Tips from a seminar | Shutterbug

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Submitted By: ronk

Location: Quensbury, NY

Joined: Mar 15 2005

Posts:

Tips from a seminar

Posted: May 30, 2005 - 5:49am

the presenter suggested several ways in which to improve one's pictures:
1- use only the center focusing spot- it is more accurate than multispot
2- Constant aperture, faster glass will focus faster because more light gets to the focusing sensor
3-dof is greater will smaller sensor size digital cameras, so the wider apertures of faster glass will enable the photog. to control dof better.

The third is true from my observations, but has any one tested or know of a trest to confirm the first 2 statements; both make sense to me.

Submitted By: prof_fate

Location: beaver, pa

Joined: May 27 2005

Posts:

Re: Tips from a seminar

Posted: June 9, 2005 - 8:32pm

2 and 3 are true.
1 is sometimes true.
Once the lowest fstop starts climbing focusing get more difficult. so much so that Canon says 5.6 is the max that AF will work, except on 1D cameras then 6.3 is max, but from 5.6 on you can only use the center focus spot. This is usually only an issue if you use a teleconverter/extender. a 1.4x will cost you one stop of light, so if you ahve a 70-300 4-5.6 lens and add the 1.4X, you lose AF at the 300mm setting as the total minumum fstop goes to f8.