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Old Nov 29, 2012, 3:59 PM   #1
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Default DOF Device?

When I play golf, I have a GPS device that can tell me how far I am from the pin.

I have a laser that can be used to tell me how tall a space is or how wide it is.

I'm looking for a device that has a laser that I point at my subject and it measures distance. The user would input the type of camera (full frame or crop) and fstop and the device would calculate the DOF.

I know there's a dof calculator, but measuring the distance from camera to subject is critical. That's where the laser comes into play.

Is there such a item to do this?

FP
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Old Nov 29, 2012, 4:21 PM   #2
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So, to make sure you've got the distance to subject exactly correct, you want to shine a laser in their eye.

Have I got that right?
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Old Nov 29, 2012, 5:34 PM   #3
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Default Set your phasers on stun....

Or up their nose, which ever they prefer.

Actually the way I want to use it is for group shots, not a single person.

A single person is much easier to get your subject in focus.

Recently I photographed a group of people and was several shots had people on the edges of the group out of focus. I obviously needed a deeper depth of field. My problem was that I misjudged the distance between me and them. So 9 of the 11 people were in focus. Two were not.

Had I known the proper distance to my subjects the most distant subjects, I would have changed the fstop.

Also, my .40 Baretta has laser sites. But you don't aim at the eyes with it.

Faithfully yours,
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Old Nov 29, 2012, 5:38 PM   #4
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Default Exif?

When I download my photos, in the EXIF information, I can read how far I was from the subject.

Is there a way for me to view that information from my camera?

If so, I could have taken a photo of the person nearest me (center focus) and one of the person furthest away from me and calculate the DOF needed from that.

Can I view EXIF on a Canon 5D ?
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Old Nov 29, 2012, 5:58 PM   #5
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Actually, presuming that all eleven people were standing in a straight line, I think it's far more likely that the lens suffered from field curvature. That is not to say that a smaller f-stop would not have helped, but knowing the exact distance to the subject wouldn't have. If the people in the center of the group were in focus, you had the proper subject distance.
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Last edited by TCav; Nov 30, 2012 at 9:41 AM.
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Old Nov 29, 2012, 10:21 PM   #6
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There are laser rangefinders made for golfing and shooting which will give you the distance info, but I don't know if the precision is good enough for what you are thinking. I haven't heard of any that can directly interface with a DOF calculator, though. You might need a DOF calculator app for a smart phone to go with it, and then, of course there is the camera bag, tripod, accessories, spare batteries, etc. You say you're a big, strong guy with a couple extra hands?

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Old Nov 30, 2012, 9:40 AM   #7
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I think you're barking up the wrong tree. The problem you have is not a DoF problem, so knowing the exact subject distance and DoF would not have helped.

Increasing the DoF would have helped, but only to overcome a shortcoming of your lens: Soft Edges.
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Old Nov 30, 2012, 10:11 AM   #8
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FP - the key to group shots is always err on the side of deep DOF - don't try to get the DOF just enough. Pick your background so you don't care how in-focus it is and use a tripod. Then, if there are multiple rows - focus middle. A general rule I use is: f5.6 for one row, f8 for two and f11 for 3 to 4.
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Old Nov 30, 2012, 11:44 AM   #9
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Quote:
Originally Posted by TCav View Post
I think you're barking up the wrong tree. The problem you have is not a DoF problem, so knowing the exact subject distance and DoF would not have helped.

Increasing the DoF would have helped, but only to overcome a shortcoming of your lens: Soft Edges.
You are assuming the group was lined up straight across his camera's field of view. Since he mentions wanting to know the distance of the nearest person and the farthest, is sounds more like they were diagonal to the camera. Without seeing the photo in question, I am unable to make that call.

FP: Most cameras do give you the ability to review the photo and read the exif, but usually only the basics. You might need to have a laptop with an exif reader such as PhotoMe to be able to read distance information. Some cameras provide actual distance info, and others just say "distant subject" or something similar.

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Old Nov 30, 2012, 1:46 PM   #10
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Quote:
Originally Posted by VTphotog View Post
You are assuming the group was lined up straight across his camera's field of view.
Yes, I mentioned that:
Quote:
Originally Posted by TCav View Post
... presuming that all eleven people were standing in a straight line, ...

Quote:
Originally Posted by VTphotog View Post
Since he mentions wanting to know the distance of the nearest person and the farthest, ...
He says:
Quote:
Originally Posted by FaithfulPastor View Post
Recently I photographed a group of people and was several shots had people on the edges of the group out of focus. I obviously needed a deeper depth of field. My problem was that I misjudged the distance between me and them. So 9 of the 11 people were in focus. Two were not.
Note:
Quote:
Originally Posted by FaithfulPastor View Post
... people on the edges of the group [were] out of focus. ...
... as in corner and edge softness.

BTW, I believe that FaithfulPastor's camera does have a device that would have solved his problem for him. It's called a Depth of Field Preview Button.

Once again, I don't think Depth of Field was his problem, but it could have been the solution.
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