Worth Buying A TeleVue Nagler 2.5mm & Barlow x5?

[Zaine UK]

Hi all,

I've been messing around on:

Field of view Calculator<script src="title2.js"></script>

With the above equipment you can get some stunning views of the planets. I have a Celestron CPC 800. Would it be worth my buying the above eyepieces to get these views, or would i never be able to focus and is it un-realistic?

[GazK]

Never mind Barlowing it, I don't think you'd ever use the 2.5mm on its own in the UK. Atmospheric conditions aren't great here and it's rarely worth going above 250 power, and most people settle at around 200x - beyond this point you're just studying the perturbations in our atmosphere instead of the object. For your scope 250x is achieved with an 8mm eyepiece. The combination you are proposing would be 4000 power!

[LukeSkywatcher]

2.5mm+5X=0.5mm

That wont work.

Forget about anything below 6mm.

Even a 6mm EP in the UK is a once a year deal due to the typical "seeing".

8mm is a good usable EP for planets.

I had my best views ever of Mars last night with my 200mm scope and an 8mm EP. As soon as i put a 2x barlow into the equation it all went pete tong.

Sure Mars was tiny in my FOV but the view was good enough for me to see the polar cap and Syrtis Major region on the surface.

[Tinker1947]

You might get away with one of these, or the 9mm for sure..

TeleVue Nagler 7mm Eyepiece 1.25"

[E621Keith]

Is there any particular reason why you want the 2.5mm?

A 2.5mm on a C8 is going to give you 813x magnification which is going to be way to high. Adding a 5x barlow will make it 4064x.

The seeing limit in UK is usually around 200x. In exceptionally good night 300x is the limit.

[Zaine UK]

Ok thanks for the advice guys. I'll just stick with what i've got. I'v got a 40mm, 32mm, 18mm, 13mm, 8mm, 6mm.

[LukeSkywatcher]

Ok thanks for the advice guys. I'll just stick with what i've got. I'v got a 40mm, 32mm, 18mm, 13mm, 8mm, 6mm.

Thats a good range to have. You pretty much have the high,medium and low ends of the scale covered.

[hemihaggis]

zaine where did you get a 2.5mm ep + a x 5 barlow .... magnification = scope focal length divided by ep focal length .

you cant really go much above x250 in uk