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Old May 3, 2005, 8:55 AM   #11
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peripatetic wrote:
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Can you really get sharp hand-held images @300mm & 1/100s?

Impressive!!

Go on - put up a picture of the beast next to the camera & the point will be clear I think.
Some folks can do it very well indeed: aaltenburger wrote: "I tried to go as low as 1/30 sec for panning, but didn't have any success. I got the desired blurr between 1/90 and 1/180. Still had a ton of OOF shots, but I'm still learning." - http://www.stevesforums.com/forums/v...c.php?id=32296



How about this shallow (i.e. no more background!):

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Old May 3, 2005, 8:57 AM   #12
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Thanks NHL and Peripatetic,

I've been doing quite a bit of thinking about the pictures I will be taking. Most will be landscape and birds around my feeders in my backyard and at the local bird sanctuary. The weight of the lens will be an issue because I do a lot of hiking and mountain biking in the Rockies. Carrying the extra weight of a large lens and tripod might be too much for a long day. I'm going to look at the DO tomorrowafter work.

//jim
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Old May 3, 2005, 9:11 AM   #13
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Touche on the DOF, but that's 2.8 not f4 v f5.6. :-)

About the Image Stabiliser though: I have the 2 lenses with 3rd gen Canon IS. The 17-85 & the DO.

Frankly on the 17-85 I can take it or leave it, it's really not that useful to me in the real world. In fact I switched it off to save batteries and didn't notice for a week! :-? You'll get no argument from me that at these focal lengths a faster lens is ever so much better. I got the 28mm f1.8 USM and I think I'm going to use my 17-85 a lot less from now on. That will be the lens that sits on the camera most of the time.

The IS on the DO though is amazing; half-depress the shutter for a second and a very wobbly picture just turns rock-solid. The general rule-of-thumb is 1/effective focal length. So at 300mmx1.6=480mm you should be trying for 1/500s. Now I know many people can handhold 1 stop faster than the ROT, and some even 2 stops, but it's pretty unusual. I can normally get 1/2 stop better than ROT if I concentrate but so far I'm a big fan of IS on long lenses.

I guess I'd say that a lot of the time 1/125s is enought to freeze motion (not for small birds, or even monkeys perhaps) but certainly for larger critters. And at 500mm effective that's 2 stops below ROT - which for me is where IS shows its benefits, if Sigma fitted their OS to the 100-300 lens it would clean the floor with everything else. As you point out - it does that optically already.

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Old May 3, 2005, 9:35 AM   #14
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peripatetic

This is @ f/4 - Again the background is blended away:




The desirable 'Bokeh' is the MAIN reason I opt for a fast lens, and not for its ability in the dark - I have said it many times and will repeat once more: Photography is all about lighting, it's what make a picture a snapshot vs a wall hanger.

People also overstate the need for tripod. You don't need a tripod unless you're shooting in the dark with is what IS allow you to do, but by then you're already into poor lighting!!!

Check EV-10 = http://home.earthlink.net/~terryleed...s.htm#lowlight
-> The truth is @ f/4 you can shoot from sunrise to sunset too by just bumping the ISO to 200-400 without the need of any support.
You can't bump an f/5.6 into f/4 (or f/2.8 ) for the 'Bokeh', people pay a fortune for this ability because it's this 'Bokeh' that makes an image special
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Old May 3, 2005, 10:28 AM   #15
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In which case you can do the same thing at f5.6 by going to ISO400-800.

Also unless I'm very much mistaken at 300mm focal length, even on APS sized sensor the difference in DOF between f4 & f5.6 is very small.

That's what my DOF calculator says anyway, in the photo above you might have an extra few inches or so either way, but it would made no obvious difference to the shot you posted above.

http://www.dofmaster.com/dofjs.html

At 5 meters from the subject on 20D with 300mm actual focal length:

f5.6
near limit 4.97 m, far limit 5.03 m

f4.0
near limit 4.98m, far limit 5.02m

f2.8
near limit 4.99m, far limit 5.01m

Even at 50m the DOF only differs from 6m @f5.6 to 4m @f4

I fear I'm missing your point.
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Old May 3, 2005, 1:27 PM   #16
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peripatetic wrote:
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I fear I'm missing your point.
I think so - You're talking about DOF and I'm talking about 'Bokeh' which is not necessarily the same thing, correct?
(i.e. "in-focus" vs "out-of-focus") - http://www.kenrockwell.com/tech/bokeh.htm


... otherwise all lenses are equals given the same parameters - which clearly they are not!
"The 200 lens opened up to F2.8 gave me the smooth bokeh I know and love but that is not possible with the slower lenses." - http://www.photo.net/equipment/canon/70-300do_2/
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Old May 3, 2005, 3:44 PM   #17
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Yes, you're quite right, not the same thing, but related.

If it's all in focus you've got no bokeh to worry about.

However I'm still not sure whether you're claiming that the bokeh is always better on a wider aperture lens or something else, for example that the bokeh on Sigma telezoom lenses is particularly good.

Different lenses at the same aperture give different qualitative bokeh. It is possible to get broad agreement on what is obviously good and obviously bad, but many lenses fall somewhere between and the DO in particular seems to have a particular quality that some like (I do - and I checked sample photos before I bought) and some don't. So there is some room for subjective preference.

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