I was photographing today one bridge with Carl Zeiss Macro-Planar T* 2/100. To my surprise the Depth of Field (DOF) was pretty narrow considering I was using f/8 and focus distance was about about 35 meters (about 115 feet). When I viewed photo at my 24" display DOF does not cover the background of the image (forest and house). This also happens if printed to large size, not only on screen.
Specially if you compare the bushes on right side of bridge against the building it's obvious that DOF doesn't properly cover the building. On other hand the detail from tiles of the roof seem to be there.
I haven't earlier had similar "problem" * with other short tele lenses. I find this pretty strange since pixels of 1D mkIII are pretty large compared to many other cameras. Has anybody else noticed this kind of behaviour from CZ 2/100 ZF? Is the DOF really shallow with 1Ds mkIII?
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Samuli Vahonen http://www.vahonen.com
* This actually is not any problem for me, it makes the photo to look like more 3D, at least when printed to large size.
Based on your camera/lens/apperture and subject distance anything beyond 97.8m (house and forest) will be oof.
Calculator here http://www.dofmaster.com/dofjs.html
I dont see how the make and model of the camera and lens can affect dof, other than their settings/focal length/subject distance & size of sensor?
Different lenses of the same focal length can have a different apparent DOF.
This can be measured, though it is not normally provided as a specification. You look at the through-focus MTF (the MTF measured against the point of focus), and the DOF is then distance range where the MTF is above a minimum level (or cut-off) that one would perceive as being sharp or in focus.
It is, therefore, possible that different lenses will require a different circle of confusion assumptions for determining apparent DOF.
Seems that according to calculators (here is mine, a little more accurate than the DOF master and has more parameters ==> more difficult to use as well...LINK) this is the case. It must be that Canons and Leica have larger apparent DOF (see Lotusm50 reply above) since I have not noticed this behaviour earlier.
During last seven years I have taken hundrets, if not thousands, landscape photos taken with short tele lenses and for reason or another I haven't seen this happening before. I have used this effect to isolate even big and far away subjects by using f/2 with CZ 2/100 ZF, but I didn't realize the DOF is so shallow also with f/8. At f/11 the diffraction starts to show it's first symptoms even on 1D mkIII, which has huge pixels. Maybe we have to start use programs developed for macro photography which combine multiple exposures of multiple focus distances to create larger DOF...or use Leica/Canon lens for landscape photos and Zeiss for other stuff ;-)
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Samuli Vahonen http://www.vahonen.com
Found another example from today's photos how the DOF calculators won't work properly: I took photo of stairs and church with Carl Zeiss Distagon T* 2/35 ZF @ f/2 from about 5 meter focus distance, which according to DOF master would mean that with 1D mark III the DOF would begin 0.79m before focus distance and would end at 1.15m after the focus distance (DOF=4.21-6.15m). However in real life DOF was much larger (I focused to the bottom of the stairs): http://www.vahonen.com/resources/External_FM_20080715D.jpg
Maybe Zeiss distagon optical design makes apparent DOF larger - And Zeiss planar design makes it smaller?
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Samuli Vahonen http://www.vahonen.com
A couple years ago I compared it to the 85L and 135L found the 100/2's DOF to be ~1 stop less than the Canon's. In general I find Canon lenses to have a very wide DOF zone. If I want lots of DOF, then a Canon lens is good bet. If I want very little DOF, then Contax lens is a good bet.
Samuli Vahonen wrote:
Maybe Zeiss distagon optical design makes apparent DOF larger - And Zeiss planar design makes it smaller?
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Samuli Vahonen http://www.vahonen.com
I think the contrary is true, retrofocus lenses have less DOF than Teles from design, however they have not the same use and are not comparable.
My guess is that lenses form the same lenght and design have not noticable different DOF, they may have different OOF rendering though. I never use these calculaters, from my experience I would say its just not possible to do your first shot all in focus at f8
I've noticed different DOF with lenses of the same focal length. For instance the OL 28mm 2.8 has much less DOF behind the focus point than the 3.5 version when both are stopped down. It's weird for sure and I also see it on the OL 24mm 2.8 - the technique with these lenses is to focus on the furthest part of the scene and stop down to get foreground sharpness.
AFAIK DOF calculations are all simplified and based on the assumption that you are using a simple meniscus lens. Standard and telephoto lenses conform quite well to this assumption, since they are of relatively simple design. But retrofocus wideangles are more complex, due to the need to accomodate the mirror box behind the lens. A 24mm meniscus lens would need to be 24mm from the sensor to focus at infinity. So the true DOF calculations for a retrofocus lens must take into account the extra lens groups used for retrofocus. You would be better served by conducting field tests and drawing up your own table for this lens. Hope this helps
DOF is not a definite quantity, it is a simple approximation of what will appear "acceptably sharp" in a photo based on a given print size. If the photo was of the barn I doubt you'd think it was acceptably sharp in a print. Being beyond the DOF limits does not mean that the image is suddenly "out of focus" or blurred out.
