Alin Rule of thumb is appr. (AFAIR) 1/3 in front of focus point, 2/3 behind. All the best Jens
mailto:[EMAIL PROTECTED] http://hjem.get2net.dk/bladt -----Oprindelig meddelelse----- Fra: Alin Flaider [mailto:[EMAIL PROTECTED] Sendt: 22. marts 2004 12:30 Til: Boris Liberman Emne: Re: My own DOF confusion Boris, I understand you were comparing DOF markings on the lenses and not DOF as resulted from your own photographic experience. Then your problem does not exist per se: simply Pentax is more conservative with DOF estimation than the Russian manufacturer. These markings are truly to be taken as a guide. Generally you need to stop down one to two more stops to achieve the desired result, depending on how much do you wish to enlarge the picture. [DOF is a function of magnification factor (or focal length, if distance to subject is constant), aperture value and size of circle of confusion. These are all invariant to the optics design; the later can only impact slightly on the distribution of DOF around the point of focus: more DOF in front or behind the focus point.] Servus, Alin BL> Anyway... I've compared the readings of DOF scale of this lens and my BL> M 50/2.0. Thankfully, it has proper DOF scale unlike modern FA 50/1.7 BL> that I also have. Industar has considerably bigger (right term?) DOF BL> for the same aperture. I cannot give the exact numbers, as I am in my BL> office. BL> Nonetheless, I am confused - how can that be? I've been told that if BL> the lens has less elements (Industar is 4 lenses in 3 groups, if I am BL> not mistaken), then it presumably should have a bigger DOF.
