Gid
Well-known
I thought I had this sorted, but I haven't. I think I'll go back to film 100% 
http://www.dofmaster.com/dofjs.html
This is a useful tool.
Clearly I have been lucky and that combined with my bad eyesight ..........
I now have to rethink how I use the RD-1, or at least be a little more careful - I do always set hyperfocal a stop down to allow for inaccuracies, so I guess that has helped.
Gid
http://www.dofmaster.com/dofjs.html
This is a useful tool.
Clearly I have been lucky and that combined with my bad eyesight ..........
I now have to rethink how I use the RD-1, or at least be a little more careful - I do always set hyperfocal a stop down to allow for inaccuracies, so I guess that has helped.
Gid
RichC
Well-known
Gid - what Allan says is at the core of things:
If you took two photos with the same lens, one on a Leica (I wish!) and one on the R-D1, the depth of field will then depend only on one thing - how large you are going to print a photo.
A 35 mm film negative is 1.53 times larger than the R-D1 sensor image, so if you make prints from each camera identical in size (e.g. 10 x 8"), the R-D1 image will need greater enlargement - which of course makes the out-of-focus areas more obvious, so to compensate you need to compensate by using a restricted DOF when shooting (equivalent, as I said previously, to about 1 stop wider than the lens distance markings).
However, if you enlarged both the Leica and the R-D1 image the same amount, the DOF is unchanged - although the Leica print will be 1.53 times larger.
Of course, both prints will have different views: the R-D1 photo is simply the central 1/1.53 of the Leica image. Just think of your R-D1 as cropping a third off your 35 mm negatives!
As I said, the above is for the same lens, so with the R-D1 you just end up with the cropped central part of the Leica view. If you want identical fields of view on the two cameras, you need different lenses - a wider one on the R-D1 or a longer one on the Leica.
If you don't move when changing lens, the DOF becomes greater the wider the lens, as Allan says. However, although the photos from the leica and R-D1 now look similar, the R-D1 image still needs enlarging 1.53 times if identically sized prints are to be made, so the DOF still needs to be approximated as 1 stop wider than the 35 mm film format distance markings on the lens.
Thus, the difference in DOF described above is simply down to how much you enlarge a photo when printing. Compared with theory for 35 mm film, DOF on the R-D1 can be assumed to be that for the next widest aperture. However, if you never print large photos, then you can get away with assuming a wider DOF than usual - perhaps matching the lens distance markings; conversely, if you print on A3 paper, you should assume an even shallower DOF than discussed.
Also, what someone or some manufacturer considers acceptably sharp differs - if you took several 50 mm lens, say, set all the lens to the same distance scale settings, and compared the DOF on the resulting photographs, the DOF would vary! DOF is thus to some degree subjective - what I might consider sharp, you might feel is out of focus! (This also accounts for the variation in DOF charts floating around the web, as the CoC differs.)
So, Gid, if you think the DOF in your R-D1 photos is fine, then it is!
As an aside, compact digicams have ridiculously large DOFs as the lenses have minute focal lengths (e.g. 7 mm)! If you could somehow shoehorn your 50 mm Leica lens, say, onto such a digicam, and you wanted to create a 10 x 8" print as above, the DOF would be very shallow - possibly off the lens distance scale! (Someone more interested can work that one out!)
I think a lot of the confusion about DOF and digital cameras has come about by gross oversimplifications and assumptions on the web - especially the one about a lens on a digital camera changing its focal length. That's what caught me out when I created the first version of my DOF charts (see earlier posts) , and went off and read the theory on DOF (actually pretty straightforward) as I felt somewhat confused when people started replying. Beware the web!!
kaiyen said:
If you took two photos with the same lens, one on a Leica (I wish!) and one on the R-D1, the depth of field will then depend only on one thing - how large you are going to print a photo.
A 35 mm film negative is 1.53 times larger than the R-D1 sensor image, so if you make prints from each camera identical in size (e.g. 10 x 8"), the R-D1 image will need greater enlargement - which of course makes the out-of-focus areas more obvious, so to compensate you need to compensate by using a restricted DOF when shooting (equivalent, as I said previously, to about 1 stop wider than the lens distance markings).
However, if you enlarged both the Leica and the R-D1 image the same amount, the DOF is unchanged - although the Leica print will be 1.53 times larger.
Of course, both prints will have different views: the R-D1 photo is simply the central 1/1.53 of the Leica image. Just think of your R-D1 as cropping a third off your 35 mm negatives!
As I said, the above is for the same lens, so with the R-D1 you just end up with the cropped central part of the Leica view. If you want identical fields of view on the two cameras, you need different lenses - a wider one on the R-D1 or a longer one on the Leica.
If you don't move when changing lens, the DOF becomes greater the wider the lens, as Allan says. However, although the photos from the leica and R-D1 now look similar, the R-D1 image still needs enlarging 1.53 times if identically sized prints are to be made, so the DOF still needs to be approximated as 1 stop wider than the 35 mm film format distance markings on the lens.
Thus, the difference in DOF described above is simply down to how much you enlarge a photo when printing. Compared with theory for 35 mm film, DOF on the R-D1 can be assumed to be that for the next widest aperture. However, if you never print large photos, then you can get away with assuming a wider DOF than usual - perhaps matching the lens distance markings; conversely, if you print on A3 paper, you should assume an even shallower DOF than discussed.
Also, what someone or some manufacturer considers acceptably sharp differs - if you took several 50 mm lens, say, set all the lens to the same distance scale settings, and compared the DOF on the resulting photographs, the DOF would vary! DOF is thus to some degree subjective - what I might consider sharp, you might feel is out of focus! (This also accounts for the variation in DOF charts floating around the web, as the CoC differs.)
So, Gid, if you think the DOF in your R-D1 photos is fine, then it is!
As an aside, compact digicams have ridiculously large DOFs as the lenses have minute focal lengths (e.g. 7 mm)! If you could somehow shoehorn your 50 mm Leica lens, say, onto such a digicam, and you wanted to create a 10 x 8" print as above, the DOF would be very shallow - possibly off the lens distance scale! (Someone more interested can work that one out!)
I think a lot of the confusion about DOF and digital cameras has come about by gross oversimplifications and assumptions on the web - especially the one about a lens on a digital camera changing its focal length. That's what caught me out when I created the first version of my DOF charts (see earlier posts) , and went off and read the theory on DOF (actually pretty straightforward) as I felt somewhat confused when people started replying. Beware the web!!
Gid
Well-known
Rich,
Thanks for the patient explanation. I do like the idea that what your lens' scale says, is what it is, so its FF digital or film . Now where's the link to that mint M6
Gid
Thanks for the patient explanation. I do like the idea that what your lens' scale says, is what it is, so its FF digital or film
. Now where's the link to that mint M6 Gid