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09-22-2014, 07:29 PM   #1
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O-GPS1 Astrotracer: gadget or technological wonder?

Greetings everyone,

I've been using the astrotracer for almost a year now (some results at O-GPS1PhotoGal). I really like that little unit because it fits my sky observing habits very well. Living near the center of a city of 3 000 000 I get most of my observing while camping with the kids when trunk space available for astro gear is far from infinite! So I went from shooting 20s exposures with 18-55 at 18 mm to shooting 2 min at 18 mm and stacking 40s shots with a 200 mm. A huge improvement for me.

I've been asked by a group of CCD astrophotographers in Quebec to make a presentation about the astrotracer next November 15. If anyone would like to share their experience or thoughts about the device, I think it would enrich greatly my presentation. I would like to know about the experiences you've had with the o-gps1. the pros the cons, what's the best lens, tips and tricks you've discovered along the way and also if you could indicated what level photographer you are and what level astronomer you are. I would be very grateful. I know there are excellent threads in this forum and in the astrophotography group about the device, and I'm going to present some of the wisdom presented there but I thought an update on the question may be useful.

Best regards,

09-23-2014, 03:30 AM   #2
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I Will write a Little when i get home
09-23-2014, 06:29 AM   #3
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There are whole threads devoted to astrophotography, granted you'll find telescopic work there too. Some are OGPS only threads, just do a search.

I use the OGPS in the field when taking pictures of insects so I can catalog my observations for science.
09-23-2014, 08:11 AM   #4
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Good Morning Sky,

Well here are some thoughts that have not made it to my long post as of yet.
  • I see two modes of operation, sky only and sky with some landscape elements. Sky only is straight forward, shoot it. Sky with landscape - you need to shoot for the sky (with tracking) and then shoot again without tracking, at a much lower ISO, and hence a much longer shutter. Then combine the two images. The O-GPS1 interface could assist in this mode much better, as you can not change the ISO without leaving the GPS mode. This is somewhat of a PIA. To get the image quality of the landscape to somewhat match the start, I have been trying to to ISO 200 or 400, which takes a really really loooong shutter times.
  • In particular for sky only, and your astro friends know this much better than us - the camera is pointed up, with its back down. Access to the back, in particular the buttons is a PIA. Plus, Pentax in their infinite wisdom, does not offer any tethering (they use to, but pulled it after the K20D for whatever reason). The flucard does not do the job. I have lost count of the times where I was going for the [OK] button and have wound up hitting something else (&^%$#).
  • A ballhead is nice, but does not provide the amount of needed control for fine positioning. I have actually went out and found a geared head that allows fine adjustments for all 3 axis. This is again something that your astro friends know better than us.
  • When shooting at the maximum time the GPS calculates, the stars in the corners start to trail around the center. If you think about it, that is somewhat expected. So for my wide angle stuff 8 to 30mm, rather than 5 minutes, I just use 4 minutes at a max. I also think I read somewhere that there is a limit on the amount of elevation that can be used. I believe that I read (somewhere here on the forum) that at an elevation of 45 degrees and higher, things started to not track so well. I have not confirmed this.
  • If I were to be really serious, I would go whole hog. But living in Arizona with the clear skies, the O-GPS1 is the perfect compromise (for me). It's easy, simple, works really well (just stay away from large metal objects). You just have to realize that this is a compromise and all things will not be always absolutely perfect in every situation. There are limitations to all of this.
  • Really fast lenses, help a lot. About a month ago I was out shooting with a couple of other folks. One brought along his brand new Sigma 30 f1.4. It beats f4 or f2.8 every time.
  • The O-GPS1 is not a panacea - it does not solve all the problems. You still have to work at it.



09-23-2014, 09:47 AM   #5
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Owing two "portable" German Equatorial EQMs (first one since1981) and the O-GPS1 (since June 2012), I can state that the O-GPS1 is not a replacement for a good EQM; nor is it adequate for really long exposure 'serious' astrophotography, but:
  • The O-GPS1 is the ultimate in portability - also on travels
  • It gives me the freedom to walk around and change both scene and viewing direction during one and the same short session
  • It can be used with any tripod - or even just a bag of rice - while "portable" EQMs may suffer from several stability problems, and
  • Calibration is quick - very quick compared to 'ad hoc' polar alignment (for me at lest)
  • That allows me to grab the opportunity, even if I only have very limited time to spend under the stars
  • Calibration is reasonably accurate (most of the time) for me. I can use lenses in the 200-300mm range for up to some 40s and yet allow myself to crop tight
  • It isn't perfect and dead-sure to use; on some nights everything conspire against me and I just have to pack up - but then again, that may also happen for a clumsy person like me with my EQMs.....
Do google 'Pentax Astrotracer Images' . That will lead you to a lot of interesting homepages and images.

---------- Post added 09-23-2014 at 07:06 PM ----------

Ah yes and don't forget to add:
  • as an "added benefit", one gets geotagging and direction of the image - all in the same, small package!
  • It carries it's own battery and thus, it does not drain the camera battery
09-23-2014, 04:43 PM   #6
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one "flaw" I have found with Astrotracer is that it doesn't do well when pointed much above 45 degrees. Not sure why because in theory the GPS should work no matter what the orientation. But that is my experience. While for some that might be a reason to not pick up this little wonder, I find it to be quite useful -- much like a flash: appropriate at certain times and less so at others.

YMMV

Michael
09-24-2014, 01:25 PM   #7
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Thanks everyone for your input, that's exactly what I was looking for.

I_O, if you were to go whole hog would you still keep the astrotracer or sell it for cash to put on your equatorial mount?
Stone G. I had never thought of using a bag of rice but wow, that is as you say ultimate portability. My o-gps1 is always with me but not my manfrotto tripod.
MJSfoto 1956, I deal with that all the time indeed. I haven't gone through all my shots from last night but it seemed to be better than usual at high altitude. I'll post some results in the next few days or so.

Thanks again, my presentation is due only in four weeks so anyone feel free...
09-24-2014, 08:37 PM   #8
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Evening Sun,

Quite frankly and in all honestly, the O-GPS1 fits what I want to do perfectly. Light weight, small in size, and a very "neat" concept - that fits on a camera. I like to shoot landscapes with the MW or just a simple star field. It lets me do that. I have become fundamentally lazy in my geezer years (getting ready for retirement). The deep astro images are really nice and I enjoy looking at them, while marveling at everything that they encompass. I am working my way out to about 200mm. I really think that around 85mm will be my limit. With that in mind, this little GPS system coupled with the movable sensor, does it all for me. It also has fixed limits and I do like that - not the technical limits of the unit, but the O-GPS is an end to itself. Going with an equatorial mount, will lead to a scope, and more gear and that really is the wrong direction for me. I want to be more of a photographer - and this let's me include just enough astro to indulge my interest.



09-24-2014, 09:12 PM   #9
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Another added benefit for those who are far more serious than I am about star shooting is that the unit auto-embeds the date, time, and location of the shots (because, thats... sort of what it's for).

So if you're on a trip and you want to log "Hey, where did I actually take this amazing shot of the milky way with that mountain..." you can look and see exactly where that shot was. It saves having to jot all the pertinents down where (if you're like me) you'll quickly forget to do so.

Anotehr benefit is that you can use it out and about in a much more public spot than you would if you were toting around a huge scope with its mount etc etc and, just as importantly, scamper off if you need to leave in a hurry. I've had to do the latter before when I had Creepy McCreeperson pop up from the bushes down by the river here (seriously, I think he was sleeping under the local bridge) and start asking me strange questions at 1 in the morning. I was able to just be like "Dude, I need to go," throw my stuff in the truck and be gone.
09-26-2014, 01:35 AM   #10
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By the way, horrible Google Translate or not, I can recommend this interview with the Astrotracer developers:


"I approached to Pentax to Astro tracer"

Direct link to interview translated:

http://translate.googleusercontent.com/translate_c?depth=1&hl=en&ie=UTF8&pre...UlVorRx0vI9Fpw
09-26-2014, 02:37 PM   #11
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Thanks I_O, funny how that souds just like me. I have an eq. mount I wanted to motorize but the astrotracer is enough for the time and money available for astronomy for now.
Sagitta, I use to have people call the cops on me all the time because someone parking in a dark neibourghood 1 in the morning is indeed suspicions. Your remark about the time is very interesting, I didn't think about that.
Stone G., Thanks for the link, there is so little technical info about the device available I will take the time to go trough this one.
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