Logitech Fusion Webcam
Fusion and Toucam Compared
Updates on bottom of page
by Gary Honis
This is the sale's hype from Logitech that got my interest in testing the Fusion for astro imaging:
I adapted a Logitech Fusion webcam for telescope use and am testing it for planetary, lunar and solar imaging. My interest in testing is to compare it to the Philips Toucam which has been working well for me for some time. Details on how I adapted the Fusion for telescope use can be seen here .
MARS Test Images:
Below are images of Mars taken with the Toucam and Fusion, three days apart under similar conditions (12/03 & 12/06/05). Seeing was very bad. Temperatures were about 20 degrees Fahrenheit and radiational cooling along with jetstream turbulence caused a boiling Mars image. For the Fusion image I could not image for the full 4 minutes since winds were moving my scope which caused the Mars image to go off frame.
For both images:
<Toucam<Fusion<CalSky Simulation
For an idea how seeing affects images with the Toucam, recent Mars images I took with the same setup and processing under better seeing conditions can be seen here.
Results:
Fusion more light sensitive?
I have had a lot of experience imaging with the Toucam and adjusting the Toucam camera settings to provide a quality image is an easy task. The Logitech Fusion, however, has different camera driver parameters. Based on my experience with the Toucam, at first I tried imaging with the Fusion using longer exposure rates of 1/14 second to 1/30 second. These settings required brightness and contrast to be set low and resulted in a poor image. I found that if I used much shorter exposure rates, such as 1/250 second, brightness and contrast settings could be placed between 90% and maximum. It appears the Fusion is more light sensitive than the Toucam. (See indoor tests below)
White balance:
I found a quirk when adjusting the "white balance" slider. When I make an adjustment, the image overexposes. But if I then click the apply button, all is well and the image returns to normal with the adjustment to white balance made. Maybe I need to read the Fusion manual, but this caused me a lot of imaging trouble before I figured it out.
Gain setting:
In K3CCDTools (vrs 1.06) when I adjust the gain setting with the slider and take my mouse off the slider, the value automatically reduces to the next increment. The when I click on OK to close the window, the gain value reduces to the next increment again. To get around this quirk, I adjust the gain slider two increments greater than the desired value before closing the window.
I did not try the Fusion in "low light boost" or "color boost" modes.
Here are the camera settings I used for the above Fusion image of Mars:
Note that K3CCDTools gives a higher resolution (704X576) for the Fusion than with the Toucam (640X480). 640X480 is also available on the Fusion. A four minute uncompressed AVI file for the Toucam is 1.08 Gig and for the Fusion is 2.82 Gig. I found that most of the video processing softwares I have don't know how to handle AVIs exceeding 2 Gig.
Comparison of some specifications, Toucam versus Fusion:
*1280x960 video resolution with non-vendor software
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Imaging chip of Toucam versus Fusion side by side:
Digital Sensor Size:
In the test stamp images below, one sees the affect of the larger imaging chip size of the Fusion versus the Toucam. A 400mm Short Tube 80 was used for all images, yet the Toucam image appears magnified. This is because the Toucam has a smaller chip and this effect is known as the "crop factor". Measuring the output images of both webcams, the crop factor is about 1.3X. Logitech has not released the size of the Fusion's imaging chip. Based on the imaging chip size of the Toucam, I calculated the Fusion's chip size as follows:
The above dimensions seem to correspond to the side by side photo of both chip images above.
First Moon Image with Fusion using 704X576 mode AVI and ED80 Refractor (12/06/05):
First Solar Image - 60mm Coronado H-Alpha - Orion ED80 Refractor (12/08/05 - poor seeing):
Note appearance of horizontal lines in above image. It is due to a noise pattern in very short exposures (see indoor tests below). The image was made from a stack of a few short AVI frames for surface detail and long exposure frames for the prominence. Seeing was very bad and I didn't use a good contrast setting, hence the loss of surface detail toward the limbs.
I also used the Fusion's 1 Meg Photo mode to take an image in 1280 by 960 resolution using the Logitech Quickcam software which saves files in JPG format and took the image below (closeup of small prominence in above photo) using a 3X barlow with the ED80:
Controlled Test Images:
I took indoor test images of postage stamps using both the Fusion and Toucam and posted the results below. A Short Tube 80 refractor was used at 30 feet with dim indoor lighting. For this test I used the following settings for both webcams with no processing other than size reduction:
(italics=Fusion only)
I took test images for different exposure lengths while only changing the Gain setting to obtain an acceptable image:
Based on the above, it appears the Fusion is more light sensitive than the Toucam as I found when imaging Mars. For the above Toucam stamp images, the Gain needed to be increased to 95% for the 1/50 second image and to 100% for the 1/100, 1/250 and 1/500 second exposures; note the drop-off in brightness.
For comparison, the Fusion's Gain setting for the 1/50 second image was 8% and the Gain needed to be increased linearly to about 50% for the 1/500 second exposure as per the table below:
Noise:
Even though light sensitivity is higher for the Fusion, noise patterns become apparent at very fast exposures. At 1/25 second, both webcams did quite well for the stamp test. Here are the 1/25 second Fusion and Toucam images full frame (640x480):
Fusion - 1/25Second:
Toucam - 1/25 second:
At 1/500 second exposure, the noise patterns become very apparent in the Fusion image. Here are the 1/500 second Fusion and Toucam images full frame (640x480):
Fusion - 1/500 Second:
Note the continuous horizontal banding and less obvious vertical bands in the above image.
Toucam - 1/500 Second:
I've been using the Fusion webcam for a few days and am learning how to adjust the settings properly for astro images; more testing and direct comparisons with the Toucam are planned. I am interested in testing how the Fusion performs for AVI videos in the 1.3 Megapixel mode at 1280x960 resolution.
UPDATES:
Part 2 - Fusion and Toucam Compared - Saturn, Mars and Moon test images CLICK HERE.
For test image results using IC Capture Software that provides higher resolution video imaging CLICK HERE.
For Solar H-Alpha and Lunar test image results using IC Capture Software CLICK HERE.
Conversion instructions for Fusion Webcam CLICK HERE.
Hi Resolution Capture to Hard Drive - Speed Performance CLICK HERE.
Animation & Images of Sun in H-Alpha CLICK HERE.
Jupiter & Saturn with Fusion settings and processing notes CLICK HERE.
3 hour Jupiter animation and images with Fusion settings and processing notes CLICK HERE.
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