Modifying a webcam for long exposures

Great clear description of the process there Dave. Thanks.

Maybe that's s.thing to have a go at in time. Though initially I think I'd be well advised to try the objects closer to home to get started. :!:

Also, I think I'll enter a thread to have a seperate 'How to...' forum for such things.
It would be sooo handy to have access to all this great info at a glance.

(Forgive me if there any such thing - I haven't looked extensively).

One thing I noticed while modding the Logitech QC Pro 4000 camera is that there is an aluminium plate under the CCD chip. The lens mounting screws into that plate so there is an ideal opportunity to add cooling of some variety to the camera. It would be easy to add a copper or brass plate to the arrangement (sandwiched between the aluminium plate and the lens mount) to draw heat away from the chip. It also crossed my mind that I could add a peltier module to the brass plate but of course the major problem would be icing up the chip since the chip would be exposed to the air. But on a more basic level I could just use a little fan to blow air across the brass heatsink. Then it would be an air coalled long exposure cam:)

I thought some may be interested in how I carried out the mod so I've drawn it up. Remember this is specifically for the Logitech Quickcam Pro 4000 (or defunct 3000). I make no warranty, its presented as is and anyone carrying out this does so at your own risk.

Just a couple of notes;

If the pin is lifted do the following;

Make a tiny little loop at the end of the wire by twisting four or more invidual strands of the wire together then tinning the lead. The trick then is to drive a sharp point into the side of the tinned lead thus making a little loop around the needle point. Then trim the wire right down to the loop and hooked the loop over the lifted pin. Because the loop is effectively pre-tinned all it takes is the tiniest touch from the soldering iron to permanently lock it in place. Trust me this is much easier than soldering a straight wire to the pin and reduces the risk of the wire detaching from the pin.

The pin described as "SAA8116HL Shutter Pin" is actually is actually the tiny via next to the CXD shutter pin. Do not attach directly to the SAA shutter pin. The Via is a little tiny copper ring which goes right through the webcam circuit board. Just bury the wire inside the via and hot glue over the whole working area when your finished. Some people tell you to use silicone but I'd be aaid its corrosive and anyway hot glue dries MUCH quicker.

Do not bend any pin more than twice if at all possible. It may take being bent three times but after that it will almost certainly break.

If you manage to break a pin (like I did) email me I do have a fix, all is not lost but your job is now MUCH more difficult.

Anyway heres the details, hopefully some of you may choose to give it a go. BTW QC Pro 4000 cams are available in Argos for 99 euro:)

Heres some other info I gleaned abour long exposure (LX) modded webcams.

Specifically I discovered that a lot of SC1 modded webcams have an annoying tendency to drop frames at random. Actually there not dropped frames just regular short exposure frame but they may as well be dropped if your doing autoguiding as the autoguider software sees a blank frame and throws a hissy fit!

After trawling through archives all day I solved the problem.

The solution is to download the driver for the SAC7 camera (which is also a modded QC Pro 4000). What you then need to do is before starting a LX session is go to the driver settings page (in whatever software your using to image/guide) and set the FPS to 5. You may also need to tinker with the POSTLXTIME setting too. After doing that I dont get any dropped frames any more.

I really wouldnt fancy doing too much imaging through a modded webcam because the noise is too great (unless you add proper cooling). Which leaves autoguiding as the primary reason to do the mod.

I suggest Guidedog as the best software I have seen for autoguiding with a webcam. Oh yeah just remembered you need to set your parallel port to EPP mode to get the guiding to work (if your doing parallel port guiding with a relay box).

SO heres what you need to build a home brew autoguider for around €135;

1: Modded webcam €99 + about €10 for mod components.
2: *Either* a serial connection cable from your PC/laptop to the handcontrol of your scope (about €25??) *or* a relay box from shoestring astronomy pricey but good.
3: Ascom drivers (if your using the serial option) €free
4: Guidedog €free
5: clear skies €priceless

There are somethings money cant buy (see 5) for everything else there's mastercard :lol:

Some more updates on stuff Jed Glover and myself have been up to in this area.

We've been reading about the possibilites of replacing the stock CCD chip (Sony ICX098AQ) with something a bit more sensitive. the main options seems to be.

ICX098BL, mono version of the stock chip. same res (640x480) same pixel size (5.6microns). Will be much better for guiding than the stock chip (I've ordered one of these). Around three times the sensitivity of the colour chip.

ICX424AL (640 x480) 7.4micron pixel size. Some folks say this is less sensitive than the 098AL but I'd say its marginal anyway.

ICX414AL (640x480) 9.9 micron pixel size. Very sensitive in a 1/2inch format CCD but quite expensive.

Looked at the ICX285AL cracking chip 1392x1024 big pixels and a price to match 485stg ex vat! Even if you were prepared to pay that money it wouldnt make sense to put this in a webcam with only 8bit a/d conversion. You can get a camera kit with this chip and a 16bit a/d convertor for 765stg+vat anyway (artemis ccd).

So once the new 098BL arrives its back to the operating theater for my webcam to get a CCD transplant. I'll post details of that procedure when I do it. After that we'll be looking at building a camera with thermo cooling based on the toucam and also seeing if we cant do something about that 8 bit a/d. If we could somehow get 16bit a/d then we'd really be suckin diesel!! Then it would be worth considering those nich large format CCD chips.

if you were to use a 16bit A/D, is it possible to use the existing pcb in the toucam?, I'd imagine you really are talking about a new circuit board for the camera, so really its a whole new camera ???