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Philips ToUCam Pro



The Package

I obtained my ToUCam Pro when the Hong Kong Astronomical Society join ordered it from oversea. We have obtained so many of them such that the whole package is of the size of a 29 inch television.

The package contains a ToUCam with a very long USB cable, the driver CD plus a stylish stand and a very very nice oval shaped case, a very classy setup. If you want an even longer cable (e.g. remote PC, or very long telescope), you can buy a USB extension cable which I had been using. There seems to be a quick starter guide plus a user manual, but I am not very sure about that since I don't need them at all. The ToUCam is so easy to use.

Background Information

The Phillips ToUCam Pro is a webcam featuring a CCD sensor giving an effective resolution of 640x480 pixels, the sensor has 659x494 raw pixels. The CCD is a Sony HAD (Hole Accumulation Diode) ICX098BQ chip which is a 4.5mm diagonal (Type 1/4) interline CCD. The pixel size is 5.6um times 5.6um.

Color mosaic filter is built-in so that it can capture color image in one shot. This is particularly handy for planet imaging. The planets rotate by itself and so at high power, and if you're to shoot them using color filter wheel, you have to complete the exposures with RGB filters independently fairly quickly. If the time limit exceed, the frames will not be aligned correctly for they're shooting at different part of the target already. With the ToUCam, however, you won't have this problem. It is a big plus here since we are going to acquire more frames for stacking to reduce noise within a small time window.

It comes with a small lens which is to be unthreaded for prime focus imaging astrophotography. Detaching the lens of the ToUCam cannot be easier, and the thread can be used for the attachment of the 1.25" adapter for prime focus imaging. With a suitable threaded adapter, the alignment will be perfect.

It connects to the PC via USB. No separate power supply is required to operate it. USB 1.1 is fast enough to delivery 30 fps at 640x480 with the help of compression. But please be awared of the bottleneck from other hardwares in your computer, they could significantly reduce the data rate which the USB can attain.

It can also captures audio along with the video signal, however, we recommend to turn it off for astrophotography to save the USB bandwidth, the disk space. Audio is useless for our purpose. Some stacking software might have problem with the audio data in the AVI file (video file), e.g. Registax.

The ToUCam is very light weight so that it will not upset the balance of your telescope, even if it is mounted on a suboptimal fork mount, since it is lighter than a small plossl eyepiece.

How to use it? Bundled softwares and freewares on the Internet.

The beauty of USB is that, it is plug and play. But before plugging in the camera, you still need to install the driver and the software for imaging capture. All the required software can be found on the CD bundled in the package.

I use the bundled video capture software and I found it sufficient. Some people might prefer other softwares for different functions. For examples, some softwares will help you to focus (QCFocus, AstroSnap), some softwares will even let you use the ToUCam as an autoguider (Star Track, AstroSnap) with certain hardware interface and mount combinations! All the above softwares can be used with the ToUCam.

The bundled software is very easy to use and it is very intuitive, so that I don't have to consult it at all. A software is bundled for webcasting so that you can try to show your real time images to your friends over the internet. My friends have seen the planets, the moon on their home PC via Internet, taken real time by my telescope inside my home.

How to adapt it to the telescope

The ToUCam is designed as a consumer based webcam, it is not a tool intended for the astronomy community, so you need to adapt it for astrophotography.

You will need to make an adapter to fix it to the focuser. You can either make one yourself or you can buy one off the shelf.

To make one, you can use a film canister, which happens to be around 1.25". Drill a small hole on the bottom, and then stick it to the ToUCam. Some people remove the lens of the ToUCam from its cell, and then re-use the thread on the lens cell by attaching it to the film canister. Notice that the alignment will affect the result, so you better buy a special one or build it very carefully.

To buy one, the most famous source is Mr. Steven Mogg. I found it to be the best, light weight, robust, and will not introduce any back focus issue. It is even threaded for standard 1.25" filter! Some of the local folks machine they own adapter and black anodize it, but it might not be easily done by everyone.

Sampling

From the experience of local amateur, the ToUCam can give finer detail than the Daws Limit which is a good reference for visual observation. Therefore, if the sky condition allows, try to push it a little bit higher and be prepared to get some surprise. Actually, I managed to capture far more detail on the Jupiter than I could have using my eyes.

In general, in order to show a particular feature, we need at least two pixels to represent it. We found the ToUCam to be around the best used at f/25 to around f/35. The exact value you are going to choose can be determined by trial and error. Usually a higher quality scope can stand higher, and scope with a smaller central obstruction can stand higher as well, since it is less affected by seeing.

Noise

When compared with typical low cost webcams in the market place, the ToUCam stands out as a very sensitive and noise free one such that it is very good at low light condition. For daily use, the ToUCam is probably one of the best webcam you can get in similar price level. However, when we want to use it for astrophotography, you will still see a lot of noise, since the light level is way lower.

To deal with the noise, we usually get as many frames as possible and then to stack it to improve the signal to noise ratio. There are a number of freewares available for this purpose, I usually use Registax, Skeye and Astrostack. And after stacking, you will see a much cleaner image and it can stand more processing to bring out all the detail which you have captured.


A typical raw image obtained by the ToUCam, the image are usually rather dim, see the noise. Notice that the background has a blue hue, it is because CCD is usually least sensitive in blue channel and so it is over amplified in low light condition.


Stacked processed image from the clip containing the above raw image


Let's come back to the ToUCam in particular. Local amateurs found that, the higher the frame rate, the more the noise will be. From our experience, 10 fps is about the optimum.

I have conducted experiment to capture at 20 fps and 10 fps respectively. With the clip at 20 fps, I have more frames to stack, however, the frames are much more noisy. The clip at 10 fps gives half of the frames, but they're relatively cleaner.

The final results are very similar. However, at 20 fps, you need more hard disk space, a much faster hard drive to keep up with the video stream. Also, you need much longer time to choose the raw frames and to stack. So, there is no point to go for 20 fps without any special reason.

Except the frame rate, the amount of noise is highly dependent on the ambient temperature. And that's why there is cooled CCD dedicated for astrophotography. The ToUCam is rather hot when imaging, so it would be nice to cool it. However, most people use the ToUCam for imaging without cooling and the results are good. Cooling, will allow one to use even higher gain at similar noise level.

As with all electronic imaging devices, the longer the exposure, the more will be the noise. However, when you shoot the planets or the moon at appropriate sampling, you will be forced to use the longest shutter, i.e. 1/25s for the ToUCam. However, in some very clear and transpareny night, I can use 1/33s but it is not common. And in reality, you have to stick with 1/25s for most of the time with a low to medium gain. 1/33s can help to freeze good images under suboptimal seeing condition with slightly less noise.

Gain is to be kept low. Gain is different from post processing in the sense that the signal from the CCD is amplified electronically by the ToUCam, and this is not to be repeatable with image processing. You have to choose a suitable value so that the brightest pixel will not saturate. You cannot tune it too much for noise level, but you have to tune it based on the transparency of the night. Of course, the higher the gain, the more noisy it will be.

Increasing the gain or the exposure time will both give more noise. And with the ToUCam, the increase in noise is more significant by increasing the gain than increasing the exposure time.

However, do not underexpose your image under any situation, or else "ring effect" will come out and it has no good cure with image processing. See below for an example:


Ring effect caused by underexposure

Therefore, there is not much you can do with software to reduce noise except sticking with 10 fps and use a lower gain value by sticking with 1/25s exposure. However, you can reduce the noise by using some hardware method. Notice that these modifications are to be done by experienced users only and they are going to void your warranty.

Cooling:

Some people cool the ToUCam with a fan, some people even cool it with Peltier device. When a fan is involved, one should try to find some which will not introduce any vibration. When it is Peltier cooled, one should find ways to avoid condensation. Very good results are obtained, some results can be seen in the website of Mr. Eric Ng from Hong Kong, search the word "Cooled" for sample images obtained with a cooled webcam made by Mr. T.P. Chan also from Hong Kong. With less noise, one can even push the image scale a little bit more. When the modified ToUCam is to be packaged in another container, one should also aware of the back focus issue.


Jupiter captured by Mr. Eric Ng with a cooled ToUCam modified by Mr. T.P. Chan, both gentlemen are from Hong Kong


Replacing the CCD chip: Some people replace the CCD chip on the ToUCam with a more sensitive EX-View chip. Not much results I have seen, and I have no personal experience on that. With a more sensitive chip, I imagine one can use lower gain for imaging so that the noise can be reduced.

Fine tuning other parameters

Even at 10 fps, some users might experience drop frame. To reduce or even elimate the drop frames, the following can be done:

  • Check the DMA option of your hard drive, sometimes it is turned off by default. Turn it on if your drive supports it. I totally eliminate all the drop frame with this option turned on.
  • Defragment your hard drive, it will speed up access.
  • Reserve a partition for imaging, or even reserve a hard drive for imaging.
  • Switch off all the background process.

You can also reduce the resolution of the frame, it can reduce the data rate. Also, you can lower to 5 fps in extreme case. For slow hard drive in laptop, you may try to use external hard drive with USB 2.0 or IEEE 1394/Firewire interface. Hard drive with slower interface will not help.

I found no drop frame with my 7200 RPM IDE hard drive with a Duron 700MHz CPU, so only moderate hardware is enough.

Other Paramters

White balance can be left as automatic. Gamma can be any value from minimum to medium, depends on the weather condition. Brightness should be used with care, since it will mislead you to underexpose your image.

Filter

To shoot the Jupiter, Saturn and the moon, we don't have to use a filter.

However, when imaging the Mars, an IR blocking filter is very important. The ToUCam does not come with an IR blocking filter and you can buy a 1.25" one to screw into the adapter like Mogg's adapter. Infrared is going to contaminate all the channels so that finer detail will be messed up. Also, it is particularly important if you try to image Mars when it is still low in the horizon, for atmospheric dispersion will worsen the situation. The blue filter might allow infrared to leak in, resulting in a false blue frame which is actually infrared! However, this is yet to be confirmed.

Notice that the CCD chip of the ToUCam has something undesirable for Mars imaging, its green and blue channel has a relatively wide overlap in the bandpass. When imaging the Jupiter and the Saturn, it is not so noticeable. Independent color filter might help the situation, but I have no experience on that.

See the early Mars images below in the 2003 opposition taken by Mr. Eric Ng from Hong Kong, they show the effect I mentioned above:


Image taken without an IR block filter, by Mr. Eric Ng


Image taken with an IR block filter, please see also the channel leakage by comparing the image of the independent channels, taken by Mr. Eric Ng.

Some Results

Here I include some results obtained with the ToUCam.


Clavius, taken with a C8 plus a 2x barlows, taken by the author



Jupiter plus Io with surface detail, taken with a 10" f/6 newtonian with 5x powermate, taken by Mr. Eric Ng


Jupiters, taken with a Tele Vue Ranger plus a 5x powermate, taken by the author

Saturn, taken with a C8 plus a 3x barlows, taken by the author

You can see more images taken with the ToUCam by Hong Kong amateur astronomers from the following websites, all of them are members of the Hong Kong Astronomical Society:


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