I didnt state the problem didnt exist. I stated I hadnt seen the problem YET. -----Original Message----- From: Pentax-Discuss Mail List Sent: Jun 17, 2022 11:37 AM To: Subject: Re: sample photos. - smc pentax A 100mm F2.8 MACRO at middle distances w/K-1   On 6/16/2022 10:17 PM, Alan C wrote: > The problem is related to lack of Multi-coating on the rear element > which was absent on pre-digital lenses. More commonly this gives rise > to ghosting (back-and-forth reflections) when these old lenses are > used on digital camera because the sensors are much more reflective > than film. The difference between the Sigma 170-500 APO & the later DG > version is indicative. > I suspect that is a possibility, I suspect the "multicoated" lenses of the day may not have been as multicoated on the rear element. I use quite a few legacy glass and the A100/2.8 macro is the only one I've noticed hot spots on, which is why I thought it might be related to the FREE design and the flat rear element.   Anyway, according to John, the problem doesn't exist, so it's all good.   bill -- %(real_name)s Pentax-Discuss Mail List To unsubscribe send an email to pdml-leave@pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.  

Actually, you said "the lens is not "quite prone" to hot spots w/ K-1" based on your not having seen them. That is quite different from saying the problem doesn't exist. You can prevaricate all you want, but you said what you said. I recall a number of years ago, before we had the problem of sensor reflections that you trashed the A100/2.8 macro for being "pseudo zoom" (your words, not mine) because the focal length shortens down to something like 68mm at 1:1. We now know this phenomenon as focus breathing. Bill On Fri., Jun. 17, 2022, 10:02 a.m. JC OConnell, <hifisapi@gate.net> wrote: > I didnt state the problem didnt exist. I stated I hadnt seen the problem > YET. > -----Original Message----- > From: Pentax-Discuss Mail List > Sent: Jun 17, 2022 11:37 AM > To: > Subject: Re: sample photos. - smc pentax A 100mm F2.8 MACRO at middle > distances w/K-1 > > On 6/16/2022 10:17 PM, Alan C wrote: > > The problem is related to lack of Multi-coating on the rear element > > which was absent on pre-digital lenses. More commonly this gives rise > to > ghosting (back-and-forth reflections) when these old lenses are > used on > digital camera because the sensors are much more reflective > than film. > The difference between the Sigma 170-500 APO & the later DG > version is > indicative. > > > I suspect that is a possibility, I suspect the "multicoated" lenses of the > day may not have been as multicoated on the rear element. I use quite a few > legacy glass and the A100/2.8 macro is the only one I've noticed hot spots > on, which is why I thought it might be related to the FREE design and the > flat rear element. > > Anyway, according to John, the problem doesn't exist, so it's all good. > > bill > -- > %(real_name)s Pentax-Discuss Mail List > To unsubscribe send an email to pdml-leave@pdml.net > to UNSUBSCRIBE from the PDML, please visit the link directly above and > follow the directions. > > > -- > %(real_name)s Pentax-Discuss Mail List > To unsubscribe send an email to pdml-leave@pdml.net > to UNSUBSCRIBE from the PDML, please visit the link directly above and > follow the directions.