Cracking tight binaries.

It’s always a pleasure to be out under dark and still skies. Saturn excelled taking x320. Mars showed an ice cap and some dark markings. I was keen to try out the 150 f8 refractor on some super close binary stars. It’s very little use to stare these out . Often averted vision or moving the field of view works. Drawing helps enormously, the eye becomes relaxed as it works to account for the view.

First up a recalled visit to a difficult triple. Struve 2872 in Ophiuchus. The companion split apart , not shy at .8″.

Some stars hold special allure , one being Lambda Cygni. This showed a bright and clean split at .9″.The high magnification holding the splendid view. Still in Cygnus, Otto Struve 410, gave a better .9″ split.

Next a favourite tester , 36 Andromedae, now opening up to an easier 1.2″.

Very pleased to get these fine splits. I had taken the 6″ doublet apart to clean a few fungi on the surface. Fungi can live in the air space. They secrete acid , eating both coatings and glass, a big lump of glass, returning it to the cell, I noticed some markings on the edges. There are 4 linear marks to line up the objectives and a cheerful note of the manufacture date , 31/01/11. It’s somewhat comforting to think that someone took a little care.

A thick rubber ring edges the front of the doublet. Snucking this in evenly gave the correct alignment when the tightening ring was applied. There are push/pull collimation screws / hexbolts on the cell. A quick check with a Cheshire , Barlowed laser and star test showed everything true.

Of particular interest has been the first light reports of the new SW 150 pro ed on Stargazers lounge. This is the next up from the 120pro. However it does not have the same glass bring an ed front element instead of the FPL 53. At £1600 it’s a lot of scope , similar in weight and size to the C6r. However I was happy to pay £300 used and put £100 Crayford on board.

I’ve had many sub 2″ binaries with the 200 f6 Orion Optics Newtonian. However it does benefit from the single straight across secondary vane . This gives good clean stars without spikes, easier for splitting.

Awaiting more clear skies and a continuing look at the bright Vesta , Comet C/21P Giacobini-Zinner and the Perseid meteor shower (12-13th August)

Nick.

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