Bulent Celasun wrote: >>and this increases the size of the image circle > >... decreases...
Nope. Moving the lens farther from the focus plane increases the size of the image circle. Also, by increasing the area of coverage, it decreases the intensity of the light falling on the imaging area and necessitates longer exposures. This is why non-TTL metering requires exposure compensation at high magnification. >Bulent >--------------------------------------------------------------------- >http://patoloji.gen.tr >http://celasun.wordpress.com/ >http://www.flickr.com/photos/bc_the_path/ >http://photo.net/photodb/user?user_id=2226822 >http://www.pentaxphotogallery.com/artists/bulentcelasun > > >2016-07-07 15:10 GMT+03:00 Bill <[email protected]>: >> On 7/7/2016 5:28 AM, Zos Xavius wrote: >>> >>> I bet its like the 60-250 and there is just a baffle inside to block >>> light for aps-c. >> >> >> That is typical behavior for lenses in general. Close focusing moves the >> glass farther away from the sensor, and this increases the size of the image >> circle. >> Anyone who has used a large format camera will be familiar with this. >> >> bill >> >>> >>> On Wed, Jul 6, 2016 at 6:24 PM, Larry Colen <[email protected]> wrote: >>>> >>>> I just did a quick test with the DA35 on the K-1 to see at which aperture >>>> vignetting becomes a problem. The short answer is that aperture doesn't >>>> make much difference, focus distance does. If you are focused to less >>>> than >>>> about 20cm/8" the lens will not vignette. Further away than that, and >>>> something occludes the corners of the sensor. >>>> >>>> That explains why when I tested it, which it turns out to have been with >>>> macro shots, I didn't see any vignetting, but when I used it to >>>> photograph >>>> the sushi, I did. >>>> >>>> -- >>>> Larry Colen [email protected] (postbox on min4est) http://red4est.com/lrc >>>> >>>> >>>> -- >>>> PDML Pentax-Discuss Mail List >>>> [email protected] >>>> http://pdml.net/mailman/listinfo/pdml_pdml.net >>>> to UNSUBSCRIBE from the PDML, please visit the link directly above and >>>> follow the directions. >>> >>> >> >> >> -- >> PDML Pentax-Discuss Mail List >> [email protected] >> http://pdml.net/mailman/listinfo/pdml_pdml.net >> to UNSUBSCRIBE from the PDML, please visit the link directly above and >> follow the directions. -- Mark Roberts - Photography & Multimedia www.robertstech.com --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
