Sample widefield shots w Astrotracer

[vineyard]

Hello,

I'd got a little GPS dongle for an old Pentax earlier this year so that the Astrotracer functionality could be used.  I thought I would try it out with an old 50mm SMC M f1.7 lens.  Here are 3 sample shots (JPEGs for size) - the first is a single shot of Hyades (60s, ISO 200, I can't remember the f-stop but it was definitely not wide open b/c the lens is definitely soft at f1.7 but gets much sharper stopped down).  The second is a stack (!) of 2 images of the Hyades.  The third is a stack of 3 (!) images of the Pleiades.  I use the word "stack" as tongue in cheek but I was curious to see what might emerge (only ABE & HT done, no calibration w darks or flats etc).

These were from Christmas Eve so the moon was out & BRIGHT (I had put a Baader M&SG filter on but even then no real chance w huge gradients).

All told I think this is a handy little thing for v mobile wide-field astro (just a camera, the GPS dongle which goes on the flash hotshoe & a tripod needed).  Best for dark skies I guess.  I want to try the AP capabilities of Pentax's std software a bit more just for fun.

Cheers all,

Vin

 

[happy-kat]

Had to read up on that device. It's clever and small is you already have a Pentax but that makes its very niche.

Those at 60s look very useable. Did you try any longer ones to see at what point your experience bottomed out?

[vineyard]

4 hours ago, happy-kat said:

Had to read up on that device. It's clever and small is you already have a Pentax but that makes its very niche.

Those at 60s look very useable. Did you try any longer ones to see at what point your experience bottomed out?

Hi, yes I suspect only Pentax have the patent for it (b/c otherwise any DSLR w image-shake compensation should be able to offer this?).

Unfortunately I didn't have time to test it methodically.  At 120s there was some trailing (but I didn't do a "Precise Calibration" option that is also apparently available, so maybe that would have made it a bit better).  There was too much LP to allow 120s anyway (even w lowest ISO).  Upto 80s was fine.  The sharpness seemed sensitive to the f-stop being used. I was silly (not being used to AP w DSLR) and left the ISO at 200 - I should have increased the ISO at the smaller apertures to see how much more could be captured even w 60-80s.  Will try to be a bit more methodical next time.

Pentax also has a "Composite" function in camera, which I think basically does some form of stacking (but w/o calibration I guess) and generates a single image.  I'm quite curious to see what that produces!

Cheers,

Vin

[scotty1]

I recently bought the GPS astrotracer,and it seems to work well for a simple astro setup. 

Not sure how well it performs with comets, I have a K5, I'm not familiar with the in-camera stacking, are you using a K70 body?

[vineyard]

On 06/01/2021 at 22:10, scotty1 said:

I recently bought the GPS astrotracer,and it seems to work well for a simple astro setup. 

Not sure how well it performs with comets, I have a K5, I'm not familiar with the in-camera stacking, are you using a K70 body?

Hi, sorry for slow reply - a few crazy things happening in the world yesterday 😂

Yes I'm using an old K70.  I haven't yet had a chance to try the in-camera stacking (the Interval Composite option) nor the Pixel Shift - but I do want to, they look intriguing.  The Starstream is fun to watch building up - if you frame it right you can probably get some v nice images with a foreground.

Cheers!

(PS - on comets, I don't know I'm afraid but it's a great idea - I didn't think of using Astrotracer for Neowise, doh)

[vineyard]

Here are a couple of images from last night (v cold).  CZ Sonnar 135mm at f8 on the K70.  30s on the AstroTracer.  Single shots, w no calibration.  JPGs for size.

 

[vineyard]

A wider lens - old Pentax 35mm f3.5 but taken at f8. The first shot 60s, the second 120s on Astrotracer (at 180s there was some slight trailing).  Both ISO 200 (w a Baader M&SG filter in front).  Both single shots.  The blur on the bottom left are clouds that were moving across.

(Had a bit of a disaster - was going to use the iOptron SkyguiderPro but somehow the tripod toppled and broke wedge - luckily no other damage done (camera was not attached).  So I thought I'd do a quick astrotracer to experiment).