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ZWO ASI178MM-cooled – UV Imaging (part 2) contd

Q4. What would the image look like at the lowest read noise setting i.e. Gain 300, using the fluorescent tube lighting?

Answer: There is a gain of just over 2 stops compared to Gain 100, while the image is not too grainy. A good compromise if looking for the fastest shutter speed.

1s image at Gain 300 using fluorescent tubing and Baader U
1s image at Gain 300 using fluorescent tubing and Baader U
1 sec exposure @ Gain 300, Baader U filter using Fluorescent light from indoor studio
1 sec exposure @ Gain 300, Baader U filter using Fluorescent light from indoor studio

Q5. What does the image look like at maximum gain i.e. 510?

Answer: It does capture the flower details but at the expense of a much grainier image and lower dynamic range, similar to using higher ISO settings. But does allow for much faster shutter speeds to be used.

Image below was taken with the fluorescent light tube of the indoor studio, using the 330AF20 filter.

2s exposure at maximum gain 510, Baader U using fluorescent light from indoor studio
2s exposure at maximum gain 510, 330AF20 filter using fluorescent light from indoor studio

Q6. Can the liveview image on the computer allow for adjusting of focus with deeper UV i.e. 330AF20+325BP10 stack, using the light from the fluorescent tubing?

Answer: Yes. With an exposure of 2.2s, it is possible to even use the tiny amount of deep UV light emitted by the fluorescent tubing to adjust focusing, which was previously impossible with other cameras.

View of flower with 330AF20+325BP10 filter stack lit by fluorescent tubing at Gain 510
View of flower with 330AF20+325BP10 filter stack lit by fluorescent tubing at Gain 510

Q7. What would the dandelion look like when imaged at 303NB3 (300-306nm) using this imager?

Answer: See below. I don’t think much UV is getting through to the sensor, due to the AR window protecting this camera. Now if ZWO do produce a Fused silicate window, then it would be worth getting it and doing a retest. For this image it would not be possible to adjust focus via Liveview due to the bandwidth being passed by the filter.

Image shot with 303NB3 (300-306nm) filter
Image shot with 303NB3 (300-306nm) filter – Gain 300 with full burst from Quantum X4D

Now there are things that I thought would be interesting to test, which I may or may not be able to do:

  • Narrower band UV imaging and stacking of these to create false-colour UV images, similar to how LRGB astrophotography images are made. The Baader U can then act as the luminance channel; perhaps using 320-340nm & my 340-390nm filter for the green and blue channels. Not sure how this will work, but it may prove very interesting.
  • As there are 7″ tablets available with a USB port and able to run Ubuntu operating system, it should be possible to connect a ZWO camera to a tablet using the free software OaCapture (which has native support for ZWO cameras) to create a more mobile setup for UV-imaging. This is definitely beyond my capabilities, so we shall see if anyone else out there can get such a setup to work.

Boon

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