Question about ASI Mini cameras

benni

Hi there,

One problem with guiding cameras is the large download time of the image, which is often 0,1 sec or so. This is problematic if you have an adaptive optics.

Wondering how I could get less latency, I noticed that phd guiding shows for my lodestar guider the option of a checkbox where it apparently can download only a part of the image in order to fasten things...

Now the lodestar guider is old. Your ZWO ASI mini cameras would be more sensitive. But they produce even larger images than the lodestar. Do they have this option too? Let phd guiding only download a few pixels around the guidestar for faster tracking? Or do I always have to download the entire image with ASI mini cameras?

If they have this option, I would consider buying one...

I currently only have an asi 1600mmc as main camera....

Best wishes,

Benjamin

Support@ZWO

The single image need about less than 1 sec download. But if take videos it will be nearly 20fps.

benni

Hi Sean,

thank you for your answer.

I asked whether the zwo driver allows phd guiding software to download only a part of the image in order to increase speed during guiding. I think that is video...

But can it be that videos are faster downloaded than images?

Support@ZWO

if use 0.1s exposure, PHD2 is faster. But, short exposure can't find guide stars, I think 1s will be good. sometimes maybe 2-5s, especially use OAG for guiding.

benni

Hi, sean,

I know that short exposures make phd faster. But I want very short exposures on my off axis guider for my starlight xpress adaptive optics, which can apparently correct in 5 ms but depends on the guider for speed...

With the lodestar guider I discovered that it has the ability to let phd guiding download only a small section of the image, a subframe around the guidestar, in order to fasten things a bit more due to reduced download traffic.

My question was if asi mini cameras support the subframe download option in phd guiding too and whether this makes latency shorter...

Support@ZWO

I think PHD2 don't have ROI function. Is there anyway to use video mode for AO? I never used AO, I don't know how does the software works.

benni

Hi, so that is how this is callèd in your drivers region of interest function...

Well thats what I asked for, and yes phd guiding should support this. It should be a checkbox named "subframes" in the camera tab.... Is this there? can you connect a asi 174 mini to phd and look for this checkbox?

As for the ao, well the starlight xpress ao can be connected to phd guiding... similarly as a mount... phd guiding then just sends commands to the ao as well as the mount... and the picture for the asi 1600 behind it gets corrected

If I use the entire frame with my lodestar guiding camera and guide the mount via ascom, I get 2,5 hz but next time I will try to use subframes or region of interest in order to try to speed this up a bit...

If the zwo mini guiders also support the roi function and are more sensitive as my lodestar, I will try it also with the zwo mini cameras for perhaps a better framerate...

Thanks,

Benjamin

Sam@ZWO

Hi Benjamin

all ASI Cameras support the "subframes" feature of PHD

benni

Sam wrote:
Hi Benjamin

all ASI Cameras support the "subframes" feature of PHD

Thanks, that was my question.....

benni

Hi, hm I now tried to use subframe in phd guiding with the lodestar guider and my adaptive optics with binning and fast exposure rates. So I now get 5 and sometimes 8 hz now (I do not know why the frequency sometimes changes), instead of 2.5 without the subframes, but the lodestar is noisy and just usb 2..

Your asi mini guiding cams have less noise but they too only have usb2... which is slow..

can you make these cameras in the future with usb3?

Since i now get it that it is really the laptop / camera / usb transmission thing that prevents my ao from correcting seeing. The ao itself probably would be able to do it. Just the guide camera download and framerate is too slow...

Support@ZWO

It's a different product line, we don't have this plan in near further.