takumar 200: do I need to guide?

[alacant]

Hi everyone

Canon 700d with Takumar 200mm f4 on well polar aligned eq6.

Question: will it need guiding for 5 minute light frames?

Cheers

[Atreta]

I think you can do it with the eq6 and the 200mm lens.  I have an heq5 and 135mm lens and could do a 10 minutes test without guiding. I have a 75-300 that could be tested to give you a better answer, but it's not working for ap at all to me. 

[ollypenrice]

What matters is the pixel scale rather than the focal length. You'd be imaging at 4.4 arcseconds per pixel I think. The PE of an EQ6 is in the 20 to 30 arcseconds area over a full turn of the wheel which is 8 minutes, from memory. So it doesn't look good! However, if you have equal and random errors you may get fairly round stars, though this is no indication of real resolution.

4.4 arcsecs is not particularly tolerant. Our Tak rig works at 3.5"PP on a mount with a PE of less than 3 arcseconds and we certainly need to guide it.

Olly

[RichLD]

I would say yes, given the pixel scale.

[don4l]

I'm currently imaging at 4.8" on an EQ6 and I need autoguiding for anything over one minute.