Louis D

May I ask why?  The focuser on it is already basically a helical microfocuser.  Adding anything above it would probably prevent you from reaching focus.  I've not read of anyone trying to replace the original focuser with another helical microfocuser.  There is this thread documenting adding a 2" Crayford focuser to one:

After using the blower, use a light rolling/flicking motion with a clean microfiber cloth like a vacuum beater bar does to carpets to get more stubborn particles lifted off the surface.  DO NOT SCRUB THE FILTER SURFACE with any cloth.  You will likely scratch it with unseen microdebris.

7 hours ago, 900SL said:

Of course, now we have been hit by a blizzard and -20 wind chill, so it will be a while before first light

Well, you do live just 6 degrees latitude south of the Arctic Circle, so you're sort of asking for it. 😉

I live just 7 degrees latitude north of the tropics, and I'm fully aware of how hot it gets here for 8 months of the year.  It makes for very hot and muggy nights of observing.  When we do get a blizzard as in Feb. 2021, we shut down entirely and lives are at risk due to hypothermia.

7 hours ago, 900SL said:

I ordered the CF 90 in the end, after going around the houses with the FLT91 (700 euro more expensive!), TS 102 CF, 106 photoline, 115 photoline, and a raft of others

I'm sure you'll enjoy your CF 90.  I really like my TS-Optics 90mm FPL-53 Triplet APO.  After actually handling it, I'm glad I didn't go any bigger as it's quite dense.  My DSV-2B mount has zero issues with it, though.

19 minutes ago, michael.h.f.wilkinson said:

Observing with the SC filter and Herschel wedge didn't ever cause me any discomfort with my 80mm F/6, as the wedge plus ND filter remove enough of the energy anyway. For bigger scopes there may be an issue. For imaging, you really need to insert a UV/IR cut filter. I must say the new SC filter looks an interesting proposition. 

By the looks of it, the newer BSC filter is indeed NIR safe.  If it didn't cost so much, I might try it.  I do have a vintage Optica b/c green line filter with ~30% transmission somewhere in the green part of the spectrum.  I tried it briefly with my wedge, but I wasn't convinced the view was any better than without it, so it did nothing to whet my appetite for the BSC.

I started using the UV/IR cut with my 8" Dob and Visual ND5 Baader Solar Film.  It always felt like my eye was getting cooked over time.  Based on the logarithmic spectrum of BSF shown below, it's no wonder I felt that way.  Clearly, it's ~ND5 at visible wavelengths, but only ~ND3.7 to ~ND4.5 in NIR.  That is more than a 10x increase in NIR transmission over visible transmission which is enough to cause discomfort for me.

The Baader UV/IR filter (similar to my Meade photographic UV/IR filter) has the following transmission characteristics on a log scale:

So it will definitely help with the BSF in my Dob where I need it most, in the NIR.  That extra ~ND2.5 in NIR really helps make things more comfortable when solar observing.

Interestingly, notice how a Baader ND3 starts to go off the rails toward ND2 above 1500nm in the IR part of the spectrum:

Thus, a 10x increase in IR transmission in that region.  I wonder how similar the ND3 filters packaged with Herschel wedges are to the Baader.

Here, notice how crossed polarizers (similar to those packaged with my Hercules solar wedge) never block IR at 900nm and above regardless of crossing angle.

That's just downright scary!  I'll take the UV/IR cut filter as one more line of defense for my aging eyes, thank you very much.

36 minutes ago, Franklin said:

I'd have thought that the likes of Lunt and other solar equipment manufacturers would have made issues like this a bit clearer, from a safety aspect at least.

Worst case, the UV/IR filter cracks or shatters for whatever reason, you clean out the mess, and try a different UV/IR that is reflective rather than absorptive.  It's not like you're in any danger of shattered glass getting in your eye or being exposed to the full force of the sun's light.  It's not much different than the more focused light cone after the wedge (4.6% of the pre-wedge energy) hitting the ND filter, which is absorptive rather than reflective.  The ND filter is very near to the scope's focal plane.

I will say that any finger grease on the UV/IR could lead to differential heating, and that might lead to an issue with cracking.  Thus, keep it spotless.

I'm curious why Baader hasn't seen fit to put their mechanical engineers to task to find out what is causing the lock-up and fix it once and for all.

6 hours ago, Giles_B said:

Polarising filter, UV/IR cut and a Contiuum. Actually it's the altair contrast booster version, not the Baader continuum, so a bit thinner, but all 3 are still a good few mm all told.

I put the UV/IR cut filter ahead of the wedge as someone on here suggested, and nothing bad happened.  It didn't even get hot.  Now I just leave it on there full time as a safety precaution for my eyesight.

5 hours ago, Franklin said:

I have read about the use of a UV/IR cut filter, for safety, but I don't understand why because the continuum cuts all that out as well, or so I believe. Sorry for flying off on a tangent in the middle of your thread btw, I'll shut up now

Line filters can leak light from outside the visible spectrum without it affecting visual performance.  Take a look at this thread which specifically tested two generations of the BSC filter.  One version seriously leaked in the NIR:

That could cause a serious amount of discomfort to one's eye while observing.

Here's what it looked like combined with a UV/IR filter:

While another BSC version did not leak NIR light:

59 minutes ago, Ricochet said:

A more lightweight alternative would be the 26mm ES62° which weighs in a 235g, basically the same as the 24 Panoptic that I use. However, I don't know how well this eyepiece will perform at f6 and I am fairly sure that the UFF will be better optically at all focal ratios.

The general consensus is that JOC reissued the Meade 5000 Plossl series as the ES-62 series since the specs and focal lengths are so similar.  If that is the case, I can speak to the 40mm focal length since I own the Meade 5000 Plossl version.  It is super sharp in the inner 50% at f/6 and then rapidly fuzzes out moving to the field stop due to astigmatism.  On the plus side, the moon doesn't distort much at all moved from center to edge.

The design is basically a variation on the Zeiss Astroplan opened up to 60/62 degrees.  Even if it had been limited to 50 degrees, their design would still have had edge issues since that would only eliminate the outer 17% or so.  Normally, these Astroplan variations are sharp to the edge at f/6 over a 50 degree AFOV as with the old Celestron Ultima, Parks Gold, Orion Ultrascopic, and Baader Eudiascopic "Plossls".

The view through the 40mm Meade 5000 Plossl in my field flattened 72ED is shown below relative to others.  Since it is a scaled design, all of the other focal lengths except for the 5.5mm, which has 6 elements, should perform similarly.

5 minutes ago, LDW1 said:

Relaxed ?  Throw in the cost comparison along with a relaxed view, to my eyes the views in any of mine are great. What does relaxed mean, not having to squint or blink or what ?  Sometimes they make me so relaxed that I almost fall asleep zooming in and out without having to change eps, lol ! Now thats relaxed !

Don't ask me, ask the OP why he has "fallen in love with the big eye glass on the let".  I've assumed it has to do with the relaxed view from longer eye relief that doesn't require mashing your eye into the eye cup to see the entire field of view.

I know I can barely use my 7.2-21.5mm zoom due to its small eye lens (16mm diameter) and tight eye relief (9mm - 11mm) even without eyeglasses.  My eyelashes keep brushing the top of the eyepiece whenever I blink.  With eyeglasses, it's like looking through a soda straw.  Without eyeglasses, my 2.5 diopters of astigmatism make for spiky star images.

Also, the zoom action is so stiff that I have use two hands to zoom.  Are the Svbony zooms' zoom actions silky smooth enough as to require only fingertip pressure?

Prism diagonals will always have a shorter optical path than mirror diagonals of the same size.  It has to do with the physics of how light travels through glass versus reflecting off of a surface.

The 1.25" diagonals will all have shorter optical paths than their 2" equivalents due to physical dimensions.

If there isn't enough back focus for a 2" Herschel wedge, and your scope's aperture is 100mm or less, you could look into getting a 1.25" version.  I use a 1.25" Hercules solar wedge myself.

3 minutes ago, LDW1 said:

Try one of the Svbony zooms for a bit of fun, a change of pace at a great price, I have 3 that I play with and I love them with solar viewing.

Do any of them have a big eye lens for relaxed viewing as put forth by the OP?  I've read that the APM SuperZoom has good eye relief due to a largish eye lens, but I'm not sure about the Svbony zooms.

6 minutes ago, Deadlake said:

Separate question, the 30 mm UFF was designed by APM. How does KUO get away with white boxing it to other companies. I thought KUA was only able to white box non ED/APO lenses/EP's etc.

Mark Ackermann here in the US designed the 30mm APM UFF as he describes in this CN post.  It's not clear that Markus Ludes of APM commissioned him and paid for the design.  KUO built it, did they pay Mark?  It's not clear that APM ever had an exclusive right to sell the eyepiece based on the design.  Perhaps APM had a limited time exclusive right to sell it, maybe a few years.  It seems like that time period has expired, and now KUO can sell it to anyone wishing to market it.

1 hour ago, johnnyp said:

@Mr Spockis the eyepiece retaining screw on the bottom of the holder (as per the stock image ) or can the holder be rotated ? 

I doubt if the holder can be rotated as that would probably unscrew it.

Unless @FLO can take a picture and demonstrate that their version of the curvy neck 1.25" diagonal does NOT have a constrictive ring at the bottom of the eyepiece holder, I would err toward getting a GSO made 1.25" dielectric diagonal.  They are sold under the iOptron brand in the UK.  They don't have a constrictive ring at the bottom of the eyepiece holder.

I have a WO carbon fiber 1.25" diagonal that has the curvy neck, and it has the constrictive ring at the bottom that causes vignetting with widest field eyepieces.  Since I only use it with a 22mm clear aperture binoviewer, I'm okay with it, though.

59 minutes ago, Nakedgun said:

~

Is this ep available under other brand names?

. 

As @Don Pensack pointed out in another recent thread:

• Sky Rover (China direct, Australia)
• APM (Germany)
• Tecnosky (Italy)
• Celestron (USA)
• Meade (USA)
• Altair Astro (UK)
• Stella Lyra (UK)

And I'll add Orion USA for the 24mm.  I think their version is the only one to include a thread-on 2" barrel.

@Moonlit Knight and @Neil H, are Celestron Omni Plossls really that much better than FLO's Astro Essentials Plossls to justify them costing double the price (or more in the case of the 32mm and 40mm)?  The 6mm to 15mm COPs are only £16 less than the BST Starguiders at FLO while the 32mm and 40mm COPs are £10 more than the BSTs.  The COPs don't seem like much of a value proposition to me when starting out.  Am I missing something when people recommend them?

If you're going to insist on using that relatively heavy 2" diagonal, rather than simply exclude 2" eyepieces due to balance reasons, how about giving an upper limit on eyepiece weight you'd be willing to allow for?  I've got a 12.5mm APM Hi-FW that weighs 555 grams, so not exactly a lightweight despite being a 1.25" eyepiece.  There are some lighter weight 2" eyepieces out there like the 40mm Lacerta ED at 501 grams that perform well at f/6 and cost under £150.

If you're only going to use 1.25" eyepiece for reasons of balance on a small scope, I'd get a quality 1.25" diagonal to further reduce the loading at the back of your scope.  A 2" diagonal adds a lot of weight in my experience with the GSO dielectric.

@LDW1 I do have to ask, are Canadians paid roughly 35% more than Americans for the equivalent job to offset the negative effect of the CAD to USD currency exchange rate?  I ask because my company adjusts pay based on the employee's local cost of living, and exchange rates certainly have an effect on purchasing power of foreign made goods or goods made with foreign made parts.

44 minutes ago, LDW1 said:

MSRP was mentioned as a comparison not the occasional, short lasting sale price(s). I stand by what I said about regular dealers prices which we all know is usually lower than MSRP here in C and thats over a broad range of dealers ! If you want to talk sale prices it can be all over the place, make up your minds.

I did quote both MSRP and sales and referenced each to the same:

4 hours ago, Louis D said:

The 31mm Hyperion has an MSRP of $226 (USD) and is on sale right now for $169 (USD).

The 30mm Celestron Ultima Edge is exactly the same optically as about a dozen other UFFs rebrandings, so let's just use the original APM UFF as the reference.  It has an MSRP of $266 (USD) and is on sale for $199 (USD) right now.  I can't help it if folks don't shop around for the best deal on rebranded optics.  I'm pretty sure KUO makes all of them.

I'll explicitly do the math on each since you're challenging my assertion that the two track less than 20% apart:

MSRP: (266-226)/226 * 100% = 17.7%

Sale: (199-169)/169 * 100% = 17.8%

The 30mm UFF tracks almost exactly the same percentage higher either in MSRP or sales price above the 31mm Hyperion.  Where did I mix the two?

1 hour ago, cajen2 said:

Ok, fine, so what 1.25" EP fits the criteria?

Not every question posed on here has an answer.

I will admit I was surprised by how cheap the 24mm Explore Scientific 68° is in the UK, £132.50 or $162.41 USD after conversion and before VAT.  The same eyepiece is ‎$269.99 here in the US, so the thought never crossed my mind to recommend it since the cheapest of the line is $219.99 before tax in the US, making it £215 after converting to GBP and adding in VAT.  This would be well above the OP's limit of £150.

Regardless, the 24mm ES-68 does not have a big eye lens and is very difficult to use with eyeglasses as a result.  The 24mm APM UFF is much better in this respect and has a 37mm diameter eye lens.

5 hours ago, johnnyp said:

I recently acquired a 2inch diagonal and a Skywatcher 28mm let eyepiece.

Do you have another scope besides the Skywatcher Heritage 130P in your sig?  There's no use for a 2-inch diagonal in it.

5 hours ago, johnnyp said:

I prefer 1.25inch accessories though as my scope balances better with them. Any thoughts on a low power 1.25 with big eye glass and pleasing views ?...I'm not exactly spoiled with the Skywatcher let so I'm easily pleased.

Big eye lens eyepieces equates to big prices.  Your Skywatcher Heritage 130P is demanding on eyepieces at f/5.  Low cost eyepieces don't generally play well with f/5 scopes.

Up your budget, and I can recommend the Morpheus, Pentax XW, and Tele Vue Delos lines.

Eyepieces: Lots has been written on this.  If you don't have astigmatism in your observing eye, you can get away with eyepieces that have less eye relief.  However, below about 10mm to 12mm of eye relief, and most folks complain about it being too tight.  For Plossls, this happens below 12mm or so.  I would go with BSTs at 12mm and below and with Plossls above that.  A good set would be 32mm and 20mm Plossls and 12mm, 8mm, and 5mm BSTs.  You also wouldn't duplicate your 25mm or 10mm eyepieces focal lengths, either.

You can try sealing the ends of the scope and the focuser with covers/plugs while outside to slow the inrush of indoor humidity that leads to condensation on optical surfaces before they have a chances to warm up.  Don't do this if it is more humid outdoors as in the summer when bringing it into an air conditioned house.  You'll trap the excess moist air inside the scope which is a very bad idea.

Dirt and debris on mirrors usually has little to no effect on optical quality.  Conversely, adding microscratches to a first surface mirror due to aggressive cleaning can lead to increased scattered light and lower contrast.

Diffraction spikes are perfectly normal.  To decrease them with curved spider vanes leads to spreading the light of those spikes across the field of view as a brightening of the background, decreasing contrast.  This can make seeing nebula more difficult.

As long as price comparisons are done consistently within a single country, in a single currency, and consistently including or excluding tax, they should be fine.

The Meade and Celestron brands tend to price their gear on the high side.  I guess they're trading on their past reputations as innovators in SCTs.  Celestron is now a Synta brand while Meade is an Orion USA brand.