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A retake on the Porter Springfield mount

Posted by Malcolm Bird 12/13/2018 01:02PM

The Porter Springfield mount concept is a panacea for old backs!

Comments:

Gregory S. Lewer [Gregory Lewer]
01/19/2019 11:02AM

I have been building telescopes since 1960, including two 8 in Springfields and a 12.5 in f6.25 modular (and actually portable) Springfield. I have accepted that the first
diagonal mirror must be a little larger. Materials include everything from heavy machined steel and bronze to teflon and poor man's carbon fiber (plywood). Viewing comfort
is excellent, like sitting at a desk with a microscope while the telescope points anywhere in the sky. Optical performance has been superb, but it is important that everything be orthogonal so that the optical and mechanical axes are co-linear. Built the first Springfield in 1962. Now building what may be my last, a 17.5 incher, f4.45 with a secondary minor axis of 4.8 inches. With two diagonal mirrors I believe each must be 20th wave or better, since the wavefront error will be additive. Keep as much of the cone of light inside
the main tube as you can, but you have to allow for the the height of your head above the level of your pupils in order to comfortably get you eye over the ocular. Hurray for the Springfield Telescope Makers and Russel porter!

John999R [John Shutz]
01/23/2019 04:10PM

Very interesting and a telescope I would like to look through one day.

Bruceb [Bruce Johnson]
02/14/2019 05:04AM

As an old person with a bad back, I love my 6" f8 Springsonian mounted on a Dob mount. I did not make it; a member of the Rose City Astronomers in Portland, Oregon did that. I could provide pictures if desired.

bmwscopeguy [Malcolm Bird]
02/14/2019 08:50AM

Hi Bruce,
I would love to see some pics of how it was done on your Dob. I am currently working on an 8"F7.5 an am debating whether I could do it on a Springfield mount.. It would likely be going onto an AZ GOTO mount - hence my interest in yours.
Cheers - Malcolm

flyboyu777 [jim duke]
10/15/2020 09:34PM

Pretty funny just seeing this article-I was thinking about this style of mount early this morning while trying to go back to sleep, having just come in from contorting with my 12.5 Newtonian in my observatory. I believe there was a doctor in California that had a 12" reflector mounted on one of these springfield mounts. In my old sky chart paperback book, there was a picture of the doctor peering through his scope.

Mutiplanetaryambassador [Rocky Dezelle]
02/01/2021 10:32PM

Losmandy take NOTE!

Funding Member

Telescopes, Astronomy, Binoculars