John

3 hours ago, michael.h.f.wilkinson said:

I will wait and see the reports of others, before ordering the XW 40, as the LVW 42 get very limited use (the Nagler 31T5 usually gives the better views, with a darker background). Buying the XW 40 would get in the way of more "urgent" upgrades (like the 6" solar scope project). Choices, choices.

I don't often use a 40mm eyepiece either so the Aero ED 40 that I have does just fine for the £50 it cost me. Its actually a very nice eyepiece

Hi and welcome to the forum.

Superb set but you will need something at the longer end. 21mm Ethos is fabulous but hugely expensive. Think about the APM XWA 20mm 100 degree as a somewhat less expensive but still excellent alternative. The set I use most often for my 12 inch F/5.3 dobsonian is:

Ethos 21, 13, 8 and 6mm and the Pentax XW 5mm so very similar to the route you are going down.

There are lots of other options as you know but after many years of trying eyepieces I have settled happily with the set above. Others have made different choices and are very happy as well of course

6 minutes ago, Adam Barnsley said:

You mean ES is better than Delos?

Much bigger, heavier and with a 92 degree field of view compared with the 72 degrees of the Delos. Optical performance is very similar. I've been comparing the ES 92's with my Ethos and Delos eyepieces. I didn't find the eye relief of the 12mm ES suited me so I've now sold that one. Still have the 17mm though. The ES 92's might not be quite as sharp to the edge in an F/4.7 scope as the Delos is though. My dob is F/5.3.

We are talking very large eyepieces here:

20 minutes ago, DaveS said:

From the original definition, the lens must be corrected for longitudinal chromatic aberration in three wavelengths, and spherical aberration in two. to do this you need three distinct glass types. ED doublets can only bring two wavelengths to a common focus,as the chart Vlaiv posted above shows. Calling an ED doublet "apo" is nobut marketing guff.

Doublets using a fluorite element seem to do a pretty good job. I don't see any false colour in my Tak FC-100DL at focus and either side of it as well.

I think you can get some sort of image from an uncoated mirror. Enough to see if the figure is decent anyway.

9 minutes ago, Adam Barnsley said:

Delos Have a bit smaller fov , but is more comfortable. Is Optic better(Delos) ? 

Delos came from the Ethos and the Ethos is a step up from Nagler optical performance (I moved from Naglers to Ethos a few years back). So, yes, I think the Delos will improve on the Nagler.

All these are really good eyepieces though - we are talking about margninal improvements, nothing more.

When I was looking for a top class refractor back in 2016 a Vixen Fluorite 102 was top of my shortlist. Didn't find one then but the last UK example of the 1st run Tak FC-100DL's was available so I decided to go for that.

Both use Canon Optron objectives at F/9 so very much equal in terms of performance I would think

Nothing will "break" if you exceed 224x - the image will just loose sharpness and contrast and look fuzzier. Often the best views come at magnifications a lot lower than max. Jupiter, for example, usually looks best with small scopes at 120x - 140x.

Your TEC 140 should be capable of showing you all those targets as My TMB/LZOS 130mm has. For Triton I use very high magnification - 300x - 350x. For E & F Trapezium there seems to be a "goldilocks" magnification - for me that is usually 150x - 200x.

The theoretical maxmimum useful magnification would be around 228x with that aperture but very often the planetary views are sharper and more contrasty (which is what we are aiming for) and somewhat lower than the max due to a range of issues not the least of which are the seeing conditions.

Very interesting read Piero. I agree with Jeremy that you have shown great determination to sort out these issues in a systematic way.

Is it possible to feed some of what you have learned during this excercise back to the maker of the scope so that they might consider some revisions to the primary cell design and execution ?

Many other owners, I suspect, would not have got to the bottom of these problems and might have either lived with mediocre performance or moved the scope on.

What telescope do you have ?

My counterweights go on a magnetic knife strip attached to the lower part of the tube of my 12 inch dob. The 2 weights are 750g and 1500g respectively. With my heaviest eyepieces (wich weight 1.3kg) and the scope at a relatively low angle I need both of them.  I have two positions on the strip that I can place them so that provides more weight variation. This is a DIY solution as I expect you have guessed !

In this pic the lighter of the two weights is in the upper position on the strip:

The Nagler 20mm T5 was in my list as well. Very sharp eyepiece and one of the most compact 2 inchers.

18 hours ago, Adam Barnsley said:

it does not matter to me. How will the Dobson and focuser handle such a weight?

I have a Moonlite focuser on my scope which handles that sort of weight without a problem. I use counterbalance weight at the bottom of the tube when I'm using these heavy eyepieces except when observing towards the zenith when I take the weights off.

Probably best to keep this topic on Meade and its future

I'm sure that you will get lots of help and suggestions with this choice Adam.

In that niche I currently have:

21mm Ethos

17mm Explore Scientific 92 degree

24mm Panoptic and 17.3mm Delos (for when I want to use 1.25 inch eyepieces only)

All are excellent in my opinion.

I've also owned an used others in this niche, again which are very nice:

22mm Nagler Type 4

20mm Nagler Type 5

20mm Explore Scientific 100 degree

20mm Myriad (which is the same optically as the APM XWA 20mm by the way)

The others you list are no slouches either.

You are going to be spoiled for choice. To narrow things down a bit:

- do you have a preferred budget range ?

- do you wear glasses when observing ?

- does the weight of the eyepiece matter to you (some of these weigh 1.2 kg) ?

My current dobsonian is a 12 inch F/5.3 but I've also owned a 250PX F/4.7. I believe all the eyepieces you list will work well with the scope but you might want to think about a coma corrector for the ones with an 80 degree or wider apparent field of view because at F/4.7 coma (from the scope mirror) will be seen in an ultra wide field even if the eyepiece is very well corrected. (edit: especially if the eyepiece is well corrected !)

I'll look forward to hearing about the choice you eventually make

19 minutes ago, Louis D said:

Sorry to hear you didn't get on with the 12mm ES-92.  How about the 17mm version?

I find the eye position easier to find and hold with minimal effort with the 17mm so I've slotted that into my eyepiece case between the 21mm and 13mm Ethos currently.

Trouble is, the case is getting rather heavy .....

I don't think anyone is suggesting that the scope in question is one of the ED doublets

Condensation on the eyepiece is not conducive to good viewing. The conditions lately in the UK means that you might have had some condensation on the objective lens as well, which again, is not going to help the clarity of the view at all.

It is worth checking the end of the eyepiece and diagonal barrels to see if a moon filter has been left screwed on - many types of these give a greenish tint to the image.

The scope is an achromatic refractor and it will show a thin fringe of violet / green around the limb of the moon and this tint may also show on the dark shadowed areas of the lunar suface such as craters and mountains near the terminator. Across the illuminated face of the moon you should not be seeing a noticable colour tint with this scope though.

I would check to see if any filters are in place, remove them if they are then try the scope on the moon again enusring that the eyepiece and the objective lenses are not fogged / or misted before observing. Keeping the eyepiece a bit warmer than the outside temperature helps stopping misting from breath / body warmth.

Thanks Joe

I agree re: not distracting the post topic any more - plenty of other chances to discuss scopes other than the Esprit 150 elsewhere.

XW's can kidney bean or have black outs when the eye cup section is not adjusted to the correct position for your eye.

Misplacement of the eye can cause this in many wide field designs though. I have recently found this with the ES 92 12mm especially, which has now gone to a new home. Others have reported the ES 92 / 12 to be supremely easy to use

I find the XW's (I have the 10, 7, 5 and 3.5) very consistent in terms of comfort, ease of use and performance. I find that I need the eye cup sections in the uppermost position with all of them - I dont wear glasses to observe.

As has been said - eyepiece choice / preference is a very personal thing though

48 minutes ago, joe aguiar said:

... I also tested my takahashi 102TSA S to my 100 f/9 evostar (I sold it few months ago BUT I did own it) and there is no comaprision the tak blew the SW model out. But for most people the SW evostar could be enough and that's great.  This is also a big difference in price too the evostar 100f/9 is $1050 (on sale now) compared to my 102 tak about $4000 which is just shy of 4x the price so ya you could buy 4 100 evostar compared to a tak BUT theres a huge difference in what u will see. I did a video on this ...

 

 

When you say "huge difference" what do you mean ?

Can the 102TSA show things that the SW ED100 simply cant show you ?

You say that the SW performance would be enough for most people but if the difference is so great what would they be missing out on ?

Some specific examples would be great.

Owning a mix of top end refractors and less exotic ones myself I'm interested in the real life differences in performance you see

To give you an idea of whether it's worth investing in, an excellent condition 10 inch dobsonian by Skywatcher would cost around £280 on the used market.

I'm pleased that you have got the diagonal back in service now Stu. Not a low cost operation but at least you get a really excellent diagonal for the outlay.

When I bought my Baader T2 Zeiss prism diagonal I don't recall the spec mentioning BBHS coatings but the same model number (#2456095) one the Baader website now specifies this:

https://www.baader-planetarium.com/en/baader-t-2-stardiagonal-(zeiss)-prism-with-bbhs-r-coating-(t-2-part-01b).html

The dealer specs for this diagonal don't mention BBHS currently so I wonder if it is a relatively new change to the spec of this product ?

Whatever, it is a very good diagonal.

Like @F15Rules / Dave though, I stuggle to see any differences in optical performance between my Tele Vue Everbright, Astro Physics Maxbright and the Baader T2 Zeiss. Yet others say they can see them as clear as a bell 

I use my T2 prism with my Tak FC-100 DL pretty much exclusively now mostly because I feel that it's compact size suits the slender lines of that scope. Not too scientific I'm afraid

Relieved to hear this Avtar. I guess the loose section of the body changed the distance between the lens elements in the optical design a little resulting in the less than pinpoint stars.