I am hoping to convert an old telephoto lens into finder scope. The added weight should actually be a plus in shifting the balance on my long tube refractor towards the back. The only issue is how to mount the eyepiece. Does anyone sell a converter that attaches to the actual lens, or will I have to take a trip down to the local machine shop?
Converting an old telephoto lens
Started by n2s-astronomy, 01/25/2010 03:41PM
Posted 01/25/2010 03:41PM
| Edited 01/25/2010 03:43PM
Opening Post
Posted 01/27/2010 01:58AM
| Edited 01/27/2010 02:02AM
#3
Thanks for the input.
I managed to put it together today, and I am impressed by the performance.
The original lens was an early Japanese made Hanimex 180-400mm zoom, with a ~65mm objective. The mounting plate was compatable with my cannon A-1. So I salvaged another connector off of a junked camera and mated it to a milled down 2" to 1-1/4" adapter.
It works best as a low power widefield refractor. Using a 40, or 32mm, The field looks very flat with sharp pin point stars. Taking it up to a 12.5mm takes the maximum magnification to around 32x; which was enough to render a good miniature view of Saturn with clearly distinct rings (I did have to close the Iris to reduce aberation). Then I decided to go for broke; used a 4mm and aimed it at the moon. The image wasn't half bad; even at 100x the little scope was able to show good sharp detail on the moon. A 25mm seemed the best all around eyepiece for this scope.
Not bad for a bunch of recycled stuff from the junk bin.
I managed to put it together today, and I am impressed by the performance.
The original lens was an early Japanese made Hanimex 180-400mm zoom, with a ~65mm objective. The mounting plate was compatable with my cannon A-1. So I salvaged another connector off of a junked camera and mated it to a milled down 2" to 1-1/4" adapter.
It works best as a low power widefield refractor. Using a 40, or 32mm, The field looks very flat with sharp pin point stars. Taking it up to a 12.5mm takes the maximum magnification to around 32x; which was enough to render a good miniature view of Saturn with clearly distinct rings (I did have to close the Iris to reduce aberation). Then I decided to go for broke; used a 4mm and aimed it at the moon. The image wasn't half bad; even at 100x the little scope was able to show good sharp detail on the moon. A 25mm seemed the best all around eyepiece for this scope.
Not bad for a bunch of recycled stuff from the junk bin.
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