M82 with just a tri...
 
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M82 with just a tripod and a static dslr


 ah
(@ah_astro)
Brown Dwarf Customer
Joined: 3 years ago
Posts: 14
Topic starter  

I don't know of other people use Pentax's astrotracker function (haven't seen anyone), but it's quite fun.
I made this image of M82 with a static mounted Pentax dslr on a tripod (nothing else). The camera calculates sensor translation and rotation based on build in gps and compass. I use an 'old' manual achromat lens (SMC-A 200/4) fitted with a baader contrast booster.

Seeing was 'so so'. Ursa Minor's dimmest star Eta Umi was just barely visible. Milky way was invisible (bortle scale6/7).

APP processed this stack of 47 lights, ISO 3200, f5.6, with 25 bias', 25 flats, 25 darks. Postprocessing done in affinity photo.

 

m82 RGB session 1 lpc cbg

 

m82 RGB session 1 lpc cbg detail

 


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(@vincent-mod)
Quasar Admin
Joined: 5 years ago
Posts: 4736
 

Very interesting, didn't know about that indeed. What is the exposure limit etc, I guess still about 15 seconds per image?


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 ah
(@ah_astro)
Brown Dwarf Customer
Joined: 3 years ago
Posts: 14
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For this example lights were taken with an exposure time of 20 seconds per image. Depending on quality of calibration (gps/compass), focal length and location of the subject, theoretical exposure times can go up to one and a half minute (200mm lens, limited by translation and rotation of the sensor). Practically, I never managed above 50" without ending up with unwanted trails. I am generally happy when I manage 20 or 30" exposure times. Other focal lengths will result in other exposure times.


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(@vincent-mod)
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That's certainly impressive for a non tracked setup, thanks, nice to know.


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(@col)
Red Giant Customer
Joined: 1 year ago
Posts: 111
 

@ah_astro

Nice. I read about some of these pentax cameras with j built sensor tracking capability I think. Was this one of these models? Nice shot at that focal length


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 ah
(@ah_astro)
Brown Dwarf Customer
Joined: 3 years ago
Posts: 14
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@cwm2col

Thanks. The above image was taken using a Pentax K1, which has the sensor build in. In the past I have also tried the separate O-GPS1 which I think gives similar results when it comes to the tracking itself.


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