2 inch eyepieces in 12" reflector

[gooseholla]

Hey.

Got a new 12 inch reflector and it takes 2 inch eyepieces. I have a 26 mm and a 32mm on their way. However, what would be the lowest useable eyepiece for it? Focal length is 1600mm (f/5.3). For example, revelation go down to 50mm, would this be of a use, or not? Also, what about going above 20mm, say a 15mm?

Thanks.

[John]

Depends how old you are really and how wide your pupil dilates at max. Personally I'd not go longer than the 32mm which gives a 5.7mm exit pupil with your scope. As a 52 year old thats probably the absolute max exit pupil I can make use of

Below 20mm you might as well use 1.25" eyepieces, unless you want the 100 degree fields of view.

[gooseholla]

Right, good to know. I'm only 26, but others who will be viewing are 50 +.

[Moonshane]

I used to have this scope and it is a superb instrument . I feel the answer would depend on how much light pollution you suffer. I happily used a 35mm panoptic but when I tried a 26mm nailer this gave a much better view given I had a lot of lp. If I observed from a dark site then I would have been happy with the 35mm. If you suffer from lp then I would suggest a max of maybe 30mm. I'd fouNd that cheaper widefiekd eyepieces even those designed for f6 went mushy when used used with the oouk f5.3

not suggesting you spend big bucks on tv eyepieces but using focal lengths by way of example. That said in my experience tv are worth the money.

[gooseholla]

One of the eyepieces - the 26m - is a Panaview, the 32mm is a GSO, I believe. Someone offered me a 20mm TV!! Might take it actually.

[John]

My 20mm TV Nagler is my most used deep sky eyepiece with my 10" newtonian

[Mr Flibble]

As already stated it depends on the individual. If it helps, I'm 35 yrs and I could use an eyepiece that gave an exit pupil of 6.4 but only in a really dark site where my pupil would be near its max dilation. If I used the same eyepiece in a not so dark site, i.e. my back garden, then I'd keep seeing the reflection of the secondary mirror which was really annoying. Now I've settled on a widest eyepiece that gives an exit pupil of 5.6 and it works well from wherever I'm viewing. Hope that may be of some help.

[gooseholla]

Can I trouble you, then, John to some questions:

1. do you think it'll unbalance the dobsonian?

2. what makes it so good? is it the magnification or just clarity of views?

3. How big is it, really, in terms of ep - bigger than a hyperion?

[John]

Can I trouble you, then, John to some questions:

1. do you think it'll unbalance the dobsonian?

2. what makes it so good? is it the magnification or just clarity of views?

3. How big is it, really, in terms of ep - bigger than a hyperion?

Q1 - probably not - the 20mm Nagler Type 5 weighs around 1lb. My 31 Nagler however weighs 2.2lbs and can cause balance problems in dobs.

Q2. For me it's an 82 degree field of view that is sharp right across and enough magnification to darken the background sky while showing quite a lot of it.

Q2 - It's a while since I used a Hyperion but I reckon the 20mm Nagler is a touch smaller, definitely shorter.

The 22mm Type 4 Nagler is an excellent alternative and some prefer it's more comfortable eye relief and larger eye lens. That one is a bit larger and heavier.

These are pricey toys though so do look at the competition - the Explore Scientific 82 degree eyepieces offer much of the Nagler's performance at less cost.