Going H-alpha: T-S Binoviewer first review.

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Having been advised to get a binoviewer for solar observation I did my homework. I chose the Teleskop-Service model rather than the Revelation simply because it has clamping bands via knurled rings. I am always misplacing thumbscrews. Not to mention the cosmetic damage they do!

On arrival, in its neat, but undersized,  aluminium protective case, the T-S binoviewer seemed sturdy and well finished. Unfortunately, the binoviewer's nose-piece presses directly against the back of the metal case. Making the neat sponge insert rather pointless in protecting the prism placement and [hopefully] long term, optical alignment. So, don't ever drop the case! Not unless you modify the protective sponge liner to better protect the nose piece.

The eyepiece clamping rings were nicely weighted for friction but the "diopter" rings were much stiffer. Making adjustment a bit of a chore. I have considerable finger strength from constant lifting, so it's not that. The visible optical coatings were pale green.

Of course the sun promptly disappeared behind a thick overcast and remained that way for days. Not even the occasional clearing at night to try the new toy on the Moon or planets. 

So I turned my attention to terrestrial targets to judge the efficacy of using two eyes rather than one: I plugged the binoviewer into the 1.25" focuser of my Vixen 90m f/11 refractor. Not an ideal choice because the single screw really struggled to hold the binoviewer with two eyepieces to support. I could actually "lift" the load to see that it was still insecure and marking the brand new nose-piece. 

My first target was a multilingual strip of printed packaging with typically small text. Which I fixed upside down to the garden gate @ 25 yards from my viewing spot. A binoviewer does not produce an upright image unless a star diagonal is used.

The results were shockingly good with pairs of 26mm and 32mm Meade 4000 Plossls. Both pairs were secondhand but bought at widely spaced intervals, years apart. By sheer luck I had managed to match the 'Japan' marked 26mm but the 32mm came in two different lengths. One longer and the other the same length as all the 26mm models. Very odd.

Not that it seemed to matter much because the binoviewer offers adjustable [diopter] collars to match eyepieces by making them parfocal. Eyepieces can also be clamped at different depths if desired. Or even individually 'ringed' with plastic pipe off-cuts. To make then automatically rest at the correct depth in the binoviewer's eyepiece holders.

Staring at rusty, cross-head screws in the garden gate became an interesting new hobby at 31x & 38x. The detail was shockingly good in "stereo" despite the overcast sky. With an incredible sense of clarity. Reading small [2mm] print was really too easy using both eyes at this distance and power. More difficult using only one eye. I had no problem at all merging the L&R images. All very satisfying so far. With absolutely no sense of eye strain from misalignment. 

Then I moved onto looking across a diagonal of the garden to increase the range to my next target. It was impossible to use the full garden width due to intervening trees. But 40 yards was still better than only 25 to test visual acuity. Again I was able to easily read the fine text and could still see the punctuation marks without much effort at 38x with the 26mm Mead eyepieces in place.

Click on any image for an enlargement.

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