Aero ED's impress

[Louis D]

I was out with the 8" Dob just now, and the 35mm was behaving much better in it than in the Mak.  With the coma corrector, it was well corrected across about 75% of the field, with the outer region not as objectionable as the 30mm WS III before refocusing.  The last 5% of the field shows a bit of vignetting, but the field stop is sharp on a bright object like the moon.  It really does seem to have a flat field, so all you see is astigmatism, which is about as strong as the 40mm Meade 5000 Plossl.  There's also no chromatism at the edge that I could see, which is admirable.  The center of the field is incredibly sharp in this combination.  I could also take in the view with eyeglasses with just a slight bit of pressure pushing in.  There was no blacking out of the field at any time.  Barlowed with a telecentric magnifier, it sharpens up at the edge immensely, much better than the 40mm Meade 5000 Plossl.  The Trap could be discerned at the edge in this mode.

Overall, this eyepiece really needs matched up with a telescope before any conclusions about it can be drawn.  I haven't encountered any other eyepiece quite like this before.  I'll have to have another go with it in the Mak before passing judgement on it with that scope.  In the Dob, it's a real keeper.

[pregulla]

Thanks for the review. I was keeping my eyes on the 35mm for a while. It is still available, and is smaller and lighter than 40mm with only slightly smaller TFoV. I have ES82 30mm, but wanted something more compact. I am not too picky about edge performance (at least not yet ) so well corrected over 75% of the field should be plenty good for me.

[Pig]

My SW Aero 40mm is very impressive, for the outlay it is pretty much perfect ? Combined with the TAK DF it delivers some awesome wide field views. I don’t think it will ever be sold ?

[Mr Spock]

It's nice to know modest eyepieces can perform well. Not everyone can afford green stuff

[Stu]

I picked up Mike's 40mm, and very nice it is too. Mainly bought to give larger exit pupils on the Mak, it has yet to be tried in anger. Hadn't thought of using it in the Tak, but will give that a go too!

[Louis D]

5 hours ago, Stu said:

I picked up Mike's 40mm, and very nice it is too. Mainly bought to give larger exit pupils on the Mak, it has yet to be tried in anger. Hadn't thought of using it in the Tak, but will give that a go too!

Let me know how it does in the Mak.  What's the diameter of your Mak's rear port?  I'm thinking the ~27mm rear port of the 127 Mak might be causing the issues I'm seeing with the 35mm ED since it behaves nicely in the 72ED and Dob which have wide open eyepiece ports.  The narrow Mak port doesn't bother my other widest field eyepieces.  I'm going to do some controlled daytime experiments this weekend with the 35mm ED and multiple scopes to characterize what is going on better.

[BGazing]

I purchased TS 40mm clone after I have mistakenly ordered 31 Hyp instead of 36 Hyp as the widest EP for my C8. 

Light, transparent, very comfortable.

I find the edges poor, but then again C8 has coma there and it's an eyepiece for nebulas. Still, Caroline's rose was spectacular one night in it, truly 3D.

Filter thread was awful, returned one and the replacement still could not accept filters, so I am mounting them on diagonal.

I can live with it, there are not that many targets for 40mm in C8, and Tak 100 will go up to 31mm at most. No point in getting a hand granade for such limited role.

[Louis D]

Finally measured the usable eye relief on the 35mm Aero ED, and I get 14mm from the retracted rubber eye cup.  Since the eye lens is recessed 7mm (I agree with Ernest on this point), it could have 19mm to 20mm of eye relief if the eye lens were flush mounted to the top of the housing.  I'm not sure where Ernest got 8mm usable eye relief from.  I measured the eye relief both outside of a scope and when used in the AT72ED.  The two measurements agreed very well.  14mm also agrees well with the feels-like ER.  It feels very similar to the 27mm Panoptic in use.  It's tight, but still usable, with eyeglasses pressed into the eye cup.

It has a 73° AFOV and effective-AFOV, so it has practically no distortion at the edge either way.  Visually, I couldn't detect any stretching or squashing as objects approached the edge.  It was a bit difficult to measure the projected image circle because of the vignetting at the field stop.  The edge gradually fades away, so Ernest's 70 AFOV might only include the non-vignetted image circle.  It was striking the difference between the fading edge of the 35mm ED and the sharp edge with no fading of the 40mm Meade 5000 Plossl.  I'm guessing the field lens or the intermediate lens group is undersized on the 35mm ED and is losing edge light rays.  The 35ED's barrel is noticeably narrower than the Meade, which doesn't show any edge vignetting.

The effective field stop measures 44.4mm, so very nearly a maximum field eyepiece.  It is barely wider than the 40mm Meade 5000 Plossl when used in the 127mm Mak.  It is noticeably wider when used in the AT72ED.  When scaling for the difference in magnification between the two, there is definitely some lost potential field of view with the Mak.  Something is restricting the field of view in one but not the other.  The 40mm Meade 5000 SWA did not show any unexpected restriction in the Mak as a third data point.  As a result, I probably won't be using the 35mm ED in the Mak since the usable eye relief is so much tighter than the 40mm Meade 5000 Plossl (14mm vs 29mm) and any additional field in the ED is fading away to the edge anyway.

[pregulla]

 It really puzzles me why would Aero ED 35mm vignette in your 127mm Mak while 40mm Meade SWA doesn't. I can't think of anything in eyepiece itself that could cause vignetting in slower scope, but not in faster one with more diverging light cones. And if it was somehow due eyepiece having problem with the slower cone of the Mak, then I would expect it to be even worse in the dob with telecentric barlow.

I am no expert though.

[pregulla]

Now I am a happy owner of 35mm, SkyRover branded. I had a short window of clear skies to give it a quick try. It will certainly replace SkyWatcher SWA70 32mm as lightweight low power EP being lighter, smaller and better corrected (and better spaced from ES68 24mm). I was surprised how small and lightweight it is. 

I don't use coma corrector and it compared pretty good against ES82 30mm: because they both show coma the difference is not very noticeable except for the very edge of the 35mm where stars get pretty messed up. Still need to compare both under dark skies, but I can see myself using it more than ES just beacuse it is so much smaller and lighter.

I tried to use 2" GSO barlow with it an causes significant vignetting, the FoV feels more like plossl.

[Louis D]

1 hour ago, pregulla said:

Now I am a happy owner of 35mm, SkyRover branded. I had a short window of clear skies to give it a quick try. It will certainly replace SkyWatcher SWA70 32mm as lightweight low power EP being lighter, smaller and better corrected (and better spaced from ES68 24mm). I was surprised how small and lightweight it is. 

I don't use coma corrector and it compared pretty good against ES82 30mm: because they both show coma the difference is not very noticeable except for the very edge of the 35mm where stars get pretty messed up. Still need to compare both under dark skies, but I can see myself using it more than ES just because it is so much smaller and lighter.

I tried to use 2" GSO barlow with it an causes significant vignetting, the FoV feels more like plossl.

The ES-82 is sharp to the edge with a coma corrector, but the various colors of the spectrum focus at slightly different points.  This was most apparent on Mars at opposition.  A red Mars was completely separated from a blue Mars at the edge.  I'm guessing differential magnification based on wavelength leading to differing amounts of distortion.

I use a TV Panoptic Barlow Interface in my 2" GSO 2X ED barlow to make it a telecentric magnifier which completely eliminates vignetting and field cutoff.  Watch the classifieds for them.  They usually go for about $50 or so here in the states.  The GSO 2" 2X has almost exactly the same focal length as the TV Big Barlow, so the PBI works perfectly with it.

Invest in a GSO/Revelation coma corrector for $120 or so.  They come up used here in the states for $70 to $80 every few months.  Just add a 25mm spacer tube between the optics element and the eyepiece holder, and eyepieces like the 30mm ES-82 that focus at the shoulder will be pretty close to completely corrected for coma.  Eyepieces that focus more than about 5mm above or below the shoulder won't have as good a correction, but it will still correct out 80% or more of the coma.  I find that means I have to go looking for it at the edge.  It also flattens the field of the Newtonian which allows stars to be better in focus across the FOV.

[pregulla]

9 hours ago, Louis D said:

I use a TV Panoptic Barlow Interface in my 2" GSO 2X ED barlow to make it a telecentric magnifier which completely eliminates vignetting and field cutoff.  Watch the classifieds for them.  They usually go for about $50 or so here in the states.  The GSO 2" 2X has almost exactly the same focal length as the TV Big Barlow, so the PBI works perfectly with it. 

That's an interesting piece of gear. Not sure I'll need one though, but I'll keep an eye to see if it comes up on the used market. I use the barlow with zoom only, and it works fine as is. It was more out of curiosity that I tried ED 35mm with the barlow. 

10 hours ago, Louis D said:

Invest in a GSO/Revelation coma corrector for $120 or so.

I do plan on getting CC eventually, it's just not at the top of my priority list. The coma doesn't really bother me yet. I don't notice it unless I start looking for aberrations specifically.