ART HELP with depth of field...

6SpeedTA95

OT Supporter
Jun 12, 2003
69,044
Oklahoma
I took a few pics of my dog this week, put the aperature as low as it would go to limit the depth of field but I still have what amounts to an infinite focus effect? :confused: what am I missing/doing wrong?

I could edit the image to make areas out of focus a bit...but I'm not sure why literally everything beyond about 20 feet is in focus...in some cases the background is in better focus than my dog. :dunno:


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1164943582_R7e7j-X3.jpg
 

Cesium

OT Supporter
Nov 25, 2004
11,661
Colorado
WTF deck that goes nowhere. :rofl:

Anyway, looking at the exif, it says most of these are at 18mm and f/8. And your dog is pretty far away from you (for this focal length). You aren't going to be blurring any backgrounds this way.

You're using the 18-55 kit lens? Your best bet is 55mm and f/5.6, and get the dog framed as tightly as possible in the viewfinder. That should do the trick, within the equipment's limits.

I can't stress the framing enough though. It's a pretty common mistake that people make at first. Get closer, get tighter.

Hope that helps at all.
 
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6SpeedTA95

6SpeedTA95

OT Supporter
Jun 12, 2003
69,044
Oklahoma
WTF deck that goes nowhere. :rofl:

Anyway, looking at the exif, it says most of these are at 18mm and f/8. And your dog is pretty far away from you (for this focal length). You aren't going to be blurring any backgrounds this way.

You're using the 18-55 kit lens? Your best bet is 55mm and f/5.6, and get the dog framed as tightly as possible in the viewfinder. That should do the trick, within the equipment's limits.

I can't stress the framing enough though. It's a pretty common mistake that people make at first. Get closer, get tighter.

Hope that helps at all.
If i had someone else throwing the toys that would be possible...but I have to throw the toy and instantly shoot with the camera...I'll get my wife out there next time to throw...and actually now that you mention it, I think I did have most of them at F8, not F5.6 or F4...

So that was probably some of it...but obviously I have issues beyond the aperature...

Yes that helps a lot...and yes I'm using the kit lens, I've got a 55-250 but thats a bit much for shooting in my backyard...:dunno:


edit: and on the deck, when we bought the house it had an above ground pool, I had it pulled out before we moved in. My wife thinks we might get a hot tub one day (we won't but I am not telling her that), so the deck stays...for now. When I rebuild it in a few years I"ll probably pull out the upper end.
 

mojito

New Member
Mar 8, 2003
62,784
things that effect dof:
aperture
focal length
subject to background distance
 

charles foster kane

New Member
Feb 14, 2007
93,467
Croatia
That said, shooting a scene like that with mostly f/8 and having your dog out of DOF ... nobody has asked what focus point you were using. It's possible the camera was focusing on like, a fence or something

or the stairs that climb to nowhere
 

Marix

OT Supporter
May 23, 2006
27,969
things that effect dof:
aperture
focal length
subject to background distance

This

And in your example you had the "worst" of all three

f/8 small aperture
18mm wide angle focal length
Quite a long way from subject only filling small part of the frame

With your current gear, you'd be better going to 200mm f5.6 and filling the frame with the dog. That would give thinnest DOF. 50mm 5.6 would also do the same, but as someone said earlier, it's about framing and choosing the right focus point. Get closer to the subject and the background will fall away more.
 
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6SpeedTA95

6SpeedTA95

OT Supporter
Jun 12, 2003
69,044
Oklahoma
This

And in your example you had the "worst" of all three

f/8 small aperture
18mm wide angle focal length
Quite a long way from subject only filling small part of the frame

With your current gear, you'd be better going to 200mm f5.6 and filling the frame with the dog. That would give thinnest DOF. 50mm 5.6 would also do the same, but as someone said earlier, it's about framing and choosing the right focus point. Get closer to the subject and the background will fall away more.
ok

thanks for the tips guys
 

mojito

New Member
Mar 8, 2003
62,784
I think it's camera to subject distance, not subject to background
:cool:

Yes and no. If the background is in the same plane, it'll still be in focus right in front of the camera, which is why we look for background seperation
 
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6SpeedTA95

6SpeedTA95

OT Supporter
Jun 12, 2003
69,044
Oklahoma
Ok, its cloudy and cold as fuck today, so unless the sun comes out I'm not going to take outdoor pics. So I took a few pics using some of the techniques here to isolate my watch from the background. So far it has helped tremendously. I used the max zoom, minimum aperture, changed the white balance to match my lighting, and put the camera on a tripod using a 2 second shot delay. The results are my best so far :dunno:

Thoughts and suggestions are more than welcome per usual...
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Playing around with some reflections
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I took a couple others with two watches which kinda jacked up the focus. Neither was in focus as the focus was right smack between the two...but I could pull out my third if necessary and use the primary focal point on the center watch :dunno:
 

Cesium

OT Supporter
Nov 25, 2004
11,661
Colorado
I took a couple others with two watches which kinda jacked up the focus. Neither was in focus as the focus was right smack between the two...but I could pull out my third if necessary and use the primary focal point on the center watch :dunno:

Place both watches on the same focal plane.

But you're getting it now.
 

Marix

OT Supporter
May 23, 2006
27,969
Yup. When I first got a dslr I did a similar thing

Now try to change the aperture, going from f4 to f22 and see what happens to the DOF. (the the camera in A mode and use a tripod)

Then you can do the same with shutter speed and ISO to help you understand 'stops' of light.

Ie f4 ISO200 and 1/100s is the same as f5.6, ISO800 and 1/200s are the same exposure but with different applications
 
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6SpeedTA95

6SpeedTA95

OT Supporter
Jun 12, 2003
69,044
Oklahoma
Yup. When I first got a dslr I did a similar thing

Now try to change the aperture, going from f4 to f22 and see what happens to the DOF. (the the camera in A mode and use a tripod)

Then you can do the same with shutter speed and ISO to help you understand 'stops' of light.

Ie f4 ISO200 and 1/100s is the same as f5.6, ISO800 and 1/200s are the same exposure but with different applications

I'm familiar with the mathematical differences between them (I'm kind of a math junkie ;) ) but was unfamiliar with how aperture impacts my DoF until reading in a book last weekend. My initial experiments this week were not too good (first post). But after reading some practical tips on OTAP I think I could make a better go of it next time :wiggle:
 

mojito

New Member
Mar 8, 2003
62,784
I'm familiar with the mathematical differences between them (I'm kind of a math junkie ;) ) but was unfamiliar with how aperture impacts my DoF until reading in a book last weekend. My initial experiments this week were not too good (first post). But after reading some practical tips on OTAP I think I could make a better go of it next time :wiggle:

there are some DOF calculators available as mobile apps

also keep in mind, you are creating a plane of focus parallel to the angle of the sensor. That plane is x wide where everything is in focus. of that distance, your spot where you focused is inside of it, and will be 1/3 of the way into the plane. So 2/3 of the total dof of in focus area is behind the place you focused on. Macro lenses will be down to a 50/50 split in front/behind.

tilt shift lenses will allow you to adjust the angle of the plane of focus.
 

charles foster kane

New Member
Feb 14, 2007
93,467
Croatia
I took a couple others with two watches which kinda jacked up the focus. Neither was in focus as the focus was right smack between the two...but I could pull out my third if necessary and use the primary focal point on the center watch :dunno:

Once again, gotta query which focus points you are using
 

charles foster kane

New Member
Feb 14, 2007
93,467
Croatia
Probably focused and then moved the camera before taking the shot. I've been guilty of that when I started out.
The guy displays next to no thought towards composition, and you are suggesting he is using the focus/recompose technique?

More likely that because of lack of equipment knowledge he's stuck on auto-focus-point-select (I don't even know what the fuck that mode is called, thats how much you shouldn't use it) or centre focus
 

Marix

OT Supporter
May 23, 2006
27,969
The guy displays next to no thought towards composition, and you are suggesting he is using the focus/recompose technique?

More likely that because of lack of equipment knowledge he's stuck on auto-focus-point-select (I don't even know what the fuck that mode is called, thats how much you shouldn't use it) or centre focus

That's a good point.. I forgot that automatic focus point exists :mamoru:
 

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