John

Ah, was considering the extendable as well. I would guess the light pollution affects the extendable ones more since they are more open, no? Any particular models I should be considering/walking/running away? Thanks...

Most people will use a light shroud with a truss / pole tubed newtonian to stop stray light getting into the optical tube. In apertures of 12" or more they make sense because they help with storage / transport of the scope but in apertures of 10" or less I reckon a solid tube is the way to go.

The Flextube Skywatcher dobsonians (awful name by the way - the last thing you want a scope tube to do is flex ) are actually a little heavier than their solid tube counterparts but, for some, the ability of the tube to collapse down is helpful for transport / storage.

I don't seem to be able to set up an avatar or signature. I think the options should be in the Control Panel, but I'm not seeing them anywhere. Any ideas?

Look under "Settings & Options" in the Control Panel - there are sub-options of "Edit Avatar" and "Edit Signature".

Hope that helps

Great collection there Vince

Clearly a man with good taste in optics

The funny thing is that it works both ways - there are eyepieces which are "infamous" for not delivering as much AFoV as claimed but also a few that actually deliver more.

The really confusing ones vary depending which production run you get - the old TAL 25mm plossl (which some reckon was actually a konig) was one of those - the actual apparent field of view varied between 50 and nearly 60 degrees with those.

It's more like the PGO at the moment - Pale Grey Oval !

Or perhaps different viewing conditions, or different eyesight?

Agreed - Synta / Skywatcher optics are of pretty consistent quality. There is much more variance in the factors you have listed.

It's taken me quite a few years to realize how much time you need to spend at the eyepiece, under varying conditions, to see anything like the maximum performance potential of a scope.

I'm sure I'm guilty of letting a number of perfectly good scopes go in the past that did not meet my expectations when it was almost certainly my weakness / lack of experience rather than the scopes

CA is something that bothers some folks more than others. Try the scope on the lunar limb, bright stars such as Vega and Sirius and bright planets such as Jupiter, Saturn, Mars and Venus and you will see it.

Have a look through a 120mm F/5 achromat (eg: a Skywatcher Startravel) and it will put the CA of your scope into perspective.

....Sorry for the thread hijack John

No problem - TAL scopes are never dull to discuss

I'm another ex-Evostar 120 owner who found the scope a good planetary and lunar performer. The CA was (on my example at least) pretty well controlled for an F/8.3 achromat and did not prevent the scope from showing the sort of fine detail and contrast that an unobstructed 4.7 inch scope should show. I did not use any sort of filter with my 120.

... I don't know about you but for me I like the fact I can tweak collimation.....

I like to tweak the collimation of doublet refractors but I felt out of my depth with the 6 element in 3 groups Apolar. I would not know where to start to correct the small amount of error that appeared in the airey disks with the example I had to review

Thanks Spaceboy

I think the 125R achromat would be much less daunting because it's a doublet in a collimatable cell - they seem to be about as common as hens teeth though

The 6 elements in 3 groups layout of the Apolar is a different matter altogether - even the TAL manual for the scope suggests that collimation issues should be referred to a skilled optical engineer. Elsewhere on the web collimation guidance for the front element (a singlet) have been published though, for those who wish to tinker.

I agree with you on the fit and finish expectations being understood by those that know TAL instruments. This can cause headaches for dealers though who would want to give the scopes a very thorough check over before dispatch to the new owner. Not a scope to be handled through a drop shipping arrangement I think

....My take on why this scope is more sensitive to non Tal eyepieces and diagonals is that optical design has a 3rd group of lenses at very end of the OTA tube where white body ends and Black Focuser housing begins. That means that drawtube can not travel deeper into the OTA as it done on extended travel focusers TAL100RS, TAL200K and typical TRIPLET APOs. They don't have lenses there. Therefore TAL125-5APO drawtube has max Length of the black focuser part. Moved all the way in, it bottoms out at the lens cell (where white body meets black focuser housing). That makes design more restrictive for over and under focus conditions that other telescopes don't have, allowing for more aftermarket accessories to work properly.....

That was my conclusion as well, having examined the optical configuration of the Apolar.

I've got a number of pairs from some nice little 8x30 Zeiss to 15x70's. I've owned them up to 25x100 but those were just too unwieldy for my taste.

As twotter says it's probably the 10x50's that get used the most though.

talteleoptics said:

Just wanted to address the issue of 2” eyepieces on TAL125-5APO before we all get confused about it from posts above. John’s result with trying Teleview 2” diagonal and lack of infocus is not all that surprising because it is a combination of 2 things: diagonal and eyepiece design, in addition to focuser design. It is not a secret that different manufacturers have very wide varying focal distance of their start diagonals, not just 2” ones. It’s a well-known fact. There is no standard to meet on that aspect. Therefore people do run into total focal distance issues with using scopes and a accessories from different manufacturers. Speaking of short focal distance star diagonals, it is also well known that 2 companies make very short focal distance star diagonals. You guessed it one is TAL and second one is Baader.

Now regarding TAL specific use of 2” eyepieces. TAL does make a 2” stardiagonal part number is ZP-90-2 see pictures . I used it many times with TAL 125-5APO and TAL UWA24mm, UWA20mm 2” eyepieces. And using them you will have of about 1 Inch of infocus travel left. So there is plenty of room to use other manufacturer’s eyepieces if you have short distance mirror design. You simply can not make focusing system that works with all possible combinations of aftermarket accessories and keep price and telescope size reasonable. TAL 125-5APO works very well with TAL accessories and I would argue many aftermarket ones. You just need to be aware of limitations for some combinations of them.

 

Some useful information there. It would have been very helpful if the information about the lack of compatibility of some aftermarket 2" accessories was provided with the scope along with a list of those that will work OK.

I've owned a used many refractors from 60mm to 150mm in aperture and from F/5 to F/13 in focal ratio and I've never had the same issue with the Tele Vue Everbright or the William Optics 2" diagonals (which I also tried with the TAL Apolar, with no joy ).

I also have to say that I believe it is very difficult to source the compatible TAL diagonal and eyepieces you list in the UK - which may be why they are still on Andy's wish list and not in his equipment case

The Delos 6 looks and sounds like another amazing Tele Vue eyepiece

It looks even fatter than the 6mm Ethos - I can't quite understand why that should be, given the large difference in apparent field of view between the two models

But at around £200 less expensive than the Ethos, the Delos is going to be a very popular product I reckon

Hi guys and girls !

I'm new here and your forum is very interesting.

I want to find and to buy a : Photo Adapter number A-9521 for AsteleT 102MN.

Try the Widescreen Centre in London - they know quite a lot about Lomo's I believe:

Telescopes UK: Telescopes & Telescope Accessories in your only London shop

Ken,

Your 10" F/6.3 newt has a focal length of 63" or 1,606mm. If you divide the focal length of the scope in mm by the focal length of the eyepiece you get the magnification, eg:

40mm eyepiece = 1606 divided by 40 = 40x

20mm eyepiece = 1606 divided by 20 = 80x

and so on.

a 32mm or 40mm would be the lowest useful power eyepiece in your scope and a 6mm (268x) would be about the highest (given our typical viewing conditions). A couple of eyepieces in between them would be useful as well - say around 90x and 150x (18mm and 11mm or thereabouts eyepieces).

philj said:

A good review John, it makes me want to get a look through one of these, a comparison with my Meade 5000 127 triplet would be interesting just to see what the different approaches to CA removal provides.....

Thanks Phil 

The control of CA was the most impressive aspect of the Apolar's optical performance for me. I've used a few ED doublets (including my little Vixen ED102) so I'm used to seeing a little CA either side of focus on the lunar limb with no CA at focus. With the Apolar I can't recall seeing any CA at all and only tiny amounts on the brightest stars.

Given that there are no really exotic glass types used, I do think the Apolar optical system has great potential if it can be precisely and consistently executed in manufacture and maintained during ownership.

Oh no, don't get me wrong John, the price quip, wasn't aimed at you(or FLO).

Just my personal belief that the 125 Apolar is priced a bit too high, here in the UK considering what a certain other scope is quoted as. Just an ongoing annoyance I have, since the importers published the price.

:)Andy.

No problem Andy - I didn't take your comment on price as a quip at all

Having seen and used the scope I tend to agree with you

Thanks for the feedback folks

On the 2" accessories issue, I was pretty surprised by this and to start with thought I was missing a trick. But whichever eyepieces I tried in the 2" diagonal (I was using a Tele Vue Everbright) I could not get close to focus before I ran out of inward focuser travel. The photos show the focuser more or less at focus with the supplied 1.25" diagonal - loads of outwards travel left but precious little inwards !.

It's possible that TAL might have a proprietary 2" diagonal which would work with the scope, in which case it would be good if it was offered to potential purchasers, even as an optional extra.

On collimation, I was tempted to have a fiddle but the number of clear nights I had were very limited and the collimation adjustment does not exactly invite attention. The supplied manual simply recommends that adjustment of the optics is referred to somebody suitably qualified. I have seen collimation instructions for the scope on the web but those don't form part of the supplied manual.

On the price - I used the figure quoted on the OVL web site:

TAL-125 APOLAR APO APOCHROMATIC REFRACTOR TELESCOPE - 125MM (4.94") f/7.5 APOCHROMATIC REFRACTOR TELESCOPE by OVL

Thanks to Steve at First Light Optics and OVL Limited I had a chance to try out one of these interesting refractors earlier this year. This is my report of my experiences with the scope :

Tal Apolar Review 05-11.pdf

There is no need to "sacrifice" a PST to convert it to a larger set up. If you cut off the "gold" tube a few inches in front of the tuning ring the back half becomes a Ha eyepiece. With a suitable sleeve, the front half can be rejoined to reconvert it to standard....

I stand corrected Peter - I did not realise that this could be done

It can be done with a refractor of the right aperture / focal ratio. The Vixen 80mm F/11 refractor is considered a good "donor":

First Light Optics - Vixen A80MF Refractor

But you need to sacrifice a PST (for the Etalon filter) and to purchase a suitable ERF filter (which are not cheap !) so the cost will exceed that of a PST or the Lunt 35. The prize is a larger aperture HA scope of course but you have to "do it right" - you can't take any chances or cut any corners when it comes to the sun.

One of our members, Merlin66, has a lot of expertise in undertaking such work.

I've recently come across this further guide to eyepieces which I thought was well written and useful :

Robins Eyepiece Guide

I used to have a Konusky 150mm F/8 refractor. It was exactly the same as the Skywatcher Evostar 150 refractor, except that the colour scheme was yellow.

I believe that the Konusky 200 is pretty much the same as the Skywatcher 200P:

Reflectors - Skywatcher Explorer 200P EQ5

Except that the yellow (older) Konusky versions have the older style (and more wobbly) aluminum tripod legs.