I'm planning on imaging the comet tonight, I'm using a star adventurer 2i, and am wondering what my tracking speed should be.
C/2023 A3 tracking speed
Wonder what the maximum exposure length needs to be, not the tracking speed (hint: sidereal). Unless you can guide on the comet. Can you?
In case you can't the relative motion of the comet is 0.14" per second. From this you can work out how long you need to expose perfore trailing becomes evident.
In case you can't the relative motion of the comet is 0.14" per second. From this you can work out how long you need to expose perfore trailing becomes evident.
30 seconds will freeze the comet and stars. 60 sec will work at 300mm and under. Any more and the comet center will show slight streaking, since tracking and guiding almost always follow the stars.
I shot the comet at 60 seconds, stripped the stars, then manually aligned the images. Lastly replaced the stars from one sub. A lot of trouble to get a stronger exposure to the sensor. On the other hand, friends with DSLRs produced fantastic single images at 20sec/800 ISO.
I shot the comet at 60 seconds, stripped the stars, then manually aligned the images. Lastly replaced the stars from one sub. A lot of trouble to get a stronger exposure to the sensor. On the other hand, friends with DSLRs produced fantastic single images at 20sec/800 ISO.
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Dave Rust:
30 seconds will freeze the comet and stars. 60 sec will work at 300mm and under. Any more and the comet center will show slight streaking, since tracking and guiding almost always follow the stars.
I shot the comet at 60 seconds, stripped the stars, then manually aligned the images. Lastly replaced the stars from one sub. A lot of trouble to get a stronger exposure to the sensor. On the other hand, friends with DSLRs produced fantastic single images at 20sec/800 ISO.
What's the best focal length?
Earlier, any FOV could produce a nice image because the comet was bright and had a long tail. Now it is dimmer and shorter. The tail is faint. So getting closer makes sense. My scope is 340mm, if you’d like to evaluate my last image (as the comet is about to set below the trees). Not much reason to get closer, I suspect. 200mm would be fine, too, but 135mm might lack impact unless there are other things in the frame (a house, trees, city skyline, etc.).
the comet is dimmer with the growing distance as it leaves the sun. Getting images will be a challenge from here on out. But not impossible!
the comet is dimmer with the growing distance as it leaves the sun. Getting images will be a challenge from here on out. But not impossible!
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Your tracking speed should be 'sidereal'. You won't be able to track the comet with a SWSA.
Without knowing your image scale, no one can give you a proper answer to this question, but generally speaking you'll probably be fine with 30 second subs..
This was with a Roki 135 and I took it as far as two minute subs tonight. My 4.2 arc second image scale allows me to get away with longer subs.
Without knowing your image scale, no one can give you a proper answer to this question, but generally speaking you'll probably be fine with 30 second subs..
This was with a Roki 135 and I took it as far as two minute subs tonight. My 4.2 arc second image scale allows me to get away with longer subs.
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