Leon I've done a LOT of research on this matter with great input from members here. The base 500 rule works reasonably but depending how far from the central true south (I can't remember the fancy name, my heads very messed up at the moment-oh, the pole) the value will drop because the further fringes will rotate more or faster (I can't even remember the terms for this condition, sorry) than the central point. A lot of Astro people tend to more use the 400 rule for wide-field from what I found, same as the 500 rule but slightly shorter exposures and less chance of drift. I myself used a more complex mathematical equation I found and came up with 16 seconds using my 14mm f2.8 Samyong (or whatever it's called). I can do 30 second exposures if close to the southern pole but when I get further out along the fringes of the MW my shots are so much crisper at 16 seconds.
I believe JA is extremely well versed and experienced in this particular subject and a very smart, helpful gentleman.
Hi Leon,
If you find the 500 rule doesn't quite work due to the declination or sensor size/resolution, and if you are keen on digging a bit more technically, here is a more comprehensive calculator: https://www.lonelyspeck.com/advanced...me-calculator/
I have found that the 500 rule works well for a 14mm lens on an iOPTRON drive set at 1/2X. Both the stars and landscape features are acceptable on an A4 print.
I have found that the 500 rule works well for a 14mm lens on an iOPTRON drive set at 1/2X. Both the stars and landscape features are acceptable on an A4 print.
I should imagine it would work exceptionally well on a guided mount?
I have a guided mount but usually prefer the simplicity of a standard tripod which is easier to travel for wide field shots.. I really should try piggyback on a scope one day.
