It's 6 years since I played with low-cost B&W TV surveillance cameras for home security use adapted for astro imaging via links above. These images here show recent experiments using a low-cost colour CMOS webcam from PCWorld costing £7.99 [£2 more in Currys!] which records direct to the laptop/PC. Using a compact Meade ETX-70 refractor [below] mag 7.6 stars are recorded in streaming video at maximum gain and mag 10.1 Tethys [Saturn's satellite] via 30cm f6.3 Meade SCT. Importantly the camera works well with the Coronado PST H-alpha telescope which has very limited back-focus. I'm indebted to *John Curruther's post on the CloudyNights Forum for his introduction to this camera and the PST application.
The complete PCB with integral CMOS sensor is precisely 1.25-inches in diameter by 1mm thick and fits a standard 1.25-inch pushfit eyepiece without modification [except for filing off two tiny batch PCB projections]. The camera has a tiny IR block filter behind the [discarded] lens which could be remounted over the sensor. Some stellar spectra below via the unfiltered webcam indicate a spectral range for the CMOS chip of 370nm - 1070nm eg violet to near infra-red - a third of the spectrum to the right is colourless IR. The adaption needs no soldering or changes to the PCB and was simplicity itself ...
1] remove one philips screw holding the golf-ball
sized camera together
2] cut the halved casing to release the USB cable
3] mount PCB in *film
canister*, between two old lensless eyepieces or locked in place with tight ring [both shown here]
4] blob of BluTack to mask the brilliant blue
LED from fogging sensor
5] Load supplied software and plug into 'scope
and USB port and go....
These are some of my related comments on the CloudyNights Forum......
"Bought my webcam at PCWorld lunchtime - hacked it with this preliminary
result from indoors through the lounge
double glazing - shows promise [on the sun in hydrogen-alpha light
through the Coronado PST telescope]. Great fun"
Last night via 12" LX200+webcam Titan at mag 8.2 was an easy bright
object east of Saturn and just glimpsed occasionally
[via multiple video playback] Tethys mag 10.1 above planet on maximum
gain. You can see the 2mm x 1.5mm
CMOS sensor [lighter area] lower right - amazing micro-engineering"
"This is my version of the PCL-100K webcam adaption with three framegrabs
of solar proms via my Coronado PST and Venus and Saturn via the LX200
from yesterday....the beauty is the whole PCB including sensor [~1% size
of DSLR APS sensor!] is contained on 1mm thick board that's precisely 1-1/4"
diameter and so fits the standard pushfit eyepiece. I've used two eyepiece
barrels sellotaped together with the PCB sandwiched between for these shots so an IR block filter can be added. Note the original kit has a tiny IR block filter that could be reused here.
The blob of Blutack covers the brilliant but tiny blue LED from fogging
the sensor. Great fun at minimal expense"
" ..PCL-100K webcam....including some excellent VideoImpression v2.0 capture software. IR block filter not used but in hazy skies tonight Mizar double and Alcor nicely resolved and Saturn recognisable [thro Meade ETX-70 scope] Targetted brilliant Venus but it ran into trees"
"tonight imaged direct via the [Meade ETX-70] rear-port with
some gain in penetration to mag 7.6 @ 5fps [max gain]
for faint field star to Mizar/Alcor group"
"Thanks...and for your other comments in my EXT-70 experiments - I always
get a buzz squeezing results from modest equipment Here's a post
midnight single frame grab from the 'movie' that just shows the mag 7.6
star in the Mizar/Alcor field... the new CMOS webcam is great fun, is much
more convenient to view and record straight to laptop and goes fainter
even with 70mm aperture that's only 1/18th the light grasp of my 12" LX200"
Specification
---------------------
Imaging sensor......1/7" color progressive CMOS, 352 x 288 pixels; 10 bit RGB raw data
Sensitivity.........15Lux @ 7.5fps
Lens Specification..F/2.4, f=2.9 mm, view angle 52 degrees [discarded for astro application]
-Focus Range........manual focus
-Depth of Field.....50cm to infinity
White Balance.......auto
Exposure............auto
Frame Rate..........320 x 240 pixels @ 5-30fps + 160 x 120 pixels @ 5-30fps
PC Interface........USB 1.1 [ok on USB 2.0]
Video Format........AVI
Video Capture Res...320x240 + 160x120 pixels
Snapshot............hardware [press switch]
Still Capture Res...Up to 320 x 240 pixels [640 x 480 interpolated]
Flicker Control.....50Hz, 60Hz
Power...............from USB port
Bundled Software....ArcSoft Videolmpression 2.0
