TAL 125R Apolar Apochromatic Refractor

[spaceboy]

Very informative and interesting report John.

I suspect this scope will depreciate hugely on the second hand market due to the lack of user collimation. I have experienced it first hand with the 200K. Despite being a superb scope the concerns of collimating a 200K meant despite the £999 price tag they rarely sell second hand for more than £350. I may be wrong but I guess this will see a similar trend for the 125R. Regards the finish on the TAL's I think this is already accepted as the norm by TAL fans and would not distract from the real reason of why they have a devoute following.

[John]

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

Edited August 28, 2011 by John

[spaceboy]

DOH!!! Sorry I meant Apolar not 125R.

If I remember correctly the manual gave the same recommendation for collimating the 200K as you say the manual dose for the Apolar. I'm positive that this is the reason for the poor re-sale value of the 200K as it certainly isn't because of it's performance. As you suggested in your report that the collimation of the Apolar might not have been spot on and I don't know about you but for me I like the fact I can tweak collimation. I know it's not everyones cup of 'T' and most would rather not mess but the way I see it is nothing, not even the bomb proof TAL's can stay perfectly collimated forever and I find it appealing that if and when collimation is required I can do it with relative ease. This appears to be near impossible for anyone using the high end TAL models.

[John]

... 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

[AndyH]

I take exception to the comment regarding Klevtsov collimation

I find collimation of the Klevtsov scopes, as easy as collimating my newts. They hold said collimation so well because of the heavy duty mechanical design.

It was said when the Klevs first appeared, they were un-collimatable. Time and experience has proved that wrong.

Perhaps the same will happen with the Apolars, once user feedback trickles through.

I just think that their price point is too high, here in the UK. They were never designed/manufactured for that price bracket, IMHO. Either that or Klevtsovs are hugely underpriced here?

Cheers,

Andy.

[spaceboy]

I take exception to the comment regarding Klevtsov collimation

I find collimation of the Klevtsov scopes, as easy as collimating my newts. They hold said collimation so well because of the heavy duty mechanical design.

It was said when the Klevs first appeared, they were un-collimatable. Time and experience has proved that wrong.

Perhaps the same will happen with the Apolars, once user feedback trickles through.

I just think that their price point is too high, here in the UK. They were never designed/manufactured for that price bracket, IMHO. Either that or Klevtsovs are hugely underpriced here?

Cheers,

Andy.

Apparently two versions were made and the later one can be collimated with limited skills. If you are saying the earlier version can also be collimated with ease I would recommend for the good of all the 200K owners out there, that you post a fully detailed how to thread.

Although the 200K I owned never required collimation it didn't stop me surfing the WWW in the attempt to find out how it is done should the day ever arise. Needless to say by my comments I never came across anything anywhere. If I had I would have been very appreciative of the person who took the time to make the details available to the masses.

Edited August 29, 2011 by spaceboy

[AndyH]

Shall do.

I'll post it on a seperate thread. Don't want to vear this thread off in a different direction.

Cheers,

Andy.

[spaceboy]

I'm sure will be considered a hero by many a 200K owner

Sorry for the thread hijack John

[John]

....Sorry for the thread hijack John

No problem - TAL scopes are never dull to discuss

[michael.h.f.wilkinson]

Getting the thread back on topic (), I still do not really see why they designed the scope with so little in focus that many common diagonals do not work. I know the further back the rear lens group is placed, the smaller (and therefore cheaper) it can be. However, placing it an inch or so further up the tube does not change things that much size-wise, so unless there is a fundamental optical reason why it can only be placed so far back, I think this does count as a design flaw.

[AndyH]

I think the spacing between the three groups of lens/lenses is critical?

So the only thing that could be improved would be to manufacture a focuser 1" shorter in the future? It does look, to the eye(thanks to John's and others pics), like a very long unit.

Off the top of my head, I can think of a scope or two, that have similar infocus issues. The Vixen VMC 200L and one or more of the Pentax APO's ? Some of the older(ish) Takahashi models were a pain to adapt to a 2" format, if memory serves me well.

Cheers,

Andy.

Edited August 29, 2011 by AndyH

[spaceboy]

Maybe it's just me but I would have thought they would have learned their lesson after the 100R. They were aware that focus travel can been an issue as it was fixed on the later 100RS so it would have made sense to check this was not going to be a problem on there top end refractor.

[Randy_Torres]

On 28/08/2011 at 02:33, talteleoptics said:

 

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

Is Talteleoptics still in business?

[John]

2 hours ago, Randy_Torres said:

Is Talteleoptics still in business?

Their website still seems to be active:

http://talteleoptics.com/

Try sending them an e.mail.