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UltravioletPhotography

Stock Lodestar X2 color is very UV sensitive


dabateman

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The Starlight express Lodestar X2 color is an unusual camera. Its designed to be a guide camera for telescopes.

Its very small and just a sensor, guide port and USB port. So you need to have a computer to run it and the computer supplies the power. What makes it interesting though is the sensor in the color version.

 

Its a Sony ICX 829 AKA sensor with a YCMG color filter grid. NOT the typcal RGGB, pattern. its also not a typical array with an odd pattern.

The pixel size is huge at 8.4 um, with only 752 pixels by 580 pixels on the chip which is 1/2 size. So the crop factor is 5.4x. Its also a CCD, not CMOS sensor.

 

No modification is needed, and this camera is a CS mount with back sensor distance of 12.5mm. So any lens will mount to it.

 

Using the KSS 60mm F3.5 quartz C-mount lens I was able to test its UV sensitivity using StarLight live software. There is no gain or ISO adjustment for the CCD astro sensors. So you just get shutter speed and aperture on the lens. All were shot with KSS set to F4 (Which is really F8). All images are saved as PNG files in software, I then saved them as Jpeg 75% in Infranviewer to upload here.

 

Flower in visible:

post-188-0-81057700-1569398041.jpg

 

Flower using 313bp25 with 330WB80 Improved filter, two UVB lights and shutter speed of 5 seconds:

post-188-0-20292200-1569398072.jpg

 

Flower using 303bp10 with 330WB80 imporve filter, single 8W 302nm light and shutter speed of 60 seconds:

post-188-0-57349300-1569398085.jpg

 

The software to run it is fun. Its designed for Astrophotography, but allows you to collect dark frames and stack with images. You can live stack images in Sum, mean or median to get better images.

 

It also seems to be the best to interpret the YCMG color array, as the developer worked with the Starlight express to get the true pixel pattern. In it you can adjust the color anyway you want.

It changes the way I look at UV false color and you can push almost anything you want. Its fun

 

Flower in visible with Wollensak 25mm lens at F4:

post-188-0-87105000-1569398491.jpg

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This is quite nifty! I tried one of this line myself a few years ago, with a monochrome sensor rather than color. It worked ok for the low light situations that I got it for, but I was not satisfied with being tethered to the computer and got the Sony A7S instead. (Of course now I have the same limitation for the TriWave, but I accept it because it’s the only practical way to take SWIR pics that I have available.)

 

Can you successfully white balance the visible pic?

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Color with this software and sensor is a bit of an art. The software options are extremely limited. You have starlight live, lodestar C and starlight vision.

I have only really played with starlight live. Nobody else can demoisac the color filter. The Raw format is FITS, which can be opened in starlight live and deep sky stacker. DSS, maybe able to demoisac it, it now has 15 different CMYG profiles.

Image J, Gimp and FITS liberator can open the raw, but not demoisac the pattern.

 

So I will have to play more. The colors are very different. I will have to image my color checker again to show the difference.

 

So you may be limited to PNG editing, which is 16bit so not too bad. It can be portable if you have a tablet. Its a tube 80mmx31mm and the Wollensak 25mm is very small on it.

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Do you have programming skills? You could easily just write your own demosaicer. ImageJ plug-in might be a thought. I would do MATLAB naturally. :)
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I have never programmed something that complex. I have figured out the array, its similar to what Fuji has, but little different.

Unless I could figure out Raw therapee, I don't think I would bother.

The color tools in starlight live are enough.

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Check out these amazing colors using a color checker.

Lodestar X2 color camera with Wollensak 25mm f1.5 lens set at f4

Using Exotrra UVb lamp

post-188-0-53490700-1569913574.jpg

 

post-188-0-80143400-1569913590.jpg

 

Using room fluorescent lights

post-188-0-71561700-1569913604.jpg

 

Yes the Grey patch seems to have color.

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No filter. Just Lodestar camera, Wollensak 25mm f1.5 lens and different lights to see how "accurate" the colors are.

I see now why all camera manufacturers went RGGB. The black to white range with grey in the middle, far right of the color checker is brown in CMYG. I can also get off white to go rose.

 

I will need to do a side by side. But am fairly certain it doesn't look that way. I don't think its pulling out some magical colors I can't see.

 

The top UVB image I had my 302nm light on by mistake, upside down. So it gave the lower white tiles some rose color on the left.

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