On Mon, Feb 19, 2007 at 09:40:01AM -0700, Joseph Tainter wrote: > Is there any advantage in using the .PEF file format other than reduced > size on the SD card? Such as better lens info in the EXIF etc. Apologies > if this has been asked before. Currently I'm using .DNG and I'm not > getting lenses like Tamron 28-75 and Sigma 70-200 in EXIF, I'm sure > somebody mentioned them appearing. > > It's a long shot but, will perceived exposure be affected? > > Regards, > > John > > ----- > > John, recognizing lenses depends on (a) the lens's chip properly > transmitting the information, and (b) the camera's firmware recognizing > what the lens transmits. Apparently for many (all?) third-party lenses, > this doesn't happen. Camera Raw can't address that.
I don't think John is talking about the well-known problem where many Sigma lenses mis-identify themselves to the camera, using lens codes assigned to certain Pentax lenses. I believe he's wondering whether there is any difference between what information is stored in a DNG and what is stored in a PEF. When this issue was first raised I put together a little utility to rummage around inside K10D DNG files, and showed that everything from the MakerNote tag in the PEF format (including, in particular, the lens ID code) was stored in a DNG PrivateData tag. But not all image viewers (even those that know how to display images in DNG format) know how to get this information from K10D DNG files. That's true even for image viewers that know how to read the Pentax private data both from PEFs and from DNGs created by Adobe Camera Raw; there are subtle differences between the file formats that make this tricky. Since then ExifTool <http://www.sno.phy.queensu.ca/~phil/exiftool/> has been updated to understand the K10D DNG file format, so it's easy enough for you to confirm this for yourself (particularly now there are stand-alone ExifTool executables for Windows and for Macs). One final nit-pick; the camera firmware doesn't have to recognise what the lens transmits (other than it having to be using the correct protocol to transmit the data). It just takes the data from the lens and stores it somewhere in the image file. As far as I know all third party auto-focus lenses transmit *something* to the camera; it's just that what they transmit isn't always strictly correct. -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net
