How can I increase the frame rate on my ZWO ASI 120MC-S?

[lukebl]

Can anyone tell me how to increase the frame rate on my ZWO ASI 120MC-S.

Even with a ROI of 288 x 276 (when imaging Mars) and an exposure of 3.2ms I can only get a frame rate of around 90fps. Surely I should get at least 200?

Admittedly, the camera isn't the fastest, and the laptop is a bit old, but I would hope for a faster frame rate.

I'm using Firecapture - is there anything in the settings I can improve? The laptop spec is : Intel(R) Core(TM) i7-6700HQ CPU @ 2.60GHz 2.60 GHz, 16.0 GB RAM.

Thanks, folks.

[barbulo]

The laptop´s specs sound good. What cable are you using? USB2 or 3?

[lukebl]

38 minutes ago, barbulo said:

The laptop´s specs sound good. What cable are you using? USB2 or 3?

It's the USB 3 cable which came with the camera, and plugged into the USB3 port

[Elp]

Is your hard drive you're writing to an SSD? Typical laptop hard drives are run of the mill and not high speed. My cams very rarely achieve their advertised FPS no matter what the ROI is reduced to.

[Cosmic Geoff]

90 fps seems very low.  I'd have to look up the fps I got with my ASI120MC, but with my ASI462MC I get 275 fps and sub-1ms exposure times on Mars at f10.

That's with a SSD equipped Dell Vostro, USB3.  With an ASI224MC and an older Vostro with HDD, USB2, I got 250 fps.

[lukebl]

1 hour ago, Elp said:

Is your hard drive you're writing to an SSD?

It's just writing to the built-in drive. No idea what sort of drive that is. How do if find out, and can I use an alternative to speed things up?

[Elp]

If it's windows, go to device manager and look under disk drives.

To be honest if you're getting 90fps I wouldn't bother with cloning and installing a new drive, I image planetary at 15-25 FPS, it just takes longer.

If you want to speed the laptop up in general and have an nvme slot or an older SATA 2 slot then by all means, an SSD upgrade will transform your laptop.

Edited November 29, 2022 by Elp

[symmetal]

Have you tried selecting 'High Speed' mode in Firecapture's camera setup. This uses a lower ADC conversion bit depth like 9 or 10 bits so gives a faster fps. As 8 bit mode is usually used in planetary this is fine. I assume you have 8-bit mode selected, as 16-bit will usually halve your frame rate. Also don't have gamma enabled, or leave it at 50 which is the same as disabled. Disabling preview debayering may give a few more fps on a lower spec computer.

Allocate around half your RAM to Firecapture's heap space on it's setup options. The first few seconds of capture are stored in RAM buffer and when full, starts writing to disk.  If your frame rate drops only after the buffer space reaches near zero this means it's the slow disk writes causing your fps drop.

Alan

Edited November 29, 2022 by symmetal

[ONIKKINEN]

That sounds like its running on USB2 speeds. Double check that no USB speed limiters are active in the capture software?

Even an older HDD will keep up with such a small ROI so dont think that is the issue.

[lukebl]

36 minutes ago, symmetal said:

Have you tried selecting 'High Speed' mode

35 minutes ago, ONIKKINEN said:

Double check that no USB speed limiters are active in the capture software

Thanks for the imput folks. I'm not sure where to find these parametres, though.

[Tomatobro]

Try creating and using a virtual ram disk using the free software. Just remember that when the PC is powered down you loose all the data in the virtual disk so transfer it to the hard drive before switch the PC off

[AstroMuni]

4 hours ago, lukebl said:

I can only get a frame rate of around 90fps. Surely I should get at least 200?

I am sure that folk can help with getting the frame rate up, But could you explain the reasons why you want that higher frame rate?

I recall Firecapture has an option to tune the USB rate and it will automatically reduce it if there are dropped packets. Are you noticing dropped packets?

This post might help

 

Edited November 29, 2022 by AstroMuni

[lukebl]

1 minute ago, AstroMuni said:

But could you explain the reasons why you want that higher frame rate?

Simple. To get more frames over the same period and get better quality. Also, with Jupiter to capture more frames over a shorter period so effects of its rotation are less noticeable.

[symmetal]

1 hour ago, lukebl said:

Thanks for the imput folks. I'm not sure where to find these parametres, though.

Click 'More', but not on the arrow on the right.

This gives you camera settings where you can set High Speed and USB Traffic. For a small ROI you can normally set the USB Traffic to 100% with no problems. If you start losing frames or get no picture turn it down a bit.

Alan

 

[lukebl]

48 minutes ago, symmetal said:

Click 'More', but not on the arrow on the right.

This gives you camera settings where you can set High Speed and USB Traffic. For a small ROI you can normally set the USB Traffic to 100% with no problems. If you start losing frames or get no picture turn it down a bit.

Alan

 

Brilliant!

Thanks, Alan. That seems to have done the trick. I'm getting 200-300 fps now. I wish I'd found that out at the beginning of the Jupiter season!

Edited November 29, 2022 by lukebl

[symmetal]

2 minutes ago, lukebl said:

Brilliant!

Thanks, Alan. That sems to have done the trick. I'm getting 200-300 fps now. I wish I'd found that out at the beginning of the Jupiter season!

Glad that's fixed it. 🤗

For info you can set the heap size on the Firecapture settings 'General' tab. This is the amount of RAM the program can use. I always have the RAM buffer setting enabled too as it gives a nice readout of the frame buffer and how many frames are available during capture. I think on later versions of Firecapture the RAM buffer automatically follows the heap size, so doesn't need to be set separately.

With RAM buffer enabled it nees to be recalculated when you change the capture ROI which takes a few seconds.

Alan