10-29-2024 02:16 PM - last edited on 10-29-2024 03:44 PM by Danny
Several years ago, I purchased the Canon EOS 60Da to be used mainly for Astrophotography. I have several Canon lenses; two are EFS types; 55-250mm & 18-135mm and neither have manual f/stop settings on the lens. The only other lens I have is a Canon 50mm that is rated f/1.8.
I am assuming that the camera can set the f/stop for the two EFS zoom lenses using the camera’s menu, which I have never done. I was using the camera most of the time attached to my telescope and the telescope was the camera lens. That way no f/stop setting was needed since I could just use the shutter speed for exposure and focus was using the telescope.
One question: Can I select the f/stop for the EFS lens using the camera and still achieve focus for astrophotography? The reason I ask is, I have a 70-300mm Sigma zoom lens that I was hoping to use on a ZWO adapter for the lens where a ZWO deep sky cooled camera could be used. I found out that the old Sigma lens (that was on a Nikon D70 SLR film camera) f/stop settings will not focus unless the f/stop is set to f/22. I tried different zoom settings and different f/stop settings and nothing would focus unless f/22 was used on that lens. Oh, I tried using an adapter to attach the Sigma lens to my Canon camera, but it produced elongated stars at the perimeter of the picture.
Second question: If I get a ZWO adapter for the Canon EFS lenses, will I have the same issue on f/stop setting or not even have the ability to set the f/stop?
10-29-2024 02:24 PM
Since f/stops are a major setting for the camera, along with shutter speed and ISO, they are accessible from the dials on the camera as long as you are in the right mode, for example Av.
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