DLSR F-Stop Settings

I have not yet attempted anything, but I was wondering how (if at all) SGP handles controlling a Canon DSLR if using a camera lens instead of a telescope. Obviously, two of the settings are already in SGP - the ISO and exposure length. However, since I’m using a lens setting the focal ratio is another option - and made a bit more difficult to do manually because my camera is typically enclosed in my camera cooler box.

Can a lens focal ratio be set in SGP as part of a sequence, or will it need to set it on the camera prior to starting my exposure set?



I don’t think SGP can do it. What I’d do is either set it on camera when you set up and leave it same aperture all night. Alternatively, you can use EOS Utility (free software that would have come with your camera) to remotely control your camera and you can set aperture with that. Downside is that you’ll need to disconnect from SGP to be able to connect to EOS Utility, then once set, close EOS Utilility and reconnect back in SGP. Hope that made sense.

There are also aftermarket programs like BackYardEOS that can do this as well as control focus with some lenses.

BackYardEOS makes a nice casual imaging program for DSLRs (I use it for things like star parties) but lacks most of the higher end features of SGP so is not great for anything very sophisticated.

1 Like

Just thought I’d follow up my own reply here. I believe what I posted about should work in theory, however…

I’m in the same boat at the moment. I broke my CCD camera so am using my Canon 5DII in the meantime. I am not used to using it. Last night I tried using the 5DII with 135L lens though SGP. I disconnected the camera from SGP and opened it in EOS Utility to focus, then the plan was to close EOS Utility and go back to SGP for image capture.

Trouble is - EOS Utility can only focus if lens set to AF. Live view and focus with EOS Utiltiy worked ok by eye. Problem when go back to SGP because as soon as try to image, I think the AF hunts and shifts. So then I tried same again, but before connecting to SGP I switched the lens to MF to “lock it”. But for some reason now I got errors trying to image with SGP.

In the end I went to APT - specifically written for DSLRs. It has an inbuilt autofocus for lenses. Worked a dream and seemlessly.

From now on I intend to use SGP for CCD or DSLR if attached to scope, and APT if DSLR with lens.