Archived posting to the Leica Users Group, 1999/04/26
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]- --------------2F565D2F05363709141F9B50 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Henry, Yes, there is a chart showing depth of field (dof) for Leica lenses but it is not a recent one, these were prevelent years ago and are not much seen these days. You can look for old (1930s-50s) books which are most likely to show this, alternatively buy Erwin's excellent CD Rom, 'Leica History in Original Documents, Part 1: 1925-1965', this reproduces many early Leica brochures which include dof scales. If you are looking for absolute minimum focussing distances I doubt you will find this information, most dof scales list several specific ditances and the dof around them, eg. 1m, 5m and infinity. As the 21mm Super Angulon (for example) has a minimum focussing distance of 16", the dof would extend from 14-17" @ f3.4 and c. 12"-32" @ f22. Of course this is all relative to what you call 'sharp', if you blow things up to a very large degree then you will need to be more critical than if you only look at en-prints or make postcards. Sharpness does not start and stop abruptly, you may call the sharpness at 14" (instance 1) sharp but others may not, you may feel that the picture shows sharpness only from 15", so this illustrates the need to determine your own standards as you suggest at the end of your mailing. Brian Bower's Leica Lens Book addresses dof and he notes that he under-values the Leica dof marking on their lenses. If he wants to ensure sharpness by his standards, he uses a stop smaller than Leitz mark. I hope this answers your query, Jem ==================================== Henry Ambrose wrote: > Is there a depth of field chart for Leica M lenses? > An example of its use would be to answer this question: > With a wide angle lens stopped down to f11 or f16 (or whatever) how > close can an object be and still be in focus? I know the distance would > be closer than the minimum focusing distance as indicated on the lens. > What I don't know is how close and how it changes at each aperture. > > Is there a published document that contains this information? Or can this > only be determined by testing? > > Thanks, > > Henry Ambrose - --------------2F565D2F05363709141F9B50 Content-Type: text/html; charset=us-ascii Content-Transfer-Encoding: 7bit <HTML> Henry, <P>Yes, there is a chart showing depth of field (dof) for Leica lenses but it is not a recent one, these were prevelent years ago and are not much seen these days. You can look for old (1930s-50s) books which are most likely to show this, alternatively buy Erwin's excellent CD Rom, 'Leica History in Original Documents, Part 1: 1925-1965', this reproduces many early Leica brochures which include dof scales. <P>If you are looking for absolute minimum focussing distances I doubt you will find this information, most dof scales list several specific ditances and the dof around them, eg. 1m, 5m and infinity. <BR>As the 21mm Super Angulon (for example) has a minimum focussing distance of 16", the dof would extend from 14-17" @ f3.4 and c. 12"-32" @ f22. <P>Of course this is all relative to what you call 'sharp', if you blow things up to a very large degree then you will need to be more critical than if you only look at en-prints or make postcards. Sharpness does not start and stop abruptly, you may call the sharpness at 14" (instance 1) sharp but others may not, you may feel that the picture shows sharpness only from 15", so this illustrates the need to determine your own standards as you suggest at the end of your mailing. <P>Brian Bower's Leica Lens Book addresses dof and he notes that he under-values the Leica dof marking on their lenses. If he wants to ensure sharpness by his standards, he uses a stop smaller than Leitz mark. <BR>I hope this answers your query, <P>Jem <BR>==================================== <P><I>Henry Ambrose wrote: </I> <BLOCKQUOTE TYPE=CITE><I>Is there a depth of field chart for Leica M lenses?</I> <BR><I>An example of its use would be to answer this question:</I> <BR><I>With a wide angle lens stopped down to f11 or f16 (or whatever) how</I> <BR><I>close can an object be and still be in focus? I know the distance would</I> <BR><I>be closer than the minimum focusing distance as indicated on the lens.</I> <BR><I>What I don't know is how close and how it changes at each aperture.</I><I></I> <P><I>Is there a published document that contains this information? Or can this</I> <BR><I>only be determined by testing?</I><I></I> <P><I>Thanks,</I><I></I> <P><I>Henry Ambrose</I></BLOCKQUOTE> <I> </I></HTML> - --------------2F565D2F05363709141F9B50--