Don Pensack

7 hours ago, globular said:

Does the 22mm Nagler make this list too? It’s on my short list, with the ES 92s, for a glasses friendly fairly wide set.
On paper it has 19mm eye relief like the 31. In actual use does it not work well with glasses?

It works fine for me with glasses, but a few people with eyes even more deep-set than mine (or with thicker glasses) report that the 22mm, like the 31mm, is "marginal".

Personal physiology probably means the "cusp" of glasses use is somewhere between 17 and 22mm of eye relief.

2 hours ago, Louis D said:

It does work fine with glasses in my experience.  I think it just slipped Don's mind.  He uses one with glasses, so that's about as much proof as I need.  I found the 17mm and 12mm NT4s to also work with eyeglasses, but they had such finicky exit pupils once the field stop popped into view that they were too tiring to use, so I replaced them with the ES-92s.

Thanks, Louis, yes it just slipped my mind.  I do use it with glasses, and it works fine that way.  I just wish I didn't have presbyopia and need a different prescription for reading my notes and DSC.

I use bifocals, and they made the bottoms as small as they could but on these eyepieces with large lenses, the bifocal section is in view and if I look down at the bottom of the field, it's out of focus due to the small bifocal section.

One of the perils of age, I'm afraid.

21 minutes ago, Pixies said:

What's the eye relief like on the 82deg ES? Any good for spectacle-wearers?

(asking for a friend)

No, the 14mm 82° has an eye relief of 15mm but the eye lens is recessed just enough it's more like 12mm.

No one with glasses can see the whole field.

There are very very few 82° eyepieces that are glasses-compatible.

They don't work with my glasses, but I have deep-set eyes.  They might work if your eye is very close to the lenses of your glasses.

On 19/09/2020 at 03:26, Charlie 2436 said:

Thanks for the advice Don. I was out last night and I noticed the sky seems to have a glow / haze to it , I guess that’s one of the drawbacks of living in a city. 
Don in what order of would you advise getting these filters ? Would I be as well going for Astronomik instead of buying cheaper and having to buy twice , also I know this might sound like a stupid question but do the 1:25” filters work just as well as the 2”.
thanks again Robert 

You will use them at low powers (under 10x/inch of aperture), so whether or not you get 2" filters will depend on that.

I think 2" is the universal size, since it fits 2" eyepieces, 2" diagonals, and 2" to 1.25" adapters (most of them).

I would start with a Narrowband filter like:

Astronomik UHC

TeleVue Band Mate II Nebustar

Lumicon Gen.3 UHC

DGM NPB

Orion Ultrablock

Then, if your interest heads more to planetary nebulae, an O-III filter for maximum contrast. 

Oh, and there are no 100-120° eyepieces from any company that are compatible with glasses.

The closest you can get are the 92° Explore Scientifics in 17mm and 12mm.

and there are not many more 82° eyepieces that are glasses compatible, either:

12.5mm Docter/Noblex (84°)

12.5,, APM Hi-FW (84°)

11mm TeleVue Apollo (85°)

TeleVue 31mm Nagler (82°)

Explore Scientific 30mm 82° 

Orion UHD eyepieces (80°)

and a few real cheapos.

On 19/09/2020 at 01:22, Alan White said:

@Don Pensack, why not the APM 12.5 like you have done??

No reason.  He was just discussing the Morpheus, that's all.

People have reported field curvature in both the 14mm Morpheus and the 14mm XW.

I mentioned those because I think the visibility of field curvature is related to accommodation (of which I have none) and the type and focal length of scope.

And newtonians of fast focal ratio can display some field curvature up to about a focal length of 1200mm if the field curvature of the eyepiece doesn't match the scope.

I wasn't implying a 10" scope is a small scope, but it can be short enough to reveal field curvature which is less seen in longer instruments.

On 20/09/2020 at 07:01, sputniksteve said:

It's probably my memory tbh. It was well collimated and a great mirror. 

I'd also suggest that seeing and sky quality etc would have made a difference. I'm in Bortle 5. 

I've not yet a good view of Jupiter with the 127. I do recall that looking great through the 12" though.

A Bortle Class 9 is fine for planets.

What matters is the seeing.  And that is estimable by this:

http://www.damianpeach.com/pickering.htm

On 22/09/2020 at 05:19, Dantooine said:

Now that’s on its way, the apm 3.5mm looks a good option for rare nights without a massive outlay... does this ever end 😱

No.

15 hours ago, jonathan said:

I'm curious about the UV cure - I have read on these forums a time of about 20 minutes, but is that direct sunlight shining through glass itself or is scattered UV sufficient, e.g. eyepiece laying on it's side?

If working with lens elements or OTA glass or mirror surfaces etc I would recommend a bulb blower (with long plastic nozzle) to blast away dust and small particles etc, I could only find a medium-sized one which I bought from eBay, I wanted a much larger version (the bulb itself the size of my hand) but couldn't find where to buy one from.  I've seen advice not to use an air duster as this can spew out liquid propellant.

Use a rubber ear syringe.  It will satisfy your size requirements and they concentrate the blast in a very small area.

Decent glasses friendly 30-40mm eyepieces:

Pentax XW 40

Pentax XW 30

TeleVue Panoptic (41mm)

TeleVue Nagler 31

Explore Scientific 40mm 68°

Explore Scientific 40mm 62°

Explore Scientific 40mm 52°

Explore Scientific 30mm 82°

APM or Altair 30mm Ultra Flat field

TeleVue Plössl 40mm

TeleVue Plössl 32mm

Lower prices 30-40mm long eye relief eyepieces will be astigmatic in about the outer 50% of the field.

If this is just a finder eyepiece, then maybe that's OK.

If this is an eyepiece you plan to view with often, then I suggest saving your pence and paying a bit more.

In my 12.5" f/5 with Paracorr II (which also adds a mild field flattening, I don't notice field curvature in the 14mm Morpheus, the 14mm XW, or the 12.5mm Hi-FW (all compatible with glasses)

and I have almost zero accommodation and have 3 different prescriptions of progressives for various purposes because of that.  I think the term is "fixed focus". LOL.

The key is that the effective focal length and radius of curvature of my scope is 1826mm, which is almost flat anyway, and with a mild field flattening, flat field eyepieces appear map-flat.

And eyepieces with field curvature appear flat, because FC in eyepieces is really small.

There are some exceptions (e.g. 35mm Panoptic), but field curvature isn't an issue, normally.

On the other hand, my 4" refractor has a 714mm focal length and 240mm radius of curvature and sees field curvature in a LOT of eyepieces.

It isn't, of course, field curvature in the eyepiece, but the scope, or, more exactly, the lack of a match between the FC of the scope and the FC of the eyepieces.

So it depends on your scope as to whether or not FC will be a problem.

A refractor?  Probably a problem.

A small newtonian (up to 10") used without a coma corrector?  Might be a problem.

A big newtonian used with a coma corrector--unlikely to be a problem.

Standard SCTs, with a curved focal plane--likely a problem.

New SCTs with corrective lenses installed--probably not a problem.

11 hours ago, Charlie 2436 said:

Thanks for all your advice. I will give it a few more nights to see if it was just atmospheric conditions on my first night. 
Is there any difference between sky glow and light pollution ?, and what is the best filter to combat them ?

 Thanks Robert 

Back in the '70s, light pollution was largely sodium vapor and warm incandescent lights.  Filters were created to cut out the yellow and orange parts of the spectrum to make the background sky a lot darker in the eyepiece so contrast would be improved.  Today's lighting is LCD, LED, halogen, fluorescent, neon, argon, zenon, arc lamp, various halogen, incandescent, and every variety of light imaginable.  As a result, light pollution is present at near every wavelength of the spectrum, so the broadband filters of the '70s are no longer effective at cutting down light pollution.  In fact, in bright environments, they scatter a lot of light inside the layers of the filter and make it worse.

They do work fairly well in dark skies to turn up contrast a tiny bit.

So in today's urban and suburban environment, a narrowband filter that passes only a few discrete wavelengths of light emitted by nebulae can be effective at making nebulae a lot more visible.  Since stars, galaxies, star clusters, and many other objects emit light at a lot of wavelengths, they are only helped by darker skies.  But at least for the brighter nebulae, nebula filters (narrowband, O-III, H-ß) can help reveal details and features and size of nebulae not visible without them.

But filters cannot help atmospheric haze, so wait for a clear and dry night.  Even here in Los Angeles, we can see stars to magnitude 5 on the clear, dry, moonless, nights.

You have to be careful with those flexible vinyl caps.

If the eyepiece has a lens in the lower barrel that is near the end of the eyepiece, the case will press the eyepiece cap into contact with the lens and leave a smudge.

ES has had this issue and switched to hard caps on those eyepieces.  APM and Stellarvue have that problem currently with their 20mm 100° eyepieces.

For planets, try a Baader Moon & Sky Glow filter, or if you're a Mars specialist, a Baader Contrast Booster (incredible on Mars).

But, haze in the sky does not help.

3 hours ago, Stardaze said:

I've just weighed my APM 20 = 694g

Mine was 678g, weighed without caps.  I wonder if they shaved the O.D. of the barrel a bit?

TeleVue did that years ago with the 13 Ethos.

On 16/09/2020 at 12:06, Dantooine said:

That’s very interesting for me. Would you say that the 22 Nagler is a good alternative to the 21 ethos?

I have a pan 27 at the moment and I think it shows about the same field as the Nagler. I have never used a Nagler so for me it’s venturing into the unknown. There is a big difference in price in the uk. 

The 27mm Panoptic has a 30.5mm field stop.

The 22mm Nagler has a 31.1mm field stop

The 21mm Ethos has a 36.2mm field stop.

Yes, I think the 22mm Nagler is a good alternative to the 21mm Ethos, though You might want a really low power, widest-field eyepiece to go wit it.

The Nagler doesn't feel like an Ethos (the 31mm is closer to the Ethos feel), because the field doesn't "wrap around the corner", i.e. you don't have to rock your head as much to see the edge.

And, the large eye lens gives a bit more of a picture window feel to the Nagler's field of view, compared to the "porthole" feel of the Ethos.

[Picture window--all the field is right there and you don't have to get close to see the large field.  Porthole--you have to get close to see the wide field and move to the right to look left and vice versa.

In that sense, the Nagler defines "immersive", while the Ethos is a little more like being in space, where there is no boundary unless you turn your head.  I love them both, but the Nagler works with glasses,

so that's where I went.  From a 22 Panoptic to a 22 Nagler to a 21 Ethos and back to a 22 Nagler.  Not really much of a sacrifice, eh.]

Frost is a common problem at the high altitude site I frequent.

Often in the winter, I have to wait for the sun to melt the ice off all my equipment (chair, table, battery) before I can pack it in the car and drive home.

Eyepieces, though, never frost up if they are left in a closed case until used, then returned to the case after use.

they can fog up from your breath, but a small fan will solve that.  I've taken to waving a small Japanese folding fan at the eyepiece when it fogs, and it always unfogs the eyepiece.

You have to be careful not to breathe on the eyepiece when using them in cold weather.

I would simply dismantle it and clean it with lens cleaner.

Unless the eyepiece is more than 50 years old, it can probably be successfully cleaned and reassembled.

I've done so with some eyepieces from the 1890s that needed a soak in acid to completely clean off the junk on the lenses, but came out clean and usable.

4 minutes ago, Dantooine said:

Is that the same or similar to the 30mm ultra flat that Altair Astro sell?

There are differences in the barrels, but the APM UltraFlat field, the Altair Ultra Flat, the Meade UHD, the Orion Ultra Flat Field and maybe one other are all the same optics from KunMing United Optics.

Someone here on SGL pointed out the Altair 30mm has a reflective spacer in it, but I don't remember whether it was visible or not in the field.

1 hour ago, Dantooine said:

Chance of a used 21E would be pretty slim I think. That says something. 

I sold mine a little while ago because I need glasses to see good stars down to about 10mm, now, so the 21, 17, and 13 got sold.

I had a 22mm Nagler from 1998 to 2010, then the Ethos from 2010-2019, and now back to the Nagler 22.  I don't find it much of a sacrifice, though the 21 Ethos is a fine eyepiece.

But they occasionally show up on used sites.  Just not often because so few of them are sold, comparatively speaking.

ES puts these on sale from time to time, and that is when the sales occur.

The 92s are more cost-effective, but less unique.

10 minutes ago, globular said:

Baader 45° erecting prisms no good? Or all Baader prisms?
I don't want to hijack the thread, but I was thinking about the Baader 2" Prism (#2456117) for my 8" Edge HD. Should I think again?

Correct, I was referring to the cost because Carbon Brush had commented he couldn't find anything affordable.

Robindonne posted a couple that were a lot less.  There are many in the market that are less expensive than Baader.

I reviewed the 9mm 120° elsewhere, but I'll recap:

--the eyepiece is sharp enough, but a bit darker than the 8mm or 10mm Ethos on either side.  Is it the 12 elements?  Or the coatings?  I don't know, but it's obviously darker.

--the curvature of the eye lens is such that ALL peripheral light coming into the eyepiece from around your head reflects directly into your eye.  The eyepiece requires you cup your hands

around the eyepiece to block peripheral light, or use a cloth over your head, or a hood that blocks peripheral light.  Otherwise, the eyepiece is impossible to use.

--the 120° field is simply too wide, not because 120° is bad, but because looking at the edge of the field toward the front of the scope has the sky in your peripheral vision, actually covering about

40% of the field you see.  To use the eyepiece while looking at the edge of the field requires blocking the light of the sky with a black cardboard or plastic sheet because you are actually looking

more in the direction the scope is pointed than you are perpendicular to it.

--correction at the very edge was very good, but not perfect (at f/5.75, coma-corrected).

An interesting eyepiece, sort of a collector's item.

In contrast, I have almost no reservations about the 92° series.