Wednesday, July 08, 2009

Comparison of white light images taken with different color filters

Date: 2009-07-08 (Around 1400-1440@GMT+8)

Telescope: Tele Vue Ranger 70mm f/6.8 ED refractor
Filter: APM Herschel Wedge plus B+W ND3
Barlows: Tele Vue Powermate 5x
Camera: DMK 31AF03
Mount: Meade LXD55

In addition to the above, different color filters were used, they include:

1. Yellow filter from Antares #12 (Japan) - exposure 1/1000s

2. Blue filter from Zhitong #38A (China) - exposure 1/108s

3. Green filter from Zhitong #58 (China) - exposure 1/45s

4. Red filter from Zhitong #25A (China) - exposure 1/736s

Registax V5 is used for the stacking job, MAP were used with 3 alignment points, around 1200 frames were captured for each individual AVI.

I guess we will agree that the blue and green ones are better of the batch, so I took two more clips for comparison:-



Finally, I have briefly compared the eyepiece view with #58 (Green) and #38A (Blue), the amount of detail is similar through both filters, but I prefer the dimmr view from the green filter. Visually, dimmer view could be more pleasing but photographically, I tend to believe that my blue filter has a slight edge here, since it allows faster shutter to freeze poor day time atmospheric seeing.

Of course, we need more experiments to confirm since day time seeing tend to vary quite a lot, even among experiments taken a few minutes apart and thus, sharper result could be a just result of momentarily better seeing, and thus might not be fully a result of better filter.

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