Last updated: 5 January 2005

Sent:	Monday, January 3, 2005 10:17:25
From:	Graham, John L (
I've gotten a couple of emails asking about how I adapted SLR lenses for
the DSI and seeing how it's been cloudy here (and likely to stay that
way for a while) I thought I'd upload a couple of pictures.

The first is one of several lenses I've adapted for use with the DSI.
This is a spare Olympus 50mm f/1.8 lens that has a 1.25" adapter glued
directly to the lens mount. In this case the adapter is a short section
cut from a spare Barlow that came with one of my Tasco refractors.
Earlier versions used a short length of 1.25" ID PVC tubing. The
mounting plate is designed to mount on my curved bolt tracker, Meade
DS-2130 GoTo mount, or piggy-back on an telescope. The centerline of the
lens is 1-5/8" from the face of the mounting plate so the DSI rests
flush against the plate; this makes it easy to stabilize and orient the
camera and helps to carry its weight.

The second example is an Albinar 80-200mm f/3.9 zoom lens with a Minolta
mounting ring. This one uses a 1.25" adapter (scavenged from another
Tasco Barlow) hot-melt glued to a dust cap. This way I can use the same
adapter on different lenses without sacrificing them to The Cause.

The few example pictures I've had time to take using the SLR lenses have
shown I can easily reach stars as faint as 12th magnitude from my back
yard which is a pretty typical magnitude 3-4 suburban sky. Being able to
capture such faint stars and with a wide field should make imaging
targets like comets, asteroids and the outer planets a lot of fun. I've
attached a recent example of a 10x60sec exposure of the Double Cluster
taken with the 50mm f/1.8 lens. The image was processed with PhotoShop
to reduce the background sky glow.





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