TAL 100mm F/8 refractor

[allcart]

I don't know when Tal started making the short scopes, but from what I was told by the owner, he had bought it several years ago. It does seem like its been modded for some reason.

Surely you can't just hack off 250mm from the tube and still expect it to focus, but apparently it does. The previous owner used it for white light solar observing.

It came with a generic diagonal and an E-lux 25mm plossl (made in Taiwan)

I need to get a first light with it and see how it performs.

[John]

You probably could hack some length off the tube and get it to focus if you have a long enough focuser drawtube. Might have some issues with the baffles inside the tube / drawtube being in the wrong positions though.

If it's been used for solar then losing a bit of the effective aperture may not have been a concern.

[Marki]

Good luck Allan! Look forward to reading your report

[allcart]

Oh yes, it seems to have a huge home brew dew shield as well. It fits perfectly but only slides off the end and does not retract. I'll take a daylight pic tomorrow. Might even look at the sun if its shining.

Anyone got a pic of a Tal logo.

[twotter]

How's this...?

[twotter]

Or there is this one...?

[Marki]

Both my TALs have a round sticker with the first logo. I've seen that second logo on websites but not on a scope yet.

[TonyD]

Oops! Wrong one.....

[TonyD]

Allan,

This I love in your sig :grin:

and more lenses than the wife knows about

[Naemeth]

Allan,

This I love in your sig :grin:

You could change yours to "and more TALs than the wife knows about" or "and a desire for more TALs than the wife knows about" .

[AndyH]

I'd say that's a Tal 100RS from the early to mid 2000's.

a/ If it's got the deep purple-ish coating

b/ that's the early Tal RS 2" R&P focuser

Someones having a laugh saying it's F8. They've never ever made an F8. Not even a prototype. I hope they didn't think chopping a bit off the tube length shortens the focal length ?!?!?!?

These older R&P scopes had a very long focus drawtube, so it might well still be able to come to focus, even with a big chunk sawn off the original length of the ota. If it doesn't, get a long extension tube. Widely available.

With some tlc of the tube(maybe a respray), you've got a nice cheap Tal 100RS !!

Andy.

[Marki]

I'd say that's a Tal 100RS from the early to mid 2000's.

a/ If it's got the deep purple-ish coating

b/ that's the early Tal RS 2" R&P focuser

Andy.

Ah. I stand corrected . I'd forgotten the RS was first made with the rp focusser.

[AndyH]

Ye olde Tal factory insignia and my favourite ..........

Новосибирский

приборостроительный

завод

[Moonshane]

wonder if he used it with binoviewers? this can sometimes mean a need for more in focus. I'd be peeling off the sticker and seeing what's underneath!

[allcart]

Update..........I've just found Astro Baby's 100rs review on the web. The logo on his 100rs looks like it could be the same one on my scope. (except that mine is painted over) Its in the same position.

There is a gold rectangular sticker at the back end which also looks like mine. Same place and same orientation. The dew shield looks identical, mine is plastic.

Biggest difference is the finder. Correct me if I'm wrong but the finder looks like it is held onto the tube with small screws whereas there are no holes in my tube but the finder attaches to the focuser. It does look like a few inches have been taken off the end, as the gold sticker is closer to the end than in Astro Baby's 100rs.

Luckily my wife doesn't read my forum sig, so I'm safe.

[allcart]

You can see the gold sticker and the finder bracket in the 3rd pic I posted. The drawtube when fully extended is 140mm.

[John]

The gold sticker looks a bit like the "don't view the sun ...." warning sticker that Broadhurst Clarkson and Fuller used to put on the scopes they sold. I seem to recall there was a version of the TAL 100 that used a Skywatcher-like R&P focuser which has an integral finder dovetail cast into it - like this scope has.

[AndyH]

I've got some pics on here of my old 100RS ...

I added the Tal 8x50 finder to mine. On these older RS's, the 6x30 finder bracket slid into a dovetail inbuilt on the top of the focuser body.

Andy.

[TonyD]

You probably could hack some length off the tube and get it to focus if you have a long enough focuser drawtube. Might have some issues with the baffles inside the tube / drawtube being in the wrong positions though.

If it's been used for solar then losing a bit of the effective aperture may not have been a concern.

I'm totally confused by all of this! If you hack off the tube, but then need a longer drawtube isn't it still effective f/10? I mean, the rays are still "doing the same thing". With the same objective, the focal plane is going to be in the same place, etc.

Or am I totally off whack here?

[AndyH]

The early Tal 125R fracs also used this focuser. Most of the ones you see for sale, 2nd hand, here in the UK now and again, have them.

[AndyH]

Solar modding folk and someone wanting to use binoviewers might want to chop a bit off the tube.

But yes, the focal length of the lens stays the same.

Someones had a brain-puff and decided doing that makes it an F8

No matter, with a bit of tlc to the paint work, you've got yourself a cheap RS !!

Congrats.

[AndyH]

I'm totally confused by all of this! If you hack off the tube, but then need a longer drawtube isn't it still effective f/10? I mean, the rays are still "doing the same thing". With the same objective, the focal plane is going to be in the same place, etc.

Or am I totally off whack here?

Imagine the light cone coming from the lens. Now picture moving the end of the drawtube into that cone. If you chop off enough of the ota, that drawtube is effectively entering the light cone, so your going to get viginetting, or as John says, basically cutting down the effective aperture of the lens to say maybe 90mm or so.

Andy.

[AndyH]

Doesn't look like theres been a huge amount chopped off the ota though.

[allcart]

I'm totally confused by all of this! If you hack off the tube, but then need a longer drawtube isn't it still effective f/10? I mean, the rays are still "doing the same thing". With the same objective, the focal plane is going to be in the same place, etc.

Or am I totally off whack here?

Exactly what I would have thought. Perhaps they used a PST or something, who knows.

Looking at your pics Andy, it is the same scope only shorter.

Does this make it a halfRS refractor. (think about it)

[allcart]

How long should the white tube be from focuser shoulder to the end of the lens cell. Mine is 750mm.