Older Kowa TSN-3 performance? (1 Viewer)

[jring]

Hi,

you have to look for a trace (or rather the absence of it) between the 3rd and 4th reflections as the TSN-3/4 have a Steinheil design doublet with the CaF2 element (which takes the role of the crown glass here) as the back element and a crown glass (usually BaK5 - it takes role of the flint here) at the front.

Only Takahashi has so far dared to offer a Fraunhofer style doublet objective with a CaF2 front element in their FS series - and only in the early nineties after their friends at Canon-Optron (who makes the fluorite objectives for Takahashi and Kowa) had learned how to coat CaF2.

Joachim

 

[Binoseeker]

No fake!

Thanks for explaining, Joachim,

Ok, so it was no trace between 3rd and 4th reflections, thus no fake.
Is the TSN-883/-4 lenses made the same way?

 

[jring]

Thanks for explaining, Joachim,

Ok, so it was no trace between 3rd and 4th reflections, thus no fake.
Is the TSN-883/-4 lenses made the same way?

Hi,

I have not personally checked an 883 with a laser but Kimmo has mentioned an air spaced doublet with fluorite element for the 883 in his review too...

https://www.suomenlintuvaruste.com/koe/optics_13_kowa883_GB.pdf

Joachim

 

[Binoseeker]

Ok,
Is there a cheaper alternative to the expensive rubber eyecup with integrated protective window, that fits the x30wide eye piece, TSE-14W ?

 

[jring]

Ok,
Is there a cheaper alternative to the expensive rubber eyecup with integrated protective window, that fits the x30wide eye piece, TSE-14W ?

Hi,

not quite sure what you mean. The current 30x wide EP for the small body Kowa (including the old TSN-1/2/3/4 series) is called TE-14WD (sometimes also TSE-14WD) and has a twist up plastic eyecup. I have not removed that to check if it contains an optical window in some way but would be most astonished if it did.

Or do you mean the old 30x wide which indeed has a fold-down rubber eyecup - but I only know that from images and would be astonished if it did contain an optical window.

Joachim

 

[Binoseeker]

Ok,

The TSN-CV66 is an expensive eyecup, with protective window integrated, for also the older x30W, with fold down eyecup.

Here is a text from kowa website about TSN-CV66:
Also compatiable with many historical models. Compatible with current TSE-9Z (20-60x) eyepiece and TSE-14WD (30x).

I am looking for a cheaper normal fold-down eyecup for TSE-14W

 

[jring]

Hi,

I don't think that this is an actual eyecup but some kind of cover to go over the twist up eyecup of the current small body 30x wide and zoom EPs and protect the eyelens from whatever....
I also don't think that this is going to be compatible with older EPs with rubber eyecup.

If you need the actual eyecup I would mail Kowa and ask if there is still old stock available...

If that is not an option, you could measure the diameter of your EP and try to get a generic eyecup from astro accesories.

Joachim

 

[henry link]

Thanks for explaining, Joachim,

Ok, so it was no trace between 3rd and 4th reflections, thus no fake.
Is the TSN-883/-4 lenses made the same way?

The TSN-883/4 have a different objective design. In those the Fluorite element is the interior lens of a fixed triplet combined with a moving focusing doublet. See the cutaway below.

 

[Binoseeker]

Ok, thanks,
I got some info from Kowa: the fluorite lens on tsn-3/4 is single coated.

 

[jring]

Hi,

first of all, thank you Henry for sharing the info on the 883!

As for the single coated fluorite element - possible on your late example, not so much on mine from the eighties. Will check when back from the tropics...

Joachim

 

[biowizard]

Curious how the older TSN-3 florite Kowas compare to the newer generations like the 883 and 770? If used with a modern eyepiece are they anywhere close to being comparable?

I happen to have a TSN 614 and 613..I'd say they're the best scopes I've owned especially for the cost...But wonder how the older TSN 1,2,3,4 stack up as a vintage scope?

I saw a couple at the Nationals that were intriguing, looked surprisingly good hanging on a scope stand,but I didn't get to examine closer....

I have the TSN-3, with the 30x wide eyepiece, and even though this scope is over 35 years old, it still has an utterly brilliant, crisp image. At the time I bought it, no-one else (including Zeiss and Leica) could match it for image quality.

 

[biowizard]

Hi,

first of all, thank you Henry for sharing the info on the 883!

As for the single coated fluorite element - possible on your late example, not so much on mine from the eighties. Will check when back from the tropics...

Joachim

Whatever the coating on the TSN-3 Fluorite front lens element, it's a very good one. There is very little reflection, and what small amount there is, is of a deep brown/amber colour, much like on my much newer Swarovski binos.

 

[z-ben]

Hi,

there might be a few late production examples which are multicoated and possibly have the protective glass above the prisms which prevents the use of Opticron HDF and SDL zoom EPs.

The two old examples I own are single coated for sure.

Joachim

This is not the case with the tsn3 I own it takes the opticron HDF even though the protective glass is in place I would say there is at least 1mm to spare .