You should also note your aperture when you get that center blue spot. You may find it is not there at other apertures. The problem is usually a FLAT rear lens element (as seen from the sensor side). Using a lens with a non-flat rear element should not exhibit the problem.
On Friday, November 4, 2016, Bill <[email protected]> wrote: > On 11/3/2016 9:15 PM, Mark Roberts wrote: > >> Collin B wrote: >> >> At work I got the FA50/2.8 macro to have something AF for working in the >>> darker warehouse area. >>> But what I've seen, and it's not just a Pentax situation, when using it >>> with >>> the florescent lights for piece shots I get this blue dot in the middle >>> of >>> the image. Have yet to work with light placement to see if I can >>> eliminate >>> it. But from what I've been reading it has to do with multiple factors, >>> one >>> of which is the nature of the film coatings and the light >>> interactions/reflections with the sensor surface. >>> I only see the situation under the fl product lights. >>> Anyone else here have similar issues when product shooting? If so, how >>> did >>> you resolve the situation? >>> >> >> It sounds like you've accurately assessed the cause of your >> phenomenon. The first thing I'd do about it – the first thing I'd do >> even if I weren't having that problem – would be to ditch the >> fluorescent lighting. It's the most awful form of lighting you can >> use. Not just because of the color balance but because it's not a >> continuous spectrum source like incandescent lighting. >> >> >> I've had the same thing happen with the A100mm f/2.8 macro. The hot > spotting is sensor reflections off an inside element. I found it is really > only a problem with high key backgrounds. It's related to veiling flare. > I use studio strobes, not continuous lighting, so while the florescent may > be ugly light, they aren't causing this problem. > > -- > 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. -- “The Earth is Art, The Photographer is only a Witness ” ― Yann Arthus-Bertrand, Earth from Above -- 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.
