Help wanted

Hi all,

I have been experimenting with a 50mm lens on my CCD and getting some nice images. However due to the presence of a bright moon, (why is it always clear then!!???) there is a strong gradient across the image which I am having difficulty in removing.

The image below is of Gemini and the IC 433 region, and is a jpg copy of the original. If anyone would like to have a go at removing the gradient, please feel free to have a go. I would be very interested in seeing your results and of hearing how you managed it.

I have Photoshop 7 as well as CCDSoft and API4WIN for my processing. I have also tried the process described in Ron's book without success.

Thanks in advance.

Maurice

Attached Image:

Hi Maurice,

the best thing is to avoid recording the gradient! Because the CCD frame is so small compared to the 35mm film you can apply a lonmg extension tube made from cardboard in front of the lens.

The idea behind it is that 90% of that glow is not from the sky background nad the moon, but from the moon shining in some angle onto your front lens. This light though not directly reaching the CCD is scatterd. That scattering is reaching the CCD!

When the air is reasonable transparent you can have great results with no gradients. When the air is dewy then the extension tube will fail, because the light was already scatterd in the atmosphere.

If your lens has a reasonable multi-cotaing you should definitly give it a try.

Good luck
Tom