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12-09-2014, 11:11 AM   #721
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QuoteOriginally posted by SirTomster Quote
What kind of shooting do you plan to do with the O-GPS1 route?

Do you want wide angle or something with Zoom?

I also have decided to get the O-GPS1. Since I am initially interested in wide frame images with some landscape feature. I currently own the Rokinon 14mm F2.8 Manual Lens. Only $300.
Here are a few images I took with just 30 seconds exposure and some post processing in Photoshop.

I cannot wait to see what I can get with the O-GPS1.






---------- Post added 12-09-14 at 11:19 AM ----------

Thanks guys!

Wow beautiful images!
I would want to get both a nice, reasonably priced wide angle and telephoto lens.
I would think a 200mm would suffice? Would the 300mm be to susceptible to vibrations on just a tripod?

Can you suggest more specifically both a good tele. and wide angle lens... if you can? That would save me hours of reading reviews, etc.. heh
Thanks! - Marc


Last edited by Suhndog; 12-09-2014 at 11:20 AM.
12-09-2014, 02:18 PM   #722
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I would check out the images posted here and see what images were done.

Checking some of the last few pages I see:

Wide Lens
50mm F1.4 (I am not sure if the old M version or the FA 50mm F1.4.) By Chris A & stanzhou
FA31mm F1.8 Limited done by MikeSF
Rokinon 24mm f1.4 by Stockhatch
Samyang 16mm F2 by nightfly
Pentax DA 14mm F2.8 by Hyndium
Rokinon 14mm F2.8 by SirTomster



Long Lens
300mm F5.6 by Chris A
DA 55-300mm F4-5.8 ED by rjpinaz

So some lens options.

Also check out the comments by Stone G and interested_observer
12-09-2014, 02:40 PM   #723
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Ok!

Thank you!
12-10-2014, 04:00 AM   #724
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Sir Tomster, really great

12-10-2014, 10:02 AM   #725
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Remember that was just me going back maybe 10 pages and checking images and the lenses. There are a lot more pages with a lot more lenses in use. But there was a good selection there.

Personally I like the Rokinon 14mm F2.8 because I got some nice images and it is fairly cheap @ $300. Although next time I might of ordered the Vivitar version (supposedly it is the same lens just different branding) because the Vivitar has a removable hood and the Rokinon does not.

Also check out these guys on lens recommendations. They only discuss wide lenses though.

David Kingham | Lenses
Into The Night Photography: Overcoming Coma Aberration - Part 2

Eventually I might look into a limited lens like the FA31 that MikeSF uses. Either that or drive to the coast and "borrow" it from him.
12-10-2014, 10:15 AM   #726
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Thank you for all your great help!

I think for now, I will use my kit lens (Pentax SMC DA 18-55mm) for 'wide' shots, and look into a tele. lens (non zoom)...
Depending on my income in the coming months, I can then consider a wide angle lens..

Have a Blessed Christmas!

I still need to get the O-GPS1 though!

Marc
12-10-2014, 01:23 PM   #727
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QuoteOriginally posted by SirTomster Quote
I would check out the images posted here and see what images were done.

Checking some of the last few pages I see:

Wide Lens
50mm F1.4 (I am not sure if the old M version or the FA 50mm F1.4.) By Chris A & stanzhou
FA31mm F1.8 Limited done by MikeSF
Rokinon 24mm f1.4 by Stockhatch
Samyang 16mm F2 by nightfly
Pentax DA 14mm F2.8 by Hyndium
Rokinon 14mm F2.8 by SirTomster



Long Lens
300mm F5.6 by Chris A
DA 55-300mm F4-5.8 ED by rjpinaz

So some lens options.

Also check out the comments by Stone G and interested_observer
Hello,
My three lenses Pentax tested with the O-GPS1:
18-55 mm F/3.5-5.6 WR => Good for Milky way
50 mm F/1.4 SMC FA => Very Good (used at F/2.0) but not WR
55-300 mm F/4-5.8 DA HD ED WR => Good but the focus is difficult at 200/300 mm (personnal Bahtinov mask used)
12-10-2014, 06:07 PM   #728
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QuoteOriginally posted by Chris A. Quote
Hello,
My three lenses Pentax tested with the O-GPS1:
18-55 mm F/3.5-5.6 WR => Good for Milky way
50 mm F/1.4 SMC FA => Very Good (used at F/2.0) but not WR
55-300 mm F/4-5.8 DA HD ED WR => Good but the focus is difficult at 200/300 mm (personnal Bahtinov mask used)

Wouldn't a (non-zoom) 300mm be best.. Generally, a zoom lens is a compromise visually (abberations, etc.)?

- Marc

12-11-2014, 03:27 AM   #729
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I need to get back in action this winter.. so many good pictures. Why I can't get as good as those


QuoteOriginally posted by Suhndog Quote
Wouldn't a (non-zoom) 300mm be best.. Generally, a zoom lens is a compromise visually (abberations, etc.)?

- Marc
I'm using 300mm prime and o-gps. I find that about 10s exposures are longest ones for me. Maybe it is my tripod or the calibration of the o-gps but I'm not getting any decent pictures on longer exposures. I also get feeling that I need to do re-calibration quite often (every 1-2h or so).

I should also try some wide field astrophotos too.
12-11-2014, 06:00 PM   #730
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Just a quick heads up for the night shooters (particularly those new to it or want to give it a try) the 'King of the Meteor showers', the Geminids, peaks Saturday night.
12-11-2014, 07:10 PM   #731
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QuoteOriginally posted by gifthorse Quote
Just a quick heads up for the night shooters (particularly those new to it or want to give it a try) the 'King of the Meteor showers', the Geminids, peaks Saturday night.
And it is supposed to either rain or snow. Waaah! Especially since it is on a weekend! Double Waaah!

Hope others can get some great shots.
12-11-2014, 07:42 PM   #732
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QuoteOriginally posted by gifthorse Quote
Just a quick heads up for the night shooters (particularly those new to it or want to give it a try) the 'King of the Meteor showers', the Geminids, peaks Saturday night.
Thank you for the 'head's up'!

Where I live, the night sky is generally black..

- Marc
12-11-2014, 07:51 PM - 1 Like   #733
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QuoteOriginally posted by ErZi Quote
I need to get back in action this winter.. so many good pictures. Why I can't get as good as those

I'm using 300mm prime and o-gps. I find that about 10s exposures are longest ones for me. Maybe it is my tripod or the calibration of the o-gps but I'm not getting any decent pictures on longer exposures. I also get feeling that I need to do re-calibration quite often (every 1-2h or so).

I should also try some wide field astrophotos too.
I think I have some answers for you. Its not your tripod nor the calibration of the GPS unit. It is your geographic location that are the root of your problems. Let me explain. The GPS satellite constellation flies in orbits that oscillates between 60 degrees North and 60 degrees South around the Earth. You are located near Helsinki Finland, if I am not mistaken, which is at 59 degrees North. So the GPS satellites fly up from the south, and essentially turn overhead and head back south again.

What does that mean to you. Well GPS is a distance triangulated system. The GPS receiver essentially gets information from 4 satellites (latitude, longitude, elevation and time) that is converted in to a distance from the known position of each satellite. If all the satellites are clustered in a single area in reference to your location, you are going to get poor fixes. You need a good spatial dispersion of the satellites for perfect fixes. A perfect spatial dispersion would be about 120 degrees apart around you with one overhead. However all of your birds are to the south of you - i.e., at best half the optimal coverage. You will get location fixes, but their quality will be somewhat wanting.

The O-GPS unit in order to do astro tracking, will want a good fix, with a good heading (direction in which the camera is pointed), with the smallest error possible, with good consistent uniform updates. You are probably getting good updates, with a random set of bad geometry (the satellites cluster more tightly from time to time, which will reduce the quality of the fix). This is probably leading to your needing to re-calibrate more often. Also, with a location and a larger than normal error component, coupled with a long focal length which is going to have a very narrow field to track in, you are going to be subject to a perfect storm of events, which leads to abbreviated tracking opportunities.

Here is a link discussing GPS location and navigation in the polar regions.
12-12-2014, 04:12 AM   #734
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QuoteOriginally posted by interested_observer Quote
Also, with a location and a larger than normal error component, coupled with a long focal length which is going to have a very narrow field to track in, you are going to be subject to a perfect storm of events, which leads to abbreviated tracking opportunities.
Thanks for an excellent overview.

I live at 56 degrees North and normally don't see large variations in positioning - position is more often than not correct within some + 10 meters. But I have made it a habbit to regularly check the electronic compass headings found by the O-GPS1 against the true headings as can be assessed with Geosetter (: freeware). Variations over short periods of time can be quite astonishing on certain days/nights.
12-12-2014, 05:10 AM   #735
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I doubt the positional error has anything to do with it as it shouldn’t affect tracking that much, even if it is was off by a 1000meters (which it isn’t). The heading and the angle up/ down however has a large impact on the result. And the electronic compass is tricky, sometimes it’s accurate, and sometimes it’s not. The heading from the compass is also affected by the angle of the camera.

Stacking is the key to success.
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