"Zooming Out"

[gsfergy]

Hi all. I recently spent a good chunk of time working with my Celestron Nexstar 8SE and have "mastered" viewing the moon and even taking some nice photos (it has been a perfect object to get started with).

But with the out-of-box equipment I'm "too close" in the eyepiece to view the entire moon when in its full phase.

So, is there a way to (sorry for the newbie words) -- "zoom out" -- and be able to see the entire full moon in my eyepiece? I'm assuming there is an accessory/attachment that would let me do this and not something I can do myself with the equipment out-of-box.

Thoughts and comments are appreciated

glen

[alan potts]

Glen,

We will need a little more information, like focal length of scope and focal length and field of view of the eyepieces you have.  In general terms though you will require a longer focal length or wide field eyepieces, or     both. If say now you have a 25mm eyepiece with a 50 degree FOV (field of view) you will need to go to either a 32mm with the same FOV or one with a wider FOV. An eyepiece   in the area of 24-26mm can have a FOV  from 40 -100 degrees though the wider ones cost much more. I would say in this area 60-68 degree is about the norm, though  eyepieces that came with the  scope will be about 50 degree.                                                                                                                                                                                                                                                                        .

Hope this help a little.

Alan

[ronin]

Guessing you mean less magnification to achieve a wider field of view?

The field of view you get is:
Eyepiece field of view / Magnification   (can be expressed different ways as magnification has the eyepiece focal length in it)

If you got plossl's with the scope they have a 50 degree FoV.

Assuming a 25mm on your scope that makes a magnification of 81x, so what you get is a FoV of 50/81 = 0.6 deg.

The whole moon should just fit in but it will be a bit to much for comfort.

You can see where this is going:

1) Less magnification = 30mm or 32mm plossl.

2) Wider FoV eyepiece.

Least costly is the 30mm or 32mm plossl.

There are 40mm plossls but the have a narrower FoV and so come out the same as the 32mm plossl's at the end.

A 32mm will give 63x and so just under 0.8 deg view.

Welcome to the world of collecting eyepieces.

As you say ON you could look at the Antares W70 eyepieces, they do a 25mm which is still 81x but at 70 deg give you a FoV of 0.86 deg. Antares are Canadian so you should find one.

Owing to how all this works a 25mm Astro-Tech Paradigm with 60 deg will give you the same view as a 30mm plossl. So it is a case of working through the numbers a little.

Will say that you may well want even wider views, Orion and the Pleiades are bigger then 0.86 deg. So investigating even wider ones could be required. The wider they are the more they cost.

[Uhwaz]

http://www.12dstring.me.uk/fov.htm

you can check here what you should be able to see with your scope and EPs just select from menu

hope that helps

[glowjet]

If you actually want to zoom in and out, why not invest in a decent quality zoom lens, your scope is an 8" f10 Schmidt/Cass with an fl of 2032. You would initially be best to take advice from FLO or the forum, as to which make and type fits the bill for your scope. However, any large eyepiece of this type will, no doubt, preclude you from going beyond Zenith, because of the projection striking the mount and causing damage. Something you would have to safeguard against, with a computerised mount 

[Peter Drew]

Zoom eyepieces are great on a 8se but reasonably priced ones have about a 40 degree field at the 25mm setting so might not fit the full Moon in. A standard zoom usually clears the base if fitted to a 1.25" fit diagonal. The Moon and planets won't get near the zenith in Canada. 

[ollypenrice]

The real solution is to go for a 2 inch visual back and a widefield 2 inch eyepiece. This will really open out the field of view. 

A caution; at some point you'll come across focal reducers for your scope. They exist, though only the F6.3 would be useful to you. However, a widefield 2 inch EP can go as wide as the scope allows without the reducer. Reducer plus 2 inch EP does not go wider than 2 inch EP without reducer. The reducer would be useful if you want to stick with 1.25 EPs. You might pick up a used 32mm TeleVue Plossl, as I did, which is a good bit of kit and reaches the maximum possible field allowed by the 1.25 format.

Olly

[nicoscy]

A 32mm plossl of any brand will do well as SCTs are forgiving to eyepieces, courtesy of their long focal ratios.

However, I would be going the other way about it, with higher magnifications to begin exploring the features of the moon (there's a "lot of meat" on the moon to do this actually).

Taking it a step further, using binoviewers on the moon takes lunar observing to a whole different level...

[m37]

I switched to a 2 inch eyepiece for wide angle stuff (not everything though; too expensive!!!). Got a cheap skywatcher 28mm for under £30gbp. Think it's a modified kellner type but it's perfectly sufficient for me.

Makes a heck of a difference.

[gsfergy]

thanks everyone! i have a lot of research and consideration to do! I appreciate all the input :)