Widefield eyepiece for f/6 SW 200P

[TwoPi]

Hi,

I've currently got a Baader Hyperion 24mm EP which I really like, but in my reasonably fast scope I do notice that stars away from the centre of the field are a little ragged and do not appear as points of light.

I was considering getting a widefield eyepiece and wondered if something like the Hyperion Aspheric 31mm EP would suffer from the same problems in my scope?

Or is there another eyepiece (preferably the same price or cheaper than the Aspheric) that you would recommend?

Thanks as always for any help & guidance you can provide.

[Andy_E]

The aspheric is better corrected than the Hyperion, but there will still be some defects at the edges due to coma and astigmatism. At this sort of price range pretty much everything is going to show some defects in the outer edges (especially without a coma corrector). Although I haven't used one, the SW nirvanas get some pretty good write ups but at around £250 for the 28mm it's a bit above price range. Again, there's the ES 82s which are also gaining popularity but for 30mm you're talking £289.99. I reckon the best middle ground would be the SW Aero 30mm... much better corrected than the Hyperions but not going to break the bank at around £125... or a hell of a lot less if you can find one S/H.

[rwilkey]

Hi Gav, I like the SW PanaView 32mm, always used it in my 200P f/5, but can be a bit soft at the edges, but it works surprisingly well in a fast scope in my opinion.

[NGC 1502]

To get truly sharp to the edge views at low power/wide field is not easy in most Dobs.

My 27mm Panoptic in my 10" OO Dob gives 44x and 1.5 degree field. There is some deterioration towards the edge of field with star sharpness. I could use a paracor to sort it, but have learned to accept it. At my last dark site visit with my club, I tried a clubmates 24mm Panoptic, that showed less deteroration towards the edge because it's a smaller field and doesn't go as far off axis.

I'd say get the best you can according to budget and live with less than perfect edge correction. See what others say, read the reviews as well.

Hope you find something that suits, Ed.

[andrew63]

I have found the 31mm aspheric soft at the edges in my refractor which is only F7. These at sellout are optically superior, I've used a few - they are the Meade swa without the stamp. You could consider the 28 SWA if they have any left. You'll have to pay well over £200 to better it, i feel.

Maxvision 68° Okular 28mm buy at Explore Scientific

andrew

[TwoPi]

Thanks for the replies, lots to think about. Regarding the Maxvision Andrew, that seems too good to be true. Is there a catch somewhere?

[andrew63]

There are a few long threads running ! A few of us have bought several of these included me, and i also owned several of the meade swa which they perform identical to. It appears these were made for meade but for whatever reason the order was not taken - possibly financial reasons. These were then just sold unbadged and i think this will be the last lot. I've owned the 16, 20, 24 and 34 meade or maxvision and all have been very good. As i said for £50 to £100 they are a great bargain.

andrew

[alan potts]

As Andrew has said have a look at the Maxvision, same as the Meade 5000 ranges, better than Hyperions. I noticed one or two members mentioned COMA, this will not be corrected by any eyepiece we have mentioned, even Televue, it is all down to the scope.

Please take note, the member using a 27mm Panoptic and seeing edge problems has only the scope to blame, it is not the eyepiece. The 24mm panoptic is as sharp a razor at the edges, but put it in a fast Newtonian and it will show coma. The odd thing about Televue eyepieces is they will show coma because the edges are well corrected, some other eyepieces are actually showing other aberations that mask the coma.

Alan

[TwoPi]

Ok, thanks again all. I'm thinking of going for one of the Maxvisions, struggling a bit to be honest now between the 68deg 24mm vs 28mm or even the 82deg 24mm...

Given the ES website talks about "good edge sharpness for f/4" with the 82deg and "good edge sharpness for f/5" for the 68deg, would that imply that with my f/6 scope that the edges are likely to be better with the 82deg EP, or is going for a smaller FOV likely to make more difference? Also I appreciate that the 82deg EP is much bigger, more expensive and some people report 82deg AFOV as being uncomfortable to use - I've never tried one so am a bit unsure.

My instinct is to go for the 24mm 68deg and sacrifice the additional FOV for comfort / relative size / darker background sky (vs the 28mm)... any thoughts or should I just man up and get on with it before they sell out?

[andrew63]

Not an easy choice - 82 are certainly less comfortable in use than 68, you have to move your around a bit. As you have a hyperion 24 already all you would gain with a max 24 is get better edge correction. At least with the 28 you would be getting a wider field and still a good exit pupil.

And of course the 28 or 24 uwa would be 2" eyepiece not 1.25. It would be ideal if you could try out a few different eyepiece at some local observing session though.

andrew

[TwoPi]

Good point, though I should have said that I'm probably going to get rid of the Hyperion 24mm. Part of me does think that sticking to 1.25" EPs will be less faffing with different adapters during the night, but then again it's not *that* much faffing... indecisive, me?

[alan potts]

If it helps at all, the 28mm was my favourite of all the SWA range, and I had all of them. I also have had most of the 82 degree range, at the moment I am doing a head to head with the 24mm UWA Meade and the 26mm Nagler. It is doing remarkablely well and in one area is better, but if I told you which I would have to kill you.

Either the 28mm or 24mm UWA will not disappoint, some say the 24mm SWA is as good as the Panoptic but this is not my findings and I had both at the same time. The Panoptic is pure class.

Alan.

[Moonshane]

some good points above but do consider balance with a smaller dob. the 68 degree eyepieces will be a lot lighter and the 82 degree a lot heavier. you can always get around the issue of course but it's something to think about. a 24mm 68 degree eyepiece gives the widest field in 1.25" and would give a 1.36 degree field which is very nice and you'd have a darker sky background / smaller exit pupil (possibly important if you have light pollution where you observe). you'd get a 2 degree field with the 30mm 82 degree but at a higher cost and weight and with a larger exit pupil (but still not bad) and lighter sky background than say a 24mm. Anything you ever buy is about compromise one way or another.

[TwoPi]

<snip>

It is doing remarkablely well and in one area is better, but if I told you which I would have to kill you.

<snip>

You tease!

Hmm, I've changed my mind several times this morning already.

[TwoPi]

OK, I think I've ruled out the 28mm now as I could get a slightly better field of view in the 82deg 24mm (plus everything will be a bit larger) and there is a bit of light pollution where I live (can usually see down to about mag 5.5 naked eye).

On the weight / size issue, my MoonLite CR2 should be arriving today and given my scope is the GOTO with stiffer movement than the normal 200P, I'm assuming (perhaps incorrectly?) that the balance shouldn't be a problem with my setup?

If that's right then I guess it's simply a choice between the extra field of view vs the additional size / possible comfort issues with such a large view.

Does anyone have any comments on whether the sharpness of stars on the edge of the field will vary significantly between the SWA & UWA 24mm on my f/6 scope? Presumably the SWA version will be better simply because it will be a smaller FOV?

Thanks again for your patience, I'll get there in the end!

[Stargazer_00]

I think you'll find, certianly I do, that lower mangifications show more coma. Field of view doesn't seem to have much effect. For instance a high manficiation 82 degree eyepiece (200x +) shows little/no coma whatsoever whereas a low magnification eyepiece shows coma on the edges. I only have 82 degree eyepieces, apart from the supplied plossls which show terrible coma in a 25mm.

My lowest magnification eyepiece is a 24mm 82 degree. I don't see any reason to pick up anything to show lower magnifications. In my largest scope a 24mm has a magnification of 68x which isn't very low at all so one naturally looks to get lower magnifications however this eyepiece also produces a 5mm exit pupil. Lowering the magnification further will produce a larger exit pupil and I like to limit my exit pupils between 0.5m and 5mm. I believe my eye can dilate further than 5mm but beyond this I find the backgrounds are too orange to be pleasing and therefore can't see the point dropping £250 on an eyepiece for slightly lower magnification and more orange backgrounds, and quite likely more coma too!

If I want lower than 68x I get another scope out.

Just some food for thought, anyway. Hope it helps in some way.

[TwoPi]

Thanks - for my scope the magnification will be x50 and the exit pupil will be 4mm.

As others have said earlier, pin sharp stars without a coma corrector will always be a challenge in a fastish Dob. Given this, I'm think I'm just left with trying to assess which will be sharper: the UWA with its description of "good edge sharpness for f/4" vs the SWA with "good edge sharpness for f/5". On the basis of your comments about magnification rather than field of view being the key factor, that would lead me towards the UWA...?

[Chris]

Thanks for the replies, lots to think about. Regarding the Maxvision Andrew, that seems too good to be true. Is there a catch somewhere?

No catch they are brilliant! I initially bought the 20mm and thought that would be it, but as soon as I got the chance to use it I decided to save for another which was the 2" 28mm. Both brilliant EP's I hope they have some more left when payday comes around.

Thats a point! Noooo don't buy them they are terrible!

Chris

[Stargazer_00]

Thanks - for my scope the magnification will be x50 and the exit pupil will be 4mm.

As others have said earlier, pin sharp stars without a coma corrector will always be a challenge in a fastish Dob. Given this, I'm think I'm just left with trying to assess which will be sharper: the UWA with its description of "good edge sharpness for f/4" vs the SWA with "good edge sharpness for f/5". On the basis of your comments about magnification rather than field of view being the key factor, that would lead me towards the UWA...?

If the magnficiation is the same I'd opt for the UWA in that example simply because it's tested well to F4 whereas the other is tested well to F5. The F4 tested eyepiece will ultiamtely give you better views on a greater range of telescopes and the view in an UWA is more pleasing than a SWA. That said you pay for that pleasure an F5 tested SWA will likely be half or less the price of an F4 tested UWA.

[TwoPi]

Just ordered the 24mm UWA! Will be interesting to see the comparison with the 24mm Hyperion. Oh, and a 16mm SWA somehow ended up in my basket too.

Thanks again for your help.

[Stargazer_00]

Excellent, let us know how you find it and be sure to put elastic bands around your socks as they're liable to fly off

[TwoPi]

Quick update: ordered from Explore Scientific in Germany last Thursday, they were shipped on Friday and arrived today. Looks like stock/ordering issues I'd read about in other Maxvision threads seem sorted now.

Even though I'd read quite a few things about it and was aware of the size, still a little shocked when I actually saw the 24mm UWA . The 16mm next to it (and the rest of my eyepieces for that matter) look like toys!

Hoping to try them out tonight, fingers crossed the skies stay clear

[TwoPi]

Was a bit short on time last night (plus there was the full moon pretty much washing everything out) but my initial impressions are very positive - the Maxvision UWA is noticeably sharper towards the edge of the field than the Baader Hyperion. And what a field! Despite the moon, just the range of stars being shown and how the view shifts as you pan the scope was very impressive. Not experienced this before and I'm liking it a lot!

No obvious issues with the 82deg field, I enjoyed the way it filled my vision and didn't feel I was particularly straining to see the edges either.

Also briefly tried the 16mm SWA, again very nice & sharp view. Found it a little awkward to use at first (I don't wear glasses and with the eye relief set correctly I felt my eyelashes brushing against the surround to the relatively small central hole in the eye 'cup'. I guess the alternative is to wind it back in a little and hover more, but I like putting my eyes directly up against eyepieces. Didn't bother me after a few minutes and for me doesn't detract from a superb quality eyepiece.

Thanks again for all the suggestions and help!

[TwoPi]

Oops, should have added to my last post for the benefit of anyone else that comes across this thread after noticing problems with the edge of field sharpness in similar scopes to my f/6 Newtonian:

As earlier posters said, the new eyepiece doesn't *completely* solve the issue - coma at the edge of the field is a fact of life in my scope without a coma corrector. But that said, for whatever reason it seems smaller & less noticeable in the 24mm Maxvision UWA when compared with the Hyperion (and for that matter the stock SW 25mm eyepiece) - all of the stars simply seem 'tighter'.

Hope this summary helps!

[Stargazer_00]

Hi Gav,

I'm sure it'll help others. Yours is a popular scope and these are popular affordable high quality eyepieces which many others will no doubt buy before they dry up.