Nikon Adapter

dbigsky

I have been considering purchasing a Nikon adapter and a ZWO camera (ASI2600) to connect my Nikon lenses to the ZWO camera. However, my best lenses that I would use are not the older lenses that allow manual changing of the aperture. If ZWO would make a Nikon adapter with the ability to change the aperture setting, this would open up a world of potential sales. For example, in my case, it would make it feasible for me to purchase a ZWO camera, a Nikon adapter, a filter wheel and filters. The newer Nikon lenses or Nikon compatible lenses like my Sigma 150-600 lens will close the aperture to the smallest setting when removed from the camera, rendering it useless for astrophotography. I think that ZWO would benefit from this small design change in their adapter.

Gadgetman

I have several ZWO cameras and EAF’s. All are great but I purchased this adapter thinking I could use my old film camera lens with either of my two ZWO deep sky one-shot color cameras. I have a Sigma 70-300mm APO Macro Super camera lens that I have used on both of my Nikon cameras; N70 (film) & D70 (digital). The lens has a manual setting for f/stops. Now if the lens f/stop is set to f/22, then the f/stop can be changed via the D70’s menu to lower numbers when on the Nikon D70 camera.
However, I found out that using the lens, connected to the ZWO adapter with one of my ZWO deep sky cameras, will not achieve focus unless the f/stop is set to f/22. I tried all f/stops and different zoom settings and could not achieve focus unless f/22 is used. This resulted in the aperture blades causing many star spikes, especially on brighter stars, since the light window is so small. Not something I was wanting to happen.
I have tested the camera lens on the Nikon D70 and found that the f/stop can be changed at any zoom via the camera’s menu and achieve focus. However, the lens must be set to f/22 on the lens. I assume that since the camera is digital it overrides the manual setting on the lens, thus allowing one to adjust the f/stop to whatever setting you want. However, I did notice that the more the zoom on the lens, the f/stop will not go down to the lowest f/stop, say f/4. I do not have the film camera to test.
So, in conclusion, I assume to use the ZWO camera, with the ZWO camera lens adapter, the camera lens must be designed to a fixed specific f/stop and focal length, which may not allow a zoom lens to be used. Ex: a 300mm lens with a low number fixed f/stop, and those type camera lenses are expensive.