Advice Please

[phantom14]

I am going to purchase  a 300mm diameter telescope, now there are two variations available, one a f4 1200mm focal length and the other f5.3 1600mm focal length, I want it for astrophotography but also I'm looking to get closer to deep sky objects I'm struggling to image with my current scope

[ronin]

Aperture is not the relevant item in AP, the f number is.

So the F/4 should be the better.

The problem is the scope will have such a cross section that any breeze at all will cause the exposure at that time to be lost.

You will also need a very solid mount, I see you have an EQ6 but I would start to doubt it being up to the job.

First forget aperture, aperture is for visual and you want a scope for imaging.

As an example an f/5 300mm reflector will give as bright an image and so the same exposure as an f/5 80mm apo.

The 300mm and 80mm is to a large extent irrelevant the f number is the governing factor.

I seriously suspect you would be better with a 100mm apo refractor then a 300mm reflector.