Sony Adapter for ASI Cameras

Chiefsmith

I tried using this adapter with Meike, Samyang, and Kamlan lenses. The Meike lenses focused to infinity with an attached nebula filter. The Samuang and Kamlan lenses would not even come close to infinity focus even without an attached filter. At first, I thought I had defective lenses. However, these lenses barely reached infinity focus when attached to my Sony cameras (full frame and APS-C formats). With that in mind, I examined the ZWO adapter and decided that something was wrong with that. Sure enough! The body is too thick and creates a backfocus that is about 1.0 mm too great to achieve any kind of sharp focus on stars. I took adapter, 60 grit sandpaper, and went to work on my wife's granite counter top. After sanding off the two ridges on the underside of the adapter, I then used a much finer grade to clean up the sanded surface.

There is now no issue with achieving a sharp focus, with and without filters, on any star that I can see.

I had earlier sent this to ZWO via their web form but there has been no reply. Since I think this is a design issue with their Sony Adapter for ASI Cameras, I am puzzled as to why they appear to be ignoring what I sent them.

Astrop

If the lenses barely reach infinity with your camera bodies doesnt that suggest there's a different issue?

Curious you had to make this adaptor thinner. My Samyang 24mm I have to add 0.7mm to this adaptor via spacer rings to achieve focus with a ZWO camera compatible with this adaptor, other FE lenses worked fine with it as is. The lens works perfectly at infinity with my FF and APSC cameras.

Chiefsmith

I am really not too smart with any of this. All I know is that the Samyang lenses, the first and then the replacement for that, are okay on my FF and APS-C cameras when just doing street style shooting. I could not get focuses stars with the Samyang using either the Sony cameas or my ASI533. The Kamlan focused much better on the Sony cameras then the Samyang, but it too was a problem child on the ASI533. Shaving off the ridges on the ZWO adapter solved everything. The Meike lenses always focused when mounted on the ASI533 without any issues and now the Samyang and Kamlan do the same.

I wish I knew what you and everyone else is doing with FE lenses to make them work on ZWO cmeras without the electric power supplied a Sony camera. My two FE lenses do not work without camera power for aperture control and focusing. Not that it matters anymore since I have the Kamlan lenses, but I am curious as to what I am doing wrong or not doing that I could not make my FE lenses work.

Astrop

Let's just say trying to use a fully auto lens isn't ideal. I can use my Samyang 24mm because I believe it's their only one which has a dedicated AP button, by holding it on power on with a body it moves to infinity by itself, I can then disconnect the lens from the body and know it's already focused near with the set aperture it was on, I then use fine focusing rings (0.1-1mm) to rack the astro camera out to get stars as small as I can.

Some AF lenses have manual override like the Sigma Arts so can be used fully manual without power.

On a body all my FE and APSC lenses focus to infinity and past it so they can be used with the bodies fine, but most lenses aren't good for AP. I initially focus with a body using magnification assist, if the body is connected to an asiair focusing is even easier. But older mechanical lenses are easier to focus than modern fly by wire lenses.