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[OM] Re: Unexpected photo opportunity - bugs

Subject: [OM] Re: Unexpected photo opportunity - bugs
From: Chuck Norcutt <chucknorcutt@xxxxxxxxxxx>
Date: Sun, 06 Aug 2006 13:50:12 -0400
Sorry, I meant to refer to the image named Flower_Flow.jpg and the link 
I provided doesn't get you fully there.  It's the next to the last image 
in the index on the left.

I guess I should also have defined hyperfocal distance.  When a lens is 
focused at its hyperfocal distance everything from half of that distance 
to infinity is in focus.

For example, if Flower_Flow.jpg was taken at the 14mm end of the 14-54 
and the aperture was f/16 the hyperfocal distance would be only 0.75 
meters.  That means everything from 0.75/2 = 0.37 meters to infinity 
would be in focus sharp enough to make a good 8x10 print.   At the 
telephoto end it's still pretty impressive.  The hyperfocal distance at 
54mm and f/16 is 11 meters which will yield everything in good focus 
from 5.5 meters to infinity.  But to give this effect you need to focus 
at the hypefocal distance.  If instead of focusing at 11 meters you 
focused at 5.5 meters the near distance would move in to 3.25 meters and 
the far distance would collapse from infinity all the way down to 17.5 
meters.

This notion of hyperfocal distance and *near* hypefocal distance can 
come in quite handy at times.  Say you're at a party in someone's house 
and it's fairly dark.  The camera can take a shot OK since you're using 
your flash.  But neither you nor the camera can see very well to focus. 
  If you zoom wide to 14mm and open up to f/4 you'll find that the 
hypefocal distance is still only 3 meters.  Turn the camera to manual 
focus and find some bright object about 3 meters away and focus on it. 
Now everything from 1.5 meters to infinity is in focus.  But since 
you're in a house going all the way to inifinity is a waste.  If you set 
the lens at 2 meters instead of 3 meters you'll get everything from 1.2 
meters to 6.2 meters in focus.  If that's a little too short for a big 
room try focusing at 2.5 meters which will get you everything from 1.25 
meters to 16.2 meters.  Once set you can simply leave the lens at that 
distance and shoot all night long in the dark without worrying about focus.

Chuck Norcutt

Chuck Norcutt wrote:
> I like this shot <http://timrandles.fotopic.net/c1016039.html> but I 
> think it would have been better to have the foreground flowers in focus 
> in preference to the background or maybe even both although I'm not sure 
> of that.  Trying to keep both in focus would dictate using a small 
> aperture such as f/16 or f/22.  Optimizing the depth of field might have 
> required using manual focus.  At f/16 or f/22 focusing just beyond the 
> flowers might keep both foreground and background in focus.  Depends on 
> the focal length you were using.  Time to learn about hyperfocal distance.
> 
> Chuck Norcutt
> 
> Tim Randles wrote:
> 
> 
>>Thanks for that explanation Martyn,
>>
>> I thought it would change the focal length. I'm brand new to DSLR and SLR, 
>> so every little bit of explanation helps. I filed this answer for later 
>> review.
>>
>>Unfortunately I didnt get underground, my duties kept me on the airstrip 
>>stacking barrells, but I did manage to get a couple funky shots there too.
>>
>>http://timrandles.fotopic.net/c1016039.html
>>http://timrandles.fotopic.net/c1016039.html ( too bad for the glare in the 
>>middle)
>>
>>These are untouched, unedited
>>
>>I'm still trying to figure out the software on fotopic to get the site to do 
>>what I would like..
> 
> 
> 
> 
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