John

Very interesting.

I'm always intrigued how Tele Vue managed to control this effect so well in the Ethos eyepieces despite their hyper-wide field of view.

It is quite pronounced with the Naglers.

I have a Lumicon O-III in the 2 inch size and an Astronomik O-III in 1.25 inch.

The Ethos eyepieces use the 2 inch filter although the 13, 8 and 6mm are actually 1.25" eyepieces so can use the smaller filter size. To keep things simple I've added 2 inch barrel extenders to those so that I can use 2 inch filters on all of them:

No problem - moved into this section

I agree with your opinion Gerry

I have a really good older Lumicon O-III but they definitely went through a wobble a year or two ago when they brand came under new ownership.

The Tele Vue Bandmate II's are superb I hear - made by Astronomik.

I have an Astronomik O-III in the 1.25 inch size which is very good and their H-Beta as well.

@Stardaze - maybe another thread on filters would be fruitful ?

Without sample analysis by a recognised lab, there is no way to tell for sure.

The vast majority of rocks that are suspected of being of meteoric origin turn out not to be.

Try contacting these people, they will be able to advise further:

http://www.bimsociety.org/contact.shtml

4 minutes ago, Don Pensack said:

I recommend replacing the soft rubber bottom eyepiece cap on the 20mm with a hard plastic one.  The rubber one gets pressed against the bottom lens of the eyepiece in the box or a case, leaving a smudge on the lens....

 

Good point - I noticed that when I was testing the Myriad 20mm which uses similar soft rubber dust caps on both ends.

1 hour ago, Stu said:

Not sure John. I get that optically you only get more detail up to around 1mm exit pupil, but in the same way that being able to increase image scale on DSOs makes them easier to see, I think increasing the mag on high power objects like planets and doubles can also make detail easier to see. Obvious caveats about not losing contrast and working within the seeing conditions still apply of course.

With my little Telementor, the airy disks are big, and it is obvious that you are not adding any more detail by increasing mag, but it does increase the separation on doubles and can make it a little easier on the Moon to see the smaller detail provided you don’t go too far. Often x140 is plenty. Have yet to try it on planets....

I'm not sure either Stu.

Generally I prefer a smaller but sharper and more contrasty image but sometimes you need to increase the scale, as you say, to enable the eye to see intricate stuff.

I do find very high magnifications useful to pick out faint point source targets such as faint planetary moons.

The concept of "empty magnification" seems to be less relevant today perhaps ?

2 hours ago, Stardaze said:

I can certainly see more of a use for the 1.25" narrow field options with your fracs, but do you use any of those with the dob regularlyJohn or predominately the Ethos? 

Most of the time I use Ethos with the dob and the 1.25" with the fracs. For high powers in the dob (300x plus) the Pentax XW's proved a touch better than the short focal length Ethos (took me 6 months of comparing them to come to that conclusion !) so the 5mm and 3.5mm XW's get used in the dob as well.

The size and weight of some of these hyper-wide eyepieces can come as a surprise if you are used to smaller ones:

3 hours ago, Stardaze said:

.. Interesting @jetstreamthat you don't go hyper wide throughout into the higher mags, as that's a question I'll need to work out too. @John clearly you do have a preference for this throughout? I had wondered whether a 12mm Delos might make a nice addition in the mid-range later on? 

To be fair I have a set of Panoptic / Delos / Pentax XW's as well so I can use whichever I'm in the mood for 

Ask half a dozen folks what their preferences are and you will get half a dozen differing opinions I think. Eyepieces are very personal choices.

The only X-Cel LX that I've owned was the 25mm which I was not all that impressed with I'm afraid. Maybe it's not the best in the range ? 

I compared the 8mm BST Starguider with my 8mm Ethos at a star party a few years back (both in my F/5.3 12 inch dob) and found the Starguider did rather well.

1 hour ago, bomberbaz said:

Looks very good for a travel scope at just 7.5kg. Just wondering why they didn't increase the focal length to make it a bit of an all rounder.

I guess the single arm dob mount will have it's limitations re: tube length.

Very dangerous items:

This is not mine but it was posted on another forum by the experienced amateur David W Knisely. It might prompt some discussion anyway:

USEFUL MAGNIFICATION RANGES FOR VISUAL OBSERVING
IN ASTRONOMICAL TELESCOPES

LOW POWER (3.6 to 9.9x per inch of aperture)(7mm to 2.6mm exit pupil):  Useful for finding objects and for observing ones of large angular size like open clusters, large faint nebulae, or some larger galaxies. For lunar work in modest apertures, it is generally somewhat on the low side, but can show the crescent moon with background starfields well. This is also the range where Nebula filters tend to perform the best. Some of the wider double stars can also be best appreciated in this power range.

MEDIUM POWER (10x to 18.9x per inch of aperture)(2.5mm to 1.3mm exit pupil):  Useful for observing somewhat smaller deep-sky objects such as galaxies, some diffuse nebulae, smaller open clusters, and moderate to large planetary nebulae. Also useful in apertures 6 inches and larger for getting at least partial resolution on the brightest globular star clusters. Often used in moderate to large apertures for detecting very small galaxies which may be invisible at low powers and for revealing details in some galaxies like dark lanes, mottling, and star-like nucleii. Very useful for wide area views of the moon, or for showing the moon systems and some of the larger features of the planets.

HIGH POWER (19x to 31.9x per inch of aperture)(1.3mm to 0.8mm exit pupil):  A very useful power range for observing fine planetary and lunar detail. This is the range where the full theoretical resolving power of the telescope is becoming visible. Also useful in moderate to large apertures for getting better star resolution in tight globular clusters or for viewing detail in the smaller planetary nebulae, as well as resolving tight double stars. This power range is sometimes compromised in apertures larger than 5 inches by seeing effects (ie: disturbances in the Earth's atmosphere which can blur fine detail).

VERY HIGH POWER (32x to 46.9x per inch of aperture)(0.8mm to 0.5mm exit pupil):  Useful for study of certain specific planetary details, and resolving very tight double stars near or just above the resolution limit of the instrument. Also useful in larger telescopes for resolving the cores of some very tight globular clusters or for detecting the finer detail and faint central stars in the smaller planetary nebulae. Quite useful for telescope collimation tests or rough star-testing. This power range is not as frequently usable with larger apertures due to seeing disturbances. For planetary viewing, eye defects like motes and floaters (along with the somewhat lower overall light level), begin to become visible and slightly annoying in the upper half of this range.

EXTREME POWER (47x to 75x per inch)(0.5mm to 0.3mm exit pupil):  Mainly used for resolution of double stars at the resolution limit of the instrument, or for detecting elongation of unresolved doubles. Powers up to 60x per inch are sometimes usable in rather small instruments for making gross planetary detail easier for beginners to see (ie: Jupiter's main belts or the Cassini Division in Saturn's rings). This power range is not often used in apertures above 6 inches due to seeing limitations, and requires very good optical quality in the instrument. Even when conditions are good, lunar and planetary views using this power range can sometimes seem less pleasing overall than at somewhat lower powers due to the lower light intensity and increasing interference from eye defects like floaters. However, this range can be somewhat useful for certain *specific* targets or details which require extreme scale. Examples include (for large apertures) seeing Encke's Division in Saturn's rings, the central star in M57, detail in some brighter planetary nebulae, or for resolving a few small specific lunar details. Powers from 75x to 90x per inch are occasionally used for very close double star elongation, micrometer measurements, or for optical testing, but otherwise, powers well beyond 75x per inch can often be nearly useless, especially in inexpensive "department store" telescopes.
 

I see they have used a 3 vane secondary support on this new model. Can't see it in the photo but presumably the same helical focuser.

It would make a great scope to have on holiday under dark skies

My 1.25 inch set goes 24mm - 17.3mm - 14mm - 10mm - 7mm - 5mm and 3.5mm (plus a few other "hangers on" !)

To be honest, most of the time I skip the 17.3 and go straight from 24mm to 14mm and then often seem to skip the 10mm and go to 7mm. Two expensive eyepieces that don't get much use but I'm loathed to part with them

Yes, it looks like a new model. Interesting scope. The 130 Heritage has been a great hit so why not a 150 ?

3 minutes ago, andrew s said:

.... My other mount is a Paramount ME II .....

Ahhh - forget the bit about "rough around the edges" then. Hopefully the AZ100 will seem of comparable quality

The AZ100 is one of those products where initial nervousness over the cost evaporates as soon as you unpack it. The design, quality of engineering, fit and finish is 1st class. The price actually quite quickly seems reasonable as you move it around and get a feel for it. Your previous pride and joys seem a touch rough around the edges all of a sudden  

I don't have experience with the APM either but Grerry / @jetstream in Canada thinks highly of them and I would be influenced by his opinions.

On the ES 100's and 92's I agree with the above but I was not keen on the eye positioning with the 12mm so I don't have that one any more (I preferred my Ethos 13 to it as well).

I think the 92's are ES's best eyepieces to date. The only downside is that they are very large and heavy - very heavy in the case of the 17mm.

I've tended to avoid scope designs that need a lot of cooling time even if they are excellent.

This Mewlon owner dealt with it by keeping the scope at close to outside temperature in a sealed box:

https://www.cloudynights.com/articles/cat/user-reviews/takahashi-mewlon-210-review-r2713

Personally I'm a big fan of the Ethos range but they are very expensive I agree.

I had the ES 20mm / 100 and thought it pretty good. The 21mm Ethos proved a touch better still but at a lot more £'s of course.

I think I would go for an APM / Lunt 100 over an ES 100 because of their ergonomics as much as anything else.

Don't underestimate the weight impact of the ES 92's - they are even heavier than my Ethos 21 and Nagler 31 and I thought those very hefty when I acquired them.

Eyepieces in this class will require some form of counterbalancing and need well engineered focusers.

I have a set of 4 Pentax XW's as part of my 1.25 inch case and think very highly of those. Their eye relief is a bit longer than the Starguiders - 20mm.

All this, and more ought to be the subject of another thread I think although it might help the original poster a bit.

It terms of correction and image quality I find that the ES 92 17mm compares well with my Ethos eyepieces. I've found the eye positioning harder to get used to with the ES but optical performance in my 12 inch F/5.3 dobsonian is very good. I think the ES 92's are the best performing eyepieces that ES has produced to date.

They are very large and heavy though.

This is a great idea but with 5 scopes I'm going to need to devise some sort of matrix to present the information in a useful form I think. I would also want to represent variables such as the seeing conditions and the varying requirements within the target categories that you have listed.

As an example, take the category "planets" and, with my 12 inch dobsonian I would say that I have found anything from 80x to 400x useful and usable depending on the planet, the conditions and my objectives at that time.

Its going to be complicated I think !

I'll give it some more thought though - not much else to do currently !

My Tele Vue labels just sit in their boxes, apart from this one which covers up a scratch in the paint