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nightfisher

When 2 Tals go to war

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Okay not so much a war but i remember the Frankie goes to hollywood song "2 tribes go to war" and thought it would make a good title :grin:

This is a little shoot out between a pair of Tal 100 f10 achromatic refractors, namely my 100RS and the much earlier 100r, i have never looked trough the 100r before, and i was very kindly loaned this 100r by DougM43, i had to borrow a dovetail to fit this scope to my mount.

As most of you will know but for those that dont, the main difference between these 2 scopes is the focuser and the lens, the older 100r has a single speed rack and pinion that will only accept 1.25 eyepieces, where as the 100RS has a single speed crayford that takes 2" and 1.25 eyepieces and has much more travel.

the lens of these scopes has changed over the years, i am aware of 3 different colour coatings, the older 100r has a lovely deep purple colour to its coatings, on the 100RS this  changed to a more green colour, and much more recently they have produced the 100RS with a rather interesting aqua blue colour to the coatings.

The purpose of this some what basic test was to try to establish if the older purple lens on the 100r gives better views than the newer one, as a couple of people have tried this and feel the 100r lens to be a fraction better.

I mounted both these telescopes on the Skytee 2 mount, needing a 5kg counter weight to get a nice smooth balance, the mount really surprised me and handled the pair of f10`s very well, it did take a little while to get them both pointing at the same object!

The main target for the test was the mighty Jupiter, and the eyepiece`s used were a 25mm silvertop plossl, a 15mm Revelation plossl and 12.5 circle T orthoscopic, the viewing conditions were pretty poor so the 12.5 was as much magnification as i was going to give it, at this point i should also point out that the lens on the 100r looks to be "showing its age" a little and could do with a bit of a clean, but i have not touched it seeing as it is not mine.

To the test,

I started this at 2130 (7/02/15) with Jupiter being nicely placed in the night sky, but as said previous the seeing conditions were far from ideal.

First up is the 25mm plossl and this gave very pleasing views in both scopes, i should note both scopes were set up at 1.25 using a tal diagonal in each so all i had to do was just swap eyepiece`s each time, of course at x40 mag the disk was very small but NEB and SEB was clearly visible in both scopes and no difference was detected

Then onto the 15mm plossl at x66 mag, this brought up the image scale, but did not really show any more detail, but was a tiny bit sharper in the 100Rs, to my eye at least, i was surprised to find i did not rate this ep in either scope, i think the word "usable" rather than exceptional would apply.

Then it was time for the 12.5mm ortho, a proper eyepiece and x80 mag. and no surprise this gave the sharpest views of all in both, and with a heavy heart i have to say maybe, just maybe a tad sharper in the 100r, i have to say i had a notion before the test that the 100RS would trounce the older 100r but far from it, with the ortho in place i do feel the 100r gave a slightly better view, maybe the purple lens coating helps to control false colour a bit better, but i felt i was getting a better "snap to focus" in the older scope, and this surprised me as i had wanted the newer scope to win hands down, there was still very little in this but yes the old lens did give a slightly sharper image with maybe a hint of better contrast.

I also spent a little time on M42 while these were set up about the only other worth while object view-able from my poor location, the brief summary being:

Both scopes gave very similar views and resolved the four main stars of the Trapezium  with pure ease, but again with the 12.5 ortho the older 100r just seemed to come to focus a little better, it would have been very nice to view the Luna surface with both scopes but the Moon was only just starting to peek over a rather annoying wall and was in the haze and murk to the east, i did have a peek with my 127 mak and the surface was boiling all over the place.

There has been many times when a 100r has come up for sale and i have been tempted to get one and swap the lens onto my 100RS, in a quest for near perfection, would i still go to this trouble, i think yes i would if i could find a mint 100r at a sensible price, to have a hybrid 100r/rs using the 2" crayford with the purple lens would make one bostin 4" f10 achro  :cool:

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very interesting reading Jules and thanks for the effort of doing this comparison.Same was done by N.English and i think he said the same that the old R lens was better but the OTA and flocking was better in the RS,so there might be the holy grail of TAL`s by marriage of the old lens into the RS OTA? :)

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An enlightening comparison  there Jules, I have always been tempted by a Tal 100, of either model and for the money they perform very well.

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Just get a Lyra and be done with it :) going on previous reviews

Yes, there are times when i get tempted with a 102 f11 a lot of people have the opinion its the marginally better scope, maybe down to the slightly longer focal length, i have looked through both Tal and lyra on the same night and there might be a bit of truth in it 

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Great review Jules... I think there is a hybrid tal out there somewhere, remember reading about it... anyone know who owns it now?

oh and I'm sire there's a TalR on ebay in Bangor recently £150 starting though...

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I guess the only way to truely know if it were consistently marginally better would be to swap the diagonals round as well.

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What a surprise,

like you I fully expected the rs to beat the r hands down. Nice choice of words "could do with a bit of a clean" (neglect) would be my choice. After reading that I wonder if the plossl eyepieces I've used are the reason I've never got on with that scope, that said I can't see myself rushing out and buying alternatives anytime soon either.

If you want to scrape some of the dirt of the lense and fit it into yours and give it a try before you go out and spend your hard earned on a doner scope then feel free. (Honestly you can't do anything to that scope that would ruffle my feathers in any way) when it finds it's way home, and there's no rush, it will no doubt end up back up the loft again where it will probably end it's days or eventually be donated to some astro club.

Great write up, thanks.

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Excellent report Jules and really fair and balanced as well :smiley:

I've only owned the older type TAL 100 and that was a long time ago. I do recall being surprised when it seemed to equal my old Vixen SP102M which was a lovely F/9.8 achromat. The TAL had cost me less than 50% as much new as I'd paid for the used Vixen.

Pity that TAL seem to have moved away from astro manufacture now :sad:

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For information there are four focuser to my personal knowledge; I have three, 2 RS one with 2" R&P and one with 2" Crayford single speed. The older 100R has a 1.25" R&P focuser.

Flocking the tube does seem to be worthwhile and not too difficult.

.

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For information there are four focuser to my personal knowledge; I have three, 2 RS one with 2" R&P and one with 2" Crayford single speed. The older 100R has a 1.25" R&P focuser.

Flocking the tube does seem to be worthwhile and not too difficult.

.

Yes i have seen all the versions, as the 125r had the vixen style 2" rack an pinion though i can only account for 3 types

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Wow ! Good report and super findings. I'd love to see how my ancient Vixen 102 achro f9.8 compares,

Nicko.

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Cheers Nick,

I only did a limited test due to only having a limited bit of sky to go at, had the Moon been up and at a high setting in the sky i would have pointed them both at my favorite object, but i dont think this would have revealed any more findings 

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Yes i have seen all the versions, as the 125r had the vixen style 2" rack an pinion though i can only account for 3 types

On the other hand my TAL125r has the same 2" Crayford as the later 100RS.

Interesting review Jules, thanks for taking the time to post this.

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On the other hand my TAL125r has the same 2" Crayford as the later 100RS.

Interesting review Jules, thanks for taking the time to post this.

I think i should have kept my 125r and fitted the crayford from my 100rs, especially as i have the skytee 2 now............cheers marki 

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That would have been good jules - would have been interesting to put the two 125rs side by side.

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I wonder if its down to the coatings or the lens qc. I might be able to let you know as I am planning on having my RS custom tuned later this year...assuming funds are made available from the house science budget :)

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Hi Jules, thanks for the side by side test, interesting read. 

I have just been out tonight and guess what I picked up? 

A 100RS courtesy of Fleabay to go on my SkyTee 2. It is the one with the 2" Crayford and blue coatings. 

Unfortunately the night sky has done a runner in Lancashire so I have been unable to test. 

Paul 

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Funny coincidence, but i am picking up yet another 100RS today, and one with a blue lens just like yours (but not yours), i have had this arranged for a good while

i look forward with interest how it performs

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Lovely report, Jules and interesting find. Interestingly, it's not the first time I've heard that the older 100R performs a tad better than the newer 100RS. Either way, whether someone got hold of the R or RS, they are almost guaranteed to have an outstanding representation of a 4" f10 achro. The Russians certainly knew how to put together some astounding pieces of glass.

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Smashing report Jules! No doubt I will follow this thread closely and probably re-read it from time to time.My own TAL 100RS dates from Oct 2011 and has the lovely blue glass,as shown in Paul's  great picture.I may have to invest in an Ortho soon!

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Not doubting your experience for one minute Jules but I have to ask........ when doing the side by side were both scopes checked for collimation and did both have the same amount of time to cool down ??

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Not doubting your experience for one minute Jules but I have to ask........ when doing the side by side were both scopes checked for collimation and did both have the same amount of time to cool down ??

Yes Nick, both put out at same time and i know my one has good collimation, if the older one has bad collimation it certainly does not show it in any way, i now have a third Tal 100....oops

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I'm waiting for the 100RS to be advertised as "Free to good home" in the classifieds. :eek::grin::eek::grin::eek:

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I'm waiting for the 100RS to be advertised as "Free to good home" in the classifieds. :eek::grin::eek::grin::eek:

might have rather a long wait

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