ES 82*30mm or Meade UWA 30mm @F/4.7

[nephilim]

Having 'nearly' come to the decision to cut my losses & give up trying with AP (not enough time, money, patience ) i'm thinking of going the dob route for purely visual.

To really make my mind up I'm going to go for a premium low power 2" ep & try it with my 200p@ f/5 & if i like the results i'll get the dobi'm thinking the of one of the above will fit the bill, i'll be getting it from the states & hoping the thieves at customs may not notice it

BUT.....I've read on a couple of threads saying that at faster than f5 even the ES would be pushed to show its best, is this really the case & if so, is it really that noticable? BTW the scope i'm thinking about is the Skyliner 10".f4.7 Basically what i want to know is will one of these EP's make me smile in a 10" dob.

Steve

[Stargazer_00]

Well I have a 10" F4.7 Skyliner and I haven't bothered with a 30mm 82 yet as I think the 24mm is perfect at this focal length. the 24mm already shows qutie orange backgrounds so I'd imagine the 30mm would be much worse.

I'll get 30mm when I upgrade my scope soon, and this will give the same views in terms of field of view and magnification, as what the 24mm gives in a 10".

I'll still have the 10", at least until I work out if it's getting enough use, and at that point I'll be able to see what a 30mm looks like in it. I feel I have enough experience now across a range of scopes to know what it's going to give before I get it.

If you are having the 200p for a while and potentially going to a 250p as your next step (same focal length) then my advice would be get a 24mm 82 degree. The maxvision is cheap at the moment, the ES 24mm looks good. I have a meade 24mm which I like but it does look odd in the box compared to the set so I'll probably sell it off very cheap at some point and replace it with a 24mm ES just to keep my OCD in check

[nephilim]

Thats given me a bit to think about thanks. The 200p is the Explorer on an EQ5 (which i'll either sell or swap for the 250px) I dont want to buy an expensive EP that is good at f5 but then dodgy at f4.7.

Steve

[estwing]

lot of good things about a WO 28mm uwan's,but not sure about them at F4.7?

[John]

Well I have a 10" F4.7 Skyliner and I haven't bothered with a 30mm 82 yet as I think the 24mm is perfect at this focal length. the 24mm already shows qutie orange backgrounds so I'd imagine the 30mm would be much worse......

Thats how I found ~30mm eyepieces in my old 10 F/4.8 newt. The Nirvana 28mm worked well enough and was sharp enough across the field to let the coma show (if you get my meaning )

but the 20mm Nagler got more time in the drawtube than the Nirvana 28 or Nagler 31 did for just this reason.

[nephilim]

I had a scary feeling i'd be going into 'green writing' territory John, I may have to re assess the scope. As a total novice to dobs can anyone recommend a 10" at a lower f ratio. I know the 8" is f6 but what i'm after is a bit more aperture. Thanks.

[Stargazer_00]

you'd be better off getting a 12" after a 8" really

[Ben Ritchie]

I dont want to buy an expensive EP that is good at f5 but then dodgy at f4.7.

Things don't break down that suddenly! To be honest though it depends on how much off-axis aberrations bother you, some people demand pin-sharp to the edge, others don't really see some fairly obvious problems or just aren't bothered by them. TeleVue, Pentax, etc. may stay flawless in fast 'scopes while cheaper options start to show problems, but worth trying to find out how much you care before spending the big money.

lot of good things about a WO 28mm uwan's,but not sure about them at F4.7?

Worked pretty well in my f/4.5 - I don't remember any obvious issues, I could probably have found flaws if I went looking, but didn't Just enjoyed the view. Nice eyepiece, although I always found the eyeguard a little awkward.

[nephilim]

Things don't break down that suddenly! To be honest though it depends on how much off-axis aberrations bother you, some people demand pin-sharp to the edge, others don't really see some fairly obvious problems or just aren't bothered by them. TeleVue, Pentax, etc. may stay flawless in fast 'scopes while cheaper options start to show problems, but worth trying to find out how much you care before spending the big money.

Worked pretty well in my f/4.5 - I don't remember any obvious issues, I could probably have found flaws if I went looking, but didn't Just enjoyed the view. Nice eyepiece, although I always found the eyeguard a little awkward.

Thanks Ben,

I'm not bothered about slight flaws as the only decent ep I have is my 9mm meade HD60 so never having looked thru a Pentax or Televue I wouldnt know what i'm missing anyway. What i'm after is a good widefield low power for globs & star-fields, a bit of coma around the edges i can cope with.

[RikM]

I also found 30mm too washed out with my light pollution, though under a darker sky the 30mm 82° performed admirably in my 250PX. I bought the 28/68° instead but the 24/82 shows a tiny bit more more sky at a smaller exit pupil and would be just about right I reckon. The eyerelief is too tight and the field too wide for my taste though so I'm happy with the 28mm.

[nephilim]

Thanks Rik, I'm also now thinking maybe a 12" now as recommended by Stargazer_00, i've 3weeks till pay day so plenty of time for more research & questions.

[alan potts]

If you want one of these I would see what you can get from Telescope house, they still have the 30mm Meade and may well want to move them along, it might even be at a good discount. I am not sure many outlets have the 30mm ExSc and I believe you would have to go outside the UK to buy one. I really don't believe there will be any difference in performance, it is just that ExSc seem to be much in fashion at the moment, and as with most fashion we here seem to be at the end of the queue.

However at F4,7 I would expect the edges to be showing signs of softness

Alan.

[nephilim]

Thanks Alan, I'm reassessing the scope now & thinking of the Revelation 12", If I do decide on the 30mm i'll be getting it from here http://agenaastro.com/explore-scientific-82-deg-series-nitrogen-purged-eyepiece-30mm.html & praying it slips through customs unnoticed.

[SnakeyJ]

I was thinking along very similar lines with my F5 200P and AR152S, I haven't gone any wider than 70 degrees AFOV so far but still find the coma very noticeable and the view is certainly softening towards the edge - I haven't tried this with the coma corrector (which I really brought for imaging but haven't had out of the box so far). None of this is a particular issue with a newtonian, but with UWAs and possibly a coma corrector/parracor I expect you'd need to consider some counterweighting to keep things nicely balanced.

[Stargazer_00]

Jake you might find if you are using 70 degree eyepieces that is the problem with abberations. 70 degree eyepieces are Erfles I believe and these are known to show quite bad edge abberationsin faster scopes (I think this includes designs like the WO SWANS) - this isnt coma - it is eyepiece induced abberation.

An 82 degree eyepiece in a 200p should be very good indeed as it would be a different lens arrangement. These typically dont show abberations anywhere near the level of the 70 degree Erfles.

That said, F5 and faster scopes will show coma the lower magnification you go with 82s as the true field of view increases. At 1200mm the sweet spot is somewhere around 18mm-20mm with 82 degree AFOV before the coma starts to become quite visible (at least to me).

[SnakeyJ]

Jake you might find if you are using 70 degree eyepieces that is the problem with abberations. 70 degree eyepieces are Erfles I believe and these are known to show quite bad edge abberationsin faster scopes (I think this includes designs like the WO SWANS) - this isnt coma - it is eyepiece induced abberation.

An 82 degree eyepiece in a 200p should be very good indeed as it would be a different lens arrangement. These typically dont show abberations anywhere near the level of the 70 degree Erfles.

That said, F5 and faster scopes will show coma the lower magnification you go with 82s as the true field of view increases. At 1200mm the sweet spot is somewhere around 18mm-20mm with 82 degree AFOV before the coma starts to become quite visible (at least to me).

Cheers Stargazer - I'm using the Celestron Ultima LX 32mm as my SWA - it is six element EP, but is this an uprated/super erfle design?

I will purchase some of the shorter fl ES 82s as budget allows probably 12mm & 8mm as these should get some fair useage and they seem excellent value based on current reviews. The wide angle end may have to wait for a later round.

[Stargazer_00]

I honestly don't know Jake. I heard those Ultima LX were good eyepieces. It'd need John or someone with more experience / time served to best answer that. I dont think those are Erfles though, if they were I dont think they would carry the reputation that I thought they did.

[Dude_with_the_tube]

i have both Meades 82 deg 24mm and the 30mm "bomb" and depending on situation i use both of them. Yes there is a tiny bit of coma but that does not bother me at the slightest.Views are absolutely excellent in either of them.Its the share size of the 30mm Ep what makes me smile every time i open my EP box.I recently had a friend of mine with his son joining for observation session and they where both speechless when we where observing star clusters through the 24 and 30mm.(it was they first time).It is a tough call to decide which Ep i like better 24 or 30,they both have they "edge" for me.

Either way,both Ep`s will perform great in 8 and in 10" Dobs and even in 14 or 16",and they will not be "dodgy" ( and i mean Meade and ES) all down to what you like design wise as Meade have they own approach to the Eye cups and ES is more or less the standard fold down one.Optically they are identical.

If on a budget and your biggest scope is planned to be 10",i would say go for the 24mm.If you are planning to upgrade the scope in the future,i would think for 30mm.(i will be upgrading closer to autumn to 14 or 16" dob)

[Stargazer_00]

Dont you think the meade 24mm in a 10" pointed at Double Cluster shows a ton of coma? I do. Elsewhere the eyepiece is fine and I dont notice much if any coma but this target and other rich star fields the coma, for me, is distracting and off putting. I'm sure with a coma corrector this would remove the issue entirely/mostly.

[John]

It's important not to confuse coma, which a fast newtonian produces, with astigmatism which is an eyepiece aberration. Eyepieces that are well corrected for fast scopes will show coma in newtonians. Lower cost eyepieces tend to mask the coma with the astigmatism that they produce. Sometimes it's a mixture of both thats being seen !

I've some sympathy with the argument that using excellently corrected ultra wide angle eyepieces with a fast newtonian is slightly pointless unless you invest in a coma corrector as well.

I was quite pleased to move to an F/5.3 newtonian where the coma is much reduced to the point where you have to look really hard to see any, even with 100 degree FoV eyepieces.

[Dude_with_the_tube]

Dont you think the meade 24mm in a 10" pointed at Double Cluster shows a ton of coma? I do. Elsewhere the eyepiece is fine and I dont notice much if any coma but this target and other rich star fields the coma, for me, is distracting and off putting. I'm sure with a coma corrector this would remove the issue entirely/mostly.

strangely i have not found that.yes there is a coma on the edge of the FOV of EP but thats beyond the 95-98% of the view so by all means it does not distract me at all.and definitively i cant not say that it is that bad that it is off putting.maybe thats only me

[Stargazer_00]

blimey, on the double cluster i see it from 40% to the edge

[Dude_with_the_tube]

I have not been out for a good couple of weeks thanks to the awesome weather,but as soon as I can ,i will do another observation of the double cluster and will report back to you Graham.

[nephilim]

Well I've put my 200p/EQ5 plus camera & bits n bobs up for sale now & i'm going for the 12" Revelation, i've been reading the reviews & the poor coating problem seems to be only with older ones so hopefully this has been rectified (I've read it has?)

I'm also decided on the 30mm ES (although that'll probably change in the next 3wks till pay day knowing me ) as the Rev is f5 & i dont really have any lp where i live (the orange glow mentioned shouldnt be a problem) hopefully i'll be ok, anyone think otherwise i'll happily listen.

[SnakeyJ]

Good luck with the new Dob Steve - not tempted by that 14.6" F5.2 Darkstar on ABS then?