Low Cost AR0130 Guide Camera

[bobro]

My attempts at imaging around the Markarian's Chain area had show that my modified Microsoft Cinema webcam found it difficult to show guide stars in this region. So I decided to look for a low cost update to this webcam. 

The AR0130 sensor is quite sensitive and is used in entry level guide cameras. It is also available as a USB connected module, so I decided to purchase one of these (£37 from amazon uk) and give it a whirl as a low cost guide camera.

To mount the module the 2 screws holding the lens were removed and the module lightly glued at 4 points to a shortened Barlow lens tube (no lens). This allowed the module to be inserted into the 1.25" eyepiece mount of my Orion mini guide scope.

PHD2 on my laptop connected to the camera and guiding (on M3) was used for testing, but before this a tour of the skies was performed to see if the camera could readily find a guide star. The result was a little surprising - the PHD2/camera module combination meant  the exposure (gain?) would be increased until a single (or perhaps 2 or 3 stars) were visible on the PHD2 display. At that point the (mainly) single star would be visible on a black background. If a star was not visible the display would turn to a noisy white, but it was quite difficult not to find a guide star.

This made it impossible to determine how many stars the camera could see as only the brightest 1 or 2 were typically visible, but the impression was gained that there were others lurking behind an increase in gain. This could be seen if guiding was stopped and a guide star allowed to drift off screen.

So guide star selection was limited to what could be seen, but didn't cause any problem in practice. Trying to image M3 (and another region nearby) without goto meant a number of movements of the main scope. The guide setup didn't need to be adjusted for any change in the field of view - there was always at least a single guide star visible on a black background - no sign of noise.

Imaging proceeded without any issues and seemed to be more stable that with the Microsoft Cinema webcam -  stars were smaller and crisper.

For guiding I am very pleased with the AR0130 module and don't expect to need to search for guide stars normally. Having a guide star at the boundary of the view may be an issue - better to move it. The module is based on the colour version of the sensor and appears to have an IR cutoff filter - this was not disturbed. A guided image of M3 is below - 13 subs @ 300 secs (cropped).

A brief test with Sharpcap, intending to use the module for polar alignment, was inconclusive due to lack of time. Operation may be different than with PHD2 and needs further testing.

[Stub Mandrel]

Excellent, did windows load the drivers automatically?

What is the focal length of your guidescope?

[rwg]

I guess you are using a webcam (DirectShow) driver for this camera - in which case your experiences with PHD2 aren't so surprising...

PHD2 doesn't attempt to adjust the exposure length of webcams at all - if you set an exposure to (say) 1s, all it does is add up all the individual frames that the camera delivers in 1s and uses that mini stack as it's frame. That explains why it only spots the bright stars - the dim ones don't even show up at all in the 1/30s exposures (or whatever the default exposure length is) that are being stacked, so they don't show no matter how many frames you stack... If you are lucky then you will be able to adjust the exposure from the camera settings dialog (just to the right of the brain).

The white frames are due to PHD stretching each individual frame as far as it can (which it does by default). When there are no bright pixels, that means a very large stretch is applied, giving the whiteout issue.

cheers,

Robin

[Stub Mandrel]

Hi Robin

This chip is clearly capable of long exposures. Do you think the altair driver would work with it?

Is it possible to control it to take longer exposures?

[rwg]

I suspect that these are 'USB Video Class' devices, so they don't need a specific driver on Windows - they will just pick up and use the Microsoft Webcam driver. Proprietary drivers like those for Altair/QHY/ZWO cameras will not work as those drivers are designed to talk to the special firmware code on the cameras of the same make.

UVC devices appear in Windows as DirectShow webcams - this means that they suffer all the limitations of webcams such as limitations to how accurately you can control exposure (powers of 2), no access to high bit depth modes, no RAW mode, etc.

If UVC has been done properly by the manufacturer then you should be able to control the exposure in powers of two - ie 1/16s, 1/8s, 1/4s, 1/2s, 1s, 2s, 4s, etc. This will appear as a standard exposure control in SharpCap or other programs capable of controlling webcams. Somewhere the manufacturer will have set limits on the min/max exposures, which will obviously limit the range available.

cheers,

Robin

[SteveBz]

Fantastic. So it looks as though phd2 stacks or probably adds the frames.

Great result. If it doesn't work with my camera,  I'll go down your route.

[bobro]

25 minutes ago, Stub Mandrel said:

Excellent, did windows load the drivers automatically?

What is the focal length of your guidescope?

Yes - automatically loaded Windows 10 drivers.

162mm focal length guidescope - Orion 50mm mini guidescope.

[SteveBz]

It looks as though we're all sitting inside hoping the clouds will clear!

[Stub Mandrel]

21 minutes ago, bobro said:

Yes - automatically loaded Windows 10 drivers.

162mm focal length guidescope - Orion 50mm mini guidescope.

Go, just try Sharpcap and see what exposure times it will allow!

:-)

[bobro]

Sharpcap shows settable Exposure from 0.1 to 500 msec. The Video proc Amp Gain setting varies the on-screen brightness.

 

[cuivenion]

Nice cam, long exposure capability in both Sharpcap and PHD will be interesting to hear about. When using my PS3 Eye cam in PHD I found I could change exposure by clicking on the properties button next to the camera in the connect equipment panel. The PS3 Eye may act very differently to your cam though, as well as the AR0130 being much more sensitive. Do you get the 1280x960 view with it?

Edited April 29, 2017 by cuivenion

[bobro]

2 minutes ago, cuivenion said:

Do you get the 1280x960 view with it?

Yes

[cuivenion]

1 minute ago, bobro said:

Sharpcap shows settable Exposure from 0.1 to 500 msec. The Video proc Amp Gain setting varies the on-screen brightness.

 

Shame you can't get a longer exposure for it, still it seems to guide very well. I wonder how hard it is to write a driver?

[cuivenion]

Edited my previous post, the AR0130 will be a lot more sensitive.

[Stub Mandrel]

I'm not sure that means a great deal, I've just set up my Lifecam and sharpcap will let me set exposure to 2 seconds, but it still captures at 26 fps.

[bobro]

I think there is some good news to report here on testing with SharpCap :

1) Microsoft Cinema webcam - although the camera 'Exposure' control can be set to 2 seconds, the capture rate is shown as 30 fps. The image display brightness changes with 'Exposure' so it looks as though this control is for gain of the image.

2) AR0130 module - the fps rate maxes at 9 fps and remains there for all 'Exposure' values up to 62.5 msec, but drops as the 'Exposure' increases : approx 6 fps for 125 msec, 3 fps for 250 msec and 1.5 fps for 500 msec. The brightness of the image increases in line with the 'Exposure' setting. With this camera the 'Video Proc Amp' 'Gain' control appears and also affects the image brightness. The sensitivity of the camera is very obvious - with the lens cap on the scope, the camera easily saturates due to light entering via the rear of the pcb. (I plan to enclose the pcb in a small box for protection.)

The images below show SharpCap screen captures for each camera.

Looks promising for polar alignment with SharpCap and the AR0130 Module..... (unless I've missed something).

[bobro]

Looks like good news for using the AR0130 module with PHD2 as well :

Camera settings - Properties - Camera Control - Exposure  has manual/auto selection. When set to manual, 'Exposure' values from -13 to -1 can be selected. When values of -2 or -1 are selected, the camera image display update rate noticeably slows down. So it looks as though the true exposure time is being set as with SharpCap. The number of discrete values (13) is the same too.

PHD2 also allows camera Gain to be set.

[bobro]

Conclusions on the AR0130 camera after testing with PHD2 and SharpCap :

AR0130 camera : to get manual exposure to adjust correctly it seems to be necessary to set the exposure to auto first before changing back to manual. 

PHD2 : works well with the camera. Manual exposure settings of -1 (approx 500msec) and -2 (approx 250msec) seem best, with PHD2 'exposure' (actually stacking of webcam images) set to 500msec or 1 sec. Easy to find a guide star - normally no need to move the guide scope.

SharpCap : plenty of stars visible with the camera set to manual exposure (set the camera to Auto first). The excellent polar alignment feature of SharpCap quickly detects stars and allows polar alignment to be accurately made. The attached image, following polar alignment with SharpCap, is 120 sec unguided (must have been lucky to have set the RA motor speed accurately as this is just a simple DC motor).

Edited May 9, 2017 by bobro

[ctron]

I realize this is an old thread, but this DIY info doesn't seem to be anywhere else on the web so I thought I would join these forums and ask here whether or not any way has been devised to increase exposure time on this cheap camera?  I recently acquired and tried one out myself, but it's barely sufficient to do the polar alignment routine in Sharpcap and I'm still not sure it will as I haven't yet had a really clear night to try it out.  The longest exposure I get is 0.5 s as was previously mentioned and I was just curious as to whether any DIYers came up with any way to increase exposure. 

 

Thank you in advance!

[bobro]

It looks like not many people have tried this module with SharpCap - just us two? My relatively limited experience shows, apparently like yours, that (for example) moonlight can make polar alignment with SharpCap a bit more difficult. However with a clear sky alignment is quick. My guide scope has a focal length of 162mm, so the field of view is relatively wide and stars bright. SharpCap has requirements on the field of view in order for polar alignment to operate.

Max exposure time of 0.5 sec will have been set in the camera firmware, so it's difficult to see how it can be increased. Note this isn't a problem for guiding as PHD2 can 'add' guide images to effectively increase the exposure time, though I haven't found it necessary to do this.

Hopefully you can try again with a clearer sky for polar alignment - and post the results.

[cuivenion]

On 13 June 2017 at 18:28, ctron said:

I realize this is an old thread, but this DIY info doesn't seem to be anywhere else on the web so I thought I would join these forums and ask here whether or not any way has been devised to increase exposure time on this cheap camera?  I recently acquired and tried one out myself, but it's barely sufficient to do the polar alignment routine in Sharpcap and I'm still not sure it will as I haven't yet had a really clear night to try it out.  The longest exposure I get is 0.5 s as was previously mentioned and I was just curious as to whether any DIYers came up with any way to increase exposure. 

 

Thank you in advance!

Unfortunately it would probably involve someone writing a driver for this particular camera, but if anyone has any alternative ideas it'd be great to hear them.

[ctron]

Packed up and returned the camera, guys, sorry.  I'm putting the funding towards a proper guide camera.  Since it would be a while before I actually purchase one, I'm still all for any updated mods on this module and, should anything significant be determined, I'll buy the module again.  Thanks for your responses. 

[Bagnaj97]

I bought the mono version of this module to test and can confirm that the altair and touptek drivers do not work with it. Or at least I failed to get the drivers working by adding the device ID into the driver inf...

[bobro]

1 hour ago, Bagnaj97 said:

I bought the mono version of this module to test

Presumably the mono version will be more sensitive and even better for use as a polar alignment / guide camera. Could you post a link to the seller of this version? Will be interested in seeing the results of your testing.

Note : I've used the (colour) camera for quite a few sessions now for polar alignment and guiding (Orion 50/162 mini guide scope) - very good results.

Thanks.

[Bagnaj97]

18 hours ago, bobro said:

Presumably the mono version will be more sensitive and even better for use as a polar alignment / guide camera. Could you post a link to the seller of this version? Will be interested in seeing the results of your testing.

Note : I've used the (colour) camera for quite a few sessions now for polar alignment and guiding (Orion 50/162 mini guide scope) - very good results.

Thanks.

https://www.aliexpress.com/item/1-3MP-1280X960-MJPEG-15fps-UVC-Linux-Android-Windows-free-driver-usb2-0-monochrome-B-W/32367460304.html That's the one I bought. Once I realised it wasn't compatible with the Altair drivers I mostly resorted to using it as a webcam, so I've done no further astro use with it.