Don Pensack

6 hours ago, IB20 said:

I’ve often thought I’d like to collect a best of each range eyepiece set at each FL, if we are talking availability in the current eyepiece market.

From my experience I’d probably think a 17.5mm Morpheus might be in there along with a 5mm XW and 4mm TOE.

Not tried an Ethos or Delos but the 13E seems well loved? Tried a Delite, fantastic optics but only tried the 13mm. Are Docters still available? Nikon NAV-HWs? Naglers? Masuyamas? Available plössls, orthos? 
What are SGLer’s experiences with their own eyepiece sets?

Why are there variances in quality of eyepiece ranges? What makes a truly exceptional eyepiece in a range and why are some poorer? Is it primarily aberration in faster scopes that highlights weakness? Obviously opinions on this can be very subjective but there usually is some consensus.

 

 

Interesting post.

My scope is a 12.5" f/5 (with Paracorr f/5.75).

These are the best in series to my eye, from over the years:

TeleVue:

Plössl--32mm; used--21mm original

Delite--18.2mm

Panoptic--24mm; used--22mm

Delos--10mm

Nagler--22mm T4 and 13mm/5mm T6 tie

Apollo 11--only used, but perhaps the best eyepiece TeleVue ever produced.

Ethos--6mm

Baader:

Hyperion--17mm

Morpheus--3-way tie among 12.5mm, 9mm, 4.5mm

Pentax:

XW 70--7mm

XW 85--16.5mm

APM:

UFF--30mm

XWA--7mm

Explore Scientific:

52°--no favorite

62°--26mm

68°--20mm

82°--6.7mm

92°--17mm

100°--5.5mm

Now I wear glasses at the eyepiece and my favorites have changed, but the above were from my tests of complete sets.

4 hours ago, IB20 said:

I love the 17.5mm but weirdly don’t feel the need for any others. I’m more interested in trying a TPL.
However if there was an 8mm Morpheus, I’d get it!

Understood, but that's unlikely to ever happen.

4.5mm, increased by 40% is ~6.5mm.

6.5mm becomes 9mm

9mm becomes 12.5mm.

And 12.5mm becomes 17.5mm.

So there was a rationale for the focal lengths.

Pentax XWs follow the same % progression, but start smaller: 3.5mm, 5mm, 7mm, 10mm, 14mm, 20mm

Whence comes the 14mm, then?  Well, in the original internal design, it looks like 14mm was about the longest focal length that could be made, so we got a 14mm to complete the set.

But, 3 years+ later, the 17.5mm came out, after some unsuccessful prototypes.  I think it is different internally to the other focal lengths, which is one reason it has a slightly narrower apparent field (72° versus 78-79°)

The first 17.5mm prototype (maybe the design on paper before the prototypes), which didn't work, is the data in Baader's spec chart.  They never updated the chart when the final version came out.

If you read Ernest Maratovich's charts and reviews, you'll also see they actually missed the exact focal lengths as well.

He measured: 17.2mm, 13.9mm, 12.4mm, 8.9mm, 6.7mm, and 4.8mm.

This is far from the only line of eyepieces where all the focal lengths are off, and some other eyepieces are in error by more than 0.5mm.

If we start measuring actual focal lengths and apparent fields, though, the market becomes filled with chaos and lots of exotic focal lengths.

How much does it matter in the field if your 13mm 100° eyepiece is actually 13.3mm and 101°?  It really doesn't.

3 hours ago, John said:

Are they responsible for the Svbony 3-8mm zoom ?

There is a certain resemblance.

I don't know, and the eyepiece has not appeared under other brand labels.

Maybe someone else has seen the eyepiece in China or on AliExpress from someone else?

19 minutes ago, John said:

I reckon this is the same eyepiece as the 30mm UFF but under different branding:

U.K. Astronomy Buy & Sell (astrobuysell.com)

UF 30mm Ultra Flat Field Eyepiece – Sky Rover Optics

If it is not exactly the same then it is very, very similar.

 

It's the same.  The manufacturer is KunMing United Optics (KUO), and Sky Rover is their "house brand".

They also sell eyepieces private label to at least 10 companies, maybe more.

4 hours ago, Elp said:

They are costly, but as a primarily imager I thought I'd reap the benefit, and they are really as good as they say they are, I was surprised how good they are visually too as prior experience using Barlow's you do notice the drop in brightness as well as edge definition. I suspect the 4x and 5x may suffer a little though in this respect.

Of course you notice the drop in brightness.  If you didn't, they wouldn't be magnifying.  The drop in brightness isn't due to transmission loss, it's due to magnification.

Generally, Barlows yield sharper edge definition due to the effective doubling of the f/ratio of the scope.  If they don't improve the edge of the field, there could be something optically mediocre about the Barlow.

As for PowerMates, the 4mm functions about the same as the 2X version, though the extra magnification might be too much.

The 5x unit has its magnification change with distance from the lens, similar to a Barlow.  I think its primary market is for imagers of planets, where it increases the size of the image significantly when used between scope and camera.

I used to use those, too, until I left one in my car on a hot day and the plastic melted against my filters and ruined a dozen filters.

The lesson to be learned is to not leave them in a hot car, I guess.  Here is what I use now--no foam, each filter in its own box.

Filters fog easily.  It's best to keep them in a case until used.

Eyepieces can just be kept capped until use.

3 hours ago, Mike Q said:

I would love to see Long Perng come out with a 2 inch 80 degree in a 5mm and 10mm LHD like their 14 and 20s. ... I would be all over that in a second 

Buy the 4mm, 6mm, and 9mm and attach 2" adapters to them in a quasi-permanent fashion.  Voilà! 2" eyepieces.

That is no different than having 2" barrels on what are, essentially, 1.25" eyepieces.

Bear in mind, this filter will enhance the gas tails in comets, NOT the dust tails.

You still want to compare the view sans filter.

On 13/06/2020 at 17:22, markse68 said:

Btw, anyone any idea how much a 2x Barlow shifts the focal point or is that a complex thing to determine?

All Barlows will move the focal plane of the telescope outward.

IF it moves the focal plane outward by exactly the length of the Barlow's barrel above the lens, it will be parfocal with the eyepiece when the eyepiece is used without the Barlow.

IF it moves the focal plane outward less than that distance, it will require in-travel of the focuser.

IF it moves the focal plane outward more than that distance, it will require out-travel of the focuser.

I have run into Barlows that do all 3.  More have required in-focus than out-focus.

How much in-travel or out-travel is required will depend on the spacing between the Barlow and the eyepiece, too.

So it will vary from Barlow to Barlow as to whether you need additional in-focus or out-focus.

One really short focal length eyepiece that IS adaptable to projection photography is the Baader Morpheus 4.5mm, which has a 43mm thread under the eyecup and for which camera adapters are available.

45 minutes ago, Louis D said:

If you have a long eye relief, low power eyepiece, try the blinking technique with the filter between your eye and the eyepiece.  This is how I've been comparing filters for false color reduction on achromats.  It's easier to see subtle differences between filters when you rapidly move them in and out of the exit pupil.  You can even try stacking filters this way to see if one is more dominant than another.  For instance, an HB or OIII should look the same with a UHC stacked ahead of it since the UHC should typically be passing both HB and OIII.

I've used the blinking technique on planetary nebulae that are so small they are little different than star images at low powers.

The nebula stays visible when almost all the stars disappear or get seriously darkened.

But for fainter objects, the difficult with this technique is that the filter is essentially a mirror and reflects back so much ambient light the objects become invisible.

Pure H-ß objects:

1. IC 434 w/B33(HORSEHEAD NEBULA)
2. NGC 1499 (CALIFORNIA NEBULA, naked eye and RFT)
3. M43 (part of the Great Orion Nebula)
4. IC 5146 (COCOON NEBULA in Cygnus)
5. M20 (TRIFID NEBULA, main section)
6. NGC 2327 (diffuse nebula in Monoceros)
7. IC 405 (the FLAMING STAR NEBULA in Auriga)
8. IC 417 (diffuse Nebula in Auriga)
9. IC 1283 (diffuse Nebula in Sagittarius)
10. IC 1318 GAMMA CYGNI NEBULA (diffuse nebula in Cygnus)
11. IC 2177: SEAGULL NEBULA (Diffuse Nebula, Monoceros)
12. IC 5076 (diffuse nebula, Cygnus)
13. PK64+5.1 "CAMPBELL'S HYDROGEN STAR" Cygnus (PNG 64.7+5.0)
14. Sh2-157a (small round nebula inside larger Sh2-157, Cassiopeia)
15. Sh2-235 (diffuse nebula in Auriga).
16. Sh2-276 "BARNARD'S LOOP" (diffuse nebula in Orion, naked eye)
17. IC 2162 (diffuse nebula in northern Orion)
18 Sh2-254 (diffuse nebula in northern Orion near IC 2162)
19. Sh2-256-7 (diffuse nebula in northern Orion near IC 2162)
20. vdB93 (Gum-1) (diffuse nebula in Monoceros near IC 2177)
21. Lambda Orionis nebular complex (very large, naked-eye)
22. Sh2-273 "Cone" Nebula portion south of cluster NGC 2264

It looks to be a hair under 33mm.  I got 32.9mm at the top of the threads on the 4mm.

The thread looks to be a fine thread, too, maybe 0.5mm

Why it is threaded, I don't know, since the eyepiece has too little eye relief for camera attachment, or for use with a DioptRx.

If you attach a camera, the lens will be outside the exit pupil and yield a smaller apparent field than the eyepiece.

This is NOT an eyepiece designed for projection imaging.

On 25/08/2023 at 13:57, IB20 said:

It’s quite interesting as I’ve no real idea about EP manufacturers. I often read that x y z EP was made in Japan/Taiwan or China with Japanese sourced glass.
Are the “bulk” EP manufacturers well known or are all EPs made by small artisan makers. How many EPs are made in a run? 100s/1000s? 

The SvBony planetary zoom seems like a punt that paid off as they are quite niche FLs whereas the Hyperflex and clone zooms have more “regular” range of FLs. Assume they must have product testers and buyers, so perhaps they tested an unbranded 3-8mm zoom and were suitably impressed but afaik that zoom is only under the SvBony brand? 

There aren't that many manufacturers of eyepieces that we all buy in the aftermarket.  I don't think any of them is a small company making a small number of eyepieces.  Many are very large manufacturing plants that make a host of products, including many that are outside the astronomy business.  Jing Hua Optical (Explore Scientific) makes mostly cell phone glass, and eyepieces are a side business for them, as just one example.

Since Svbony seems to be a unique brand name on the 3-8mm zoom, it is likely they commissioned it to be made.  Whether they, or the factory that made it, designed it, I don't know.

The factory size and the number of customers they can sell an eyepiece to as a private label product determines how many can be made in a batch.  It could be 100 or 500 depending.

Well, we are also lacking choice in glasses-compatible eyepieces.

There are many, but only a few *lines* of eyepieces, and usually a dearth of:

--short focal lengths below 5mm

--with ultra to hyperwide fields of view

--or choices of apparent field from 45° to 100°

Example: take the 4.7mm and 3.7mm Ethos.  Shrink the apparent field from 110° to 85°.  Increase eye relief to 19mm.

I bet the eyepieces would be the same size, albeit with a larger eye lens diameter.

Comet filters like the Lumicon, and now the Baader, help you see the gas tail more easily.

But they don't help on the dust tail, which reflects sunlight.

So it will depend on the comet and which details you want to see.

51 minutes ago, Louis D said:

I'd like to see an integrated light intensification line of eyepieces at a reasonable price.  I know there's EEVA and nightvision stuff, but it's so hodge-podge right now.  Some sort of elegant, compact system.  I mean, if they can offer that ZWO Seestar 50 for $500, you'd think someone could offer an eyepiece sized light intensification/collection unit for $500 to $1000.

Living in a dreamworld, Louis.

Eyepiece size night vision devices (e.g. Collins) were $4000 15 years ago, and there has been a lot of inflation since them.

Camera capture takes longer (not real time), but it's a LOT cheaper.

1 hour ago, IB20 said:

What do we think the next big EP range could be, what even are we lacking? Could we see a new Vixen range since the SLVs and SSWs have been discontinued? Are Televue due something new out? Baader? SvBony?

Tak surprisingly have released the TPL line which are Plössl-like, a little on the quirky side but have been getting some decent early reports from users on CN.

Personally I’d like some Tak UWs or extension of the TOE line, rebooted Vixen-HRs and LVWs; perhaps even some new Televues without undercuts…

 

What I'm looking for is a TeleVue 85° line with enough eye relief for glasses at all focal lengths.  Nagler Type 7?

Probably Ethos prices, but that's OK with me.

8mm, huh?

All of these are available in 8mm:

Svbony 3-8mm Zoom

and

1 hour ago, Ags said:

SLVs discontinued??????

No fear.  SLVs and NPLs are not discontinued.

SSWs are discontinued, but that happened a while ago.

26 minutes ago, Louis D said:

Definitely not ring of fire.  You get a rainbow effect when photographing it.  Below, see how the ES-82 30mm (6th row, second from left) is exhibiting classic CAEP (rainbow ring) but no SAEP (black ring), and the Meade MWA 26mm (5th row, far left) shows massive SAEP and in the second image from the left shows slight CAEP with the camera pulled back from the exit pupil midpoint to defeat SAEP.

The Morpheus 14mm (second row, second from left) has barely any SAEP and no CAEP at all.  There's also no obvious color cast relative to other eyepieces not exhibiting either SAEP or CAEP.  Strong SAEP really throws off my camera's auto white balance, making things more yellow.  The Morph 14mm also shows a nice, sharp field stop.

I'm not doubting what you're seeing, it's just that I don't see the same thing in my copy of the eyepiece.  Perhaps yours is faulty/defective in some manner?  How long have you had it?  Did you buy it second hand?  Was it always this way?

Louis, I see it quite well in your image of the 14mm Morpheus, the 14mm Pentax XL, the ES 17mm 92°.  It's not as strong as some others, but it's there in your images.

However, I just tried my 14mm in my 102mm f/7 triplet and saw no CAEP.  So I suspect it might be due to how the eyepiece handles the CA of the doublet image.

How or why, I cannot say without further research.

OK guys, the issue with the 14 Morpheus could be the same issue with the 31mm Nagler, 30mm ES 82°, so Pentax, etc.

The eyepiece was not designed for daylight observing if that is the case.  Nor were those others.

At night the coloration is invisible.

It is called "Chromatic Aberration of the Exit Pupil"(CAEP), or "Ring of Fire".   Louis D here on SGL has many pictures of it.

It simply means that not all colors are fully corrected at the exit pupil.

It's not due to being too close or too far away from the eyepiece.

If you bought the eyepiece for daylight use, you simply bought the wrong eyepiece.

If you bought it for nighttime use, you will like the eyepiece.

The one possible time you might see it at night is with the Moon entering that zone at the edge of the eyepiece.

However, as mentioned below, I tried the 14mm in my 102mm f/7 triplet apo on some land targets just now, and though there is a thin blue ring right at the field stop, I did not see any Ring of Fire issue--no CAEP.

So I wonder if there is an interaction between the doublet lens and the eyepiece, or that the eyepiece is wide enough to display lateral CA from the objective lens.  I don't know, but the results posted by Elp

are completely different that what I just saw.  Is it possible the field lens is installed backwards?  Is it possible the eyepiece is defective in some way or has been assembled incorrectly?

I couldn't say without comparing it with another sample of the same eyepiece.

4 hours ago, MalcolmM said:

Just for comparison,  here's a Nagler 16mm in the same setup. This time the FOV goes from 0 to 33cm.

Apologies to @Louis D for using his technique; I don't think I have achieved the quality of his images.

Malcolm 

This one has edge vignetting and chromatic aberration of the exit pupil (aka "Ring of Fire")

4 hours ago, MalcolmM said:

Here's my attempt to show the edge distortion in an FS60CB (f 5.9)

The rhs of the FOV is at 0, the lhs at 20 so the total FOV is roughly 65 cm on the ruler. The last 3cm of the rulers on either side are quite difficult to see without squinting and moving your head.

I've no idea how this would relate to star shapes at infinity but to my eyes, the ruler is pretty sharp up to roughly 75% out. But there is definitely a gradual decrease in the sharpness as you move to tbe edge.

Malcolm 

And noticeable edge vignetting, too.