Suggestions please - guide camera selection

[JohnP]

I use a modified LX webcam (uncooled) - Never had noise probs with guiding...

[The Thing]

I use a modified LX webcam (uncooled) - Never had noise probs with guiding...

I have an SPC900 LX with a mono chip. However it keeps crashing PHD1 - must try it with PHD2! It certainly is sensitive and has a cold finger on the chip to the ali case so a bit less noise on a cold night as well.

[RobertM]

I have tried out Roberts ASI120MM, I was not impressed.

It didn't pick up any more guidestars that the QHY5 though the image was cleaner. It kept crashing PHD2 (tried it as an ASCOM camera and a WDM camera) and also Sharpcap 2 which has specific customisations for this camera. It wouldn't work over an extension hub (which I always use) or any other hub. Testing inside with the 8mm lens showed a pattern as if horizontal hold on an old TV (for those who remember such things) needed adjusting, this varied with the USB speed setting (available in the WDM driver but not the ASCOM driver). There were no other external USB devices plugged in. I was using the latest drivers from their site.

However Robert said he hadn't really used it and I have also read on-line that ZWO admitted a faulty batch that exhibited some of these symptoms...

That's interesting, I must admit that I've not noticed any issues with the solar imaging I've done - for instance the video of the plane across the sun was made with that camera.  I will try to repeat your findings when I get it back, let ZWO know and push for a replacement if confirmed.

Thanks for your findings and hope it didn't waste too much of your time !

Addendum: it's nothing to do with the 50Hz flicker of light bulbs/flourescents of whatever is it - just a thought.

Robert

[The Thing]

Hi Robert,

I might have another go outside tonight if the murk clears. I will try a smaller ROI, smallest I tried was something like 640x400, I tried binning x2 and longer exposures/less gain.

The main showstopper for me is that it won't work using a hub,  I have found this stated on the ZWO forum and many other places! I am surprised they make a product which doesn't let you use all its features at USB2 speeds even it that means limiting the features set but I suppose they are in a feature war, it should probably be a USB3 device to get the most out of it.

Meanwhile I am going to stick the SPC900 on the OAG and have a go at Comet Lovejoy about 4am Saturday as it's brighter than ISON and high in the sky at night! Clear skies.

[Carole]

There are a couple of Atik16iC cameras on ABS at the moment for slightly less than a QHY5 and I gather these make good guide cameras, plus it will be a cooled small chip CCD camera to have a go at small object cooled CCD imaging should you so wish (so long as you hang on to your current guide camera and "put up with it" for such occasions).

Not sure if this is of any interest to you.

Carole

[MarkS]

... have a go at Comet Lovejoy about 4am Saturday as it's brighter than ISON and high in the sky at night!

Hardly any difference in brightness now but Lovejoy is much better placed!

[Mike]

Meanwhile I am going to stick the SPC900 on the OAG and have a go at Comet Lovejoy about 4am Saturday as it's brighter than ISON and high in the sky at night! Clear skies.

I was up at around 3am this morning so had a look for it. Found it easily enough with a pair of binoculars in a moonlit sky. It didn't have a long tail and looked more like a globular cluster than a comet but was clearly visible and pretty bright.

[The Thing]

There are a couple of Atik16iC cameras on ABS at the moment for slightly less than a QHY5 and I gather these make good guide cameras, plus it will be a cooled small chip CCD camera to have a go at small object cooled CCD imaging should you so wish (so long as you hang on to your current guide camera and "put up with it" for such occasions).

Not sure if this is of any interest to you.

Carole

Yes, but they are enormous and wouldn't get on the OAG between my big fat scope and the Canon!

[Carole]

Yes, but they are enormous and wouldn't get on the OAG

Ah yes, I had forgotten you were using an OAG.

Carole

[The Thing]

I have been having fun with my QHY5 this afternoon.

Seemingly most of the noise and banding originates from the CMOS and is made worse by the quality of the USB power supply. I considered adding a separate 5v feed to the camera but opted to try something else. I added a 1000uf electrolytic capacitor across pins 1 and 4 of the USB B female socket in the camera to smooth the power supply. There is plenty of room for the component if wires are run to the back of the circuit board. This appears to have cured a lot of the issues!

This was taken with SharpCap2 and is picture of the lightbulbs in the ASI120MM picture below with the same exposure settings. Lens was hand held as the CCD is further back in the QHY5 and couldn't focus with the ZWO to C mount adaptor. There is no banding evident and it looks very clean to me. I have looked at a 10s light excluded image in PHD and that looks good too. Now I need some stars.

[Mike]

That's very interesting and shows the circuit design is very poor if the addition of a component costing less than a penny can greatly improve the output. But then decoupling capacitors are missed out of lots of circuits.

[The Thing]

That's very interesting and shows the circuit design is very poor if the addition of a component costing less than a penny can greatly improve the output. But then decoupling capacitors are missed out of lots of circuits.

I was suprised at the difference it made. Previously I had been disappointed when I wanted to try the camera for planetary images, it was just tooooo noisy, I might give it another go.
I had read that on board power regulators (5v->3v) are underspecified for the needs of the CMOS so this was the only simple thing I could think of that might make the power supply better given that 3 other USB ports will be making varying demands on the hub I use.

[mickw]

Worthy of inclusion in the "technical docs sticky"

Is there a link or is it your design ?

[The Thing]

Worthy of inclusion in the "technical docs sticky"

Is there a link or is it your design ?

My idea, haven't seen anyone else do it. I'll take some piccies - two bits of wire and a capacitor woarrr! But wait until I've tested it on stars before you get too excited!

[mickw]

My idea, haven't seen anyone else do it.