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A-DEP focussing on the 10D

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Hi � My first question on this forum so please be gentle! A very

specific question on the A-DEP mode used in the canon eos 10d which I

am thinking of buying�.


There are a few articles on the net on the differences between A-DEP

and DEP modes (the latter I use pretty frequently on my current eos

50E). There are also a few articles on this forum but none seem to

address my point exactly.


I understand that A-DEP requires some framing luck to work properly

as it is a one-step process and not a 3 step process. However,

assuming that you are able to frame your near and far points to cover

at least 2 of the 7 focussing points, does the camera then focus ~

2/3 of the way from the distant to the near point (ie. hyperfocal

distance) and then set the minimum aperture needed; OR does it use a

less sophisticated focus setting rule before setting the minimum



Also do you get the opportunity to see the chosen aperture value and

thus set focus to manual (ie. Fix it) and then put the camera in AP

mode to increase or decrease the DOF knowing the at the lens remains

focussed at the correct distance between your near and far points?




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IMHO, if you have a digital camera, about a week of experimenting with it (using the instant feedback) gives you enough 'feel', to use MF, and aperture priority so that you can outperform A-DEP. Again, thats just my opinion. I think it is more work and time-consuming to learn every inch of all the automation then it is to learn to use shutter and aperture, and once those two are understood thouroughly, it's much easier to understand & use the automated modes.


Anyhow, that doesnt really help you and doesnt answer any of your questions, but just a thought.

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The ~2/3 distance is a less sophisticated "rule of thumb"! Actually what it uses (I assume) is the same algorithm used in all other EOS bodies with a DEP or A-DEP mode, which puts the focus point 7/17 ths of the way from the near to the far point. 7/17 is Canon's best guess of the split for subjects at "normal" distances, i.e. not closeup macro shots and not "everything including infinity" shots.


No Canon body does an actual detailed DOF calculation, they just use the 7/17 estimate.


The aperature and shutter speed information is displayed, so you can copy those setting to manual mode if you wish.


Here's a link to my website and a <a href="http://bobatkins.com/photography/eosfaq/eosfaq24/9miscellany.html#q27">more complete explanation</a>


And of course...if you do buy a 10D, please think about doing so using one of the vendors that support photo.net. If you use their links from the <a href="/">home page</a> photo.net gets a small credit which helps to keep this site running. Thanks.

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