depth of field or lack of...

guitarkid · Oct 18, 2006

if you are using 58mm 1.8 or any prime for that matter, and you need lots of light, and you don't want massive depth of field, are there lenses out there that can stay at 1.8 while keeping everything in focus.....i have heard of these. i know that everything is a sacrifice, but there were times where i needed 1.8 to allow more light in but was just too much depth of field.

Big Mike · Oct 18, 2006

That does not make sense... :scratch:

When shooting at F1.8...you have very little DOF (at most distances).

are there lenses out there that can stay at 1.8 while keeping everything in focus

Do you want everything if focus? That would be a large DOF...which you seemingly don't want.

Do you want more things in focus or less things in focus?

guitarkid · Oct 18, 2006

sorry for the confusion. i want more things in focus at 1.8

i heard there may be expensive lenses out there with some kind of ring on the lense that allows you to set the DOF regardless of the Fstop. you can keep it at 1.8 and have more DOF or less. so basically, DOF is not affected by the Fstop, if you so desire. i have never heard of this. so yes, set it at 1.8 with large depth of field. sounds too good to be true.

Big Mike · Oct 18, 2006

Yes, too good to be true.

The lenses with 'aperture rings' are just a manual way of setting the aperture. DOF is the physical result of a few factors. Aperture is the main one, focal length plays a factor, distance to subject, size of medium/projected image...which has to do with the distance of the lens to the 'film plane'.

Google 'circle of confusion' and you can learn more.

Basically, no you can't get more DOF while shooting at F1.8. You could back up, so that the lens is at infinity focus...then anything past the focus point will be in focus...but that's not always practical.

Most digicams would do a good job of this for you....because their sensors are so small...they have a deep DOF.

You could probably find a DOF chart for your lens/camera combination...again, Google is your friend.

Also, look up hyperfocal distance. The DOF will always (I think) extend 1/3 back toward the camera and 2/3 forward from the focus point. So get the most efficient use of your DOF...you will want to focus 1/3 of the distance...from your closest subject to your farthest.

fmw · Oct 18, 2006

Depth of field involves aperture, focal length and distance. If you want more depth of field you use a smaller aperture, shorter focal length lens or photograph things that are further away. There is no getting around that. A 58mm lens at f1.8 will only have everything in focus if the subject is at infinity.

There are tilt and shift lenses that can help with focusing more of a subject, but only if parts of the subject are out of focus due to the lens being out of parallel with the subject. There is no way to truly add depth of field without dealing with one of the issues in the first paragraph.

guitarkid · Oct 18, 2006

thanks guys for clearing that up

Torus34 · Oct 18, 2006

There just ain't no free lunch, Man.

cosmonaut · Oct 18, 2006

Try this out. It's worth the time. I wish I had this hand held or on my PDA.....
http://www.dofmaster.com/dofjs.html
Cosmo

DepthAfield · Oct 19, 2006

Agggghhhh!!! This is the best utility-based photo site Ive seen in quite some time.

Thank you!

gizmo2071 · Oct 20, 2006

Probably not the best option.
You could try multiple exposures and layering afterwards?
A fronted focus picture and one focused further back, should help with a better depth of field.

rt45 · Oct 25, 2006

I think you may be thinking of a Tilt Shift lens? You can get your DOF to run perpenducular to the camera instead of parallel to it. More info can be found here: http://photo.net/equipment/canon/tilt-shift However, I've never used one myself so i could be losing my mind...