Louis D

4 hours ago, Stu1smartcookie said:

true enough , i haven't but then again i think the op isn't looking at that kind of money judging by the scopes he listed . I'm purely in the doublet range .

I was genuinely surprised after having used doublets for years at just how slowly a triplet cools.  Basically as slowly as the 127 Mak, if not slower.

I just wanted to put that out there to avoid someone else like me upgrading to a triplet and being shocked by how slowly it acclimates.  If quick acclimation is the goal, definitely stick with doublets.

On 28/07/2022 at 20:30, Zeta Reticulan said:

For years I've wondered about the Hyperions. How are they in scopes at f/7 and faster?

I assume you've read @John's comparison of the Hyperions with the Vixen LVWs from which they were cloned?  If not, it's a good starting point.

6 minutes ago, Stu1smartcookie said:

what about a nice refractor ? Decent focuser , No cool down time .

I guess you've never used a triplet refractor.  Mine takes at least 30 minute to acclimate.  All sorts of pinched optics looking artifacts until then.

Since I buy most astro gear used, I'd go for the 127 Mak because they show up so often in the classifieds, at least here in the US.  I don't think I've ever seen a SW Heritage 150 on the classifieds.  I know used prices have gone up recently, but in the last 4 years I've picked up two Synta 127 Maks for $200 each.  One was for me and one was for my grown daughter.  Keep in mind you'll need to budget for a mount and tripod for the 127 Mak while you can technically use the SWH 150 right out of the box on a table top.

If it's anything like the 12.5mm APM Hi-FW, you can roll the eyecup down over the exposed threads more easily than with the knurled ring in place to maximize eye relief.  It's a little tricky until it's snugly ringing the threads, then it stays nicely in place.  It's the second one from the right below.  I couldn't get the eye cup to roll down and stay down over the knurled ring.  I now know that @badhex needs less eye relief; but I thought I'd share my learnings with KUO eyepieces having that knurled ring in case others need more, rather than less, eye relief.

I use a GSO CC in my f/6 scope with a 25mm spacer ring.  It nicely cleans up the coma in my widest true field eyepieces and in my UWA eyepieces like my ES-92s.

Binoviewers help in six main ways I've found:

1. With two eyes, the brain selectively filters out floater blockages from one eye with information from the other eye creating a much better image.  It has its limits when floaters in each eye obscure the same part of the view.  Try closing one eye for a while and look at a clear blue sky.  You'll see obvious floaters.  Now open both eyes and look again.  Fairly quickly, the obviousness of the floaters dissipates quite a bit.
2. Overly bright objects like the full moon, the solar disk, and planets at opposition are much improved with two eyes.  I chalk it up to the brain not being able to combine a super bright image with a pitch black (or nearly so) image.  On both the full moon and Mars, I have gone from seeing a washed out disk to high contrast, detailed views just by switching to my binoviewers.
3. Two eyes working together is much more natural for the brain to process, and low contrast details just seem to pop in binoviewers that were all but indiscernible with one eye, even with dimmer objects that aren't washed out in monovision.
4. Eye strain disappears and viewing become very relaxing with binoviewers once you get everything dialed in perfectly (which admittedly can take some trial and error).  I stared at Mars for 20 to 30 minutes at a time without fatigue.  It was an amazing feeling.
5. The apparent field of view appears about 5 degrees wider than when monoviewing with the same eyepieces.  My 60 degree AFOV microscope eyepieces appear to show about a 65 degree AFOV.  I think your brain normally stiches together two images of slightly different viewpoints into a wider TFOV image (try closing one eye to see how much TFOV you lose); so instinctively, you perceive a two eyed view as being wider even if it is showing the exact same view as monovision.  As such, I don't feel compelled to search out ever wider AFOV eyepiece pairs.  Besides, you can't see the edges except in peripheral vision because the moment you look off axis, you lose one, and sometimes both, eyepiece views.
6. You don't need ZAOs, TMB Monocentrics, Vixen HRs, or Tak TOEs to see low contrast, fine detail with binoviewers.  Fairly basic eyepieces that are well executed give excellent views in BVs in my experience.

The vignetting would be fairly moderate and would only be visible in the outer field for truly maximum TFOV eyepieces.  You'd probably have to look at a clear blue sky to detect the vignetting.

1 hour ago, vagk said:

Is Pentax XW 3,5mm a good choice for maximum magnification in combination with SW ED80 (planetary and double stars)?

It gives 171x.

Mine is certainly sharp enough, but I rarely use it.  The exit pupil gets super tiny with scopes slower than about f/5 and my eye floaters become intrusive.  I have to keep flicking my eye to get them out of the way for a fraction of a second to get a sharper view.  Bright planets and the full moon tend to get washed out looking at those high powers for some reason.  You'd think the high power would take the brightness, but it doesn't.

I got much better views of Mars at the last opposition using an entry level binoviewer and a pair of vintage 15x microscope eyepieces with a nose piece from a vintage Meade 140 Barlow to reach focus and to boost power by 3x.  Depending on how much you pick up the various pieces for, it might be a wash cost-wise.

I bought my used GSO CC over 6 years ago, so it is likely close to a decade old.  It had the pot metal screws that jammed and then sheared off in one of the holes.  I would surmise that the use of these screws greatly predates the pandemic.

I would get a 32mm Plossl to max out your true field of view.  I find low power views very rewarding, bright, and sharp.  They also help when centering an object for higher power viewing.

17 hours ago, jm3 said:

For instance, I'm at Bortle 8-9 and have an 8" dob.  I *think* I located and saw M10 the other night (hunting around with an angle gauge on the OTA), but it looked like a barely visible circular fuzzy dust smudge.

At what power were you observing it?  If you push the power up to at least 200x, you might start to see some outer straggler stars and brighter core stars resolving as twinkling pinpoints of light.  Globular clusters take power and aperture really well because they start to resolve at high power in large scopes, which cuts through light pollution.

M10 from Hubble:

Do you see how some stars are intrinsically brighter?  Those are the ones that start to stand out from the fuzzy background collection of dimmer stars at higher powers.

The only SCT I've looked through that inch for inch rivaled a Newtonian with a hand figured mirror and undersized secondary for planetary views was a Celestron Edge HD (8" in particular).  With a 10mm Delos, Jupiter was sharp, false color free, and showing lots of fine belt details.  It was stunningly better than the multitude of standard SCTs around the observing field that night.  I think it's down to the optics putting all the light bundles where they're supposed to be:

22 hours ago, Zeta Reticulan said:

I thought most zooms fundamentally had a moving Barlow element. One problem with zooms is the limited field of view at low magnification.

That's the way varifocal eyepieces like the Speers-Waler 5-8mm and 8-12mm eyepieces work.  They have constant AFOV and are nowhere close to parfocal.

Zoom eyepieces have a Barlow-like group at the bottom that moves downward while a middle group moves upward to maintain some semblance of parfocality.  The downside of this approach is a non-constant AFOV.

17 hours ago, Richard136 said:

Thanks

Yes, good point re astigmatism in outer field.

I wear glasses but don't require them for using binoculars.

Most of intended use is landscapes and wildlife.

A pair of compact porro prism binoculars would work fine for daytime use for up to 10x.  I've used a pair of Nikon Venturer 2 10x25s for years to good effect.  They're compact enough to fit in any case or pack.  They're not quite pocketable, though.  The exit pupil of 2.5mm matches or exceeds most folks daytime pupil dilation.

For nighttime use, you'll want to target an exit pupil of around 5mm to 7mm.  For 8x, this would be 40mm to 56mm.  For 10x, this would be 50mm to 70mm.  You have to be dark adapted for a long time, and young, to reach 7mm pupil dilation to properly take in all the light of a 7mm exit pupil.  Thus, I recommend 5mm as plenty of exit pupil.  Thus, the popularity of 7x35, 8x40, and 10x50 binoculars.

Roof prism binoculars are generally weather sealed, internally focusing, and difficult to knock out of alignment, but they really need phase coatings to get sharp, contrasty views comparable to porro prism binos.  Unfortunately, I've yet to see phase coated binoculars migrate down to the $100 end of the market, which is about all I want to spend on something I use so infrequently.  They also can't have large objectives due to their straight through light path, limiting the side-by-side size of the tubes.  This is why I recommend porro prisms despite their weight and size at a 5mm exit pupil.

1 hour ago, Alexmar said:

if indead 50x will be the limit i will refund it and order my 150/750 scope.

Those 76mm/300mm scopes are insanely difficult to sight onto a target due to their diminutive size and table top use.  I messed around with one at a star party that a fellow astro enthusiast had set out for the public to play with on a long, folding table.  He'd picked up a couple of them from thrift stores over the years for about $20 each.  I ended up lining it up on Jupiter by shooting from the hip since I couldn't get behind the scope to properly sight long the tube.  I wouldn't expect a newbie to be able to do that.  Once on Jupiter, I could see at least one band on it and the Galilean moons, but the view wasn't all that sharp even on axis.  I think it had a decent Plossl in the focuser, but I don't recall noting what it was.  The outer 50% of the field was noticeably blurry thanks to the f/4 spherical mirror and massive coma.  They're really intended as gifts for little kids who have low expectations.

Typical zoom eyepiece designs have two moving groups of lenses, one at the bottom and one in the middle.  The upper, final image forming lens group generally is more similar to one of Konig's designs than to a Plossl.

4 minutes ago, Richard136 said:

I've used Celestron SkyMasters in the past (70mm) and wasn't very happy with the field curvature (at least on my pair)

With the amount of astigmatism in the outer field, why would field curvature even matter?  I've got a Galileo 15x70 that is great in the inner 50% of its 65 degree AFOV, but if I purposefully look at the edge, it's blurry due to astigmatism that no amount of edge refocusing will help.  However, that's all in peripheral vision.  I just swing the binoculars to center whatever was at the edge to the center, and all is well again.

Are you going to be using these binos handheld or mounted?  How much power are you looking to use?  What are your intended use cases for them?

For all around use, I really like my 8x42 porro prism binos from the 90s.  They have a 65 degree field with 18mm of usable eye relief just like the 15x70s.  I think they employ the exact same eyepiece design.  I don't have to take off my eyeglasses to use either.  This is a good thing because I have 2.0 and 1.75 diopters of astigmatism in my eyes; so at these low powers, everything is blurry even in focus to my eyes.  You never did say if you have eye astigmatism and need to wear eyeglasses for sharp vision even with binoculars.

16 minutes ago, Kon said:

By the way, the other image is tripping my eyes 🤪 but I only see blue and red lines. Is that a good think?

That's right, but imagine seeing red and blue/green star images stacked on top of each other.  They don't blend to magenta, or any other color, to my eye.  It doesn't hurt like the stripes image, but the effect still "trips out" your eyes.  Sometimes, you can't avoid bright stars in nebula because bright nebula often contain young open star clusters.

The eye tripping out is because the human eye can't perfectly focus the far ends of the visible spectrum simultaneously on the retina as exaggerated below:

3 hours ago, TBRHussaR said:

Is it better to just own more eyepieces?

To answer the second question, it depends on your budget and eyepiece case size.  If I'm going to use a Barlow during an observing session, I'll just leave it in the focuser while switching eyepieces because fumbling with a third item in the dark is not fun when you only have two hands.

In general, the matched Smyth lens in long eye relief, high power eyepieces works better than trying to Barlow a lower power eyepiece to the same power.  However, it costs more to have a bunch of high quality eyepieces in your eyepiece case.

You could also put an elastic band of some sort around the lower threads to screw the extension/eyecup down onto.  The friction should resist unscrewing upward.

2 hours ago, Kon said:

The Astronomik allows some red through, does that make much of a difference compared to a narrow band UHC?

If your eye is sensitive to far red, it can be useful to pick up Hα emissions.  However, based on my experience with my 1990s Lumicon UHC filter, bright stars are both blue-green and red at the same time, so they are incredibly weird looking and difficult to focus simultaneously onto your retina:

The improved DGM NPB looks the part below:

You should be able to pick up all of the useful emission bands except for the C2 Swan bands (mainly from comets).

4 hours ago, Zeta Reticulan said:

4 hours ago, Zeta Reticulan said:

my ADHD strikes again! Ooh look ... shiny!

I've never actually used it.  I keep forgetting I bought it. I'm getting worse ...lol.

Squirrel!!!!

8 minutes ago, Don Pensack said:

The US has a 25% tariff on Chinese goods.

Do you know if APM is successfully skirting that tariff by mislabeling eyepieces as Germany?

8 hours ago, Zeta Reticulan said:

David Knisely has written a lot on filters. 

In case you missed it, the OP led off with a link to that page.