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Post by BillW on May 7, 2015 15:05:18 GMT
Hi,
A while back I tried using an imaging source camera to detect meteors.
It's never been designed for this and it turned out to be be pretty much useless compared to the trusty 902's.
However on the SonotaCo forum one of the well know continental observers Matej Korec posted about tests done with a QHY guiding camera.
These show some promise although there are driver issues. If these can be resolved at £200 it could be a useful tool!
I'm keen to move to a smaller pixel size to try and improve my spectroscopic resolution but this comes at surface area/quantum efficiency cost.
Has anyone else tried different cameras for video type observing?
cheers,
Bill.
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Post by stewartw on May 7, 2015 18:09:08 GMT
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Post by allanuk on May 7, 2015 20:44:45 GMT
What is the requirements for a camera to use for spectroscopy Bill? What minimum frame rate or exposure do you need to use or can you use sensup and longer exposures?
I understand the need for sensitivity and a good resolution, but when the pixels get smaller, the resolution may be better, but the camera is generally less sensitivity for the same size chip. There are many cams out there with good resolution and very usable with long integration times for deep space objects, but they fail miserably for meteor work at 25fps.
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Post by BillW on May 7, 2015 22:42:56 GMT
The requirements? To have both tiny pixels and huge pixels at the same time! ;-)
I built a ccd camera in the mid 90's and as soon as you start assembling the components you realise everything is a compromise between competeing parameters. Especially if you start trying to tweak it.
From my experience, 10-15 fps with the small corresponding increase in exposure time but with the smaller pixel size MIGHT be a step in the right direction. Matej's example videos do show promise. The perseid fireball I captured 3 years ago is the only event I've seen where I'd like to have had a higher frame rate to capture a really fast change in spectrum. Everything else has been fairly sedate (so far!).
I might cough up and get one to experiment with myself.
No doubt these things will come up on Saturday. Looking forward to the meeting.
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arp
Full Member
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Post by arp on May 14, 2015 16:55:51 GMT
Hi Bill,
I have a QHY5L-II-M camera that I've been using this year to obtain differential photometry of PHEMUs (Mutual PHEnomena of the Jovian satellites' eclipses and occultations.)
It uses a 1/3rd-inch format CMOS sensor with 14-bit (I think) digital output via USB cable. I use FireCapture software. Its maximum pixel setting is 1280x1024.
It came bundled with a C/CS-mount adaptor ring and a couple of 1/3d-inch format lenses, a 1.25mm fish-eye lens and an 8mm f/1.0 lens as well as other accessories. With the adaptor ring it takes my other video lenses, such as 12mm f/1.2.
I haven't had any joy yet getting it to talk to UFO Capture, but I'll look into it this summer. As SonotaCo mentioned, the appropriate drivers are required.
Cheers,
Alex.
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arp
Full Member
Posts: 96
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Post by arp on May 15, 2015 8:58:13 GMT
Hi Bill,
The Watecs are well-publicised for meteor work, but please also consider the Mintron range.
I've had one for years and used it for occultations and meteors - and longer exposure deep sky images. In recent years it developed a mush of hot pixels, so I got myself a new Watec 910 HX/RC.
Cheers,
Alex.
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arp
Full Member
Posts: 96
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Post by arp on May 15, 2015 18:47:19 GMT
Hi all, I contacted the author of this presentation given to the 2014 IMO Conference in Giron, France www.imo.net/imc2014/imc2014-zoladek.pdfwww.imo.net/imc2014/2014-49-zoladek-final.pdfand he encountered a lot of problems using a QHY5L-II-M camera with UFO Capture, even after using a special driver supplied by QHY. He takes 1-min exposures using EZPlanetary software then processes the stacks. So, the camera might be worth trying for spectroscopy, but it's not currently supported for reliable real-time captures like our Watecs. Cheers, Alex. |
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arp
Full Member
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Post by arp on May 17, 2015 21:44:17 GMT
Hi all,
The required QHY5L-II ver 2.5 WDM driver was no longer on the QHY website, but William reminded me of the web archive
web.archive.org/web/20140916160841/http://qhyccd.com/en/top/download/
In UFO Capture I then selected this native QHY WDM video option, chose the Intel IYUV codec, read in the PF640x480N.ufi then set the exposure time to 40ms and maximum gain.
The UFO Capture Preview screen only refreshes once a minute or so using this driver and camera. (I used FireCapture to focus the lens and to align on Vega.)
UFO Capture locked up occasionally, although I managed to record a test video using the camera's 1/3rd-inch 8mm f/1.0 lens. The lim mag didn't go very deep, but see the attached pic from a recording of Vega rising.
I'm quite happy using my Watecs for meteor work, but this has been an interesting exercise. More tests needed.
Cheers,
Alex. |
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Post by BillW on May 18, 2015 8:40:35 GMT
Hi,
Thanks for the info. I get the feeling it might not be a viable option to use UFO for this particular camera.
Running it at even lower resolution seems to defeat the purpose!
The strategy descibed by the Polish Fireball Network guys may be the best bet at the moment.
For my purposes it might very well have some advantages but the 910 will take some beating for ease of use and overall performance!
Cheers,
Bill.
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Post by BillW on May 20, 2015 20:17:54 GMT
Success! (well maybe....;-))
My QHY5 arrived and it a blinding epiphany It occured to me we might be looking at this from the wrong angle.
The native WDM driver will be outputting whatever it's outputting in a size that UFO capture will not be looking for. I think that's whats hanging it up. The driver is conflicting with the max input of the normal version. That might well be complete nonsense as I'm not a computing expert.
BUT UFO capture HD does have these pixel counts. Downloaded the HD trial, set up the camera and viola! It picks up the camera, plays the video feed and records and replays seemingly OK.
However the preview seems a bit "jumpy" and the slow frame rate is really obvious in the playback. My laser pointer in the garden was really hopping around frame to frame.
I'll need to have a play with UFO HD and see how it behaves. It's got potential so roll on the Perseids when it starts to get dark again :-)
cheers,
Bill.
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Post by BillW on May 20, 2015 20:33:05 GMT
Here's a quick test image.  the video is ~175MB Mmmmm. I'm gonna need a bigger hard drive..... |
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arp
Full Member
Posts: 96
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Post by arp on May 21, 2015 8:36:57 GMT
Hi Bill,
Interesting results!
I considered testing it with UFO Capture HD - to match its full resolution - but I'm awash with projects, so didn't want to spend lots of time on another investigation. :-)
I see that the HD version is time-limited to 30 minute sessions without a full licence (~£140). That's long enough to do test captures.
Look forward to seeing your findings.
Cheers,
Alex.
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Post by allanuk on May 21, 2015 10:40:15 GMT
What is the full resolution of this cam?
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Post by BillW on May 21, 2015 11:59:10 GMT
Alex,
Yep, the hefty license fee is a bit of a deterrant but those 30 minutes soon evaporate. This might be indicating other driver problems or just a slow drive, I don't know, but it takes a good minute to go from a standing start to detecting. If it's timing from the off then time is disappearing, also it takes ~15 seconds to go from recording back to detecting, again more time when the clock is running. I'm probably close to the limit already in just an hour of basic tests.
The other issue is that even ~ 12 - 15 fps the playback seems to be fixed at 25fps so the playback looks seriously speeded up. There may be settings for this but I haven't got that far yet! Under the "set" button the qhy camera controls for gain and exposure appear and can be adjusted so if it produces a comparable star field to the 910 then I will be very impressed but we'll see....
Alan,
The highest resolution is 1280x1024.
cheers,
Bill.
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Post by BillW on May 23, 2015 23:34:23 GMT
With a clean installation (XP SP3) on an old dell 780 (3Gnz, dual core) I can get 15fps to run normally (-ish) with UFO HD. (Must be close to chop off!) It does seem to have a need for particular operations to be done in a particular order though, not quite turn-key like the PAL video systems. By way of an experiment I stuck the trusty 12mm f1.2 onto the qhy5. attached the 830g/mm grating and used a compact flourescent lamp as the source. This is the result.  It's a bit chunky due to using a 25mm mirror to reflect the light into the camera so it's a very wide source. The effective resolution is therefore very low in this example. However the dispersion measured across the length of wavelength span is down to 0.6nm/pix. This is where it starts to get a bit more interesting. By way of a comparison this is a picture I dragged off of the the net.  Good to see the laws of physics in action, the spectra are more or less identical, mercury is mercury anywhere! cheers Bill. |
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