Tal 100RS...So, come on. Just how good are they?

[Trumpetnut]

Interesting to note that mention of chromatic aberration is normally linked to the phrase 'on brighter objects'. So, at what magnitude is chromatic aberration not noticed? I suspect that it depends on magnification.

[MAN or ASTROMAN]

 I really enjoyed your post Qualia -Quite Poetic,and very true.Different scopes,and Bino's for that matter,seem to bring out different qualities to the objects we choose to view.Each view having it's own beauty.* Neil English has some very complementary things to say about the Tal. Will check him out,and report back!*

[John]

Interesting to note that mention of chromatic aberration is normally linked to the phrase 'on brighter objects'. So, at what magnitude is chromatic aberration not noticed? I suspect that it depends on magnification.

Depending on the achromatic refractor specfication, CA seems to cease to be a visual issue on mag 3-4 or fainter stars and deep sky objects. It's still there of course but it's effects become unobtrusive.

[JonC]

Hopefully going to borrow one of these from a friend, he purchased it about 15 years ago, didn't get one with it and shoved it in a cupboard. One of the reasons he didn't get on with it was running out of travel on the RA. If I can get it up and running he might consider remounting it.

[John]

Hopefully going to borrow one of these from a friend, he purchased it about 15 years ago, didn't get one with it and shoved it in a cupboard. One of the reasons he didn't get on with it was running out of travel on the RA. If I can get it up and running he might consider remounting it.

I seem to recall that you need to re-set the RA and DEC slow motion travel on the TAL 100 mount reasonably often. It's easy to do and only takes a couple of minutes. This strip-down guide for the mount might help:

http://www.astro-baby.com/TAL%20Telescope%20Rebuild/TAL%20EQ%20Mount%20Strip%20Down%20Guide.htm

[Trumpetnut]

Magnitude 3 or 4? Really? That means that, what? 80% of objects aren't affected by chromatic aberration? I'm guessing that most non stellar deep sky objects aren't affected either?

[JonC]

Thanks for the link. Just found a good video review of the mount with a few setup tips. Main thing is that it runs out of travel, but appears to be quick and easy to reset.

[Stu]

Magnitude 3 or 4? Really? That means that, what? 80% of objects aren't affected by chromatic aberration? I'm guessing that most non stellar deep sky objects aren't affected either?

Not sure if the exact limits, but yes, something like a fast f5 150mm scope which would be pretty horrid on planets would give nice contrasty views of DSO's I should think

[John]

Magnitude 3 or 4? Really? That means that, what? 80% of objects aren't affected by chromatic aberration? I'm guessing that most non stellar deep sky objects aren't affected either?

It's a "guesstimate" because it will depend on the degree of CA that the scope is producing but my experience with achromats, mostly F8-F10, suggests thats about right. Extended DSO's are affected the least.

With my ED refractors CA is only visible in tiny amounts around the brightest stars.

[MAN or ASTROMAN]

Right,over to Mr English,who is a great fan of the 'classic' four inch Achromatic Refractor. This information comes from his excellent 'Choosing and using a Refracting Telescope'(Springer books).I'd heartily reccommend this book to anyone interested in refractors.Not only does he cover the history of Refractor development,but he reviews a whole gamut of readily available scopes achro and apo,of varying focal lengths.He also touches on 'collectable scopes'-though he does have a seperate volume on this subject. Anyway,I digress,-so what has he to say about the TAL 100R and 100RS models?   He describes the 100R as a "personal favourite",with "razor-sharp images with minimal false colour,and little in the way other aberrations that can ruin an image.They're built like Tanks,tested in sub zero conditions,and feel re-assuringly old school."  Also "he's looked though several examples,and they've al performed like CHAMPS. He praises the 100RS focusser,and remarks on the scopes ability to split doubles. He quotes a TAL enthuisiast as stating " This is a high end refractor for those of us on a burger and fries budget".   I'd include myself in this category!     As a Tal owner,I'm biased.From personal experience,I love the build quality- I've little to compare it to,but my SW 130p is like a tin can in comparison.I can certainly live with the CA ,which is the price you pay with A chros. It really is a classic scope,and I would never dream of getting rid of mine. I can't really understand how you can get a scope so good for so little outlay,to be honest!

[RikM]

The amount of CA you see can depend on the eyepieces used as well. I used to have a 5" f/9.8 achromat and with Revelation Plossls and Baader Hyperions it gave very pleasing planetary views. When I switched to Pentax XW, the higher transmission and purer colour rendition made the CA much more apparent unfortunately. Older TV Plossls and Meade 4k UWA worked well tough with their slightly warmer tone.

[Astro_Baby]

A word on the mount, it does run out of RA travel as the mount doesn't use a conventional type set up for the RA.  The travel from lock to lock varies in time depending on the speed of the object - so the moon will produce quite a short time from lock to lock.  Its just a weirdness with the mount.  The basic TAL mount is quite sturdy and well made but very basic.  None the less with gentle handling of its controls it can provide a smooth(ish) ride for the TAL 100RS.  To REALLY get the best from the scope it needs a more solid mount.

I use the TAL mount for grab and go but for the best experience an HEQ5 allows the scope to really show its mettle.  A TAL100RS is so far inside the HEQ5s comfort zone it really provides some solid stability and shows how much a truly solid mount contributes to image quality.  A stable mount is worth easily an inch of aperture in my book and maybe more.

I tend to use lighter eyepieces with mine typically orthos but occasionally plug in the bigger Pentax XWs and in the past a rag tag collection of Skywatcher Panaviews, TMB IIs and Hyperions.  I cant honestly say the CA is better or worse with any of them but I haven't ever really looked.  I tend to look at what I can see rather than fuss about trying to find faults and aberrations with various combos of eyepieces.

Something to be wary of with the TAL mount is it does require the scope to be balanced quite well or else the weight of a big eyepiece will tend to force the springs in the mounts mechanism to open wide and disengage the slo-mo controls so its best with the basic TAL mount to stick to eyepieces of a similar weight or else balance the scope for heavy at the start of the evening to reduce any problems later on.

I very seldom use mine with the TAL mount to be honest, its not that the mount is worse than most mounts supplied with mid priced scopes but for me its not much more hassle to take the HEQ5 as I prefer to run with a tracking mount anyway.  Removes all the wobble from the viewing and heightens the views somewhat when you don't have to fuss about with slo mo controls at all.

How bright does an object need to be before CA makes headaches for you - that depends on what you can live with.  For me the Moon displays a purple haze on its limbs but it doesn't bother me much to be honest - it just creates a fringe.  You can knock some of this out with a pale yellow filter (cheaper than a fringe killer filter) and by happy coincidence also helps boost the contrast on Jupiter and Saturn.

Something else thats a plus for the TAL by the way is the exceptionally good diagonal and, if your really lucky, the 25mm eyepiece - so get one with its original bits and you have a very good diagonal and also a rather fine 25mm Plossl into the bargain.

[antares2063]

Hi  and greetings from singapore..

I bought my Tal100rs like just a month ago, its the 2nd refractor I've known and the views are pleasing . I purchased just the OTA alone and it came with a nice 1.25in. Diagonal (so robust) , and 2 plossls (25mm and 6.3mm) .

I brought it to a dark sky site with me last weekend and saw so many DSOs with it. The only target that had a slight trace of CA was Jupiter. 

By the way, off topic abit, is the Tal telescopes yahoogroups inactive these days? I signed up there actually but it was so quiet. 

Regards,

Junwei

[John]

I've managed to get hold of an older TAL 100 RT and I've given it first light this evening so I thought I post a few comments in this thread.

I bought a new TAL 100RT back in December 1999 and owned it for about 3 years before moving on to other (many other !) scopes and selling it on. The TAL 100RT that I've currently managed to get my hands on is nearly as old, having been made in May 2001 according to the signed and dated page in the manual. It has the old 1.25" short travel focuser and the dedicated TAL mirror diagonal with a flange to fit it to the drawtube. The objective lens coatings are the "purple" variety and the scope does have the plastic dew shield rather than the shorter metal one my original TAL 100 had.

The mount is the TAL equatorial on a tall wooden tripod. The tripod is taller than the one that my original TAL 100 came with but the mount is the same design. The original 25mm and 6.3 TAL plossl eyepieces are present although the 25mm has a slightly oversized barrel which is a very tight fit in the TAL diagonal and it won't fit at all in my other 1.25" focusers.

The scope has been well used and the tube bears some honorable chips to the paint here and there as a testimony to it's 14 years service. The objective lens and diagonal optics are in very clean condition though, I'm pleased to say. The focuser works well enough over it's short range but I'll need to take some care because when it reaches the outward end of it's range the drawtube could fall out of the focuser body as there is nothing to retain it.

For the first light tonight I mounted the scope on my Giro II mount on my tall wooden tripod. I've not yet got the TAL mount and tripod set up yet. Targets included Venus, Jupiter and Saturn, quite a few tight double stars and despite the less-than-dark skies, Messiers 57 and 13.

Initial star testing showed that there is a slight collimation issue with the scope. The diffraction rings around brighter stars are slightly offset from concentric. Despite this the scope did really well on all the targets I pointed it at notably splitting a 1.5 arc second double star (Lambda Ophiuchus), also dividing Delta Cygni, Izar, Epsilon Lyrae and a few others, allowing magnification of 250x plus on tight doubles, showing very nice views of the planetary targets, little CA on Venus and Jupiter, none noticable on Saturn and showing the Cassini Division, disk banding and 4 Saturnian moons without much trouble.

I'll make the effort to try and improve the collimation over the coming weeks now that I've had a taste of what the scope can do, although it does not seem to be holding back the performance much as far as I can see.

It's been 12 years since I looked through a TAL 100 and re-visiting the experience has been hightly enjoyable and more than a little impressive. The views this well used 14 year old scope from Russia have given me this evening are as good as any I've seen with any 4" aperture instrument. The standard TAL 6.3mm plossl deserves a mention too. For an eyepiece which can be picked up for £20 on the used market it gives an excellent account of itself showing sharpness and control of light scatter that belie it's modest cost. Top marks TAL

[Qualia]

Fantastic review, John and glad to hear you have had time to catch up with an old companion

After reading your report, I'm wondering whether something is up with my own Tal (collimation etc) or my eyes. For example, on Venus I get a fair bit of CA and around Jupiter there's sufficient hint to sometimes be distracting. On Saturn, I'm incapable of seeing Cassini's division with any clarity and too often the planet itself, rather than being lightly banded in a few zones is more a yellowish-white globe throughout. I used to think it was just a case of aperture, for all I had to compare the Tal to was the 10" but since receiving the smaller 3" and running both scopes at the same time, I realise this isn't the case.

Regardless, it sounds like you had a cracking evening and the scope really does look rather fetching on that tasty wooden tripod

[Stu]

Sounds very impressive John, high praise indeed! I've often wanted to have a go with a TAL, maybe one day I will.

Is there any consensus as to which versions are better? There seem to be various different coatings around....

[Roy Challen]

Fantastic review, John and glad to hear you have had time to catch up with an old companion

After reading your report, I'm wondering whether something is up with my own Tal (collimation etc) or my eyes. For example, on Venus I get a fair bit of CA and around Jupiter there's sufficient hint to sometimes be distracting. On Saturn, I'm incapable of seeing Cassini's division with any clarity and too often the planet itself, rather than being lightly banded in a few zones is more a yellowish-white globe throughout. I used to think it was just a case of aperture, for all I had to compare the Tal to was the 10" but since receiving the smaller 3" and running both scopes at the same time, I realise this isn't the case.

Regardless, it sounds like you had a cracking evening and the scope really does look rather fetching on that tasty wooden tripod

I'm wondering the same re. collimation. The cassini division was hinted at but not very distinct, and I could only spot Rhea and Titan (first time ever for Rhea ), some subtle banding could also be seen. This could be because Saturn was too low down in my heavily light polluted sky, the focuser not playing ball (really don't like it), or the collimation is a bit off. However, all the above planetary details were easier to see in the RS at the same time with the same ep.

[nightfisher]

John, an excellent report on a first light and welcome back to the TAL club, sounds like you have a really good one

[nightfisher]

Sounds very impressive John, high praise indeed! I've often wanted to have a go with a TAL, maybe one day I will.

Is there any consensus as to which versions are better? There seem to be various different coatings around....

Stu, with out doubt the best to get is the EARLY 100RS, this has the purple lens and a 2" rack an pinion focuser, the newer RS with crayford has the best focuser but not the desirable purple lens

[nightfisher]

Fantastic review, John and glad to hear you have had time to catch up with an old companion

After reading your report, I'm wondering whether something is up with my own Tal (collimation etc) or my eyes. For example, on Venus I get a fair bit of CA and around Jupiter there's sufficient hint to sometimes be distracting. On Saturn, I'm incapable of seeing Cassini's division with any clarity and too often the planet itself, rather than being lightly banded in a few zones is more a yellowish-white globe throughout. I used to think it was just a case of aperture, for all I had to compare the Tal to was the 10" but since receiving the smaller 3" and running both scopes at the same time, I realise this isn't the case.

Regardless, it sounds like you had a cracking evening and the scope really does look rather fetching on that tasty wooden tripod

Rob, you should be seeing better detail, my 100RS shows superb detail with  Saturn

[John]

Interesting comments and some varying TAL 100 experiences clearly

The CA is definitely there on the brighter objects such as Jupiter and Vega and, as it got dark, the amount showing around Venus increased as well although the phase and planetary liimb remained well defined despite this. I guess it's just not as much CA as I was expecting although it's been a while since I observed through a 4" F/10 achromat.

I'm going to put the TAL 100 side by side (quite literally) with my Vixen ED102SS when I get a chance. That should be a very interesting comparison. ED doublet F/6.5 v's crown / flint F/10.

I've some ideas on how to get the collimation closer to spot on. The diagonal on these scopes can be collimated but I'd prefer to get the focuser and objective tilt right first if possible. I've popped the back plate off the diagonal to check that it's got the collimation adjustment (it has) and found that the back plate was engraved with the details of an even earlier model, a TAL 100RM, serial number 0041 wheras mine, according to the manual, is a TAL 100RT, serial number 0632. Maybe TAL re-used old parts at some point ?

[Blazar]

I really don't like TAL's......................much. ;-)

Awesome kit....just setting one up for solar work using a quark.....going to take some time to get it just right though....

[Jim Steele]

Cracking review John,

Must be a trip down memory lane for you, its hard not to enjoy using a TAL and they do have the feel of a scientific instrument rather than a mass produced consumer item.

I'd be interested to hear your comparison between the RT and the Vixen ED doublet once you have had them both under the stars.

a TAL 100RM, serial number 0041 wheras mine, according to the manual, is a TAL 100RT, serial number 0632. Maybe TAL re-used old parts at some point ?

I thought the 'T' in RT always signified that it came with wooden tripod, where as the 'M' refered to a motorised mount? Either way I guess the numbering issue just adds to the querkyness of them.

Ben

[John]

.....I thought the 'T' in RT always signified that it came with wooden tripod, where as the 'M' refered to a motorised mount? Either way I guess the numbering issue just adds to the querkyness of them.

Ben

Thats what I think Ben.

It's interesting to think that some person, probably in a long white coat, working in a factory in Novosibirsk, Siberia on Thursday 24th May 2001, actually applied the stamps to the page in the manual and wrote his / her signature underneath. 

[RT65CB-SWL]

Not really. Achromat refractors occupy an important niche in the telescope scene, have done for hundreds of years and are well appreciated by many. All telescope designs have their pros and cons and it's a matter of deciding which you can live with and which you wish to avoid. Like all telescope designs there are low cost achromatic refractors aimed at beginners and there are also very expensive ones aimed at the specialist afficionados.

A low cost beginners telescope looks like this:

21061__AstroMaster_70AZ_2.jpeg

It's still a useful instrument.

My TAL 100 RT looked like this:

tal100rt.jpg

Not a toy I can assure you !

I know which on I would go for...