(-E- for eighteen milimeter from the camera body plus 8,3mm from the E-bayonet ring) You can increase this length with this rings:
You need 28,7mm more distance to reach the well known 55mm DSLR distance back focus. Please hold in mind that 2mm thick filter
will lay out the focus point of about 0,7mm extrafocal. Also please notice that T2 rings will obstruct the image corner of full format sensores.
This is also made to receive 55mm DSLR cameras (e.g. 11mm T2 bayonet ring and 44mm canon body).
Your Sony camera body has a back focus length of 18mm (E bayonet=eighteen) plus 8,3mm our whide T-ring is 26,3mm so you need
an extender with the length of 28,7mm to come to the required 55mm.
https://www.baader-planetarium.com/en/baader-variable-locking-t-2-extension-(12-16mm)-incl.-lock-ring-(t-2-part-33).html set to 13,7mm
It is also possible with other tools, such as a small and rigid screw driver. But this way you can only insert it in one drilling and have to apply a lot more force to unscrew it counterclockwise, but it is possible.
The Sony Alpha 7 cameras – especially the 7S and 7SII – are very interesting for astronomical purposes because of their high sensitivity, short backfocus light weight and very compact body dimensions. We produce a very short T-adapter for Sony E-Mount/NEX bayonet, which adds only 8.3 mm onto the 18 mm backfocus of the camera housing. This enables an adaptation to all backfocus-critical systems like HyperStar or fast Newtonians. All other T-adapters with T-2-thread which are commercially available at the moment do vignett the light path. We have encorporated the well-tested system of our Protective EOS-T-Ring into the Sony-adapter: Besides the T2-thread, the design also includes an M48-thread – and even bigger – the outer part of our ultrawide S52-clamping system. We will soon offer a 2" nose-piece with S52-ring-clamp. This 2"-nose-piece does provide you with an unobstructed clear inner diameter of 46mm and eliminates vignetting with the Sony Alpha 7 cameras even with very fast optical systems. The Baader SONY-E-Mount/NEX bayonet T-Adapter already got introduced in our last newsletter.
Please check out the GIF-Ani which explains how to refit from T-2 to M48 (center) – as well as the gain in clear aperture (left/right).
|Net weight (kg)||0.04|
|Optical length (mm)||8,3|
|Usage||zum Anschluss von (D)SLR Kameras an das Astro T-2 Gewinde|
|Camera Adaptable||Sony E/NEX|
|Inner Diameter / Clear Aperture (mm)||41|
|Inner Connection (lens sided)||S52, T-2 (M42 x 0,75), M48|
|Outer Connection (eyepiece/-camera-sided)||Bayonet|
|Compatible Brands||Astro T-2, Baader Planetarium|
|Type of Adapter||Camera Adapter|