Don Pensack

7 hours ago, Zermelo said:

I have a saved search on eBay for second hand Morpheuses. It finds one about once a month, but they're often priced more than the new price.

What about AstroBuySell.com/UK/  ?

10 hours ago, Louis D said:

Well, they're $169 apiece new in the US, so well above what I would consider as mid-range eyepiece pricing.  I consider $100 apiece pushing that title.

Used, they're going for around $90 +/- $10 here in the US.  I suppose if your budget allows, they would qualify as mid-range when purchased used.

There are also the various Redline 70 degree eyepieces out there as well in that same price range new and used.  The 22mm is excellent.  The rest have varying levels of aberration issues.

Mid-range may be determined by your pocket book.

I consider <$100 to be inexpensive (Paradigm, X-Cel LX), $100-$200 as average price (Hyperions, BST 70°, UFF), $200-$350 as medium price (XWA, XW, Morpheus), $350-$500 the low end of high-priced (Delos, Naglers), and $500-$1500 as high priced (Ethos, Nikon HW, Leica Zoom).

My data for the US puts the median price at ~$100, so the pricing pile resembles a pyramid.

6 hours ago, Louis D said:

Do you care if correction is horrendous or if the zoom is gargantuan and varifocal?

Excellent correction, of course, and smooth in operation, and equally well-corrected at every focal length, and parfocal through the range.

Weight limit one kilogram.  2" size.

Can it be done?  Maybe.

Will it be done?  Unlikely, as it would have no use in spotting scopes, the home of most zooms.

I'll adopt the use of zooms when they have a constant 80° field from 8-24mm.

On 21/01/2024 at 06:10, Neutrinosoup said:

Thank you all!

I’ve hopefully secured a 25 BST Starguider from another member here (sale pending) which I’m sure my daughter will be delighted with. I’ll keep an eye out for a higher magnification starguider eyepiece 10,8,5.  Probably an 8mm would pair nicely x48 (25mm) x150 (8mm).

(8 inch Dob 1200m focal length).

Focal lengths are, IIRC, 25mm, 18mm, 15mm, 12mm, 8mm, 5mm, 3.2mm, so no 10mm is available.

I was just going to recommend the Hi-Hat adapter, but John beat me to it.

I think CloudyNights exhibits the opposite of nationalistic tendencies, actually.

There are thousands of posts about saving money by buying from China directly, which injures the US distribution supply chain and eliminates taxation for the consumer, taxation that pays for schools, roads, police, et.al.

So buying directly from China saves money, but indirectly harms the country where the consumer lives.

If anything, this is anti-nationalism, but does evince a degree of anti-social narcissism.

I give credit to the EU for charging VAT when the item is imported.  The US imposes a tariff only if the order is larger than $2500, and the tariffs are very low.

Tele Vue is likely wary of the way Chinese manufacturers now seem to be selling out of the back door directly to consumers.

And the fact they all steal designs and sell them private label to anyone willing to place a large enough order.

If I were the Naglers, I'd be afraid that my designs would end up under other labels and sold directly to consumers by the factory.

Not to mention the steep curve of raising the quality control to the TVO standards.

One mystery to me is that Baader has been able to sustain an exclusive on the Morpheus eyepieces for so long.

The Hyperions were likely an adaptation of a previously-existing product, and have been available under other labels, but the Morpheus were and still are unique.

It might indicate that some Chinese companies are willing to be exclusive, so good luck to Tele Vue if they are contemplating this.

7 hours ago, JeremyS said:

Does he say “you’ve got the best Pentax eyepieces”, Don?

LOL.

You know what I meant, but your response is funny.

It points out the imprecision of the English language at times.

1 hour ago, Bivanus said:

Interestgly enough it was an offer for this zoom on a Canadian site some weeks ago when I was still there. Is it good ?

Bear in mind, it is not a zoom in the traditional sense.  It is a variable focal length eyepiece, and substantial refocusing is needed every time you change the focal length.

like this:

I keep a small, folding, Japanese fan in my pocket and fan the eyepiece.

It clears the fog without the giant sucking sound.😄

The questions are ambiguously-worded.

For Example:

Having undercuts on the barrels?

--Very important

--somewhat important

--not important

--no opinion.

Hypothetically, if you love undercuts, you'd pick the first response, because you consider it important that they are there.

If you hate under cuts, you'd also pick the first response because you'd rate having them as very important, i.e. it would make a difference to you when choosing an eyepiece.

It should have been worded:

Do you want undercuts on eyepieces?

--Yes.

--No.

--no opinion.

6 hours ago, Voxish said:

I assume the same could be said for scopes, yet my frac has a made in the USA sticker on it.

The lenses in the refractors are from Japan, but the rest of the scope, and the assembly, is from the US.

21 hours ago, JeremyS said:

I prefer to buy optics from certain countries and not others, if possible. I appreciate it that TV EPs are manufactured in USA or Taiwan.

Tele Vue eyepieces are made in Japan or Taiwan.  Not one is made in the U.S.A.

4 hours ago, Voxish said:

I read somewhere that ES eyepieces wreck Baader click-locks over time. I don’t know if anyone can confirm that or not

It has been the source of more than one call, over the years I was in business, of how to remove an eyepiece stuck inside a Click-lock.

In every case, it was an eyepiece with a conically-tapered undercut, like the ES.

Tele Vue is never going to remove the undercuts on barrels.

It's pointless to ask.

As they say, colloquially, in the south of the US, "That dog don't hunt".

Where Tele Vue is concerned, it's a moot point.

I notice they asked whether we considered it important which country was the source of the optics.  Hmmm.

On 03/01/2024 at 17:42, Louis D said:

Sure they do when they're above the shoulder.  There's some vignetting and lots of in-focus is required, but it does work.  I've got the bare upper section of a 12mm ES-92 with a 51mm physical field stop that actually measures in use to be 48.4mm, probably due to cutoff from the internal shoulder step.  Chromatic aberration is so bad toward the edge that I've never noticed vignetting.

That's not a "simple" eyepiece, i.e. an all-positive design with the field stop below the field element.

Field stops in 2" all-positive designs max out at ~46.5mm.

What do you mean by "bare upper section?  Did you remove the field lens?

ES says the field stop int he 12mm ES92 is 19.6mm, i.e. the eyepiece has a "virtual" field stop that can't be measured by measuring an internal stop.

5 hours ago, Nik271 said:

Wow, that's 80mm focal length eyepiece in the photo! My calculator shows that it's maximal apparent field of view will be 2 arctan(5/16) or about 35 degrees, and this is assuming a 50mm field stop. 

Without distortion, the apparent field at 80mm and a 46mm field stop would be 32.1°.  Field stops in simple eyepieces don't exceed 46-46.5mm in a 2" eyepiece.

Add a typical 4% distortion and you get about a 33-1/2° field.

9 minutes ago, Sunshine said:

How would this orthobarlow compare to a TV 2x powermate? or is this basically Tak’s answer to the powermate? 

I don't believe the Takahashi Barlow is telecentric.  I think it is a standard telenegative design, which means the magnification will vary with distance from the lens.

So I don't think it is Takahashi's answer to the PowerMate.

I've seen telecentric Barlows from TeleVue, Explore Scientific, Harry Siebert, and Astrotech.  JOC, who makes the ES stuff, also makes the same telecentric Barlows for other brands, like Bresser, et.al.

5 hours ago, John said:

Thanks for the warning. I don't think any of my current 1.25 inch eyepieces have such barrels but I'm sure to have used some that do have conical barrels in this adapter at some time over the 7+ years I've owned it. I don't recall any problems but I am be forewarned now and aware 🙂

It seems to me that practically all ways yet devised to hold an eyepiece into a focuser tube have some drawback or other. Or is there a perfect design that few know of ?

 

Possible the best I've found to hold 1.25" eyepieces is the Twist-Lock adapters.

They are not all the same.  The best ones tighten with the least rotation and have internal compression rings (they truly are compression rings as they compress all the way around simultaneously)

that extend all the way to the opening of the adapter (so they grab that short section of 1.25" barrel above the undercut), have smooth sides with no undercuts, and are threaded for 2" filters.

Example: Olivon Twist-Lock adapter.  I retouched this image to see the length of the internal 'collet'.

This is not the only such adapter, but it is one of the best.  I added an extension on the bottom so a Barlow wouldn't hit the 2" filter.

Forgot: I painted the inside with Black 3.0 paint to eliminate reflections.  In the picture, you can see the bottom, where the filter has removed the paint, 

but the area above that is very very black.

2 minutes ago, Louis D said:

I thought the Baader ClickLock system used a torque mechanism preventing over tightening.  I thought that was the point of the clicking.  Once you reach that point, it won't tighten any further.  I've never actually used one, so I'm totally guessing here based on my experience with torque wrenches.

No, it clicks as you tighten it.  You can super tighten it--to the point it is hard to unscrew.

Alternative: Baader Morpheus eyepieces.

A bit wider than the Delos and just as easy to use.  Also, slightly smaller and less expensive.

5 hours ago, John said:

The Baader Click Lock that I use is the T2 - 1.25" Baader one and it works brilliantly IMHO. It uses a different gripping system to most adapters with longitudinal rods that press against the whole length of the eyepiece barrel. No snagging on undercuts.

I have used the 2 inch Click Locks but also felt they were rather bulky although they worked well enough for me.

Do not use this type on an eyepiece with a conically tapered undercut--the rods will bend out of their holders and it will ruin the binding system.

At worst, they will catch, making the eyepiece extremely difficult to remove.

He makes a really big deal about the fact the Baader Click-Lock does not center the accessory inserted.

However, being shoved off center by 0.002" to 0.004" (0.1mm) at most is really not a problem.

Even a coma corrector's sensitivity to being off center is minimal.

Focuser axis error tolerance for high power collimation is 0.002D with a Paracorr 2, where D = diameter of the primary objective.

In a 10" scope, that is 0.508mm, where the off-centering due to being shoved to one side never seems to exceed 0.1mm in well-machined focusers.

So, whereas he was disappointed the inserted accessory didn't stay centered in the Click-Lock mechanism, the issue is really not an issue.

Even if the focuser has sloppy machining and the shove is 0.2mm off center.

Astrophotographers can correct with flats, and visual observers will never notice.

That is true of the 2" to 1.25" Click-Lock adapter as well.