My New Toy!

[orly_andico]

I have a 2.5mm Vixen LV. It is way too much magnification for my 90mm triplet. As cloud_cover said, floaters and the overall dim image seriously detract from the viewing experience.

[Jonarsh]

Thanks for the feedback guys...so what's the highest powered EP I can go? The fl is 480mm and its f6.
Sorry noob question here.... ;D

[cloud_cover]

I thought you said f/6.8?
Generally you want to keep magnification to a maximum of 50x/inch or a minimum exit pupil of 0.5mm The easiest way to calculate this is to divide the f ratio by 2, which in the case of an f/6 scope gives you 3mm (so 2.8 is fine)
On the corollary, the maximum focal length eyepiece is f ratio x 7, or in your case, 42mm, which gives you an exit pupil of 7mm.
This of course does not take into consideration atmospheric seeing and your telescope's light cone.

[orly_andico]

An 80mm f6 scope with a 3mm ep is putting out 160X, for a 0.5mm exit pupil. This should still be OK I think, but it will be very dim.

IMHO if you want stunning planetary images, whip out that webcam and use a barlow. I still get a kick out of it, even though I see the results several minutes later.

[Mariner]

I thought you said f/6.8?
Generally you want to keep magnification to a maximum of 50x/inch or a minimum exit pupil of 0.5mm The easiest way to calculate this is to divide the f ratio by 2, which in the case of an f/6 scope gives you 3mm (so 2.8 is fine)
On the corollary, the maximum focal length eyepiece is f ratio x 7, or in your case, 42mm, which gives you an exit pupil of 7mm.
This of course does not take into consideration atmospheric seeing and your telescope's light cone.

F/6.8 would be mine. And I have used the 2.8 to push my 80mm on both the moon and Saturn with sharp views of both. Probably means my eyes are still in good condition at this point in time. But as I mentioned before, the 80mm is too small for dedicated planetary use and is more suited for cruising.

[Jonarsh]

Thanks for the valuable insights guys!

Hi Mariner, when you used the 2.8mm EP, are the rings on Saturn visible? Also, I have a Televue 2.5X Powermate, don't think it is suitable with this EP right? As it will get super dim....

[cloud_cover]

Saturn's rings are just recognizable as attachments to the planet's sphere in a good 10x50 binos and at 30x they are clearly distinct as rings. So yes, this eyepiece at 171x should provide a very clear view of the rings. You might even catch the Cassini division.
The Power mate 2.5 is far too much power at 428x, which is a magnification more suitable to 8" and larger instruments. Also, above 300x the steadiness of the atmosphere plays a very important role as well.
Keep the power mate for other eyepieces

[Gary]

Hi Jornash. How smooth is the manual tracking for this mount? Try tracking a bright star (or Saturn) at high magnification (e.g. 150x) to gauge its performance.

[Jonarsh]

Thanks for the info. Cloud cover!

Hi Gary,
The bearings are quite smooth, but haven't have a chance to test out at higher magnification cos haven't got the eyeeice yet...will let you know once I got the chance

[antares2063]

hi Jonarsh, just to share with u..im using a 80mm refractor too , focal length 500mm, with a 5mm eyepiece i can see the rings no probelm. No motorised mount so i also have to let saturn drift across my FOV and play "catching"

Regards,
Junwei