The Bintel Projection lenses in 32mm and 40mm focal lengths are useful if you can't get your telescope to reach focus with a conventional camepter and T-ring.
Many Newtonian telescopes don't have enough focuser in-travel with a DSLR cam - the Bintel Projection lenses provide a solution.

The top of the eypiece housing unscrews(T2 thread) allowing a T-ring to attach directly.

With the same fine optics as Bintel's Plossl range it also makes a great low power eyepiece!

The Bintel Superview Camera Projection eyepieces are one of the simplest ways to couple your DSLR to a telescope. The top section of the eyepiece unscrews allowing an M57 to M42 adapter to be fitted. The M42 T-thread can then allow the appropriate T-Ring to be attached and thus adapts to your DSLR camera.

M57 to M42 adapter and T-Rings sold separately.

https://www.bintel.com.au/product/bintel-m57-m42-t-adapter/

A low-power eyepiece, good for open clusters, nebulae and galaxy clusters. Includes a soft rubber eyeguard and an M42 T-thread for projection photography. High quality optics, fully multi coated, and affordable!

The Bintel Superview Camera Projection eyepieces are one of the simplest ways to couple your DSLR to a telescope. The top section of the eyepiece unscrews allowing a T-Ring to be fitted, thus adapting to your DSLR camera.

The Bintel Superview Camera Projection eyepieces are one of the simplest ways to couple your DSLR to a telescope. The top section of the eyepiece unscrews allowing an M57 to M42 adapter to be fitted. The M42 T-thread can then allow the appropriate T-Ring to be attached and thus adapts to your DSLR camera.

M57 to M42 adapter and T-Rings sold separately.

https://www.bintel.com.au/product/bintel-m57-m42-t-adapter/