10 replies to this topic

[Ed Kessler]

Oh well, I now own two binoviewers!

Since I own two Takahashi telescopes, I decided to try out their Twin View binoviewer. I was only able to find a few comments about them on the net. (Almost everyone was very positive with the exception of the single review on CN which made comments about ghosting.) But I decided to take the plunge anyway for several reasons.

An advantage/disadvantage (depending on how you "look" at it) is that they are 45° units. This allows for use without a diagonal and thus, I hoped, also without the use of any OCA. I had always been a bit frustrated with the more or less constrained views of my Denk II's and their OCA system, especially on my Mewlon which starts out at f/12. The disadvantage is that for longer instruments or instruments on shorter tripods the 45° angle yields an uncomfortable viewing position. However, for me, my FS-102 and 180 Mewlon are relatively short scopes and I use tall tripods and an adjustable viewing chair so I reasoned that the angle wouldn't be that much of a problem.

The Twin View's arrived today and they exhibit TAK quality from top to bottom. The IPD adjustments are remarkably smooth. I immediately plopped in a pair of 32mm TV plossls, tightened down the compression ring holders and sure enough they came to focus w/o the supplied 2.1x barlow with a lot of room to spare in my FS102. I also tested them with my TAK 24mm LE's and had the same results. The views were bright and crisp although the 32mm TV plossls seemed to black out more than in my Denk II's. Perhaps this is because of the 45° angle. I also think they vignette just a bit. Could someone tell me the size of the prism in the Twin View unit? All the instructions are in Japanese.

Alas, it's snowing like crazy here so I won't be able to look at the stars for a while and test them on the sky, but my initial impressions are quite favorable.

I also bought a 2" nosepiece to adapt the Twin View to my focuser.

Finally, the instructions state that the back focus introduced by the Twin View is ~5.5".

I can't wait to test them on the night sky.

More to follow . . . but here's a few photos.

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[Ed Kessler]

Another view . . .

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[Ed Kessler]

The 2" nosepiece . . .

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[STEEL]

The Twin View can work with the Pentax 75 SDHF?

[Chopin]

Ed, very nice!

I look forward to your first light report.

[Rusty]

They certainly look businesslike...I'm also anxious to see your opinion!

[David E]

I like that unit Ed. That would make a nice binoviewer for birding in my back yard!
David E

[Ed Kessler]

I like that unit Ed. That would make a nice binoviewer for birding in my back yard!
David E

It would be bright and sharp, but w/o a diagonal the images would be upside down, I think!

Ed

[Solar B]

Now your talking these look the bizz
Brian

[Ed Kessler]

Here is a brief update on the Takahashi Twin View Binoviewers:

My setup tonight was the FS-102 and the Twin View without the 2.1x barlow/corrector(?), 32mm TV Plossls (26x, ~2.0° FOV) and 24mm TAK LE's (34x, ~1.5° FOV).

I tested the binoviewers on the 2 Day Old Moon, Venus, Sirius, and M42.

There was definitely some "ghosting" on Venus and Sirius. When Venus was focused properly, I noticed two ghost images to the right of the planet above and below it. On Sirius they were there as well albeit dimmer. What was odd is that I could focus the ghost images. This was especially noticeable on Venus. When I focused on Venus the ghost images were pale, diffuse spots, but when I focused on the ghost images they looked like star images at first.

The performance of the Twin View on the Moon also exhibited a very dim ghost crescent above the actual image but was much more easily ignored.

Optically, the Moon and M42 were stunning! At these low powers the entire lunar disk was in the FOV and the details of the craters were sharp and bright. I think I'll be spending a lot of time observing the Moon with the Twin View's. The detail in M42 was equally fascinating. Stars were pinpoints and there was nice detail in the nebula (for a 4" scope).

I was a little disappointed with the ghost images, hoping that Takahashi had corrected that problem which was reported a couple of years ago. They obviously haven't. I guess I also need to keep in mind that I was testing the Twin View's on three of the brightest objects in the sky at low powers. The next test will be to see if the ghost images will be evident while using the barlow at higher powers on the Moon and planets.

One other interesting thing I noticed is that when one adjusts the IPD of the Twin View, the focal point changes slightly. Hmmmm!

I did not find the 45° angle to be a problem with the FS-102. I simply extended the tripod legs a bit more.

I'll report more as I continue to use them.

Ed

[Rick]

One other interesting thing I noticed is that when one adjusts the IPD of the Twin View, the focal point changes slightly. Hmmmm!

This is a known feature of the microscope-derived binoviewer.

cheers,
Rick