 10:27 AM   #4
Damn Brit
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With a long lens, blur is possible at any speed. the sheer length of the lens magnifies any shake.
Don't forget also that you were photographing a moving object.

05-05-2009, 10:40 AM   #5
edl
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QuoteOriginally posted by boom Quote
Panning slowly to follow the relatively slow commercial jet, hand propped on a window sill. Focus is OK, as evident in the 100% crop. Other images obtained at 1/180, 1/500 were sharper than this.

Any input?
If you were using 1/3000, there's no need to pan.

I would also input the lens length into the camera upon startup so it could adjust accordingly.

I bet a sturdy tripod and no panning would eliminate your blur issue.
05-05-2009, 10:41 AM   #6
edl
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QuoteOriginally posted by boom Quote
Other images obtained at 1/180, 1/500 were sharper than this.
Perhaps because you stopped down the lens at 1/180 or 1/500 (increasing lens performance) compared to being at a larger aperture at 1/3000?
05-05-2009, 10:42 AM   #7
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Hi guys,

I'm fairly confident SR was turned off, as I knew I was going to be panning. I was shooting on a window ledge, but the window was open.

The softness I attribute to a combination of focus error, mirror lens, and atmospheric perturbance. That, I'm not worried about. The conditions weren't ideal and I accept that. I'm just confused by the motion blur. Interesting theory on the fast shutter/MLU, what I did notice, is this lens is so light that shutter release will shake the camera as well.

Focal length should be 500mm, I probably didn't enter FL information on the camera that time. More the reason I don't think SR was on.

One other thing, this lens is fixed at F/8. I'm not sure where the camera is pulling F/4 from, and I doubt I can input that.
05-05-2009, 10:50 AM   #8
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Thanks for all the feedback guys.

Just want to clarify that this is a 500mm F8 reflex. It's a dumb lens so the only variable is the shutter and focus.

Here's one of the better ones taken at 1/500. Weather here has been dismal.

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05-05-2009, 01:54 PM   #9
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500mm reflex is iffy even on a good day.

Cheers. Mike.
05-05-2009, 02:18 PM   #10
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QuoteOriginally posted by Ex Finn. Quote
500mm reflex is iffy even on a good day.

Cheers. Mike.
I guess that did not help much.
Looks like out of focus and just the way a reflex can look.

Cheers. Mike.
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