Quote:
Originally Posted by Crater101
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So I'm looking for something that...
- Would fit on a mid-weight camera tripod;
- Would be able to be packed into a bag for air transport without breaking any weight allowances;
- Would be taking a weight of only a DSLR and lens (either a modded Canon 60D or 6D, lenses include Samyang 14mm f2.8 & Canon 135mm f2, maybe a Redcat 51 MkII at most);
- And would preferably have it's own power source / battery inbuilt or replaceable, as I probably won't get the chance to use external power.
So if anyone has thoughts, experiences, or inside knowledge, I'm all ears.
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Hi Warren,
I know you said you didn't have such a great experience with one of the Skywatcher star adventurer mounts, you didn't say which one, but seem to recall it might have been the Skywatcher Star Adventurer GTI from past threads (??? backlash), anyway I used their earlier AZ mount, the Skywatcher AZ GTI and got a good result , albeit with 10 second exposure at 135mm focal length on full frame.
And I think that's the key..... Use a moderate Tracked Exposure duration which considers focal length. Sort of like the untracked 500 or 600 second rule, but applied to tracked exposures on mini mounts with moderate periodic error. In my case above @135mm focal length & 10 seconds, there was no star trailing evident with reasonably nice clean stars into the corners.
Having looked at many images on trackers even including Pentax's very clever, although somewhat limited, Astrotracer, which moves the sensor to track the stars, I would say that for a tracked exposure on one of these mini mounts, one should look at using something around a 2000 to 3000 rule (product of exposure duration in seconds and focal length in mm). You could reduce that guide somewhat, depending on how critical you are of perfection and the distance you are from the celestial pole.
In the case of my image, an exposure duration of 10 seconds and Focal length of 135 made it 10x135 = 1350
Final Image is 49 x 10second images at f/2.8 ISO 100, Nikon D750, Sigma 135mm f/1.8 & tracked with SW AZ GTi. Polar alignment was by compass and inclinometer.
Eclipsed Moon & Rho Oph Lunar/DeepSky Image
Based on the results i'd suggest that 20-30 seconds would also possibly be OK, but I'd push the sensitivity first, since the above image was taken at ISO 100, maybe even open the lens to f/2 as a trial.
BTW Canon & Nikon, if you're listening ..... ADD AN ASTROTACK FUNCTION
Best
JA