Is it worth me getting a 6mm Ep

[Jemmo]

I do quite a bit of planet observing I have a pretty good 9mm Ep and am getting either a 15 or 20 for nebulas etc. would it be worth getting a 6mm one or because I have a 9mm is it not worth it

[dannat]

from the suburbs it may be rare you can sue 1250/6 = roughly 200x
the 9 though at 1250/9 =138x, may not be enough
I find 150-160x a good mag for use routinely at 7.5-8mm

if you get a cheapish 6mm you may be able to use it when see'ing warrants

[Jemmo]

Thank you Dan

[Jemmo]

Also Dan I have a x2 Barlow if I Barlow my 9mm will that be good enough in he suburbs

[dannat]

I think 9mm x2 yielding 4.5mm ~275x mag will be too high to use

[knightrider]

In addition to Dans comments, depending on the length of your scope and the power 6mm will yield. Mine is 1200mm long and 6mm will bring me 200x mag as dan brought out. However I find this to be good for me on most nights but I live in a more country town.

This is the eyepiece I always use eyepiece on planets.

[BeanerSA]

I bought a 6mm planetary eyepiece. It sucks in anything less than PERFECT seeing conditions.

[astroboof]

I find a UO 6mm orthoscopic is the king of my planetary EP's, but it was an older university optics model from 10 years ago. God, the sweet views that has given me.

Bought a 4mm UO late last year, new model. Fantastic in +5 seeing, crap for most of the atmospheric time though.

In short- if you are going to go as low as 6mm for planetary viewing, you might as well spend. Second hand can be fine too.

All depends on what you are plugging them into as well, plus your own eye conditions, and so on, and so on.

Good 6mm contrasty EP, so versatile- think planetary Nebulae too, and tiny globular star clusters so dim that they need a lot of light through well corrected lens elements kept to a minimum.

Most seasoned astro hogs will have a few ortho's. even the ones with panoramic TV's- just so they can get a feel if nothing else. ;)

[Suzy]

I agree with what others have said regarding the 7mm ep. I've found that's the most used one for me on planets.
With my 10" dob @ 1200 F/L it gives me 170 X magnification.

But there's still plenty of times I've been able to use the 5mm, despite living amongst light pollution in the suburbs. It's had enough use that I justified getting the 3.5mm- some nights have been pretty amazing for planets and I wished I could've gone lower. Granted, it won't be used a lot, but it's there when needed :D . And it should blow me away when observing the Homunculus nebula in eta Carina and splitting tight double stars :astron: .

[AstralTraveller]

My UO 7mm ortho gets a lot of use in both the 10" f/4.5 and the 6" f/8, and the eye relief is useable - just!. I also have a 5mm and find it is generally too much mag and too little eye relief. BTW also have the UO 9mm ortho and it beats my 9mm T6 Nagler for on-axis brightness and resolution, but of course the Nagler has a much bigger fov and is more comfortable to use.

[GeoffW1]

I would agree with this assessment. Most times it would be a pain to use. I can't usually get less than 8mm to work.

Cheers

[doppler]

But when you get that perfect night its great to bump the magnification up. I've managed great views with a 6mm ortho and 2x barlow through my 8" f6 newt. (eq mount RA drive) on a few occasions in the last couple of years.

[Tropo-Bob]

Adrian, Tell us about the telescope U plan to use the 6mm EP on; then I may be able to give a more informed opinion.

[Tropo-Bob]

Ignore that, I have found the previous thread saying the you have a 10" F5. (1250mm FL).
It depends on the steadiness of your atmosphere but how much U wish to spend. I have a 6.7mm Meade EP which I like using at higher powers because of it 82 degree field of view. It makes tracking easier. The ES 6.7 EP seems similar & has lots of fans.
However, I also have a Tak LE 7.5mm EP. This almost always gives a quality image with my scopes, whereas the 6.7mm does not on some of the less steady nights.

[Renato1]

Personally, I think 200X is bare minimum for looking at planets. A 6mm eyepiece gives you 208X which is close enough.

For me, a 5mm eyepiece giving 250X would probably be as high as I'd go in a dob - and I'd quickly start getting annoyed with tracking the planet.

Try your 9mm with a Barlow. At 278X, you will either be impressed at what you see, or impressed with your self for keeping the planet in the field of view. Or find it darn annoying.
Good luck.
Renato

[erick]

I have a 5mm TMB/Burgess (or one of these "look-alikes"?) which I use in my 305mm f5 dobsonian. So 300x. Most nights that I look through it at planets or Moon, I pack it away again. Very occasionally I look and Wow! I've even been able to barlow x2 sometimes. If you can afford to have one in your eyepiece case for those rare wonderful seeing conditions, it is worth it. Yes, without tracking you need quality mechanicals on your scope and a very soft touch with your "tracking" hand.

ps. don't buy a 6mm plossl - eye relief is very short.

[uwahl]

I have a Pentax 6 mm that I use with a 10" Meade f8 giving 333x. Under exceptional seeing I have used it to view the core of Omega Centauri - WOW! (Central Queensland, 30% humidity, rock steady atmosphere.) These conditions are rare and usually it's too much even for the planets. Ok for the moon.

[gaa_ian]

Interesting discussion on EP's ! I have a number of customers looking for higher magnifications (for the planets principally) on for example an 800mm FL scope (F4)
I have not really used a EP of less than 7mm having used longer focal length scopes. Has anyone had experience using for example 5 or 6 mm UWA (58 deg apparent field of view) Skywatcher Eyepiece on shorter focal length scopes ?