I may be incorrect about the image difference between a refractor & reflector. I **should** know, but I would need to check. In any event matching the alignment of the TTL extension with the O-GPS1 attached (to the telescope tube, presumeably) would add another complication (possibility for error in precise alignment) that may or may not be successfully overcome. For example the O-GPS1 doesn’t like being near metal, and how do you gyrate the telescope with TTL/O-GPS1 attached to perform the precise calibration?
Hope this helps. Darren Addy Kearney, NE On Sat, Jun 9, 2018 at 10:10 AM Darren Addy <pixelsmi...@gmail.com> wrote: > Your TTL idea would be unnecessary on a refractor, so you must be thinking > of using a Newtonian design. In that case I don’t think it would work > because the image is reversed. I think the program in the O-GPS would be > designed to shift the sensor in only one direction (the one that work with > ordinary camera lenses of a refractor-sort of design). Not sure though. > > Also, keep in mind that the maximum exposure time possible with the > O-GPS/AstroTrack gets shorter and shorter as the focal length gets longer. > A shorter exposure time with a longer focal ratio is the opposite of what > you want for catching photons in astrophotography. > > Respectfully, > Darren Addy > > On Fri, Jun 8, 2018 at 3:15 PM luiz felipe <luiz.fel...@techmit.com.br> > wrote: > >> pretty much divided between the Vixen Polarie and the O-GPS 1. just >> because if I get to use a small newtonian reflex, the camera will be >> pointed at 90 degrees from the subject, and I don't think de astro >> function of the O-GPS 1 can handle that. >> >> the Vixen Polarie is small, and seems able to handle both the APS >> Pentaxes and a small reflex telescope - and as long as it's properly >> aligned, the pics should be ok. >> >> as far as money goes, it's one OR the other, and that's why I'm looking >> for advice. building a barn door star tracker is the third option, but >> I'm not really with time to make a proper unit. toughts? ideas? >> >> thanks!!! >> >> -- >> luiz felipe >> luiz.felipe at luizfelipe.fot.br >> >> -- >> PDML Pentax-Discuss Mail List >> PDML@pdml.net >> 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 > -- “The Earth is Art, The Photographer is only a Witness ” ― Yann Arthus-Bertrand, Earth from Above -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.