TAL 125R Apolar Apochromatic Refractor

[John]

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

[FLO]

That is one heck of a 10,000th post John

Steve

[nicnac]

good review John, i enjoyed reading that

Thank you

[step_hen]

Great review John, and a very interesting scope design. Congrats on your 10,000 post!

Stephen

[AndyH]

Always enjoy reading your reviews John !

Cheers,

Andy.

[bombassa]

Sorry my english is not so good but I understand that the scope in question has a 2" focuser but you can't really use a 2" diagonal with it because of problems with inward travel? Is this correct? This sounds serious.

Great review btw!

[twotter]

Enjoyed reading that and congratulations on your new Bright Star status

[MikeP]

Well written and comprehensive review John.

Congratulations of reaching 10,000 posts too.

Mike

[shaunster]

Great review

The scope sounds like a real bodge if you cant use 2" eyepeices, its a serious amount of money you would have thought they would have looked at that??

Edited May 25, 2011 by shaunster

[kris h]

Great review John , Do they cost £1500 on the Flo its says £486-

£987 & to call for there price , im looking to get a good 5" to 6"

refractor in the near future the WO 120 Megrez is around the same

price looks a little more tempting .

[Whippy]

A superb review John and congrats on making the 10k .

Tony..

[AndyH]

Once again, great report and equally excellent pics.

Some musings

The scope works in 2" mode, with their 2" gear, so I've read. This same problem was found on some of the 100RS's. Bit of a bummer considering the 2" diagonal and eyepiece aren't imported though

Never understood why they don't design some of their scopes with non Tal extras in mind? A bit insular or blumming minded?

Regarding the finder - I agree that they should have used their 50mm one on this scope. Whilst the 30mm finder is really nice the 50mm is truly outstanding. The port for illumination is threaded the same as their polar scope illuminator on their 2 H/Duty stepper mounts. So the wire that leads from the mount to it, can also be used on the finder. Perhaps with an extension lead. It uses a std small headphone type jack thing.

Yes, the rings are spaced to fit on the Tal mounts, with no dovetail needed.

Collimation - Done with the front lens adjusters. Some Germans and lately some Russians have tweaked theirs. *edit: In retrospect, most folks probably wouldn't want to though.

Pricing? I'm saying nowt

Cheers,

Andy.

Edited May 25, 2011 by AndyH

[John]

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

[AndyH]

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.

[John]

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

[JamesM]

Many thanks for that report which made very interesting reading. John, the first picture got me a bit worried as I thought you were burying someone in your garden! I have to say I would now be a bit hesitant at getting one of these. I don't mind the welding or the rough paint as in a way it kind of adds to the charm especially if what's in the tube makes up for it but reading between the lines I sensed you were a shade underwhelmed by the view? If you add in the focuser issue perhaps the price is a little high which is a shame because for some strange reason, I really wanted this to be a 'dribble' scope, one in which everyone was itching to get hold of one and perhaps there would be a small waiting list all helping to build up that sense of anticipation. I shall have to find something else to dribble over now!

Again many thanks for the review John as it was very well put together.

James

[michael.h.f.wilkinson]

Really interesting report. As others have said, not being able to use common 2" kit is serious. I will not even consider this scope if ever I look into bigger fracs, unless they clean up their act.

[Crunchard]

Very clear and concise review, thank you.

The restriction on 2" equipment could be very telling...

[philj]

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.

I think the Tal is not alone in the finish quality stakes these days, my Meade has some real quality parts but then is let down by small things like paint finish in certain areas

A shame about the 2” issue though, if the back elements are fitted in the Crayford body there wouldn’t be any room to shorten this to achieve focus without disturbing the optics.

Price wise I reckon it’s still not bad for an apo and in a similar ball park to the slightly larger Meade 5000

As an old scope fan I like the fitted wooden crate, all scopes should be supplied with one; ali cases with foam inserts just don’t compare IMHO.

Philj

 

[John]

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.

[talteleoptics]

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.

[AndyH]

One of these 2" Tal diagonals has been on my wish list for some time.

I have one of those 24mm UWA eyepieces. Lovely lump of glass.

Andy.

[John]

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

[talteleoptics]

John,

I completely understand the desire to have an idea on what will and may not work with that scope from aftermarket accessories prospective. 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. Undestandably TAL made sure their accessories work with it as it was designed. Since I worked with TAL for some time, (not worked for TAL to be clear) my guess is that they will not be testing aftermarket sets to provide compatibility charts. May be Andy is our only hope? 

Regards

Roman

[John]

....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.