distance scale

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Mike - 28 Mar 2007 02:45 GMT

Hi,
I new with dslr , just bought Canon Rebel 400 and couple lens.
Why EFS 17-85 IS contains distance scale window but EF 70-300 IS does
not?

Thanks,
Mike

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Paul Furman - 28 Mar 2007 03:23 GMT

> Hi,
> I new with dslr , just bought Canon Rebel 400 and couple lens.
> Why EFS 17-85 IS contains distance scale window but EF 70-300 IS does
> not?

Newer lenses tend to leave that out in most brands, probably because
autofocus is the new game for quite a while. Another problem is those
usually came with DOF & hyperfocal markings and those are incorrect on
crop frame DSLRs.

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Scott W - 28 Mar 2007 04:51 GMT

> > Hi,
> > I new with dslr , just bought Canon Rebel 400 and couple lens.
[quoted text clipped - 5 lines]
> usually came with DOF & hyperfocal markings and those are incorrect on
> crop frame DSLRs.

The DOF marking work fairly well if you use the markings about on f
stop faster then what you are actually shooting. For example if you
are shooting at f/5.6 you would use the DOF marking for f/4. Of
course the marking for the focal point does not change, just the DOF.

Scott

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Wolfgang Weisselberg - 28 Mar 2007 19:48 GMT

> I new with dslr , just bought Canon Rebel 400 and couple lens.
> Why EFS 17-85 IS contains distance scale window but EF 70-300 IS does
> not?

Price, distinguishing more expensive lenses from cheap(er) ones,
usually not needed for 'consumer' lenses.

-Wolfgang

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Matt Clara - 29 Mar 2007 00:29 GMT

> Hi,
> I new with dslr , just bought Canon Rebel 400 and couple lens.
[quoted text clipped - 3 lines]
> Thanks,
> Mike

Distance scales used to be the standard--now they're the luxury. Plus, it's
difficult to accurately represent distance scale over a variable aperture
zoom.

--
www.mattclara.com

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David J Taylor - 29 Mar 2007 08:05 GMT

>> Hi,
>> I new with dslr , just bought Canon Rebel 400 and couple lens.
[quoted text clipped - 7 lines]
> it's difficult to accurately represent distance scale over a
> variable aperture zoom.

Why is it difficult for a variable (maximum) aperture? Do you actually
mean a zoom where the focus does not stay the same as the lens is zoomed?

David

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