Questions about field of view

[Radscanner]

I wonder if someone with knowledge of Mak or SCT scopes could please confirm this: These short scopes with cassegrain optics are long focus lengths and high F numbers and I keep reading that they are not very good for deep sky because their FOV is narrow. But what I don't quite get is that surely if you simply put say a 32mm eyepiece on it that would halve the magnification compared to a 16mm EP and widen the FOV to that approaching an F5 reflector scope with the 16mm eyepiece (or thereabouts). In other words can an F5 and F10 scope end up with a similar field of view by simply by using half the eyepiece magnification power on the F10?

Or is it that even with a very low magnification these Cassegrain scopes are still giving too narrow a field for deep sky objects or wide messier objects?

Thanks to anyone who can clarify.

[Radscanner]

...as annendum to the above, I'm also wondering what the specification "Angle of view=1.4 degrees" in the list of specs means for scopes on suppliers sites. Does this mean with a set eyepiece, or set magnification or something else, because surely it depends what magnification you use?

[Capricorn]

Yep, that works. Nice long focal length eyepiece 25mm, 30mm, 32mm is OK.

Ultimatly if you have a 6" SCT then you have a 6" telescope, it collects the same amount of light if refractor, SCT/Mak. reflector.

It does mean that an f/6 scope with a 30mm eyepieces gives less magnification the the f/10 SC, same diameter objective.

This lesser magnification means that the smaller image has a greater concentration of the light squeezed into it so the small image is brighter. It is really this brighter image that is more suited to DSO's. Usually at the initial stages of locating the damn things.

I have seen M1 through a 6" SCT. M1 is small and dim, the SCT is a long focal length, it was there and visible.

The "ease" of getting greater magnifications in a Mak/SCT means that you tend to lose field of view so Andromeda, Pleiades will not usually fit in all at once. Andromeda will not make it in most scopes however so not really much difference - use binoculars for it.

Simply buy LONG focal length eyepieces, go DSO hunting.

[RichieP]

I think SCT and MCTs are fine for visual observation of most DSOs. With a long focal length eyepieces you can get over a degree field of view. With my 150mm mak (1800mm focal length) I can get 1.33 degrees with a 60degree 40mm eyepiece.

The problem, in my experience, comes in finding objects in the first place, as you don't have the luxury of a low magnifcation, wide field view to help you get on target. Perhaps not a problem if you use a goto mount though.

Regards

Rich

[Radscanner]

Thanks for the clarifications. Appreciated.