I am looking at a tandem setup with two scopes so I can take L images on one scope and camera and RGB on the other. I am a user of SGPro and am familiar with most features so I have several questions on getting a tandem setup to work:
Can I do this with two instantiations of SGPro on the same laptop?
I will have an OAG on one of the scopes and so will guide through this setup. The second setup does not have a guide camera, so how would I get it to take the light frames as SGP always looks for the guider when starting a sequence. Is there a way to do a sequence while bypassing/ignoring the “starting guider” that I see when a sequence starts?
If two instantiations are used is it possible to do dithering and how is this coordinated?
Yes, this is exactly what I do. Just run two instances of SGP and make the instance without the OAG a “dummy” instance. For the dummy instance simply don’t choose a mount or autoguider, disable any plate solving or anything else that requires mount or guiding interaction. Basically just set it up to take pictures and autofocus only.
SGP does not yet support coordinated dither. I don’t dither and haven’t for a long time now. While dithering does have some benefit, in general I haven’t noticed any adverse effects of not dithering.
Joel, Sounds like you will potentially lose a “dummy” instance exposure since it could be in the middle of an exposure when the “main” instance triggers a meridian flip. Or is the meridian flip coordinated between the “main” instance and the “dummy” instance?
There is no coordination between the SGP instances so yes I lose the exposure being taken by the dummy instance during the flip. In general I lose 10% of the exposures from the “dummy” instance due to various things like the meridian flip or flexure. But I figure that the time lost isn’t all that much more than a coordinated setup where one instance has to wait on the other to finish.
Also, dithering would be much more problematic though - with a lot of exposure losses on the dummy instance. Until a potential coordination for dithering is available (if ever), it’s best to turn dithering off. Even if a coordination is developed, the time lost waiting on one or the other could be large unless exposure times are roughly equal or multiples.
I have done this extensively to save time. I have two Optical piggy backed. The long one is 600 mm the short one is about 400mm … The long one is the main master sgp with guiding phd and dithering.
I make sure the control is always done on the longer exposure of the two. My typical is that one is 300sec exposure. The other I set at 120sec or 180 sec as a complete dummy. Just camera and exposure sequence. The second slave one is also doing auto focus but either manual before I do imaging or at a 1.5c temperature change. Time wise I match the number of 300sec and 120 sec exposures. For instance 12x300sec will translate to 20x180sec on the shorter SGP.
Camera wise I make a point to have the highest resolution camera on the shorter focal tube. This allows me to stack without loosing too much resolution at the end. I stack both sets separately and then match the two resulting integration using RegiStar to align and fix orthogonal distortion.
I am mostly OSC CMOS type of AP. This is a great time saver as I typically do on tube on a LPro for luminance and I do Ha or a double/triple/quad filter to isolate Ha and OIII channels. I sometime do just one channels on the second tube (Pure Ha or OIII).
In the end I can maximize my time. I live in a swampy sky bortle 6-7 city. good seeing is rare and this is a key to doing great AP. Saving time.
The only caveat, is SGP is not perfect when running two instance but it is manageable. but that is another story.