11 replies to this topic

[highfnum]

story told to me it was for positive projection photography

info from 1968 catalog  

BTW 22.50 in 68  is about 200 dollars now

 

 

[Russell Smith]

Very interesting. Perhaps one of our members that are still doing film astrophotography will chime in.

[davidmcgo]

I have one I bought to get a bigger exit pupil with my Questar 3.5.  The apparent field is tiny tiny tiny.  The field stop is no bigger than the 30mm ASP.  So maybe 20 to 25 degree apparent.  It does let me pick up some galaxy views like NGC 4565:under a dark sky but not a very pleasant view.

 

Dave

Edited by davidmcgo, 23 February 2025 - 04:11 PM.

[deSitter]

Very cool but only usable at f/7 or longer

 

Remove the barrel and you have an excellent magnifier!

 

-drl

[John Rose]

Back in the later 80's I believe Roger Gordon did a review of long focal length eyepieces for S&T. One of those was included. Maybe I will locate the article. 

[apfever]

It is the upper right eyepiece in the rows.

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[apfever]

Lights, camera, Action, but in a still.  All the characteristics are the same from performance to mechanics. It focuses so far out that the extra long barrel on the eyepiece was needed to keep the draw tube secure. 

The image is an eccentric neighbors house that I use for caustic test of CA.  It has black stripes on white and stark long angles for daylight contrast. There is also a line of winter trees to kick off fringe glow branches. 

The F4ish fAstroscan provides University grade central shadow, analytical quality.  The field of view is difficult to imagine see. 

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[apfever]

The field stop is 0.9075" aperture going by the outside retaining ring for the field lens. This is the only one I've seen lightly threaded onto this black end cap thing that is double threaded. My guess it that it was a stick on by a previous owner. The end cap has a nice matching finish to the tops. 

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[highfnum]

Keep in mind 50 Ramsden not exactly same as hastings

[deSitter]

Lights, camera, Action, but in a still.  All the characteristics are the same from performance to mechanics. It focuses so far out that the extra long barrel on the eyepiece was needed to keep the draw tube secure. 

The image is an eccentric neighbors house that I use for caustic test of CA.  It has black stripes on white and stark long angles for daylight contrast. There is also a line of winter trees to kick off fringe glow branches. 

The F4ish fAstroscan provides University grade central shadow, analytical quality.  The field of view is difficult to imagine see. 

That's like a 12mm exit pupil "Just a little bit over the line."

 

-drl

[deSitter]

Keep in mind 50 Ramsden not exactly same as hastings

The long barrel likely means that the field stop is the end of the barrel.

 

The Hastings eyepiece was apparently the ne plus ultra for a planetary eyepiece, but at 5mm, not 50mm I would be using that Hastings as a magnifier more than anything else! Most good jeweler's loupes are just triplets.

 

-drl

[apfever]

They all kind of run together for me. Here's a good tie in to this CN discussion of Hastings. https://www.cloudyni...stings-triplet/