If you had a 4" refractor and could only have three eyepieces...

[TonyD]

OK, the 12.5mm is a keeper. But what others of those Circle T orthoscopics that Lyra have would you recommend, while they are still on the shelf. Which ones really push it regarding eye relief.

Note: I don't where glasses.

Note to self: start a thread on contact lenses and viewing...

Cheers

Tony

[cs1cjc]

I do not have the volcano tops, but instead Antares models which are similar to BGO. I find both the 9mm and 6mm usable without spectacles, but the latter is very tight. To my surprise the 9mm is just about usable with spectacles.

[RikM]

I wear glasses while observing so that limits my options but I would chose the same three EP's that use most of the time now. Pentax XW 20mm, 10mm and 7mm. (I would probably go for a 5mm rather than a 7mm but I haven't actually used one so I'm sticking to current experience). The Nagler 3-6mm Zoom is great though but I can't use one for too long.

[estwing]

just when we were talkin about decent ortho's,have a look on my post" these come up often"

[Astro_Baby]

eR is always a rough one to redict what others will cope with, for me anythng below 7mm is a non starter but others find 5mm OK and some can go go the very edge with stuff like 3mm.

I can live with 9mm very easy, easy relief is very comfy but then ai have a Mak to use it in where 9mm yields max usuable magnification. The trickiet one to use ai always think is in fact the 25mm where the very long eye relief makes i quite hard to use unless your sitting down.

I find the 9mm and the 12mm the most used and the sharpest with highest contrast but the 18mm is nice too, its just not as nice but its sisters are so good its got stiff competition

[staffop]

Hi all, sorry to resurrect the thread, but i've a 4" skywatcher 102 refractor f5. I noticed most of the conversation was around the f10 so assume any recommendations for that won't be applicable to my f5. I'm new to this so didn't realise what a minefield EP selection would turn out to be. My understanding is that the pre-supplied EPs are ok, but could definitely be improved. I also wear glasses so eye relief is a nice to have. Soooooooo.......

1. Do i buy a cheapish barlow (£25) or push the boat out and get the deluxe version for £70?

2. Do i buy an expensive new 9mm (e.g. Celstron X-cel LX) or try a fancy zoom for a bit more flexibility (e.g. hyper flex 9-27mm)? Is the 9mm zoom as good as the celstron fixed 9mm?

3. Is there a maximum magnification i shouldn't exceed with my set up - is 5mm pushing it?

4. Would i be better concentrating on lower mag (25mm +) considering the nature of the scope

5. Is the supplied diagonal acceptable or should i also look at upgrading that?

Sorry for all the questions!

[John]

If you have an F/5 achromat refractor I'd not spend a lot of money on getting it to show high power views - they are just not designed for that.

I'd stick to wide / low to medium power views which are the scopes forte. The supplied diagonal is OK unless you decide that you want to use 2" eyepieces for a wider field of view.

[staffop]

Thanks John

[staffop]

Sorry, one more thing.

I've read that i'd need x150 magnification to get a reasonable view of the planets such as Saturn. With a 500ml focal length that means i'd need an EP with a FP of 3-4mm (i think) - does this mean that realistically i'm not going to get a good view as those powers are too high for my f5?

[damnut]

Evostar 120 f8 - 23mm Axiom , 13mm T2 Nagler, 9mm Myriad

[John]

Sorry, one more thing.

I've read that i'd need x150 magnification to get a reasonable view of the planets such as Saturn. With a 500ml focal length that means i'd need an EP with a FP of 3-4mm (i think) - does this mean that realistically i'm not going to get a good view as those powers are too high for my f5?

Yes, thats the point I was making. 80x - 100x is about the max with such scopes and they are not at their best even then. You can see that Saturn has rings and it's brightest Moon Titan at that power.

[Moonshane]

I agree with john's comments. Views of the moon and planets were better through my current 80mm ED at 150x than through my old 120mm f5 Startravel at the same sort of magnification

that said, the larger aperture really helped with white light solar, tight double stars and DSOs. as always it's about compromise.

[happy-kat]

In the baby brother ST80 I an happy with what my Williams Optics super planetary long eye relief 6mm eyepiece showed. Yes Jupiter had CA but it was miles less than using the supplied 10mm. X66 mag it was small but crisp and could see the two main cloud bands.

[staffop]

Thanks all, it really is the hobby that keeps giving. Never realised when i started down this path how much there was to absorb. That said, i had an incredible view of an almost full moon the day i opened my scope which blew the socks of everyone (even with the supplied eyepieces) and was equally amazed i could see the Jupiter/Venus conjunction and could even make out the crescent aswell as pinpricks of light i assume were Jupiter's moons.... Loving it!

[Moonshane]

be aware that even the highest quality eyepieces will only have marginal benefits. it's a rare thing to be able to see anything with a very expensive option that cannot be seen with the 'free ones'.

[happy-kat]

You have a great portable telescope. Have you used it at a dark site?

[staffop]

You have a great portable telescope. Have you used it at a dark site?

Not yet, but i'm close to the Brecon Beacons so planning on heading up there soon. Would i be better off with lower magnification EPs in dark sites?

[staffop]

be aware that even the highest quality eyepieces will only have marginal benefits. it's a rare thing to be able to see anything with a very expensive option that cannot be seen with the 'free ones'.

That's interesting Moonshane, what would be the reason for upgrading in that case - should i just stick with the supplied EPs? Would i be better spending my money on a different accessory?

[Moonshane]

Better eyepieces = better views but it is mostly aesthetics. Don't get me wrong I have only Televue eyepieces in my case but they are not magic bullets.

Ferrari vs skoda. They both arrive at b and you see the views along the way out of the windows. I'd recommend a red dot finder, right angle optical finder, red torch, seat and star map before eyepieces.

[staffop]

Thanks Moonshine, it came with a red dot finder, so covered there. I've not heard of a right angle optical finder so will investigate those (i love the way this hobby keeps opening up new terms and kit). Definitely need to get the red torch, but was thinking of  sticking to a star gazing app such as Sky Safari rather than a physical map. Also sorted the chair, but you did forget to mention the cushion which i've found is essential for my old bones!

[happy-kat]

I have found the view is better but it won't remove chromatic aberration if the scope has it, but I have consistently found the 10mm poor compared to what I replaced it with, perhaps I got a duff 10mm, though I have not replaced the 25mm as that one does the job fine.

[John]

The design of the "stock" eyepieces that are supplied with scopes is, as you might expect, a simple one. It's broadly based on the Kellner eyepiece design using 3 lens elements. This design can work quite well with long, slow telescopes such as F/10 - F/12 refractors but the simple eyepiece design struggles to control aberrations such as false colour and astigmatism when dealing with the steeper light cone of the faster scope such as an F/5 refractor. Add that to aberrations that a fast achromat objective lens produces itself and this is why the images can seem less than optimum with these simple eyepieces. They get you up and running though, which is very important   

[Ohmless]

for years I had an f/10 achromat and used three eyepieces(at the most).  I used a 25mm sterling plossl, a 12mm BST, and an 8mm BST when I stopped using that scope.  I recently moved up to a 6" reflector and use a 5mm BST instead of the 8mm BST I used in the refractor.  Three eyepieces is probably all you need.

[staffop]

Thanks all, i've taken the plunge and bought the Hyperion zoom, can't wait to try it out!

[YKSE]

Thanks all, i've taken the plunge and bought the Hyperion zoom, can't wait to try it out!

Congratulations  , you've made THE most flexible choice of first upgrade IMHO, vey good optical quality for observing, both night sky or solar (if you have intention to do so later on), simple grab&go solution, more time for observing instead of changing eyepieces, and it works as the single alignment eyepiece too if you get a synscan mount.