Need help on white balance setting and focusing:

[Jonarsh]

Hi guys,

I need some help regarding white balance setting on my 5D Mark III. I seem to be capturing a lot of light pollution coming in after long exposures, and the background of the sky is either yellowish or reddish....how do I ideally get a dark sky but with the target full of details and color?

Also, for focusing, is there a method? I am using live view x 10 on my 5D and then trying to adjust the focusing on my Omni 127 Xlt manually but can always seem to get a pin point sharpness, do I need to get any device?

Thanks!

[orly_andico]

Buy BackyardEOS and use it to control your camera; this will also download the images as RAW.

However, you can't do anything about the yellowish/greenish background - that's light pollution from high pressure sodium lighting. The only way to reduce it is with a light pollution filter. I would suggest the IDAS LPS-P2 (not the V4). The filter basically blocks the frequency of sodium lighting. It will be far from perfect, but still better than nothing.

[Jonarsh]

Thanks Orly! Will give it a shot....

[cloud_cover]

Hi Jonarsh:
1. Regarding Light Pollution, as Orly said, ideally you'll get a LP filter, preferably a UHC type filter. Don't bother with Broadbands, they are not very effective in Singapore. This will, however, drastically increase your exposure times and are effective only for emission nebula and planetaries, as a rule. Stars and starlight objects such as clusters, galaxies etc. are not helped by the UHC filter and are in fact dimmed. In these cases the best solution is either to generate subs as long as the light pollution will allow, or to apply a "Petrol filter" and drive up somewhere else

2. Regarding background: You will need to minus off the light pollution (even if you use a UHC filter). One way is to apply an inverse mask and then merge the layers. Another cruder way is to set a typically light polluted point as the greypoint but it will not correct for gradients (places where the light pollution glow is stronger, such as when shooting over the CBD's direction). You can google the various techniques.

Hope it helps!

[Jonarsh]

Thanks for the tip cloud cover! Will check it out...