Tak FC-100DC vs Vixen FL102S on the Moon

[Sunshine]

On 03/06/2020 at 03:24, Stu said:

I’ve been wanting to put these two side by side since getting the Vixen, and after sorting out my observing area and getting the Rowan AZ100 in a better place, I finally did it last night. The AZ100 performed beautifully on the Planet tripod once balanced correctly, which involved bring the Tak back quite a long way in its rings because of the lightweight prism and orthos. The slo mo controls are actually much quicker and easier to use than the handset on the Vixen GP, more intuitive to get the direction right and quicker skews. This more than offsets the loss of motorised tracking I think so I will use this setup for solar white light and Ha in future too. I’ve popped a couple of pictures of the solar setup in here for reference.

To try to keep things as fair as possible, I just used Baader Genuine Orthos, and rather handily a 5mm and 6mm gives x148 and x150 respectively (Tak then Vixen).

Originally I was going to use the Baader Zeiss T2 prism in the Vixen, and the Baader BBHS T2 Mirror in the Tak, but after an initial look and swap between scopes, I could see a definite benefit in the prism, a little sharper and more contrasty. What to do? I then tried my Tak Prism, which despite some recent comments to the contrary I find very good, and it levelled things up nicely so I felt it was now a fair fight. That in itself was a surprising finding, the mirror in the BBHS has recently been replaced so should be at top performance.

Initially I viewed with a 12.5mm and 9mm, but felt like the mag difference was too much for meaningful results, so switched to the shorter focal lengths and set to work.

I observed many different features, trying for threshold craters and rilles which I thought might separate the two. I looked at Plato craterlets, the Copernicus craterlets, detail on the sides of smaller crater walls, Messier and Messier A and domes. I wasn’t so worried about knowing the names of what I was looking at, just comparing the views.

The result? Under the fairly steady conditions I had last night, and at x150 mag, I was unable to separate them. On occasion I would switch from one to the other and think that the second one gave a worse view, but it was only ever down to seeing variations. When the seeing was the same, the views were the same.

My old favourite Izar showed identical, and beautiful views in both scopes. Perfect airy disks and diffraction ring, clear separation and colour difference between the two components.

The Double Double initially looked a fair bit better in the Vixen, and the faint star nearby did not show in the Tak. Curious? Yes, but problem solved by a quick defocus which showed the leaves of the hedge cutting into the Tak view! Once clear of this, the views were the same again.

I will try again with some tighter doubles when I get the chance to see if I can tease any differences out.

So, I have one old and one new scope, both 4” and both giving excellent performance. What to do? My only decision is to keep both! I love the look and character of the Vixen, and the portability of the Tak. The Vixen has the longer focal ratio and gets to x300 with the Nag Zoom vs x246 for the Tak which is useful on occasion. The Tak binoviews easily, the Vixen doesn’t seem to have the inwards focus, although it may with the Tak prism.

I often leave the Tak setup for Solar white light, but the Vixen won’t reach focus with my Baader CoolWedge, so knowing I’m not missing anything with the Vixen I can keep the Tak for Solar during the summer and use the Vixen for Astro.

So, a rather dull, but still interesting score draw I think.

Please forgive the old loo seat in the pictures.... being kept for firewood at some stage!! 🤪🤪

 

These two refractors side by side just about made my eyes water a bit, this is refractor nirvana.

[Deadlake]

Fluorite vs fluorite seems to be a wash in this case, how about compared to an FPL53 scope? I’ve not got a mount so I can not do a side by side comparison but from memory my LZOS has better colour, it shows a film like view with more contrast. Given the Strehl is close between the two scopes I wonder if it’s the smoothness of the lens or just fluorite based lens have better transmission properties?

Ps: @Stu wonder as you now have darker skies and more contrast it changes anything.

Edited August 14, 2021 by Deadlake