How can average be very good?

[rob7]

Can anyone clear up my confusion regarding the quality of eyepieces to use in a F10 schmidt C6? From what I 'think' I've gathered so far, it's important to use very good quality ep's in a fast scope, but, isn't so necessary to have very good quality ep's in a slow scope. If this is the case whats the science behind it? I was originally intending to start 'upgrading' my Revelation set and was looking at Baader ortho's or similar or better, as a stepping stone. Would I see a optical quality difference in my C6s between say a Revalation 9mm plossl and a Baader 9mm ortho. [THE SCIENCE BIT MIGHT STOP ME WASTING MONEY ON A TELEVUE ETHOS IN THE FUTURE]. [[i'd be so lucky...lucky,lucky,lucky!]] Sorry..

Thanks in advance, Rob.

[Whippy]

Rob, what basically happens in your (or indeed anyone's) scope is that light is brought down to a point, that's called the light cone. In a 'fast' scope, the light cone is steeper than in a 'slow' scope and an eyepice has to work harder to show the image without any distortions. So in say, fast newtonians like my C8N that has a focal ratio of f5, eyepieces can show distortions like blurry stars (normally, I would have to re-focus to see what's on the edge of the field of view) around the edges while in my Intes Mak which is f12, there's none at all. So your C6 is 'slow' at f10 and you can be less picky about what eyepieces you buy. You don't have to buy EP's that don't show any distortion, but it's nice if you do ...

I think that's right anyway!!

Tony..

[rob7]

Cheers Tony for de-fogging my mind. I still have a F5, 12" dob to cater for, so some nice eyepieces would be useful there, I suppose. Being a beginner [astrodumb], I'm trying to collect equipment which is reasonably priced and suitable for both of my scopes to keep the overall costs down, but unfortunately what works in one might not work in the other very well. Perhaps I should have only bought one scope and concentrated my equipment purchases on that... [ NAAAIRRR!, I ACTUALLY WANT LOTS OF SCOPES!!] teehee.

[blinky]

For the F5 'scope I would avoid the very cheap EP's but I have Meade Series 4000 EP's for my F6 Newt and they work fine for me You can pick them up new and 2nd hand very reasonably.

[rob7]

Thanks for the suggestion of the series 4000's. Because I have only ever owned the Revelation ep set and never had the chance to look through a 'supposedly better' ep in the 1.25" size, a big part of my internal debate is would I get better views in a 'a step up' in price ep as in comparison to the Revs'. Theres lots of thing I would like, such as LP filters, heater strips and controllers for anti dewing, lazer colli's and so on, so purchasing better eps if there not going to really stand out would go further down my budget list for now. If I were the chancellor in my house, I'd buy owt and everything! [probably a good thing Im not!!]

[blinky]

TBH I am not reallysure how much an improvment you would get. The revelation EP set gets a very good review.

[James]

How do you find your Revelation eyepieces? As blinky says they review quite well. If you are reasonably happy with them then it may be an idea to invest in some of the other accessories you mentioned. An f/5 scope needs to be fairly well collimated to get the best out of it so a laser collimator could be helpful and if dew is a problem then a dewshield or dewstraps would be a good idea - you could have the best eyepiece in the world but if your scope isn't collimated right or its all dewed up then the eyepiece won't impress you!

HTH

James

[MartinB]

Another thing to think about is your field of view. this is quite small in your SCT so having a couple of wide angle EPs are very handy - for getting M81 and 82 in the same FOV for instance. Now you don't need anything to expensive - a moonfish 30mm UWA is a terrific EP for the money and works beautifully in an SCT. However it is the wide angle EPs which suffer in a fast scope and you have to pay a lot of money for something to perform well around the edge of the FOV. Having said that, I still enjoy the view with my moonfish and F5 12" dob. Plossls work well in fast reflectors and don't need to be too high end, although top quality teleview plossl is a top notch performer at a fraction of the price of a wider FOV Televue panoptic or nagler.

A good plan would be to gradually acquire a Moonfish 30mm UWA a couple of half way decent plossls, a good 1.25" barlow such as the Celestron Ultima and a high power orthoscopic (if you don't wear glasses) for planetary viewing. If you get the EP habit (which can be very wallet harming) you can then start scanning astro buy and sell for those bargain high end EPs that come up quite regularly.

It's easy to get too carried away, a good plossl can serve you very well. As James says, good collimation is key to enjoyable observing along with dark adaptation and a comfortable observing position.

[rob7]

To be honest the Revelations have gave me some great views including banding around mars a few nights ago. This was on the F10 though. I do rate the views through the Rev ep's its just I'm not aware of the 'possible' improvent using other ep's with the fact I haven't used any others yet. I think I'm longing for something 'magical' to happen. Regarding tight collimation on a F5, that's where I struggle most. I can colly the sct pretty easily, but haven't got the knack yet with my newt, which you and others on sgl have emphasied is a must on. Recently I have aquired Meade series 5000 2" 32 + 40mm ep's which work wonder for both scopes. Couple that with a recent series 5000 2x telextender purchase, I'm doing fine in some areas. Thanks very much for all the imput as it really helps. The astronomy learning curve is fustrating sometimes, but at the same time always fun!

Rob.

[Whippy]

If you can collimate a SCT then a newt should be easy peasy!

Where you can spend 'silly' cash on EP's is getting a wide field of view that works on a fast scope. Televue Naglers are the business with a super-wide view with no distortion (Martin VERY kindly lent me his whilst at Kelling and it's wonderful) but you pay top-dollar prices for them. Maybe worth an investigation would be the Baader Hyperion range. They give a wide field of view and they work pretty well in fast scopes if you use them with the 1.25" fitting and they don't cost the earth either.

Tony..

[rob7]

I 'cuddled' some hyperions when I took a window shopping trip to Rother valley optics. Trouble is I still haven't a clue what field they are suppost to excel at? I think some sort of expanation was given, but it didn't permantely register. Theres too much choice out there!!

Rob.