Calculating How Long Before Object Drifts

[Adam Isa]

Hello all. I remember going on a website before that told you, based on your location, length of telescope etc etc how long you had before the image would drift for astrophotography. Does anyone know of this website, or even something similar. Regards.

[davew]

Sorry can't help with the website but I'll have a go. It mainly depends on focal length and area of shooting in the sky. So, if you get a 50mm camera lens pointing at the Celestial Equator expect less than 30 seconds. At the pole, no drift but slight rotation. A 100mm lens at the C E will give 10 / 15 seconds. 200mm 5 seconds and so on.

Unless someone knows better. If in doubt, try it and see.

Dave.

[barkis]

If you have a scopes drive off, a star will drift about 15 arc seconds in one second of time.

You need a high power to see the movement. It would be barely perceptable in a low power view

Ron

[davew]

I've got hold of a table for camera lens photography.

Any good ?

Dave.

[Adam Isa]

Thanks for the replies, some good suggestions there and that table will come in use Dave.