Go Back   Steve's Digicams Forums > Digicam Help > Newbie Help

Reply
 
Thread Tools Search this Thread
Old Nov 21, 2008, 4:31 PM   #1
Senior Member
 
Join Date: Jul 2005
Posts: 774
Default

I've been taking portraits of my dog sitting on an old 1960's office chair. My D300 immediately realizes this is a portrait and AF on my dog's face every time. My camera was set to "Auto AF". So his face is always in focus. Everything around his face is blurred out. How much depending on my aperture setting. What if I want to get his entire body in focus (his head is at the left side of the frame his hind quarters to the right) without the chair also being in focus. Would that be possible? Or would upping (increasing the aperture #...decreasing the opening) the aperture just end up making everything in the frame in-focus?

Some one here did mention that I needed more distance between me and my dog. Something I didn't have the luxury of in this room. With more distance would that better my chances of getting my dog's entire body in focus (but not the rest of the area around his body)? Even though the camera auto AF's on his face? Would using "single-area AF" and placing the AF point on the middle of his body help?
DarkDTSHD is offline   Reply With Quote
Sponsored Links
Old Nov 21, 2008, 5:26 PM   #2
Senior Member
 
terry@softreq.com's Avatar
 
Join Date: Jun 2004
Posts: 2,539
Default

Anything is possible.

You could try setting a smaller aperture. For instance, if you took the shot
with an F/5.6 aperture, then try F8. The narrower aperture give you a little more depth of field.

To be exact, however, you could try "calculating" the depth of field using
a depth of field calculator:

http://www.dofmaster.com/dofjs.html

Then you can figure out exactly what aperture (for the given camera and lens) will give you exactly the depth of field your looking for.
terry@softreq.com is offline   Reply With Quote
Old Nov 21, 2008, 5:49 PM   #3
Senior Member
 
Join Date: Jul 2005
Posts: 774
Default

[email protected] wrote:
Quote:
Anything is possible.

You could try setting a smaller aperture. For instance, if you took the shot
with an F/5.6 aperture, then try F8. The narrower aperture give you a little more depth of field.

To be exact, however, you could try "calculating" the depth of field using
a depth of field calculator:

http://www.dofmaster.com/dofjs.html

Then you can figure out exactly what aperture (for the given camera and lens) will give you exactly the depth of field your looking for.
Thanks Boston. But as I asked...if I increased the aperture from 5.6 to 8 would the entire scene not be more in focus? I think so. What I'm trying to do is get my dog's entire body in focus with everything else in the frame slightly blurred. Wonder if that was possible.

Will take a look at the DOF calc link you provided. I think I toyed around with one not too long ago.

Regards
DarkDTSHD is offline   Reply With Quote
Old Nov 21, 2008, 5:55 PM   #4
Senior Member
 
terry@softreq.com's Avatar
 
Join Date: Jun 2004
Posts: 2,539
Default

It's hard to say what the effect of closing down the aperture by one stop might be.

It depends on the camera your using, how far you're away from your subject, and what lens focal length (mm) your at.

Perhaps by closing down one stop you might get an extra foot or two of depth of field - which sounds like what you want.

Consider just tinkering with it and see how you go.
terry@softreq.com is offline   Reply With Quote
Old Nov 21, 2008, 5:58 PM   #5
Moderator
 
Join Date: Aug 2004
Posts: 8,529
Default

short answer is 'no'. You're just not going to be able to get18 inchesof 'backward' dof (i.e. if face is the focal plane, roughly1.5 feet behind and1.5 feet in front) and magically cut it off an inch later. Typically for portrait work where you want the background slightly out of focus you would position your subject further from it. The DOF calculators won't be a whole lot of help - all they really tell you is how much will be in focus. You don't get complete blur right after that.
JohnG is offline   Reply With Quote
Old Nov 21, 2008, 6:12 PM   #6
Senior Member
 
Join Date: Jul 2005
Posts: 774
Default

Thanks for your input guys. But as I mentioned the set up is....dog laying on wood chair so that his head is at the left side of the frame and his hind quarters at the right. As if he is looking to the left side of the frame. What is happening is my D300 is auto AF on his face leaving everything around it slightly blurred. Trying to get his entire body in focus. Not just his head.

If his hind quarters were more at the rear of the chair and his head at the front then maybe that DOF converter might be of more use.

I'll keep experimenting of course. Just wondered. Maybe if you guys can see the photo I'm talking about...
Attached Images
 
DarkDTSHD is offline   Reply With Quote
Old Nov 21, 2008, 6:22 PM   #7
Senior Member
 
terry@softreq.com's Avatar
 
Join Date: Jun 2004
Posts: 2,539
Default

That's actually a pretty good shot.

Not sure what focal length (mm) and aperture your using.
terry@softreq.com is offline   Reply With Quote
Old Nov 21, 2008, 6:57 PM   #8
Senior Member
 
Join Date: Jul 2005
Posts: 774
Default

[email protected] wrote:
Quote:
That's actually a pretty good shot.

Not sure what focal length (mm) and aperture your using.
Focal length was 55 using my 17-55 and the aperture was set to 5.6. And thanks. This is one of my favorite photo's of him. Even if you can't see his eyes due to his position in relation to the natural light coming from the window and his hair. But If I could have got his entire body in focus...
DarkDTSHD is offline   Reply With Quote
Old Nov 21, 2008, 8:00 PM   #9
Senior Member
 
terry@softreq.com's Avatar
 
Join Date: Jun 2004
Posts: 2,539
Default

It depends how far back you were.

I would guess you were five feet away.

At that distance, F/5.6 at 55mm would have given you 6 inches depth of field.

F/8 would have given you about 9 inches depth of field.

F/11 would have given you 1.1 feet.

Not sure exactly how much depth of field you would have needed to keep the whole dog in focus.

Had you backed up to 10 feet away, F/5.6 would have given you 2.27 feet.

I doubt any photographer could have got the whole thing set up properly the vary first time and got the effect your looking for.

In hindsight, I suppose you could have "bracketed" the aperture, by taking a couple of shots of your dog at F4, F/5.6, F8 and F11 and see which one you liked the best!

Nice dog however, you got the option of taking lots more nice shots!
terry@softreq.com is offline   Reply With Quote
Old Nov 23, 2008, 5:55 PM   #10
Senior Member
 
Join Date: Jul 2006
Location: Tumbleweed, Arizona
Posts: 1,381
Default

There is a wealth of information on line, and one of my favorite sites has a number of photographic calculators (not that I go there all the time, but it has its uses).

Try http://www.dofmaster.com/dofjs.html

Using your numbers Canon 300D, 55mm, f5.6 at 5 feet you will get about 6 inches of depth. Increasing to f11 the dof enlarges to 1 foot. f16 grows the dof to 1.5 feet

Here is a sample of the calculator...

<well I tried to cut and past the output but - upon posting it was a mess...>

Built into the calculator is a lot of information explaining just what it is and how to use it .

Hope it helps...




interested_observer is offline   Reply With Quote
 
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -5. The time now is 7:31 PM.