johninderby

The new version does look like an “economy” version of the old familiar one. Televues must have GREEN lettering on them. The new version with lettering changed to green.

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From the Televue website. 2" Big Barlow Offered in a 2x magnification, the Big Barlow is ideal for Newtonian scope owners. It will be parfocal with both 2" and 1¼" eyepieces in this application. Features include 1¼" eyepiece adapter, threads for 48mm filters, captive lock screw and full multi-coatings. Note: The Big Barlow is not recommended for use with 2" diagonals because it's length prevents it from being parfocal. With some telescopes, focus might not be reached, particularly when the interface lens is also used with it. A far better approach with no potential problems in any scope or with any eyepieces is to use the 2" 2x Powermate (PMT-2200). See the Powermates page for a discussion of Powermates vs. Barlows.

The one with the white writing is just the current version. BTW the big. Barlow isn’t recommended for use in 2” diagonals because of the length of the barrel. For 2”diagonals the Powermate is recommended.

Clear now.

Clearing and not looking too bad here now.

Re: Herschel Wedge and a newt the problem is that with any mirror type scope like a newt or cat it’s the design of the scope that’s the problem. In a refractor the light goes directly from the objective into the wedge but in a mirror scope the light bounces around and would overheat the scope itself.

Hmmm.....now what to look at tonight???

Dare I believe tonight’s forecast?

Opticstar AR90s f/8.8 Wanted something not too expensive for my white light solar set-up and decided the Opticstar AR90s f/8.8 would be a sutable. Light weight scope and can be used on a photo trpod setup or my AZ-EQ5 GT. Had sold the Bresser Messier scope I had been using but decded I really needed a dedicated white light scope and the Opticstar was cheaper than another Bresser when you get the dual speed focuser option and a more suitable focal length. Added a small carry handle bought from WDS Ltd. Why aren’t carrying handles standard equipment on all scopes?

Price has doubled since then but this was in VG condition. John

1967 edition

The corrector does look like plain uncoated glass but it isn’t. It is coated. There’s a good thread on the subject.of secondary mirror rotation.

Little old book. Lost my original copy when I moved so picked one up on eBay.