Uh huh. I don't really know how to calculate DOF, never really understood it (yes, I know there are cards and things). But I agree, I think we get so we unconsciously aware. Like on a wide angle, I will figure with f/8 most things will probably be in focus. While with a long telephoto, at f/8 I don't make that assumption. Depends what I am shooting of course, but it may have a much shallower DOF. Anyway, It is something to be aware of.
Thanks, Marnie aka Doe :-) ============= Yes it is. Look at it this way, if you set a 50mm at f/2.0 it has a 25mm opening, now if you set a 100mm at f/2.0 it has a 50mm opening, but at f/4.0 it has the same 25mm opening that the 50mm does at f/2.0. So, if the magnification of your viewing image (print) is the same (which Bill took care of by slightly enlarging his 70mm image) then the DOF will be the same. (Note that you can control the magnification by changing distance also, but that will change the perspective of the image.) Sounds pretty complicated, but it is not actually. These are some of the controls you have over your images, at the camera. And in actual use it soon becomes pretty much unconscious. In the mean time you can cut and paste the following and print it on a 3x5 card to keep in your camera bag. 1) Magnification and aperture diameter control DOF 2) Focal length, subject distance, enlargement factor, etc. control magnification. Note, how many things affect magnification. 3) Distance controls perspective. 4) F-stop and shutter speed control exposure. 5) Shutter speed controls motion blur. 6) ISO adjusts for light level. NOTE: There are many interdependencies there, in other words, changing one thing also changes others. -graywolf --------------------------------------------- Warning: I am now filtering my email, so you may be censored. ************************************** See what's free at http://www.aol.com. -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net
