Louis D

2 hours ago, cajen2 said:

I might one day invest in the 4mm - it's relatively cheap!

The 14mm and 20mm seem to receive universal praise.  There's very little known about the 4/6/9mm versions.  There's are recent CN thread asking for information on them, but little has come to light.  One learning from one post is that they may suffer from SAEP (kidney-beaning).  It's not even clear how severe it might be.  Jump in and get one and let the world know what you think of it.

I remember someone using a long 6" refractor on a DM-6 at a local star party.  It worked fine with it until you wanted to change eyepieces without losing your target.  It has no axis clutches, so you had to carefully keep the scope from nosediving while swapping heavy eyepieces (2+ pounds) in and out.  That's one of the reasons I upgraded from my DSV-1 to DSV-2B mount.  I love the latter's axis clutches while swapping eyepieces.

22 hours ago, Cosmic Geoff said:

Maybe your binoculars are out of collimation - a common problem with binoculars especially if dropped or knocked. 

Exactly.  I literally bought a pair of used binoculars off of CN classifieds that were way off on collimation.  The seller claims they never had merging issues.

22 hours ago, Space Hopper said:

(I've asked before on here for this : a dedicated forum for binoviewers, as well as splitting up 'Scopes / whole setups' in to smaller, better organised groups, like refractors, reflectors, cats & casses etc, but my request was just ignored without logical explanation 😒)

When I asked, the responding moderator said it was to prevent siloing of discussions.  However, by that measure, why not just lump all equipment discussions together?

His numbers pretty well agree with what I measured.

• Sharpness is excellent from 8-5mm with falloff below that.
• Focal lengths were pretty accurate for 8-5mm, with 4mm being off a bit (4.3mm) and 3mm being 3.5mm.
• Eye relief decreasing from 11mm to 6mm going from the 8mm setting to the 3mm setting seems about right.  I just couldn't measure it accurately with the limitation of my methodology.

Where we noticeably diverge is for AFOV:

• AFOV for me was 8mm=58°, 7mm=59°, 6mm=59°, 5mm=60°, 4mm=61°, 3mm=61°, so a nice, almost linear progression in size increase.
• I did not detect any of the decreasing, increasing, decreasing AFOV going from 8mm to 3mm with a minimum at 6mm of 55.5°.

I re-edited my AFOV image to more dramatically show how the AFOV increases from 8mm to 4mm in a fairly smooth manner, and then remains constant to 3mm:

This doesn't fit with Ernest's numbers very well:

Hmmm.  The thread that would not rest in peace.  Put to rest initially in 2006, resurrected in 2011, 2013, and now 2023.  This might be something of a record for SGL.

15 minutes ago, LDW1 said:

I am very familiar with Glen's products having owned 5 of his scopes and various eps, I thought maybe you had an in somewhere. I am an Antares fan !

Unless you get lucky and find a Canadian Astro/Photo shop with new-old stock zooms sitting on the shelf, you're probably going to have to depend on the secondary market.  Since you're in Canada, you're well positioned to make inquiries.  BTW, that zoom was a stretch for my astro budget back then.  I think I paid about $270 after all the cross-border costs were figured in.  That's about $480 today.

I will say that the 5-8mm zoom is very enjoyable to use once you get past the non-parfocality of it.  It is sharp edge to edge at f/6.  I compared it directly to the new Svbony 3-8mm zoom here:

6 minutes ago, Stu said:

The irony is that by making statements about high end zooms being mentioned, this has led to the thread being dominated by it.

I’m not sure if @Chaz2b is interested in these at all, so perhaps a comment back here will help push the discussion where it is wanted.

I'm done now.  I was in the middle of composing the above reply when I got the notification, but I wasn't going to abandon it.

5 minutes ago, LDW1 said:

Sounds good, can you find me one !  Maybe a few others on here would maybe like one as well ? Can you let me know ?Maybe talk to Mr. Speers directly.

I would suggest putting out a Wanted ad on UK based classifieds and also on Astromart and Cloudy Nights classifieds in the US.  There just might be someone willing to part with theirs.  I've had mine since new in the 2000 time frame, but I won't be parting with mine anytime soon.

It was Antares in Canada that marketed them.  I bought mine through O'Neill Photo in the Toronto area back in the day because they had no US dealers.  He closed up his shop long ago due to retirement.

Mr. Speers's first name is Glen.  I gather Glen Speers is still actively designing and manufacturing his Speers-Waler eyepieces in Canada, now in their Series 4 iteration.  Perhaps Antares could put you in touch with him to find out what he's up to these days.

16 minutes ago, LDW1 said:

Yes about the APM and even moreso the new Svbony equivalent but many, many, many observers want more range for their $ than what they offer. Thats why I personally didn't buy either, we aren't all moon / planetary focussed ! As for the others, we all have our experiences.

I'd probably be happiest with a 4 position 2" turret.  That way, I could quickly swap out a 40mm SWA for a 17mm HWA, then to a 10mm/9mm SWA, followed by 5mm SWA.  This would cover all but my binoviewing observing pretty well.  It's rare that I jump to 17mm HWA and say to myself, would this look better in a 22mm UWA instead?  The same goes at 9mm to 12mm.  I almost randomly choose one because the view doesn't change a whole lot in that range.  It is really only at the highest powers where you're teasing out the highest usable power that night that zooms really strut their stuff.  That, and in binoviewers where turrets aren't really feasible and eyepiece swapping is a pain.

20 minutes ago, LDW1 said:

I am waiting for one to come out like my 76° eps upwards to 100°, now thats widefield. When I find / get one it will be my only one but until then. Only incorrect based on interpretation !

Unless you demand parfocality, my 5-8mm Speers-Waler Zoom has a constant, measured, 78 degree AFOV through its range.  Of course, I consider it a varifocal rather than a zoom, but it was sold as a zoom.  They also made an 8-12mm version.

There was also a device that could be inserted between the Smyth lens group and positive lens group for early Nagler type ultrawide field eyepieces to convert them into ultrawide angle zooms.  I can't find references online to it anymore, but I think it was called "Zoom-Set" or something similar.

1 hour ago, LDW1 said:

In the 2nd paragraph of their OP they mention Svbony zoom eps so I proceeded to give my experience with easily obtainable zoom eps, nothing more, nothing less. Whether anyone reads is not an issue, a concern. If you have more in hand experience than I that is good, the more knowledge the better. The Sv's do perform extremely well for their cost, just ask my Mark IV that I sold, lol !

You are correct, and the OP does have the BHZ and prefers it to the Celestron Regal zoom (of which I have several and have never noticed any kidney-beaning).  I haven't read of anyone touting any of the Svbony zooms replacing their BHZ except for the 3-8mm replacing their BHZ+2.25x Barlow combination.  Aside from outreach usage, I doubt the OP would be particularly happy with the Svbony zooms.  I suppose the Svbony zooms are cheap enough that the OP could buy a few and try them out.

3 hours ago, LDW1 said:

Absolutely no doubt but at what price for a zoom eyepiece ? Especially on an average nite sky !

3 hours ago, LDW1 said:

We started out with reasonable priced zooms and now the rarer, much, much higher priced ones are showing up as is usual, lol.

Look at the OP's equipment list.  I have a feeling a rather ordinary zoom like the BHZ would not be well received and would be resold or returned.  By way of comparison, the Leica in particular is supposed to rival Pentax XWs in sharpness and contrast.  It just suffers a bit at the edges in sub-f/5 scopes compared to the XWs.

Perhaps a SV171 Svbony 8-24mm zoom?  They're only $51 on Svbony.com right now.  I have no idea if there's a UK equivalent website, however.  It's no Baader Hyperion Zoom, but if you combine your budget for multiple eyepieces into one, it would be no worse than a series of Plossls when used at f/5 as in your scope.

There's also the Celestron/Skywatcher 8-24mm zoom which might come in cheaper in the UK.

I'm seriously OCD, and my eyepiece case(s) have no particular order to the eyepieces.  It's more of a situation of where newer eyepieces would fit in the positions of older, retired eyepieces (or in adjacent, empty areas) because I didn't want to buy new P&P foam each and every time I upgraded eyepieces just to keep them in numerical order (cheapness wins over OCD for me every time).  I literally have the positions of my eyepiece memorized, along with what used to occupy those spots previously, so no OCD issues for me in the dark.

The 19mm Panoptic is diminutive and was designed with binoviewer usage in mind, along with the 24mm Panoptic.  A natural result of this is limited eye relief, which you've stated is not an issue for you.

If you like small, jewel like eyepieces, you'd probably love the 19mm Panoptic.  You might also want look into the 16mm Nagler T5 which has a slightly larger TFOV while being only a tiny bit heavier than the 19mm Pan.

6 minutes ago, Stu said:

Whilst not widefield, there are wider afov options out there, albeit at some cost.

The APM zoom is between 66 and 67 degrees afov throughout its range from 7.7 to 15.4mm

https://astrograph.net/epages/www_astrograph_net.mobile/en_GB/?ObjectID=18789787

The Leica ASPH zoom is 8.9 to 17.8mm and is approx 60 degrees at the low power and 80 degrees at the high power. It needs an adaptor for either 1.25” or 2” as it is designed for spotting scopes. Superb eyepiece.

https://www.wexphotovideo.com/leica-zoom-eyepiece-25x-50x-ww-asph--1768793/

Speaking of high end spotting scope eyepieces popular with amateur astronomers, there is also the discontinued ZEISS DiaScope Vario 15-56x/20-75x (6.9mm to 25.1mm) which is popular for its extended zoom range.

I use a GSO CC in my GSO 150mm f/5 Newt.  It gets the job done with wide field eyepieces.  For Orthos and Plossls, the difference might not matter much to most observers.  Because it imparts some spherical aberration on axis, I remove it for high power viewing of planets to get the sharpest image possible.

I bought a few 48mm vintage camera lens color filters to try since they can be directly threaded onto 2" eyepieces.

First up is a Rokunar Yellow K2 - #8 which appears to be very close to the original Wratten spec for a Yellow #8 with a 19% cut-on around 480nm.  In fact, the Hirsch Yellow #12A appears to be very similar to the Wratten #4 spec with a 42% cut-on around 470nm.  The Meade Yellow #8 seems paler than even the Wratten #3 spec which specifies a 38% cut-on at 460nm.

I've run the Rokunar Yellow K2 through my spectrograph and found it to be about midway between my (GSO) Yellow #12 and Hirsch Yellow #12A.  On Venus, Jupiter, and the moon, it performs more similarly to the #12A than to the #12.  It cuts all violet while imparting only a slightly deeper yellow cast to the image than the #12A.  The #12 imparts a noticeably yellower cast to the image than either of the other two.

Here's the lineup of my various yellow filters as seen through the spectrograph:

Next up is a Rokunar Green X1 -#11 which appears to be very close to the original Wratten spec for a Yellow-Green #11 with a 26% cut-on around 480nm, a peak of 50% or better from 500nm to 550nm, and a 19% cut-off around 610nm.  This is almost exactly where achromats are best corrected.  It is almost identical to the R89 Moss Green in appearance, spectrographic analysis, and in use on Venus, Jupiter, and the moon.

Here's the lineup of my various green filters that I've found useful with a fast achromat as seen through the spectrograph:

From what I've read online, it has a T2 thread on top if it is the 1.25" version.  The Maxview II version seems to have a 58mm thread on top.  You weren't specific about which version you bought.  I think both are hidden by the thread-on eye cup adapter.

You would need to find the appropriate step rings to get from there to whatever lens thread exists on your camera lens.

Except at very high powers where the new Svbony 3-8mm zoom excels, I find myself jumping in 3x increments generally.  Thus, a 3x zoom like an 8-24mm works out to 1 to 2 useful focal lengths for me.  I tend to start at 40mm with a 2" eyepiece, then I jump up to a 12mm to 17mm eyepiece to get a closer look, if it comfortably fits in the field of view.  From there, I generally jump up to a 5mm to 7mm eyepiece if it is a small object or has some fine details I want to examine more closely.  Thus, most 3x zooms only cover the middle range and miss at both ends.  I'd need a 2", 8x zoom (5-40mm) with a 70 degree AFOV to be really useful for my style of observing.  If it was well corrected like XWs and Deloses with 18mm of usable eye relief, I'd easily pay $1000+ for one just for the convenience.  However, I've never heard of anyone seriously considering bringing such a zoom to market.

7 hours ago, stormioV said:

Great review. Would this be a useful addition to my LX90 for Lunar observing. Or would it mostly unuseable.

You're going to be starting off at a small exit pupil at 8mm (8/10=0.8mm) progressing to a very tiny exit pupil by the time you get to 3mm (really 3.5mm, so 3.5/10=0.35mm).  If floaters are not an issue with your eyes, and you have really good seeing conditions (going from 2032/8 = 254x at 8mm to 2032/3.5 = 581x at 3mm/3.5mm), you might make good use of it to probe the limits of your scope, seeing, and eyes.  Have you tried experimenting with these high powers using your existing eyepieces and a 2x or 3x Barlow already?  Also, your collimation will need to be spot on for best results at these powers.

3 hours ago, Zermelo said:

Some of the testing that I did for this review was using a 150mm f/5 Newtonian

As did I after I wrote this initial report.  I didn't see any noticeable degradation going from f/6 to f/5.

32 minutes ago, Highburymark said:

There’s a tiny bit of edge false colour in the XWs

Agreed on all but the 3.5mm.  Did you see chromatic aberration at the edge in your 3.5mm XW?  My 5.2mm XL is also free of color to the edge.  After seeing the chroma at the edge of the 7mm, I decided to keep the 5.2mm rather than "upgrade".

Has anyone ever come up with a binocular collimation methodology or technique that doesn't rely on an expensive, precision optical test bench?

2 hours ago, jetstream said:

Have you compared the 4mm DeLite to it Louis?

No, just the Svbony 3-8mm zoom at 3mm which actual 3.5mm.  The XW stomps all over it in eye relief, field of view, sharpness, and control of chromatic aberrations.  This should surprise no one.

I don't spend a lot of time at tiny exit pupils.  The only reason I picked up the XW was because Amazon dropped the price to $216 years ago, so it was too tempting to pass up.