Flattener/reducer

[Simon Newton]

Hi, I am a beginner at this but was hoping someone could help withe a question i have.

I have a canon 750D unmodified that i wish to couple to my SW 80ED. I understand that i would need a reducer/flattener for a more crisp image, would anyone know the back focus distance the 750D has so i can get the correct extention tube, Thanks in advance.

[Ouroboros]

@Simon Newton I have a hunch it’s the same as my 450D. So the flange to sensor distance is 44mm.  In which case you won’t need a spacer at all. But maybe wait for confirmation on that.  

[Budgie1]

Back focus for the SkyWatcher reducer/flattener is 55mm from the rear of the lens in the reducer/flattener to the front of the camera sensor.

So all you need is a standard M48 adaptor for a Canon.

[M40]

Hello and welcome to the site 👍.

This is my understanding of the required distance. If you get the matched SW 80ED reducer and with the Canon adapter bolted to the reducer you will get the required 55mm. Nothing else should be required. If you get an alternative reducer, the alternative reducer then has its own working distance, for example, the TS optics 0.79x reducer on the SW80ED would need 58mm. The Canon 750D without an adapter has a flange focal distance of 44mm. This is the distance between camera sensor and front of camera. When you bolt the canon adapter onto the camera, the adapter being 11mm creates the required 55mm. Phew....  HTH 

Three answers all within one minute, all saying the same thing 🤣 excellent

Edited May 23, 2021 by M40