2" vs. 1.25" eyepieces

[Astrokev]

Hi All,

Probably a daft question, but I'd be grateful if someone could advise on the key advantages of investing in a 2" focusser/eyepieces compared to 1.25" ?

My current 1.25" works fine, but what am I missing out on?

One day I plan to be able to image through my DSLR, so I guess a 2" focusser would be much better for this in terms of general robustness, but what are the other advantages (apart from taking some strain off my wallet!).

Thanks

Kev

[Ags]

2" eyepieces give you a wider field of view. That's all. In my telescope, the widest field of view I can get with 1.25" EPs is 1.25 degrees. If my scope would accept 2" EPs (which it doesn't) I would be able to get 2.05 degrees.

[Astrokev]

Thanks Ags.

Is this loss of field because the 1.25 drawtube cuts into the light cone from the secondary, whereas a 2" drawtube allows the full cone to reach the focal plane unobstructed?

Thanks

[Ags]

I think it is the tube of the EP itself that is the limiting factor, but I'm not sure.

[brantuk]

The big benefit of course is that with the wider fov you can fit the larger objects like galaxies and open clusters more fully into the view

[Ags]

The big benefit of course is that with the wider fov you can fit the larger objects like galaxies and open clusters more fully into the view

Too true - the pleiades through my telescope look like a picture of someones face, but cropped so you only see the bottom half of their eyes, the top lip of their mouth and their nose. It's such a shame the 4SE does not take 2" EPs. Sniff.

[Peter Drew]

The 2" fit has benefits for prime focus photography and the use of long focal length large FOV, large diameter eyepieces. Check the field stop of your eyepieces, if it's less than around 30mm then there is no benefit regardless of the type of design or focal length as this is the limiting factor.

[red dwalf]

one thing i`m not sure about with my 6" sct is that the hole where the visual adapter screws onto is only 1.25" so what differance would a 2" diagonal and 2" eyepiece make if the light comes in from a 1.25" opening ?