This is useful if you cannot see your target or are in a very difficult field to confirm.
The other night I was wanting to capture comet C/2017 T1 (Heinze) from the backyard with my Canon 60Da and 70-200mm telephoto set at 200mm. So I focused on beta Cass, then shifted the mount for what seemed like a reasonable amount and took a test shot. My finder starchart field was too wide for me to confirm the starfield on the image, and my fingers were freezing up at -25C, so I took a chance that it was good enough.
The next day, I found out it wasn't. Then I remembered in my youth in the light-polluted skies of downtown Montreal, using RA and Dec sweeps that began at a bright star, then swinging the scope in fixed increments to arrive at my target.
It's a pity the StarAdventurer does not have setting circles. Okay, but it does have enough to do it:
Dec: 15 full turns of the Dec knob move the camera exactly 90 degrees! 1 full turn = 6 degrees
R.A. See those tabs or teeth above the RA clutch? Moving the scope 4 of those tabs is 1/5 of a circle: 1 Tab or tooth = 1h12min RA! You should practice the RA movement in daylight (or a mild night), because you have to hold the scope steady while first lossening the RA clutch. Once well loose, shift by the appropriate number of full and partial teeth. IN THE RIGHT DIRECTION. Yes, the first time I did this at -25C, I moved the scope the wrong way in RA. Sigh. But when I checked the field the next day, it was bang on the amount of shift. …this is why it is good to practice in the backyard before wasting opportunities in a dark sky….
Just in case like me, it was not obvious from the start, that the camera platform on the StarAdventurer is designed so that the long part of the frame is aligned exactly N-S in Dec, while the short part of the frame covers RA. Assuming you attach the camera directly instead of using a ball head.
Alister.
The other night I was wanting to capture comet C/2017 T1 (Heinze) from the backyard with my Canon 60Da and 70-200mm telephoto set at 200mm. So I focused on beta Cass, then shifted the mount for what seemed like a reasonable amount and took a test shot. My finder starchart field was too wide for me to confirm the starfield on the image, and my fingers were freezing up at -25C, so I took a chance that it was good enough.
The next day, I found out it wasn't. Then I remembered in my youth in the light-polluted skies of downtown Montreal, using RA and Dec sweeps that began at a bright star, then swinging the scope in fixed increments to arrive at my target.
It's a pity the StarAdventurer does not have setting circles. Okay, but it does have enough to do it:
Dec: 15 full turns of the Dec knob move the camera exactly 90 degrees! 1 full turn = 6 degrees
R.A. See those tabs or teeth above the RA clutch? Moving the scope 4 of those tabs is 1/5 of a circle: 1 Tab or tooth = 1h12min RA! You should practice the RA movement in daylight (or a mild night), because you have to hold the scope steady while first lossening the RA clutch. Once well loose, shift by the appropriate number of full and partial teeth. IN THE RIGHT DIRECTION. Yes, the first time I did this at -25C, I moved the scope the wrong way in RA. Sigh. But when I checked the field the next day, it was bang on the amount of shift. …this is why it is good to practice in the backyard before wasting opportunities in a dark sky….
Just in case like me, it was not obvious from the start, that the camera platform on the StarAdventurer is designed so that the long part of the frame is aligned exactly N-S in Dec, while the short part of the frame covers RA. Assuming you attach the camera directly instead of using a ball head.
Alister.
