Louis D

Perhaps try a quality Barlow or telecentric magnifier ahead of it to use the 5mm to 8mm settings at higher powers to take advantage of the more generous eye relief at those focal lengths?

17 hours ago, Don Pensack said:

In this industry, they expect you to make up the loss by resupplying all your stock during the sale period and selling the lower cost stock at the full retails after the sale is over.

Are you allowed to skip the sale and simply resupply at the sale period wholesale price?  If so, when the sale is over, you still have stock to sell at a decent profit.  If not, what about using shell companies to participate in the sale, buy at sale wholesale prices, but list items as out of stock, and then move that stock to the actual selling company after the sale?  I wonder if JOC monitors their sellers closely enough to notice this stock shuffling is happening.  I know NYC based photo retailers used to do a huge business with gray market items bought overseas to take advantage of differing sale prices and currency fluctuations.  These items would be moved into the US to be sold at higher prices.  This is the sort of stock shuffling I'm thinking of, but strictly within the US.

4 hours ago, MortonH said:

The ND3 filter is installed at the bottom of the eyepiece holder as expected but the polariser is supposed to be separate. I unscrewed the eyepiece holder but couldn't remove the filter. I'm pretty sure the polariser isn't installed in there as well.

Correct.  Mine arrived in a bubble wrapped zip bag as I recall.  It was just tucked in with the wedge to the side.

4 hours ago, MortonH said:

I shouldn't need a variable polariser as the prism polarises the light. I just need a single polariser to attach to the eyepiece and then I can rotate the whole eyepiece to vary the brightness.

When I had a Lunt wedge a few years ago I had a continuum filter instead of a polariser but I was hoping to avoid a green image this time.

Yes, a single polarizer will work, but you have to get the rotation position angle right before you can start observing.  This can be a pain in the eye when swapping eyepieces while solar observing.  Setting a variable polarizer to a certain maximum brightness allows you to start observing right away when swapping eyepieces.  If it's still too bright, rotating the eyepiece allows for further dimming just as with a single polarizer.

Also, since the wedge is not at the Brewster angle, you're not getting perfect polarization, so full dimming with a single polarizer may not be possible.  Thus, you might not be able to dim it enough for your liking, but the second polarizer in the variable filter guarantees you can get there.  I'll have to try this out with a single polarizer on my Hercules wedge sometime to see how dim it can get.

Again, single or variable polarizers are quite cheap from China via AliExpress or ebay, so no worries financially about replacing the missing one.

14 hours ago, Ags said:

Also, the field of view seems much larger than 56 degrees, it felt “widefield” if that makes any sense.

Photographically, I found the AFOV to vary from 58 to 61 degrees, so it qualifies as widefield, just not super wide field (SWA) which generally starts at 65 degrees.

6mm and 7mm are clearly different in AFOV.  I went back and remeasured my photos.  Sure enough, I was off on the 6mm for some reason.  It actually works out to a 59.7 degree AFOV at 6mm.  Mea culpa.

21 hours ago, jetstream said:

Perfect! there are few eyepieces that have ever reached this level and I hope to complete the set, and use them. They are bizarrely good IMHO. I wonder what their minimum number of units would be needed to get them interested in another run?

I've read that Chinese eyepiece manufacturers (probably from Don) will make a run of eyepieces for you in your choice of livery with a minimum order of 300 per focal length.  However, this is for eyepieces still considered to be in current production.

I don't know about Japanese manufacturers like Vixen who have much higher production costs, though.  It may simply be a minimum cost that they want to recapture regardless of order size.

I know when the companies I work for send an ASIC out to a fab for build, the NRE (nonrecoverable/nonrecurring expense) has risen from $1.5 million to closer to $10 million or more over the past 25 years.  I would think that restarting discontinued eyepiece production might incur a similar (if much smaller) NRE regardless of order size.

You're right.  A narrow notch filter or dim to dark color filter actually works much better without the additional ND filtering.  I've done that with my Optica b/c line filters that only transmit 30% over a <10nm bandwidth at best.  They're much too dim to be useful otherwise.

8 minutes ago, LDW1 said:

The variable polarizer has nothing to do with safety, its just to vary the brightness, tone it down same as when viewing the moon. Even if it is too bright its safe, don't give a wrong information. The 1.25" models don't have variables, my 2 Lunts sure didn't.

Safe maybe, but usable or comfortable, not really.  Where did I say it wasn't safe?  I said it's intolerable.  There are no features to be seen at that level of brightness.  It's just basically a featureless white circle of intense brightness.  There are plenty of features to see on the moon without a filter of any sort.

In fact, I had to jerk my head away when I first tried looking through it without further filtration.  It's nothing like viewing the moon without a moon filter.  I've never experienced that sense of impending eye damage while viewing the moon.

Maybe this wedge works fine in Canada without further filtration, but the noon summer sun in Texas is just too bright for my liking without additional filtration.  It might be fine with the rising sun in a Texas winter, who knows?  My horizon views are blocked, so I wouldn't know.

Don't even think about looking through it at the sun without the variable polarizing filter in place.  The image is way too bright for human eyes to tolerate.  I think it defaults to somewhere around an ND3 to ND4 brightness without additional filtration.  You need to be at about ND5 for safety sake.

I'm sorry your experience with it has not been as positive as mine has been.  Everything was nice and tight and still is, and it came with the variable polarizer.

It needs about an additional ND2's worth of dimming to be usable.  I bought a Svbony ND3, but it was too much.  A moon filter wasn't enough.  I decided that the variable polarizer was still the best option.

I set the variable polarizer to just about the brightest I can stand the image to be by trial and error (just take a quick peek off axis through the eyepiece to gauge the brightness).  I then do final brightness adjustment by rotating the eyepiece in the holder to take advantage of the partial polarization caused by the wedge.  Put another way, I dim down the view by eyepiece rotation to whatever level seems best for whatever feature I'm observing at that moment.  If I can't get it dim enough, I'll take out the eyepiece and adjust the variable polarizer downward in transmission amount.

I would go ahead an order in a variable polarizer from AliExpress or ebay.  They're not that expensive in the 1.25" size.

15 hours ago, Merlin said:

Years ago a well known British amateur astronomer, possibly G.D.Hole, had a window pane optically worked for £10,000.

The problem as I see it for professional usage, how do you keep an optically flat window perpendicular to the telescope's optical axis at all pointing angles and positions?  It might be possible with a slit aperture in a domed observatory with some sort of expanding bellows to maintain the seal around it to avoid thermal air currents.  Another issue would be thermal strain on the glass if there is a temperature differential between the inside of the observatory and the outside world.  Also, reflected light could become an issue causing glare on the optical window.  Perhaps with enough engineering forethought and post-implementation rework, it might be doable.

I wonder if that lower "TOE" image used to accompany the following Vixen comparison of the HR line to the 2.5mm LV:

They basically threw the LV under the HR bus.  Those Vixen pages seem to mostly be gone now that the HR line is discontinued.

However, it might be the 2.5mm Vixen LV internal diagram despite the odd lens and group count.

3 hours ago, Stu1smartcookie said:

Care to elaborate Louis , for the record .   

Click the link and read the Wikipedia article? 

Basically, some of the largest and nearest stars have been professionally resolved.  You didn't put any qualification on "best and largest telescope".

10 hours ago, Stu1smartcookie said:

Stars are only points of light in the best and largest telescope of course

Not necessarily.

Kind of cool looking in a hyperspace jump or blackhole suction sort of way, though. 😁

Now that seems more plausible.

None of the ad photos show up anywhere else on the web using an image search, so that test of a scam posting fails.  It begs the question, where would the poster have gotten the images from?

I searched around the internet and the best diagrams of 3 element doublet-singlet eyepieces were on Telescope-Optics.net.

I cropped and combined together four Kellner or "Reversed Kellner"-like designs below for easy comparison:

There was no mention of a true Reversed Kellner design on that site.

3 hours ago, Ratlet said:

After seeing some of the connectors that are still common in astronomy setups it doesn't surprise me they've been slow to adopt.  £200 for an ipolar that still uses a mini usb!

I still see some used electronic setups relying on RS-232 connectors in the classifieds.  I think to myself, how would I rig up a way to talk to it?  Some sort of USB dongle?  What about drivers?

Same here.  I'm thinking a harmonic mount would be terrific.  My biggest gripe with regular GEMs is that they require counterbalance weights.  Really?  It's been how many years since harmonic drives became common place in manufacturing robots (with no counterweights), and they're only now making it into astro mounts?

Yep.

Bumping for today.

I'm jealous.  It would probably take a Carrington level event for me to ever see the Northern Lights from Texas.

Sure you can observe through glass.  Can you observe well through ordinary window glass, no.  Generally, you can still pick out the high contrast details like the positions of Jupiter's moons and the features along the moon's terminator.

If you go to the trouble of replacing your glass with optical glass polished flat to within 1/10th wave or better and coat it with anti-reflective multicoatings, you'd stand a much better chance of being able to do critical observing of low contrast objects.

Consider this.  I don't know of a single observatory, professional or otherwise, that observes through glass of any type.  The scope is always open to the elements.

26 minutes ago, Littleguy80 said:

We’re all the way up to an iPhone 14 now with the 15 coming later this year.

Maybe Apple is keeping Canada behind the technology curve and they've only released up to 12 there. 😉

6 hours ago, Ags said:

Optically the Speers WALERs are great. Just very long and awkward. I prefer the ergonomics of the 6.7.

I guess it comes down to optical pickiness versus budget.  The TV NT6 13mm would seem to tick all the boxes except for price.

At that focal length in 1.25", I really like my APM Hi-FW 12.5mm.  However, it's probably too large and heavy for your intended use case(s).

What's wrong with the Speers Waler 13.4mm in your signature?