Archived posting to the Leica Users Group, 1999/07/07
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]There is a dandy depth of field calculator on the Internet at: http://www.serve.com/ballen/DOF.html Also, there is a really nice portable version for the Palm at: www.users.bigpond.com/bitwareoz called Focus+ These programs confirm that Jim is correct. The reason the Summilux has "less" DOF than the Noctilux at the same subject distance is because it has a smaller field of view. They will give identical DOF at equivalent f/stops only if you move in with the Noctilux to frame the identical image. Now, to answer Jim's project, I looked at the Leica brochure and found that the Noctilux has a 45 deg field and focuses to 1 meter, while the Summilux has a 31 deg field and focused to .75 meter. Using the handy calculator, at their respective close focus distances (as reported in the brochure) the Noctilux has a DOF of .9 in and the Summilux has a DOF of .3 in. Jim is again correct! BTW, the Summilux focuses to an object of 192 x 288 mm, while the Noctilux only goes to 410 x 615 mm. Flamers on your marks: The R lenses can do better on close focus. I have to get a life. Bob Rose ==== Date: Wed, 07 Jul 1999 17:14:43 -0700 From: Jim Brick <jimbrick@photoaccess.com> Subject: [Leica] Re: .. I believe DOF is determined by image size. That is, if you set a Noctilux at f/1.4 and frame a scene, then set a 75 Summilux at f/1.4 and frame the same scene exactly like the Noctilux (The Noctilux is closer to the scene than the Summilux in order to have the exact same image on film) the DOF of both lenses will be exactly the same. If you stand at exactly the same place and take the photograph, at f/1.4, with both lenses, the Summilux will record less of the scene than the Noctilux. 75mm vs. 50mm. The Summilux will have less DOF, in this circumstance, than the Noctilux. The f/1.0 DOF statistics belong only to the Noctilux. The Summilux at f/1.4, focused at it's closest position, might possibly have less DOF than a Noctilux at f/1.0 focused at its closest position. Perhaps exactly the same. This is a good project for someone. I believe the 75/1.4 close focus/image size is the best of the M lenses. I have a photo of a tulip, printed 16x20 on Ciba, that I took with my 75/1.4, at f/1.4, and focused at its closest position. The DOF is literally the front surface of the tulip. Barely a few millimeters. Jim