Louis D

6 hours ago, Ricochet said:

As far as I know they are the old 66° gold line eyepieces in a nicer housing. I had a 15mm gold line thrown in with a second hand scope and it was the worst eyepiece I've ever looked through. Apparently the other lengths are better though. 

At what f-ratio did you test it?  I've found the 20mm performs fine at f/18 in my Barlowed binoviewer and nearly as well in my f/12 Mak.  They do suffer at f/6, but the central part is no worse than a 20mm Plossl.  I would presume the 15mm to perform no worse since they're a scaled design.

Worst eyepiece I've looked through was a 20mm generic RK (Reversed Kellner?).  See below for an f/6 comparison with other eyepieces at this focal length.  The SVBONY 68 does quite well in comparison.  For the $20 I paid for it, it's hard to fault it.

Also, be aware that not all planetary copies are the same:

7 hours ago, Zermelo said:

There also appears to be a Svbony 2" 1/10 wave dielectric for £60.65:

https://www.amazon.co.uk/Dielectric-Diagonal-Astronomical-Telescope-Adapter/dp/B07QXW921T/ref=sr_1_2?keywords=svbony+dielectric+diagonal&qid=1636485256&sr=8-2

I'll have to check my $50 2" dielectric Amazon diagonal against that one.  The biggest problem with it is that the 2" compression ring is mounted too high and forces eyepieces with undercuts up at an angle.  Otherwise, it works just fine.

From Wikipedia:

In observational astronomy, a double star or visual double is a pair of stars that appear close to each other as viewed from Earth, especially with the aid of optical telescopes.

This occurs because the pair either forms a binary star (i.e. a binary system of stars in mutual orbit, gravitationally bound to each other) or is an optical double, a chance line-of-sight alignment of two stars at different distances from the observer.

I really like the GSO 2" dielectric diagonals.  I don't think the quartz upgrade makes any difference that I can see (I have both versions).  I really like their zero added height 1.25" adapter.  If your 1.25" and 2" eyepieces all focus at or near their shoulders, then this really speeds up switching between them because of minimal refocusing.  The casing is built like a tank, so flexure isn't an issue even with the heaviest 2" eyepieces.

I believe they are sold as Revelation Astro in the UK as well as TPO in the US.

If you've got the available in-focus, and the planets are always low along the horizon for you; then I think the ZWO ADC is well worth a try for as little as it costs relative to premium planetary eyepieces.

I usually see them sell quickly for a high percentage of new cost on astro classifieds if it doesn't work out for you.

http://skyinspector.co.uk/atm-dispersion-corrector--adc/

https://astronomyconnect.com/forums/articles/zwo-atmospheric-dispersion-corrector-product-review.34/

http://www.weasner.com/co/Reviews/2019/ZWO_ADC/index.html

The Zhumell Z8 is discontinued.  The Apertura AD8 and Orion SkyLine 8" are the same thing and the latter is currently available in the US.  It's also sold as StellaLyra in Europe.  All are made by GSO in Taiwan.  It's a really good starter scope.

Another really good option is the Explore Scientific (Bresser in Europe) 8" FirstLight Dob.  The big altitude trunnions make for better motion in that axis than either the GSO or Synta (Sky Watcher, Orion SkyQuest, etc.) Dobs with their smaller diameter axles.  There's an affordable 2 speed focuser upgrade available to bring it into parity with the GSO Dob.  JOC presumably makes both the ES and Bresser versions as it is their parent company.

Just don't try to use canned air to blow off dust as this is the result:

1 hour ago, JamesF said:

So for example I have always been able to sell honey in 1lb jars, but I'd have to weigh it out as 454g (or whatever the correct number is if I've misremembered) when filling the jars, and 454g would have to be the most prominent weight on the label.

Being an engineer and being a stickler for precision, I always want to measure these items to see if they are exactly 454g as labelled and not 453g or 455g.  If not, false labelling.  1lb leaves a lot of wiggle room when it comes to measurement precision.

Is pound cake referred to as 454g cake there?

40 minutes ago, JamesF said:

Can we go back to driving on the left yet?

James

I'm surprised the EU never got on your collective case for not switching.

20 minutes ago, Tiny Clanger said:

Now you're just adding to  their confusion 🙂 ... our American readers spell metre 'meter' 

I always wondered if Brits prounce meter "metray" like resumé since the r and e are reversed.

2 minutes ago, Mr Spock said:

Yes, to be clear:

Metre - a unit of measurement

Meter - a device for measuring things

 

You're kidding.  There's no consistency, and yet they're pronounce the same?

How do you spell better?  Good, bettre, best?

16 minutes ago, StevieDvd said:

And just to confuse  - a yard of ale.

For our American readers, that's a yard as in about 1metre - not as in back-yard.

No confusion here, though the closest to your "long necks" here that I can recall was a 1983 Budweiser poster:

No one has brought it up, but do you have astigmatism in your observing eye?  Check you eyeglass prescription's CYL or cylinder amount.  If it's greater than 1.0 diopter, you might want to looking into longer eye relief eyepieces at the longer focal lengths.  If you don't wear eyeglasses at all, then you're all set to use whatever you want.

Keep eyepiece weight in mind with that scope's helical focuser and two pole truss design.  I would imagine flex might start being a problem with heavier eyepieces.  However, since it can't accept 2" eyepieces, this tends to naturally keep eyepiece weight down.

The complete line includes 10mm, 15mm, 20mm, 26mm, 32mm, and 38mm focal lengths.  They are also sold as Apertura and Omegon Super Wide Angle (SWA or SWAN) among other names.

2 hours ago, DaveS said:

The centimetre isn't an SI unit. Millimetres and Kilometres are SI as they are multiples of 10^3.

The more you know.

Just an American meme associated with NBC PSAs.

5 hours ago, ollypenrice said:

Living in France, I once asked our local builder's merchants if they might carry imperial allen keys. I should've known better.  The owner stifled a grunt, which became a guffaw and ended in side slapping laughter and tears. The entire staff gathered round to hear what the Englishman had asked for. Soon they and half a dozen customers were variously roaring, slapping their sides and weeping with mirth. When one of them recovered the power of speech he just muttered, 'Mars lander,' and they were off again. 

So you went on Amazon and ordered them and had them the next day with Prime delivery.  A few years later, the local hardware store closed up.  Who's laughing now.

1 hour ago, Carbon Brush said:

@Louis D  Torches have actual flames coming out of the end.  I have no idea what Brits call the latter.

The device with flames is called a blowlamp.

You have reminded of an encounter with US airport security some years ago.
I had persented my belongings for security check. Among them was a small pocket torch (or flashlight).

The security person picked it out of the tray and looked at it, turned it around, looked further, turned it again....
I said 'its a torch' and was ignored.
The turning over, around, and puzzled expression continued.
I repeated 'its a torch' and was still ignored.

So I took the torch from the puzzled persons hand, flicked the switch and demonstrated it.
'Ah flashlight!' was the security response and it was accepted as good to carry.

 

You're lucky it wasn't confiscated the moment you said it was a torch.  They're prohibited on flights because you could start a fire in the cabin with them.

4 hours ago, wimvb said:

Why not say 21 decimeters? It is a fairly round number without any decimals. And it sounds/looks huge.

(Do I need to add an emoticon here?)

Edit:

Of course I do. Here goes.

  

Back in the 70s, we were pitched decimeters as the natural replacement for feet.  Apparently, it never caught on anywhere.  I always hear people's height described as centimeters in SI units.

7 hours ago, Tiny Clanger said:

What really worries me about your account isn't the 'two countries divided by one language' thing, but that someone in the US employed a security person apparently unfamiliar with the concept of switches ...

You have no idea have unintelligent TSA agents can be.  It's what you get when you offer super low pay and terrible working conditions.

4 hours ago, johninderby said:

 

Since Weed Wacker and Weed Eater are both registered trademarks, retailers have to use the generic term for them on web pages.

Do retailers in the UK list vacuums as Hoovers on their web pages despite that being the most common term for them over there?  Probably not since it's trademarked.

9 hours ago, Voyager 3 said:

Several mm ? Then is it even possible to focus the field together at once even in a flat scope ? 

Nope.  However, I added enough spacing in front of my TSFLAT2 in my AT72ED to flatten its field once as an experiment.  Once I did that, it actually has only mild astigmatism to the edge.  That eyepiece design holds great promise if the designers would simply add a field flattening group ahead of the field stop.

I did the same with my Pentax XL 14mm and found it to be perfectly corrected edge to edge.  Again, I wish the designers had added a field flattening group to it.

1 hour ago, johninderby said:

A wrench in the works just doesn't sound right. 😁

I'm guessing you jest in earnest, but that is exactly the phrase in American English.  A spanner in the works sounds wrong, wrong, wrong.  We may even embellish it as "throw a monkey wrench in the works".  Do y'all ever use the term "monkey spanner"?

22 hours ago, Marvin Jenkins said:

The idea that a French mechanic has ever said “pass me the 9/16ths spanner Jean-Claude” makes me laugh.

Well, to make it fully American, it would be wrench, not spanner.  Spanner has at least one specific usage for spanner wrenches with pins on the ends for rotating round retaining rings with holes in them.  No one in the States ever says spanner by itself, though.  It just sounds incomplete without wrench.  Just like no one here calls flashlights torches.  Torches have actual flames coming out of the end.  I have no idea what Brits call the latter.

1 hour ago, Ags said:

I thought the typical eyepiece curves opposite to the telescope, so surely a flat eyepiece is likely to be an improvement?

Maybe in that case (like the 14mm and 20mm Pentax XWs) it would be.  In my experience, the 10mm Delos, 9mm Morpheus, 30mm ES-82, both ES-92, and 9mm Vixen LV all appear flat to my eye.  The 27mm Panoptic might have a bit as do some of the Nagler T4s (17mm springs to mind).  The 14mm Morpheus has a bit as well, although Don P. doesn't see any in his copy.  The worst are the 80 degree, 30mm WideScan III clones.  They have several millimeters of curvature center to edge.