Re: Vixen Polarie - not Pentax, but I'll use with Pentaxes - any toughts?
Darren,there are some issues with this idea indeed. but I'm willing to try. calibration is performed by rolling the unit on 3 axes, isn't it? IF the communication between O-GPS and camera works through the extension, maybe rolling the connected unit before attaching to the telescope is possible. the reverse position of the image and how the sensor should move to keep proper framing is something I didn't think about until now - IMO a test is the best way to see what will happen. maybe the communication fails with the cable. anyway, since I don't have the telescope right now, I'm going for the O-GPS1 - and adding a TTL extension just to see what happens. even the smaller tracking time of the O-GPS will be an improvement to what I can do today - should allow me to lower the ISO and get cleaner images. Thank you for the comments - will post any results, later. even receiving "imported goods" here in Brasil is a challenge. -- luiz felipe luiz.felipe at luizfelipe.fot.br Date: Sat, 9 Jun 2018 10:10:35 -0500 From: Darren Addy To: Pentax-Discuss Mail List Subject: Re: Vixen Polarie - not Pentax, but I'll use with Pentaxes - any toughts? Message-ID: Content-Type: text/plain; charset="UTF-8" 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 -- 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.
Re: Vixen Polarie - not Pentax, but I'll use with Pentaxes - any toughts?
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 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 > 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.
Re: Vixen Polarie - not Pentax, but I'll use with Pentaxes - any toughts?
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 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 -- 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.
Re: Vixen Polarie - not Pentax, but I'll use with Pentaxes - any toughts?
Darren, Larry, thanks for your toughts - precisely the kind of info I'm looking for, from hands-on knowledge. Darren, I have used my phone's level and a compass to set the camera for Iridium trail photos and to look for comets, and am near the equator - no real need for a latitude wedge, just some tripod leg tuning until I'm close to 4deg tilt in the right direction. since I intend to keep the exposures as short as possible (yet longer than my current 2 sec limit), some small errors should be acceptable - and from what I understand, the Polarie is not plagued by the tracking error a tangential barn door drive is famous for. the need to manually track between exposures with the O-GPS is part of the reason why I am interested in the Polarie/ barn door drive, added to the possible use of a smallish reflector. the calibration proccess - in theory - does not frighten me. I will have a setup to make either way. one question, for you users - this O-GPS 1 calibration holds with the camera sleeping (not off but after the metering time-out)? for me, the best about the O-GPS is both size and faster setup/ calibration - or am I wrong about the real world calibration? last night, talking to Larry, it did pass my mind a curious notion - that **IF** the O-GPS1 actually communicates with the camera by means of the flash contacs, **AND ASSUMING** said comm would still happen through a TTL flash cable, would it be possible to align the O-GPS1 with a telescope tube and get the correct tracking? context: under 1000mm tubes, most likely in the 500 to 650mm. anyone with the O-GPS and a TTL flash extension willing to make a field test?? it could also open the way to some sideways traking and curious images. thanks yet again, and not only for the ideas, those pics ARE outstanding!!! -- luiz felipe luiz.felipe at luizfelipe.fot.br history Date: Fri, 8 Jun 2018 23:17:41 -0500 From: Darren Addy To: Pentax-Discuss Mail List Subject: Re: Vixen Polarie - not Pentax, but I'll use with Pentaxes - any toughts? I have the Vixen Polarie. I had an O-GPS1 for a time, but sold it. I now have the AstroTrack built into the K-3ii. The biggest differences are: No annoying calibration necessary with the Polarie, but it must be polar aligned. (I built an adjustable wedge for the latitude part of the equation, so if your tripod is level and the wedge angle correct, the only thing you need to dial in is the azimuth alignment.) https://flic.kr/p/pVVUTv Both systems will face limitations at longer focal lengths, but you can do a lot with 200mm or less. This was taken with a 90mm Tokina AT-X macro on the jankity set-up above. https://flic.kr/p/qzf4Xi The O-GPS will track during an exposure, but the camera will need to be repositioned as the earth?s rotation moves it out of frame. The Polarie will track the object whether you are taking exposures or not (meaning you can use an intervalometer to take multiple exposures (for later stacking, for example) I think the biggest problem with my current Polarie set-up is flex. Even with a high quality ball head, it can be frustrating to think you have your object framed properly, tighten the bullhead down, let go, and find your object is no longer framed as you like. This problem gets greater the more weight you try to hang of of it. Both solutions are more for wide field astrophotography. But nice things can be done with the O-GPS and the DA* 200mm f2.8 as this French Pentaxian shows: http://poirierstephane.free.fr/photos/index.php?/category/132 However, it is worth pointing out that the same lens on a polar aligned Polarie could achieve the same results. Hope this helps. Darren Addy Kearney, NE On Fri, Jun 8, 2018 at 3:15 PM luiz felipe 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!!! -- 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.
Re: Vixen Polarie - not Pentax, but I'll use with Pentaxes - any toughts?
I have the Vixen Polarie. I had an O-GPS1 for a time, but sold it. I now have the AstroTrack built into the K-3ii. The biggest differences are: No annoying calibration necessary with the Polarie, but it must be polar aligned. (I built an adjustable wedge for the latitude part of the equation, so if your tripod is level and the wedge angle correct, the only thing you need to dial in is the azimuth alignment.) https://flic.kr/p/pVVUTv Both systems will face limitations at longer focal lengths, but you can do a lot with 200mm or less. This was taken with a 90mm Tokina AT-X macro on the jankity set-up above. https://flic.kr/p/qzf4Xi The O-GPS will track during an exposure, but the camera will need to be repositioned as the earth’s rotation moves it out of frame. The Polarie will track the object whether you are taking exposures or not (meaning you can use an intervalometer to take multiple exposures (for later stacking, for example) I think the biggest problem with my current Polarie set-up is flex. Even with a high quality ball head, it can be frustrating to think you have your object framed properly, tighten the bullhead down, let go, and find your object is no longer framed as you like. This problem gets greater the more weight you try to hang of of it. Both solutions are more for wide field astrophotography. But nice things can be done with the O-GPS and the DA* 200mm f2.8 as this French Pentaxian shows: http://poirierstephane.free.fr/photos/index.php?/category/132 However, it is worth pointing out that the same lens on a polar aligned Polarie could achieve the same results. Hope this helps. Darren Addy Kearney, NE On Fri, Jun 8, 2018 at 3:15 PM luiz felipe 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 -- 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.
