Cannot find any stars for HFR measurement in image

I am using a Canon EOS 70D taking 20s exposures at 1600 ISO. I have SGP set to stretch with “Low” setting. However, when using Frame & Focus to capture an image … then previewing the image, only my auto focus target star shows up, even though there are numerous other stars in the frame. I used these exact camera settings in other apps with excellent results and can see the entire star field in the preview. The focus is very good after using Bahtinov mask.

I use three sequencing apps (APT, NINA & SGP) and try to use identical settings in all three. For example, when I take an image to use for plate solving, centering or auto focus, I shoot with my Canon EOS 70D DSLR … 20s at 1600 ISO and then do a basic stretch so I can see the star field.

Both APT & NINA can use the resulting image successfully to do a plate solve (ASTAP), a frame & center or as the starting image for an auto focus routine. However, SGP cannot seem to produce a usable image even from the identical settings.

In the link below I have provided several screen shots as well as my SGP log and sample images from the other apps.

In SGP, I was trying to capture an image to measure HFR for use in the auto focus step size formula. When I click the “Star” icon to display HFR readings, nothing happens and the image preview window says “No Stars”. And when I check the “save image to disk” box, SGP hangs. I must then kill SGP in the Task Manager (screen shot in the link).

I was anticipating your request for a copy of the image file, but I now have no way of saving it to share with you. I will share several screen shots and my log file.

I would very much appreciate some help getting this resolved. I love the functionality of SGP and if I can get it to work, it will become my GoTo sequencer for deep sky objects.

Thank you,


Link to Logs

Useful Info
OS: Windows 10 Pro - Build 1909
Ver: - Commercial License

Last night we had clear skies, so I ran a little test. Got my rig pointed and focused on Alioth in Ursa Major. Using 20s exposures at 1600 ISO with my Canon EOS 70D saving all in RAW format, I took three exposures with three different apps. The images taken with SGP are significantly different! I analyzed them in PixInsight and they are much dimmer and show very few stars. I have uploaded the sample images here: Error

Although I have scrubbed through the SGP settings several times, I MUST still have something wrong. I would very much appreciate some help getting them correct. As I have said, I really like the functionality of SGP and want to use it as my main seqencing app.

Thanks again,


I have again reviewed the PDF version of the user manual and carefully read pages 37-39. Following this guidance, I have configured my Canon EOS 70D as per the manual and am still having issues with Frame & Focus images.

I think I know what this is. You are only taking 1 second exposures :slight_smile:
It is to do with the mirror lockup setting. SGP can do a double take - which, when coupled with the mirrorlockup feature on the EOS triggers the mirror and then shortly afterwards does the exposure. If the mirrorlock settings are out of sync - then you get an exposure equal to the short delay. In your case, you set it up as 1 second (mirror settle time in the EOS settings)
Let’s say we choose to ignore mirror lockup (hardly relevant on long exposures). Disable it in the EOS menus and in SGP - change the 1 mirror settle time to ZERO.

Thanks Buzz … I will give it a test tonight.

I reset the Canon EOS camera settings in all my equipment profiles as follows:


I will apply these new profiles to all my saved sequences.

And when I checked the Mirror-Lock feature on the camera, it was already turned off.

I will post some images from tonight’s session here.

I have a similar question about Frame and Focus. There are stars evident at 5 second exposures but the text indicates there are no stars, hence no HFR results. If I look at a file saved to disk the normal HFR overlay of values appears. But of course for the auto focus to work it must find an HFR value as the Frame and Focus is running. I assume there is a missing setting on my part or misunderstanding of procedure. Thanks in advance, and thanks for creating SGP.
Eric S

It is worth experimenting with a longer exposure and check you have not excluded too much of the image with the trimming option.

Thanks for the tips. I had not thought of the problem that a too tightly cropped image would necessarily limit calculating the HFR. Good point. Though in my case it was not cropped. I will experiment with a longer exposure when I am back at the scope. What is interesting to me is if the same field was imaged and saved, when viewed and a right click on the image was done, the calculation of the HFR was successful. Mind you it was a longer exposure than in " Frame and Focus", so that might be the answer. Thanks again.
Eric S