Happy Coincidence

[iPeace]

On 16/07/2018 at 22:22, John said:

I'll be glad to have another opinion on this pairing - sometimes, when you observe on your own a lot, you do start to wonder if you are seeing things differently to other people 

Right...no pressure, then.

I've taken this just about as far as my skills, knowledge and aptitude will bear. Which is not far, but I will gladly share what I've got. I've waited long enough, and so have you.

So, we have our dark horse combo:

Acquired for the fun of finding out for myself how close this gets to the performance of the bad boys, speaking of which:

These are the ones I chose as most likely competitors, out of several, in order to have a common feature set which makes the most sense to me. Nagler Zooms have less eye relief and smaller FOV; so do Vixen HRs. T6 Naglers have wider FOV and Pentax XWs are larger and heavier. They all get used with joy, but lately when on the road with a short refractor, which is how I get most of my gazing done, I've always brought the DeLites along for high power and have been glad I did. Moon, planets and doubles handled very well indeed.

So, if the HyperFlex, wearing its Baader Q Barlow, were to be able to convincingly match up, I'd be impressed indeed.

I know next to nothing about eyepiece design and construction - and perhaps the world is a better place for it. So I forgive myself for not being entirely convinced the DeLites are merely happy to see me - they surely must be wearing barlows of their own under their shiny black suits...

...but that is of course mere speculation on my part.

(continued)

[iPeace]

(I'm taking the liberty of making separate posts here in this thread so as to keep the writing manageable on my phone - apologies for any semblance of hijacking... )

However...the concept of a zoom-barlow combination is common enough, and in order for the HyperFlex to really become a mainstay for me, it would have to do at least as well as the Baader Zoom. With a barlow. And Baader does a barlow especially for the Zoom, you just screw it into the nosepiece:

Alternatively, you can fit it to an extension tube assembly, like so:

In this case, including a focusing eyepiece holder for extra flexibility:

But why stop there? Baader does another well-regarded barlow, the VIP, which, as supplied, gives 2x :

Or, you can add spacers to get more magnification:

...but it does start to look a bit silly.

So, I'm on holiday and I've brought the stuff along to see whether anything works any better than anything else.

(continued)

[iPeace]

(continued)

As for ergonomics, the candidates all have nice eye lenses, the HyperFlex having the smallest, but not by much:

Each having comfortable eye relief, their eyeguards can be adjusted to most anyone's taste.

As for stowability, while the DeLites require a more tailored packing solution, the HyperFlex and Q barlow each fit in one of my standard-issue neoprene eyepiece sleeping bags:

While the Baader Zoom comes with its own pouch and its barlow assembly also fits.

In short, for my own purposes, the HyperFlex and Q barlow have a very nice form factor. If it could do well enough to save me bringing along two DeLites, well... Or indeed, if the addition of a Hyperion barlow or VIP barlow to the Baader Zoom - which has a tendency to tag along in any case - could let me leave two other eyepieces at home, that wouldn't be bad, either.

So just a bit of fun with this stuff, to see what it does for me. Scope for this outing is Moose, my TV-60.

As portable a decent small refractor as you're likely to find, I suppose its limitations may not tolerate shortcomings of eyepieces particularly well. If so, it's a neat way to weed out pretenders...

(continued)

[iPeace]

(continued)

To be clear, I've been using the HyperFlex alongside the Baader Zoom for some weeks now, experimenting with different barlow combinations and generally letting my impressions form. I could go on in this manner indefinitely, but it's time to share, so here goes.

The Baader Zoom is a known entity for me, a comfy bit of kit whose usefulness tends to outweigh any shortcomings. I wasn't expecting any miracles to happen when combined with a barlow, just decent views at powers higher than at the unbarlowed 8mm stop. This it does well enough, both with the Hyperion barlow and with the VIP.

The HyperFlex does...surprisingly well. I was ready for the view to be in some small way inferior, and when unbarlowed it seems decent enough, if not exceptional. But my first nocturnal look through it combined with the Q barlow was definitely a 'hey' moment. Very sharp. Very nice. Then as indeed now, I found myself switching back and forth between HyperFlex and Baader, trying to determine if either is better when barlowed, and only coming up with very slight nuances which I've yet to quantify or qualify. For me, between them there's so little in it that any preference would have to be based on anything but the actual view. Well, perhaps a slightly wider field in the Baader, but otherwise...

(continued)

[John]

Please don't stop there Mike - gripping stuff !

[iPeace]

5 minutes ago, John said:

Please don't stop there Mike - gripping stuff !

There's more - and I promise you'll have it - but must away now for dinner with The Other.

[iPeace]

(Apologies for the delay - I was having some trouble accessing SGL for a while.)

So, having established that, to my eyes under my skies, the HyperFlex combined with the Q barlow is indeed surprisingly close in performance to the Baader Zoom with a Hyperion or even a VIP barlow, the Big Question remains - what about matching the bad boys? As a Trusted Source has to some extent heightened one's expectations, this is not one which I take lightly. Could the Q'ed HyperFlex do well enough for me so as not to reach for something with green lettering?

Let me just set the stage here. We're on an island in the Aegean, with very little actual cloud but highly variable seeing. I've heard tell that dust from the Sahara actually blows over on its way to mainland Greece. One moment things can be pretty decent, while the next can make you think you've mounted the Ouzo bottle by mistake. Add to that my insistance on portability over aperture, and you find that using 60mm at powers of 90x to 120x to full effect can be a challenge.

(continued)

[Paz]

This is a very interesting thread. I got a Mk4 8-24mm zoom a while back and at first I was a little disappointed because I noticed some field curvature and scatter that I don't get in my SLVs which were what it is competing against. Eye relief was not so good as the SLVs and the apparent field of view at longer focal lengths was smaller. I found though that the zoom looked best at 8mm and felt it was designed at that end with the compromises being built in on order to zoom out rather than the other way around... if that makes any sense.

However I stuck with it and depending on the scope and targets I complement it with a 32mm plossl to go wider and a 1.5x Barlow or a 2.5x Powermate to cover down to 3.2mm - pretty much the whole range of focal lengths one would use in practice.

What I have found is that despite not being a match for my SLVs in outright quality of view in fact the zoom eyepiece has been picked out of the lineup for action most of the time (I'm not sure if I should be admitting this!). I took it on holiday and it was so simple and flexible it was winning, and any grab and go weekday sessions always see the zoom come out.

Planetary and solar observation is good as I find picking the right magnification matters most for me on those and you can tune the magnification to just the right amount

As well as saving time changing eyepieces (and time agonising about whether to change eyepieces!) I always clean my eyepieces when I come in (just a blower and making sure they have dried out) and doing this with one eyepiece saves a lot of time compared to cleaning 3 or 4 or even more so I am not staying up so late.

[iPeace]

(continued)

So you switch. You swap. And switch again. And try different combinations. And try to see any differences there may be.

Trying to split the silly vote with the VIP barlow at max power.

And where this all really matters, of course, is at highest magnification. Trying to squeeze out some Martian detail. That type of thing.

But when the surface of the Moon is intermittently awash with jet-propelled goo, you're never really sure. Yes, you get some good fleeting glimpses, and are happy with whatever happens to be in the diagonal at the time, but real honest comparison?

(I'm building up to the clincher here - can you tell?)

(continued)

[GavStar]

6 minutes ago, iPeace said:

(continued)

So you switch. You swap. And switch again. And try different combinations. And try to see any differences there may be.

Trying to split the silly vote with the VIP barlow at max power.

 

That eyepiece stack is almost as bad as the night vision plossl stack!!! ??

[iPeace]

(continued)

So how to turn the dodgy seeing into an advantage for this comparison?

Well, you turn and face the Double Double. Epsilon Lyrae is of course the pair of double stars which is easy to find, but depending on equipment and conditions, not always easy to split into four.

I know from experience that Moose, when loaded with green lettering, will render a clean split in half-decent conditions, so it could be a reasonable benchmark.

Seeing was not good. The Q'd HyperFlex was struggling, close but not a good split. The Baader did no better. But sure enough, the DeLite did manage to show a clear split. Nothing close to the best view you can get under better conditions, but fully convincing.

Let me be clear: this was not a night on which to even try to enjoy splitting double stars - you just know it's not going to be worth it. But the target surely served the purpose of determining the marginal hard performance gain provided by a DeLite.

Additionally, let me say that it wasn't a one-glimpse thing. All the eyepieces got plenty of time to catch the best moments of seeing and to show the best they could do on the night. And on better nights, I'm sure that both barlowed zooms could get it done to satisfaction.

So, what do we know? Well, both the Q'd HyperFlex and the barlowed Baader are compelling tools, the performance of the HyperFlex being smashing value for the dosh. Would I prefer one over the other? Well... the Baader is like an old pair of slippers for me, just fits and I'm used to it. Yes, it's a bit more posh and has a bit more FOV and comes with a nice pouch, but if you're on a budget and raw performance is the main consideration, a HyperFlex - in one of its many branding guises - is not to be ignored, especially if pairing it with a Q barlow will provide useful magnifications for your scope.

I've a few more bits to mention and questions to ask, but must away now again to get some holidaying done.

Back soon.

The carnage following a night's testing. Just waiting for the raid by the OCD police.

[John]

Thanks for the continued reporting Mike - hope the hoiday is a success as well !

I'm pleased that you found the 7.2 - 21.5 zoom plus Baader 2.25x barlow combination did well against fine alternative options.

I'm tempted to try another Baader zoom but this time with the bespoke barlow to see for myself how that gets on as a high power observing tool.

One additional positive conclusion is that there are so many options available to us these days that give very satisfactory results

 

[iPeace]

Can't help but think that it's a big ask for an eyepiece to deliver when used with such a small, short scope. All things considered, the HyperFlex and the Baader both do a really good job.

I can imagine a larger, longer scope being something of a more level playing field on which the already marginal difference dwindles...

Anyhoo, one thing I did notice when observing the Moon - when it had just drifted out of view, it was sort of as if a torch was being shone down the tube at me. I looked for this in both barlowed zooms and in the DeLites, but only saw it in the zooms. Not a problem at all for me, as it did not occur as long as any part of the Moon was actually in view, but I am curious as to whether this is a known (named) phenomenon.

To be clear, this only seems to appear at higher magnification and in the area about a Moon's width around the actual disk.

[John]

I think I've seen that same effect in the zoom as well. I think it's called off axis scatter / glare or something like that. I have also seen it with a 4mm Radian eyepiece, oddly, but not the 3mm in that range.

It must be tough to control the effects of a very bright light source just outside the field of view. Remarkable that some designs can do it so well.

[iPeace]

That certainly sounds about right. I could also see it if I moved my eye off axis while the moon was in full view.

[Louis D]

I've also heard it called stray light control.  It can be handy when looking for dim companions to bright stars to put the primary star behind the field stop to block the glare.  The new Vixen HRs are supposed to be very good at blocking stray light outside the field of view with lots of well placed baffles.

[Louis D]

I picked up one of these 7.2-21.5mm eyepieces from Surplus Shed here in the states when they had a 60% everything sale a while back based on this thread.  I finally got the chance to try it out the other night under the stars.  It is indeed very sharp nearly to the edge, it requires a fair bit of refocusing between focal lengths, and the zoom action is fairly stiff, but not terribly so.  Using a 2x Meade 140 barlow element to boost power sharpened things even further.  I can understand why @Johnreally likes this particular eyepiece/barlow combination.

If you don't wear eyeglasses, it is indeed quite a nice zoom for the money.  However, I do wear eyeglasses at the eyepiece due to strong astigmatism and the measured 9mm to 11mm of usable eye relief (depending on focal length) made using it pretty miserable with eyeglasses.  I'll probably be passing mine along to someone with no (or at least weak) astigmatism in their observing eye.

I measured the AFOV to be 33 degrees at 21.5mm and 49 degrees at 7.2mm.  The effective field stop was measured to be 12mm and 6.5mm at those two focal lengths yielding eAFOVs of 32 degrees and 52 degrees, respectively.  Thus, distortion is quite low, growing a bit toward the shorter focal length end.

[John]

Interesting report Louis.

The AFoV on my zoom seems a little more generous than that when I've compared it (the actual view of the sky as well as the illuminated field) to reliable eyepieces of known AFoV - I'd say 38-55 degrees approx. I've not actually measured the field stop though.

The eye relief seems comfortable to me but I don't wear glasses to observe.

 

[Louis D]

2 hours ago, John said:

Interesting report Louis.

The AFoV on my zoom seems a little more generous than that when I've compared it (the actual view of the sky as well as the illuminated field) to reliable eyepieces of known AFoV - I'd say 38-55 degrees approx. I've not actually measured the field stop though.

The eye relief seems comfortable to me but I don't wear glasses to observe.

 

I suppose AFOV and TFOV could vary between the various marketing badges if the purchaser asks for a particular batch to have a larger physical field stop inserted at the expense of additional edge aberrations.  For what I paid, I'm perfectly happy with my purchase.  It was less than the cost of dinner for two.

[John]

1 hour ago, Louis D said:

I suppose AFOV and TFOV could vary between the various marketing badges if the purchaser asks for a particular batch to have a larger physical field stop inserted at the expense of additional edge aberrations.  For what I paid, I'm perfectly happy with my purchase.  It was less than the cost of dinner for two.

Have you had a chance to compare this zoom with your Celstron Regal 8-24mm zoom ?

I recall from past posts that you were impressed with the Regal zoom.

[Louis D]

17 hours ago, John said:

Have you had a chance to compare this zoom with your Celstron Regal 8-24mm zoom ?

I recall from past posts that you were impressed with the Regal zoom.

No, but the thought crossed my mind.  It was getting late and I was getting tired, so I left it for another night.  I can say that the Regal zoom has just enough usable eye relief (14mm to 16mm) for eyeglass wearers and a significantly wider AFOV (44 to 63 degrees going from 24mm to 8mm).  It is also much easier to zoom one handed.  It would really come down to does the new zoom have a sharper field of view center and edge than the Regal.  If I do a head to head comparison, I'll post my observations here.

[Louis D]

On 19/12/2018 at 14:44, John said:

Have you had a chance to compare this zoom with your Celstron Regal 8-24mm zoom ?

I recall from past posts that you were impressed with the Regal zoom.

I finally got out last night after the holiday crush to compare the two.  The non-barlowed 7.2-21.5mm zoom from Surplus Shed has much better snap-to-focus than the Celestron Regal zoom at f/6 at the widest setting in my AT72ED and 127mm Mak.  It also has very little astigmatism as you near the edge.  The Regal has noticeable astigmatism in the last 25% of the field.  However, the 33 degree AFOV was noticeably more claustrophobic than the 44 degree AFOV of the Regal.

At the high power settings, it was about a tie as far as snap-to-focus, but the SS zoom appeared a bit sharper in both scopes.  However, the SS zoom had really noticeable edge of field brightening (EOFB) in the outer 50% of the field whereas the Regal showed it in maybe the last 5% to 10% of the field in the 127 Mak.  As a result, the Orion nebula appeared to be surrounded by an equally bright halo of nebulosity.  Astigmatism remained well controlled in the SS zoom at highest power, but the Regal showed noticeable astigmatism starting at 50% out.  The SS zoom also appeared to be perfectly flat of field while the Regal required a bit of refocusing for the edge.  Again, the SS zoom's 49 degree AFOV was more claustrophobic than the Regal's 63 degree AFOV, but it was quite acceptable given that it was similar to a Plossl in size, entirely in focus, sharp, and relatively free of astigmatism.

The SS zoom is nowhere close to parfocal as it zooms, requiring several millimeters of movement of the focuser to regain focus during zooming.  The Regal is nearly parfocal, requiring only a slight movement of the fine focus knob on the refractor to touch up focus between the two ends of the zoom range.  I suspect that younger eyes might be able to accommodate this without refocusing.

Eye relief with eyeglasses was just usable with great concentration it turns out in the SS thanks to the incredibly narrow AFOV.  The Regal was much more comfortable, relaxed, and the view was easier to hold in this respect.

Mechanically, the SS zoom is super stiff, requiring two hands to twist the zoom.  The Regal can be zoomed with a light touch from a single finger by comparison.  In this respect, it's much nicer than even the Baader zooms I've used at star parties.

I didn't try the barlow trick because the f/12 Mak already confirmed what it can do at slow focal ratios.  That, and it was clear the SS was sharper everywhere than the Regal.  However, the SS zoom could never be considered a workhorse, general purpose zoom because of the incredibly narrow field of view at the lowest power setting, stiff zoom, limited eye relief, complete lack of parfocality during zooming, and intense EOFB at high powers.  It is best confined to the role @John found for it.  That of a high power, super sharp, ortho-like zoom where you are concentrating on the central FOV.  In that role, it excels.

[John]

Thanks Louis, very interesting

I have to conclude that the SS zoom and the 7.2 - 21.5 zoom that I have are different products though. Mine has some quite different optical and mechanical characteristics to those you describe

[rhw1967]

Any ideas where to get this from ? I Google if and up keeps popping the cheap Seven zoom

[Ricochet]

12 minutes ago, rhw1967 said:

Any ideas where to get this from ? I Google if and up keeps popping the cheap Seven zoom

Google 7.2-21.5mm zoom and you should get hits on this model. 

Opticstar look like they are currently cheapest: 

http://www.opticstar.com/Run/Astronomy/Astro-Accessories-Telescopes-Opticstar.asp?p=0_10_5_1_8_330