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Posts Made By: Ulrich Rassner

November 21, 2012 09:46 PM Forum: Equipment Talk

ICX 618 vs ICX 098 comparison measurements

Posted By Ulrich Rassner

This is my first post here, let's see how it goes.
Thanks to a fellow astromarter, I acquired a camera with the Sony ICX 618 chip (Flea 3 FW-03S1M mono, no IR filter). I had a hard time finding a direct comparison with the older Sony ICX 098 chip. Since I still have my first planetary camera with the 098 chip (DMK21 AF04.AS) I wanted to find out they compare.
This was my setup:
Both cameras with the detector about 10 inches from a LCD monitor with an Astronomik luminance filter (to filter out IR and UV). Camera was controlled with Astro IIDC. On the monitor I put a uniform color images made in photoshop White (RGB set to 255), Red (R255 G0 B0), Green (R0 G255 B0) and Blue (R0 G0 B255). I took images with a gamma of 1 and gain set to the minimum setting. Exposure times were 6 ms for red, green and blue and 3 ms for white. Histogram analysis of the entire frame was done with imageJ to determine the gray value of the image and standard deviation as a measure of image noise ( with 0=black and 255=white). Following are the grey levels for the ICX 618 and ICX 098 in parenthesis.
White 203(161 - 21% lower), Red 117 (74 - 38% lower), Green 201 (164 - 22% lower) and Blue 104 (91 - 12.5% lower).
Interestingly for the images with the 618 chip the standard deviation was usually 5-10% less, suggesting a lower noise level.

I then put then looked at what exposure time the image was saturated (white). For the 618 chip the exposure times for saturation were about 25% shorter White, red and green, but less than 10% shorter for blue. This was only a very crude test.

When I took the luminance filter off, the differences between the 2 chips became much more pronounced, indicating the higher sensitivity to infrared of the 618 chip (the front of the monitor is warm to the touch).

In conclusion, I expect to see about 25% shorter exposure times with the 618 chip compared to the 098 chip.

P.s. I will update this once I have a UV pass filter and IR pass filter to see how the chips compare for IR and UV.

Any feedback is appreciated.

January 19, 2013 09:10 AM Forum: LUNATICS

Lunar X this month?

Posted By Ulrich Rassner

Thanks Mr. Kraus and Mr. Love, Thanks to your posts I learned about Lunar X . I just took the telescope outside to check what I could see last night. At first I could not see any of the Lunar X. However as the hours passed it slowly came into view (unfortunately as the moon was setting). About 1/2 hour after midnight the x became clearly discernible, but seeing really deteriorated. It did not help that there were a few tree branches in the way and the inversion was quite bad.