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Old Jan 5, 2005, 9:46 AM   #1
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I am about to buy a 20D (first digital SLR) but am confused about how important the speed of the lense is in the digital world.

At 4.5-5.6 this would be pretty slow in the film world. Is lens speed less important for 'digital light'?
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Old Jan 5, 2005, 10:00 AM   #2
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DFWJ wrote:
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I am about to buy a 20D (first digital SLR) but am confused about how important the speed of the lense is in the digital world.

At 4.5-5.6 this would be pretty slow in the film world. Is lens speed less important for 'digital light'?
Why would a lens be slower or faster in digital world? Lens is a lens.Maybe I am missing something.


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Old Jan 5, 2005, 10:06 AM   #3
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That's my thinking. However, I have not seen speed referred to in any reviews of these nifty new digital-specific lenses.

My guess is that flexibility of 'film speed' without removing the film in DSLRs makes the problem less significant from a convenience point of view.

Just can't find anything much about lenses or recommendations that take speed and depth of field characteristics into account. Just general comments about buying Canon or Nikon 'quality'.

David.
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Old Jan 5, 2005, 10:26 AM   #4
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IMO lens speed is not very critical at the wide angle end since most objects will be cover by the large DOF anyway unless you're doing a lot sunrise/sunset landscapes.

Faster lenses are quite critical at the tele range where they'll 'buy' you the shutter speeds... on late afternoons or cloudy days quite often one has to shoot at high ISO to catch far away wildlifes at reasonable shutter speeds - the faster the lens the more shutter speeds are available... (@ least 1/200 to 1/600s for 200/600 teles)

There's another benefit to faster lens: The 20D high-precision AF kicks in at f/2.8 or larger -> which is very critical when the DOF get thinner, and then there's the better 'Bokeh'
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Old Jan 8, 2005, 12:13 AM   #5
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Thanks NHL.

I love the 17-85 focal length for general coverage, but feel, as a walk around for people and kids etc it will be too slow.

Am considering the EF 24-70 f/2.8L USM. It has no IS, but at 70 (112) max length would seem not to be a problem hand held. Very expensive though!

Only regret is that it stops a bit short of the full 135 range.

How do you think this lens would go with a TC? Aperture would be down to 5.6. Do you reckon this would be a problem hand held without IS?
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Old Jan 8, 2005, 7:15 AM   #6
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DFWJ wrote:
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Am considering the EF 24-70 f/2.8L USM. It has no IS, but at 70 (112) max length would seem not to be a problem hand held. Very expensive though!
IMO it all depends on how confident you are @ stepping out from the Canon "maketing machine" - http://www.pbase.com/fstopjojo/sigma_2470

I could have bought any 'L' zoom with IS - Instead I paid more for the Sigma 120-300 f/2.8 since I was very satisfied with their 70-200 f/2.8 EX (among other very nice macros and WA) - I do own other Canon lenses though...

The Sigma EF500DG Super flash too beats the limited 420EX hands down for the same price, but folks just keep buying the Canon's because they are turned away by all this 'imcompatibility' hype. I bought a 550EX at first, but then end up with two additional Sigma EF500DG Super for remote Slaves (and they recycle quicker too!)




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How do you think this lens would go with a TC? Aperture would be down to 5.6. Do you reckon this would be a problem hand held without IS?
The Canon TC would not fit this lens I believe
... so you have to get a generic teleconverter here, but if you close the lens down several stop it should be usable. IMO shop in the 70-200 f/2.8 range since you are already covered by the 17-85mm kit - Other folks use this lens for outdoor portraits (people/kids) because of the 'bokeh' @ f/2.8. The Sigma EX have the HSM which is also ultrasonic (fast quiet and with full-time manual AF overide).
FYI - http://www.stevesforums.com/forums/v...48&forum_id=65

You already know what I think about IS on action, especially with kids running around... :G
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Old Jan 8, 2005, 8:54 AM   #7
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NHL

You're a mine of information.

I've got cold feet regarding the 17-85.

Have been used to 3.5 constant 70-210 on my film SLR and see the 4-5.6 on the 17-85 and think late evening etc not feasible.

On the other hand, still in yet-to-buy mode, I presume that the 20D's low noise capabilities would allow increasing ISO settings to compensate for lack of large apertures on the 17-85 without too much comopromise in quality?:?
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Old Jan 8, 2005, 9:29 AM   #8
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Correct!

You should also consider the new Minolta 7D if you did not buy in any 'system' yet... If you're into IS it's pretty much a no brainer! - http://www.stevesforums.com/forums/v...56&forum_id=87

... Contrary to what Steve's said, according to other users the 7D capability at high ISO is pretty amazing not unlike the 20D
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Old Jan 8, 2005, 4:44 PM   #9
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DFWJ wrote:
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... I presume that the 20D's low noise capabilities would allow increasing ISO settings to compensate for lack of large apertures on the 17-85 without too much comopromise in quality?:?
I've been absolutely amazed at the images I'm able to get out my 20D using ISO 3200 and Neat Image....

I shot this last night and printed a 13X19 today... all i can say is it's amazing.


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Old Jan 8, 2005, 6:14 PM   #10
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DFWJ, just as an FYI, the 17-85 kit lens for the 20D has been discussed here on Steve's prior to this thread. You might want to check out this thread:

http://www.stevesforums.com/forums/v...mp;forum_id=65

ps: I own the 17-85 lens and I find it adequate in many darker conditions and superlative in a range of other conditions. It doesn't have to be an L lens before I'll be satisfied. It depends much on what you shoot.
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