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Skywatcher Aero ED 30mm 2" Eyepiece

John

By John
in Member Equipment Reviews

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John

John

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I was lucky enough to be able to borrow one of these from FLO recently and I've jotted down some notes on how it performed which I've attached (hopefully !) as a PDF file - just click on the large thumbnail below to open it.

Thanks to Russ for his notes on the eyepiece, Ant for converting my report to a PDF and Steve / FLO for the loan of the Aero ED30 :(

John

PS: Just thought I should add that FLO is First Light Optics (see link at the top of the page) and the Skywatcher Aero ED 30 details can be found here:

http://firstlightoptics.com/proddetail.php?prod=sw_aero_eyepiece

SW_Aero_2__30mm.pdf

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John

John

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One of the issues discussion of longer focal length EP's seems to throw up is exit pupil size. Since reading into this a while ago I've stuck fairly firmly to around 30mm as the optimum for my F/6.5 and F/5 focal ratio scopes so my Nagler 31mm produces exit pupils of 4.77mm and 6.2mm respectively - as a 49 year old I guess the latter is about the max for me. Maybe I'm being too inflexible though - I've assumed that I would start to suffer kidney beaning and secondary shadow issues with the newt if I go longer - am I being a bit pessimistic ?.

John

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James

James

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One of the issues discussion of longer focal length EP's seems to throw up is exit pupil size. ........... I've assumed that I would start to suffer kidney beaning and secondary shadow issues with the newt if I go longer - am I being a bit pessimistic ?.

For a time I used a 40mm Paragon and a 36mm Baader Aspheric in my f/4.7 Newt and most of the time they worked fine. There were occasions when I could see the secondary in the Paragon - I'm guessing that was when I was at home and light pollution stopped my pupils expanding very far but I'm not sure.

I wouldn't rule out a longer focal length eyepiece for you John but preferably you'd get a chance to try one out first.

James

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John

John

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When I first saw Celestrons Eyeopener kit advertised I thought they had invented a way of expanding your exit pupils !!

I'm sure I've read somewhere of some way of temporarily doing this or at least enhancing your eyes sensitivity to light ???? - they will be drug testing at the end of Messier Marathons next .....

John

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Andrew*

Andrew*

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John, re: the exit pupil thing - I always avoided encroaching on 35mm in my f/5 newt, but when I tried the 38mm Panaview that all went down the drain.

Even in the f/4.5 dob (8.4mm EP), I found the view very comfortable - I didn't see the secondary shadow at all, and with this combination I saw nebulosity in the Pleiades, so whatever light loss occurred it didn't matter one bit!

Already the Panaview is on my buy list for its large field and great performance in all my scopes, but perhaps the Aero will take over... watch this space!

Andrew

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coliea

coliea

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This would mean the 30mm Aero would give me a 3.1 degree TFOV in my SV102, which is the same as a 35Pan but at a higher mag (24x instead of 20x).

I don't get that ??? - the 30mm Aero is billed as a 68 degree AFoV eyepiece and that's certainly what it looked like when I used it - no more. That means that it would show you LESS sky than the 35mm Pan surely. ???

John

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John

John

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This would mean the 30mm Aero would give me a 3.1 degree TFOV in my SV102, which is the same as a 35Pan but at a higher mag (24x instead of 20x).

I don't get that ??? - the 30mm Aero is billed as a 68 degree AFoV eyepiece and that's certainly what it looked like when I used it - no more. That means that it would show you LESS sky than the 35mm Pan surely. ???

John

Col,

I seem to have accidently edited your post rather than quoted it (which was my intention). Really sorry about that - I'm still getting used to the new forum software !.

I'll ask the other mods if your orginal can be re-instated in it's original form.

John

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coliea

coliea

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No worries John.

I was saying that as the SW Aero ED seemed to be the same eyepiece as the Astro Tech Titan II, and as both seemed to be from United Optics...

http://www.united-optics.com/Products/Telescope_Accessories/Eyepieces/2%27ED_Eyepieces/2%27ED_Eyepieces.html

...I requested the field stop diameters from UO to calculate the TFOV in my scope as described by Tele Vue here:

http://www.televue.com/engine/page.asp?ID=131

UO replied with the following FS values:

ED30 - 38.2

ED35 - 44.2

ED40 - 51.0

I believe the field stop diameter formula described by Tele Vue returns a more accurate measurement of TFOV, and indicates a TFOV of 3.08 degrees for the 30Aero in my SV102, compared to 3.12 degrees for the 35Pan with it's FSD of 38.7mm.

Col

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John

John

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I've not managed to do that comparison personally Shane - Andrew may have though - I'll bring this to his attention.

Of course most eyepieces are going to look "a bit seagully" compared to the 24mm Panoptic :(

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Andrew*

Andrew*

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Hi John/Andrew

did this comparison opportunity ever happen? I am just wondering whether my WO 33mm SWAN would be bettered by the 35mm Aero in my Dob. It's lovely (the SWAN) in my refractor but gets a bit seagully in the dob.

cheers

Shane

Hi Shane,

Yes, I did the review. I will post it tonight :(

To save you the suspense, I think the Aero would do better than the SWAN in your scope :D

Cheers

Andrew

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  • 7 months later...
sixela

sixela

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I don't get that ??? - the 30mm Aero is billed as a 68 degree AFoV eyepiece and that's certainly what it looked like when I used it - no more. That means that it would show you LESS sky than the 35mm Pan surely. ???

That's actually a very subtle thing: the TFOV= AFOV/Mag is only an approximate formula, because different eyepieces have different levels of rectilinear (pincushion or barrel) distortion and associated angular magnification distortion (by the way, you necessarily need some pincushion distortion to have zero angular magnification distortion).

An eyepiece with more pincushion distortion will "stretch" the outher field (mangifying it more) and so the resulting true field of view will be less large than you'd expect from the AFOV, even when the AFOV reported is exact.

An eyepiece with less pincushion distortion will show relatively more sky than the AFOV and focal length may make you believe.

It's quite a thorny subject full of pitfalls; if you're interested in the math, all the effects, the interaction with the eye, and what difference directing your gaze to the edge of the field makes, read

Distortion and globe effect in binoculars

Extreme wide field eyepieces are usually optimised for zero angular magnification distortion, because that is what preserves local angles and sizes when you direct your gaze around the field. Ultra wide field are usually optimised in the same way, but some will actually have even more pincushion distortion to correct for other things (field curvature, edge of field astigmatism) and the globe effect will be very pronounced if you dare directing your gaze in the middle of the field and panning the scope, rather than letting the scope rest and browsing through the field.

In the 70° AFOV class, though, all bets are off. Except in wide fields used in terrestrial spotting scopes, where you can expect eyepieces to follow the circle or even tangent condition more accurately.

Pans have a lot of pinchusion (more than that necessary to get zero angular magnification) so they show relatively little sky.

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sixela

sixela

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Hi John/Andrew

did this comparison opportunity ever happen? I am just wondering whether my WO 33mm SWAN would be bettered by the 35mm Aero in my Dob.

Oh yes. I really like the SWANs in extremely slow scopes (f/10-f/15) --excellent on-axis performance and build quality--but I think in fast scopes they're a lot worse than even the 26/32/38mm Kunming United Optics SWAs, let alone the Paragon reincarnations (which are better still).

The Paragon reincarnations (don't ask me to list all the names!) are a bit strange. There's a bit of edge of field astigmatism but in longer focal length (not ratio) scopes it's less bothersome because the field is flatter, so instead of feeling in a ship at Warp 5 you tend to see little crosses if your eyes accommodate well.

There isn't much, but in contrast to other eyepieces (where a slower f/ratio dramatically decreases the amount of edge of field astigmatism you see) there continues to be just a bit even up to f/8.

But on axis they really are excellent. I compared my "official" Paragon with a 40mm Pentax XW in my 16" f/4.5 (f/5.1 with Paracorr) and the Paragon was just as good!

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