Connecting Canon EF lens to ASI183MC

cpl42

Has anyone successfully attached a Canon EF lens to an ASI183MC or MM? I suspect that this is possible with a Canon T-ring adaptor, so what I am asking is whether there is a need for a spacer to get a focus without having to screw the lens's focuser a considerable distance past its normal camera position (i.e. shows close to infinity at star focus)?

cpl42

eastridingstars

Yes and no. I attached an ASI183MM and a filter wheel to a Samyang 135 that is Canon fit. It only worked using this lens to M48 adapter and small spacers: https://www.firstlightoptics.com/adapters/astro-essentials-samyang-lens-to-m48-adapter.html Assuming backfocus on the Canon EF range is also 44mm, should work the same. It is possible that the ZWO EFW to EOS II adapter will work using the ASI183MC as you use a filter draw rather than a filter wheel. The ZWO adapter is intended for the ASI1600 but it was close to achieving backfocus with the ASI183MM and a Brightstar filter wheel. Essential to use calipers to measure the distance.

wholeunkempt

eastridingstars I attached an ASI183MM and a filter wheel to a Samyang 135 that is Canon fit. It only worked using this lens to M48 adapter and small spacers: https://www.firstlightoptics.com/adapters/astro-essentials-samyang-lens-to-m48-adapter.html driving directions Assuming backfocus on the Canon EF range is also 44mm, should work the same. It is possible that the ZWO EFW to EOS II adapter will work using the ASI183MC as you use a filter draw rather than a filter wheel. The ZWO adapter is intended for the ASI1600 but it was close to achieving backfocus with the ASI183MM and a Brightstar filter wheel. Essential to use calipers to measure the distance.

Provided Canon's EF lens family has a similar 44mm backfocus, you should be good to go. As the ZWO EFW to EOS II converter employs a filter draw rather of a filter wheel, it is conceivable that it will function with the ASI183MC. While the ZWO adaptor wasn't quite able to achieve backfocus with the ASI183MM and Brightstar filter wheel, it came close.

cpl42

Thank you, eastridingstars, for your prompt reply.

It is as I suspected: I will need a spacer between the camera and the T-ring adaptor. I have a set of these but whether there is one that is suitable is another question. I'll look at the camera specs and the T-ring I have and see what I need to make up the 44mm you mention. If I have to look elsewhere, your link should help nicely.

As I don't have the ASI183MC as yet (they are not due until July at my preferred supplier), it might be a while before I sort things out. When I do, I will post another reply spelling out my results for others to benefit.

cpl42