dark current noise

Astrotripper wrote:

So I made my own, "slim" adapter by combining parts of two completely different adapters. I'll try posting some photos of it later.

Here it goes. Some photos first:

From left to right: home-made adapter, store bought adapter, barlow lens with filter on one end and T thread on the other

E-PL1 with the big adapter

and with the home-made adapter, a pretty big difference

And with the barlow lens attached, ready to be mounted onto the telescope (1.25" nosepiece)

Top-down view of home-made T-ring

and a side view, where it's clearly visible it's been hacked together from two different adapters

So, the base for this slim T-ring is a cheap chinese L39 to Micro 4/3 lens mount adapter. This is the outer shell. I choose this one specifically, because I knew (from the photos) that it was a two part thing with the actual L39 screw mount being a separate part held in place by three little screws (one of which is visible in last photo). I figured I could simply replace that internal part with analogous part from another T-Ring, effectively replacing that L39 tread with T thread.

That donor adapter was Kipon's T-Ring for Sony Alpha DSLRs, which was the first camera I mounted onto my telescope. It was also a two piece adapter with the T-threaded part held in place by three screws, so it was trivial to extract it. However, that little bugger was slightly too large to fit into it's new home, so I had to sand it down to appropriate diameter. And as illustrated, it was also a bit thicker, so it's not flush with the outer shell, but it doesn't matter. I've had no problems with it so far, and I was even using it in freezing temperatures.