tag:blogger.com,1999:blog-27557058.post1722679199551114684..comments2024-01-18T05:34:40.549-07:00Comments on Behind The Lens: Depth Of FieldGeorge Barrhttp://www.blogger.com/profile/06745541057122821349noreply@blogger.comBlogger4125tag:blogger.com,1999:blog-27557058.post-80291330989259063772011-06-19T16:15:09.910-06:002011-06-19T16:15:09.910-06:00The "basic facts" you listed about DOF i...The "basic facts" you listed about DOF in your answer to Wayne, are likely one of the most clear and concise explanation I ever met.<br />But ... there's always one ... since my early days I always knew that the closer the subject the shorter is the DOF, and this is one thing I seem unable to fit into your list.<br /><br />So should we add a #4 with subject distance or am I missing something?<br /><br />Given that I suspect the latter is more likely the case, could I tap into your expertise on this when you spare a minute?<br /><br />TIA<br /><br />ASAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-27557058.post-57603036100872051442011-05-23T16:23:37.116-06:002011-05-23T16:23:37.116-06:00You win the math George. So (1.5 X 1.5) / 1.5 = 1...You win the math George. So (1.5 X 1.5) / 1.5 = 1.5 times more depth of field. I infer this means that I should adjust the hyperfocal distance by 1.5. At f11 & 28mm the hyperfocal distance is 9.1 ft. on my chart. So therefore, 6 ft for 18mm DX lens. I'll have to go shoot some more test photos. Cheers.<br />WayneAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-27557058.post-38661942240990988152011-05-23T12:27:40.664-06:002011-05-23T12:27:40.664-06:00No:
you forgot the square of the change in focal ...No:<br /><br />you forgot the square of the change in focal length, so more depth of field with the 18 on the small sensor, vs. 28 mm. on the large sensor (film).<br /><br />GeorgeGeorge Barrhttps://www.blogger.com/profile/06745541057122821349noreply@blogger.comtag:blogger.com,1999:blog-27557058.post-29194082736034921772011-05-23T10:18:48.080-06:002011-05-23T10:18:48.080-06:00Thanks for the clarification George. Here's m...Thanks for the clarification George. Here's my take on this based on your explanation. My 18-55 lens on my Nikon DX camera at 18mm gives an equivalent focal length of approx. 28mm. At 18mm I should gain approx. 1.5 times apparent depth of field because its 18mm (as opposed to 28mm). But I lose that 1.5 times gain because of the magnification to 28mm. Result is gain in depth of field - nada. With that 18-55 lens on my DX camera at 18mm (equivalent to 28mm) I'll have approx. the same depth of field as at 28mm (with my 28-100 lens) on my film camera at the same f-stop. (And I should use the equivalent focal length, i.e. 28mm, not 18mm, when considering the hyperfocal focus distance in a table.) <br />Therefore, is it true that contrary to popular belief, a DX sensor camera does not have greater depth of field than a full-frame sensor (or film) camera? Or do I have to go back out and do some more test shots? I have generally been using larger f-stops with my Nikon (usually no more than f11) because I thought a DX camera had greater depth of field (the popular belief), to avoid sensor dust showing up, and my lens has no gain in sharpness beyond f11. But I don't see a greater depth of field in my photos. <br />I have no doubts about (very) small sensor cameras. I have seen images from these and they definitely have way more depth of field. Four/thirds? The popular belief is that they have more depth of field.<br />WayneAnonymousnoreply@blogger.com