SPC900

[kaybee]

Astro-imaging's not my thing (at least, not at present or for the foreseeable future), so this is more an "out of curiosity" question. I see the SPC900 webcam crop up frequently when browsing peoples' lunar/planetary images. I believe this model has been discontinued now, but seems to command a high second-hand price.

What makes this particular model so desireable? Given that it's been discontinued has it not been replaced with something "better"? What makes it more desireable than say XBox camera's which I also see mentioned?

~Keith

[knobby]

Very roughly... It has a CCD sensor which is very sensitive to low light and the board controlling the sensor is hackable to allow longish exposure times

[JamesF]

The primary reason is probably the sensor used in the camera.  For whatever reason, Philips happened to use a sensor that has a good low-light performance and is relatively low-noise too.  The camera may no longer be made, but the same sensor is still used in a number of the lower-end planetary cameras.

That it is relatively easy to modify and not too hard to butcher for long exposures helped too I'm sure, but I think the primary reason is the sensor.

As to why it hasn't been replaced with something "better", well it never was a camera intended for astronomers.  It was a webcam and webcam designs have really moved in a different direction from those that would interest a planetary imager.  The Xbox camera is fine for what it was intended for, but for astro-imaging it is quite noisy and not as sensitive as the SPC900.

James

[kaybee]

Ah that would make sense... A bit of a one-off in terms of providing desireable hardware then.
Are low-end planetary cameras (using similar/the same sensor) considerably more than a second-hand SPC900?

[lensman57]

Ah that would make sense... A bit of a one-off in terms of providing desireable hardware then.

Are low-end planetary cameras (using similar/the same sensor) considerably more than a second-hand SPC900?

The sensor is relatively sensitive or rather was at its time, it has long been taken over by larger more sensitive sensors. The electronics are still stuck in the late 90s early 2000s, it has a USB 1.1 class data bus. Reason people still try and mention it is probably more nostalgic than performance related as it had a 1/4" format sensor which is atleast 50% less sensitive than the run of the mill modern sensors that have 1/2" or larger format sensors. Some people are still asking £70.00 or so for these old webcams and some people still happilly pay for them. They were fine for their time and their time has been and gone, if you  find one forout £30.00 get it for fun and experimenting but don't expect too much. As James said you could get a an Xbox webcam for a fiver and it will do nicely for the Moon and messing around.  There are other webcams the same sensor, , planetary cameras with proper USB2 bus for downloading a lot of data quite fast but be honest they are not worth the asking money for the performance. Stick to ASIs and DMKs that is what I'd say.

A.G

[JamesF]

Ah that would make sense... A bit of a one-off in terms of providing desireable hardware then.

Are low-end planetary cameras (using similar/the same sensor) considerably more than a second-hand SPC900?

There are some using the same sensor in the £90 to £100 range (Scopium have one, and TS I think) and there's the ASI034MC using a CMOS sensor for a bit more.  I've not seen any images from these cameras though (other than images used for marketing, which I'm not inclined to take as indicative of the camera's likely actual performance in the UK).  I've seen the occasional DFK21.AU04 going for not too much more than £100 second hand once or twice recently too.

Even if you paid £60 for an SPC900 I'm not aware of another camera that comes close for that price.  The Xbox camera is fair enough for bright targets such as the Moon, but struggles a bit with Jupiter and Saturn.  The Lifecam Cinema/Studio is perhaps better though still not as good as the SPC900, and isn't too easy to use because not all the controls are exposed by the driver (probably not by the firmware) and by the time you've bought the camera and a housing to put it in after modding it you're probably not that far off £60 anyhow.

Now the SPC900 is getting hard to come by it would be very interesting if there was a back-to-back test of some of these cameras in different aperture scopes so people wanting to get into solar system imaging on a restricted budget had some idea of what is out there.

James

[kaybee]

Thanks guys. Very informative.  I've long enjoyed browsing the images people achieve and is was really tech-related curiosity about, as James you said, why something that wasn't intended for this purpose became sought after. 

Who knows, maybe one day the bug will bite and I'll give it a try myself.

Agreed, it would be very interesting to see an "image-out" between cameras conducted with a fixed post-processing regime.

~Keith

[Steve Ward]

It might be old technology but the SPC900 out performs things such as the Orion Starshoot Solar System IV which is from £85 - £99 ... 

[JamesF]

It might be old technology but the SPC900 out performs things such as the Orion Starshoot Solar System IV which is from £85 - £99 ... 

I'm far from certain, but I believe the SSIV uses the MT9M111 CMOS sensor which is I think about 20% of the sensitivity of the sensor in the ASI120MC.  If I've understood correctly then one might hardly be surprised if it turned out to be rubbish

James

[leelee970]

This is a good site to give comparisons - although not updated.

http://homepage.ntlworld.com/molyned/web-cameras.htm

[rwg]

Having spent a lot of time getting SharpCap to support SPC900 cameras as well as possible, including the LX modified ones, I can definitively say that the sensor - which is the strong point of this camera - is horribly crippled by the need to send the image data back to the computer at USB1.1 speeds.

A single frame from the camera without compression runs to ~920k. The Usb 1.1 bandwidth is approximately 1350k/s. So you can see that without compression the camera would only be able to handle 1.5 frames per second because of the USB limitation! In order to get the frame rate it does, the camera compresses the images both spatially and in the time domain (ie frames are not independent but are sent as a difference against the previous frame). The higher you turn up the frame rate, the more pronounced these compression artifacts become. I discovered this with the LX mode - when you finish an LX exposure you send a signal to reconnec the sensor to the ADC. You'd then expect to get one frame with all the image signal in it among the stream of black frames you get when the ADC is disconnected, but you don't... You get a series of frames - maybe 4 or 5 that all have traces of the LX image in - one of them has most of it.

My advice would be to keep clear of this camera in this day and age, especially at the £70+ prices that are seen so often. For Lunar/Planetary imaging, a more modern webcam will be not only cheaper but should give a better image due to the higher resolution and USB2 speed. A couple of years back the Microsoft Lifecam Cinema was highly regarded for this, but not sure what today's targets are.

If you want something capable of long exposures, you probably have to start looking at the dedicated cameras produced by QHY, ASI, etc, which will get you exposures of 10s +, although possibly with rather more sensor noise than is ideal. These seem to be priced starting at about the £120-£160 price point these days.

[Disclosure : I work with both ASI (ZWOptical) and QHY in conjunction with getting their cameras to work with Sharpcap - there are probably other equivalent cameras to the QHY5LII, ASI120MC, ASI034MC etc by other manufacturers, but I have no experience of them]

Robin

[JamesF]

This is a good site to give comparisons - although not updated.

http://homepage.ntlworld.com/molyned/web-cameras.htm

Yes, much has changed in a couple of years and I don't think too many of those are still available.  It's not entirely helpful that in that table the sensitivity is shown as "lux" which clearly can't be the entire story, whereas others show quantum efficiency or V/lux-sec.

James

[JamesF]

My advice would be to keep clear of this camera in this day and age, especially at the £70+ prices that are seen so often. For Lunar/Planetary imaging, a more modern webcam will be not only cheaper but should give a better image due to the higher resolution and USB2 speed. A couple of years back the Microsoft Lifecam Cinema was highly regarded for this, but not sure what today's targets are.

I never managed to get images out of a modded lifecam cinema that I felt were comparable to those I could get from my SPC900, even trying back-to-back on the same night with the same scope.  I'd expect it to be better on the Moon, but I didn't try it for that.

People keep saying there should be something more modern/cheaper, but if so what is it?

James

[rwg]

I never managed to get images out of a modded lifecam cinema that I felt were comparable to those I could get from my SPC900, even trying back-to-back on the same night with the same scope.  I'd expect it to be better on the Moon, but I didn't try it for that.

People keep saying there should be something more modern/cheaper, but if so what is it?

James

Funnily enough I always felt the opposite - never got anything decent on Jupiter out of the SPC - always found the Lifecam seemed to do much better. Still, haven't really used either for a couple of years now except for testing purposes, bug fixing, etc.

I wonder if the problem is that modern webcams have gone down the path of increased pixel count and reduced pixel size, which is OK in good light and probably helps drive down costs and device size, but is less useful for the sort of thing we are after.

There is probably also less interest in webcam modification now since there are many more purpose built astronomy cameras available at (fairly) reasonable prices.

Robin

[rjc404]

I bought my SPC900 second hand for about £30 just as a starter cam to see if I liked planetary imaging or not.

I realise they are hard to come by (it took about two weeks of watching classifieds on Astrobuy/sell or whatever it's called to find mine) but for the price it's been a great introduction for me.

I'll definitely move onto a more capable and reliable planterary camera in due course but this has been a good little cam just for learning the ropes.

Rob

[JamesF]

A single frame from the camera without compression runs to ~920k. The Usb 1.1 bandwidth is approximately 1350k/s. So you can see that without compression the camera would only be able to handle 1.5 frames per second because of the USB limitation! In order to get the frame rate it does, the camera compresses the images both spatially and in the time domain (ie frames are not independent but are sent as a difference against the previous frame). The higher you turn up the frame rate, the more pronounced these compression artifacts become.

For clarity (I'm sure Robin knows this, but other readers may not), this compression isn't a specific feature of the SPC900.  It's common to many video/web cameras which produce a video stream rather than a sequence of individual frames.  Often they heavily compress the colour information whilst doing less (or no) compression on the luminance part of the signal.  This is all lost information that you can't get back and not a good thing for imaging, but it's very handy for transient video data.  When you select IYUV or YUY2 or whatever in SharpCap that's actually setting the compression method used for the video frames.  The compression needs to be greater (at the same frame rate) in the case of the SPC900 because of the limited USB bandwidth.

One of the benefits of springing more cash on a dedicated imaging camera is that it won't do this.  The ASI120, DFK etc. all give access to the full capture data giving a much better result.  (I don't have a colour QHY camera so I can't definitively comment on them, but I imagine they're just the same.)

James

[JamesF]

I wonder if the problem is that modern webcams have gone down the path of increased pixel count and reduced pixel size, which is OK in good light and probably helps drive down costs and device size, but is less useful for the sort of thing we are after.

I think you're exactly right here, Robin.  I don't think for planetary imaging we're really that bothered about total sensor size or pixel size anywhere near as much as sensitivity.  I get the impression that webcam manufacturers are also heading towards as much automation as possible in terms of gain/exposure settings etc. which also doesn't suit imaging.

James

[lensman57]

Astro-imaging's not my thing (at least, not at present or for the foreseeable future), so this is more an "out of curiosity" question. I see the SPC900 webcam crop up frequently when browsing peoples' lunar/planetary images. I believe this model has been discontinued now, but seems to command a high second-hand price.

What makes this particular model so desireable? Given that it's been discontinued has it not been replaced with something "better"? What makes it more desireable than say XBox camera's which I also see mentioned?

~Keith

Hi keith,

I hope that having read through all the posts by  myself and other good people you get the idea that this SPC is now a dead horse, my advice is to save up and get an ASI 120 mono, more sensitive by orders of magnitude, great resolution and bit depth ( dynamic range ) and also dual purpose as a sensitive guide camera and it can down load huge amounts of data as fast as your computer can handle, the price difference is about £200.00 but atleast you don't have to upgrade in the near future. To put the price in perspective an IDAS LP filter costs nearly £150.00 for a 2" version so £260.00 for a good sensitive planetary camera is something of a bargain. It is up to you now.

Regards,

A.G

[JamesF]

If you want the kind of results the ASI120MM can achieve and you're prepared to stump up that kind of cash (plus, say, another £200 for decent filters and a tray or wheel if you want colour) then I'd agree.

I'm happy to go against the flow however and suggest that if you want to dip your toe in the water and spend less than £100 to do some colour planetary imaging there still isn't much to beat the SPC900, even at £60.  I and many other people would be very pleased to find otherwise, I am sure.  I note Robin's comment about the modded Lifecam.  I'm prepared to give that another go before I sling it in the classifieds.  This is how I got on last time I tried:

http://stargazerslounge.com/topic/168060-spc900-vs-xbox-live-webcam-vs-lifecam-cinema/

James

[Pete Presland]

the SPC900 is far from a "dead horse" one sold on the dreaded ebay for £122 last week

its is a nice entry level webcam at a sensible price (£60-70) but i think newcomers google it and see the images and get a bit carried away. it is obviously not as good as a dedicated mono webcam, but then it is a lot cheaper. from own experience i did not rate the SPC900 very highly at all, but that probably says more about my imaging ability at the time than the camera.

[JamesF]

£122!  That's mental!  Almost tempts me into selling mine.  At that price I could buy a better camera for the project I intend to use mine for and still have change.

James

[DaveGarland]

Ditto! I'm going to have a look on eBay and see what they're going for. I must admit I've never been too impressed with mine but then again I did get a strange amount of enjoyment out of dismantling the lens and adding the adapter etc. I do quite like the look of those ASI's though.

[Pete Presland]

£122!  That's mental!  Almost tempts me into selling mine.  At that price I could buy a better camera for the project I intend to use mine for and still have change.

James

i did think those days had passed when morgans computers flooded the market a couple of years back, but i supose it shows how popular imaging is!

[CSM]

For a dead horse it can produce very good images as is clearly shown on the forums here and elsewhere.  I managed to get mine from Morgan computers May 2011 for just £42, I think the last batch that was produced, and it works brilliantly on the Moon, Jupiter and Saturn.  The USB issue doesn't seem to be a problem.  Am using a Windows Netbook 7 Starter and wxAstrocapture.

[kaybee]

Hi keith,

I hope that having read through all the posts by  myself and other good people you get the idea that this SPC is now a dead horse, my advice is to save up and get an ASI 120 mono, more sensitive by orders of magnitude, great resolution and bit depth ( dynamic range ) and also dual purpose as a sensitive guide camera and it can down load huge amounts of data as fast as your computer can handle, the price difference is about £200.00 but atleast you don't have to upgrade in the near future. To put the price in perspective an IDAS LP filter costs nearly £150.00 for a 2" version so £260.00 for a good sensitive planetary camera is something of a bargain. It is up to you now.

Regards,

A.G

Hi A.G.

I guess if I was tempted into imaging at some stage that's the way I'd go.  In all honesty, I'd probably buy something cheaply (like a lifecam), accept it's limitations, see how much I liked imaging and then invest in a dedicated astro-imaging camera if I was taken with the concept.  I suppose the key to that approach is accepting limitations early on and accordingly not being disheartened with the results, especially with the amount of post-processing to learn.

To date the equpiment I have, and have recently invested in, is geared purely towards visual.

~Keith