Previously I had purchased a T2 (male) to M48 (female) adapter to allow use for astrophotography with my 2″ Astronomik CLS-CCD filter. But as I am intending to get a mono imaging camera and a filter wheel with a set of LRGB filters. Hence I needed a way to adapt the 2″ filter to use between the filter wheel and my off-axis guider. I was pleased to find a M48 (male) to T2 (female) adapter on eBay, which has M48 male threads and female T2 threads through the entire thickness of this adapter.
This adapter is something new that I’ve not seen before. It is 5mm thick and has 48mm male threads through the entire thickness on the outside of the adapter, while the internal threads is T2 (42mm with 0.75mm pitch). It looks very similar to the M42mm step-down ring which threads onto an M39 enlarging lens to allow it to adapt onto an M42 focusing helicoid.
With this adapter mounted onto the female side of the Astronomik CLS-CCD filter, it allows for my filter to be mounted onto a T2 system.
The T2-M48 adapter I bought previously is now mounted on the male side of the Astronomik CLS-CCD filter to allow it to mount on the male side to a T2 system.
The good news is that with the Orion thin off-axis guider and the Astronomik CLS-CCD filter mounted together, it measures a total of 23mm thick. With the 12.5mm back-focus distance for the imaging camera I am waiting for (ZWO ASI178MMC cooled imager), and the 19mm thickness of the Xagyl motorised 1.25″ filter wheel, I should be able to get very close to the 55mm distance between the Baader Coma corrector and the imaging sensor for it to work optimally.
It just goes to show that some new adapters are coming out which can be useful for astrophotographers. So it is always worth looking for adapters which never previously existed as you may just be surprised.