How can I get a faster guide cam frame rate in Phd2?

tempus

I use a 178MM as guide cam with an exposure of either 0.5sec or 1 sec depending on the seeing to guide my AM5. I have lowered MX DEC and MX RA to 200ms. When I look at the guide logs I see that each exposure and correction that follows take 2.2 sec to finish. How can I get that 2.2 sec frame rate down? Would connecting the camera into a USB3 port vs the USB2 port at the back of the camera give me additional speed? Can a ROI be used?

KC_Astro_Mutt

You can use ROI in PhD2, however, that will eliminate the multi-star guiding. I have this same issue using mini PC's. I believe it's just a processor issue. Best I can get is 0.3 frames/second, so fast guiding for my AM5 isn't an option. ASIAir has no problem with it though, so that's what I have to use.

MrAstro

KC_Astro_Mutt
"Best I can get is 0.3 frames/second"
Could you tell how do I know the frame/second ? I am using a PC, PHD2 and ASI 290mm mini camera.
Thanks

KC_Astro_Mutt

Also, binning will get you faster frame rates, but in my experience, does nothing to improve guiding.

KC_Astro_Mutt

MrAstro It shows in one of the little boxes in the lower right area of the main screen.

Kevin_A

It seems that using a PC with phd2 is the issue as I can get 2 frames per second with my 290mm mini using asiair without issue at 0.5s exposures.

KC_Astro_Mutt

Kevin_A I think it's specifically the mini PC's. The weaker processors and lower standard hardware just weren't made for speed. Perhaps one with a better grade chip, like an Intel Core i5 plus might be fine. My ASIAir has no problems with it. I have both the ASI178MM and the ASI290MM.

MrAstro

KC_Astro_Mutt
Did you mean in PHD2 or ASIAIR ?
I am using PHD2, not asiair.

Thanks for your reply

tempus

Would using a smaller sensor camera help? Like the 120MM?

Fredvallee

Hi, I have the same guiding camera. As far as I remember , in PHD2, you have to check "allow subframes" (aka ROI) in the camera menu in advanced settings, AND enlarge the search area to the maximum 50x50 (I had continuous disconnection without this second parameter set like that). Last but not least the max duration of your pulse has to be lower that the frame period you expect otherwise PHD2 will wait for the guiding pulse to last to process the next image. I do not yet have received my AM5 but I tried fast guiding rate on a NEQ5 and I had to choose between fast rate or DEC backlash compensation as long backlash compensation pulses were suspending the guiding pulses in RA.
Hope this helps, Frédéric