light pollution!

oxygn · Post by **oxygn** » Sat Mar 19, 2005 1:15 am

hi guys,

how do we reduce or even get rid of horrid light pollution in the photo?? photoshop editing or have to use LPR??

Thanks,
Colin

ISO 1600
30 sec - F/5.6
D70

light polution picture

ariefm71 · Post by **ariefm71** » Sat Mar 19, 2005 9:38 am

a lower ISO may help

oxygn · Post by **oxygn** » Sat Mar 19, 2005 11:21 am

thanks Arief. so am i right to say that if i use a lower iso, i would need a longer exposure time to collect the same amount of light that a higher iso would in a shorter time but the advantage is that i would not get too much skyglow in my pic?

Thanks,
Colin

Post by **weixing** » Sat Mar 19, 2005 11:38 am

Hi,
The lower ISO will not reduce sky glow. Use a LPR Filter to reduce the sky glow will be a better choice.

Have a nice day.

tanguan2001 · Post by **tanguan2001** » Sat Mar 19, 2005 1:00 pm

I use an LPR filter, which helps a lot. The other thing I have noticed is that at around midnight the level goes down quite a bit. So I now image mainly past midnight - but I miss my sleep!

TG

oxygn · Post by **oxygn** » Sat Mar 19, 2005 11:05 pm

hey all,

thanks for all your replies. if i'm shooting thru the the camera lens instead of the telescope, how do i use a lpr filter with that?

what kind of lpr is recommended?the ones that attached to the eyepiece or the ones that attached to the back of the scope(which cost more i think)?? are there anymore types?

and which brand of lpr filters would you guys recommend?

thanks again,
Colin

tanguan2001 · Post by **tanguan2001** » Sun Mar 20, 2005 8:00 am

Colin,

I use the Celestron LPR which fits to the rear cell of my C9.25. It's very good quality - no ghost reflections, provided used before the Focal Reducer.

One way of using an LPR with camera lens would be to get a 2" mounted one, and the appropriate step ring for the front of your lens.

Thinking of doing just that with my H alpha filter.

TG

MooEy · Post by **MooEy** » Sun Mar 20, 2005 10:55 am

they do have lpr filters bigger than 48mm, prolly all the way up to 82mm. but those are very very expensive.

http://www.sciencecenter.net/hutech/filtlist.htm

~MooEy~

oxygn · Post by **oxygn** » Mon Mar 21, 2005 12:19 am

tanguan2001 wrote:Colin,

I use the Celestron LPR which fits to the rear cell of my C9.25. It's very good quality - no ghost reflections, provided used before the Focal Reducer.

One way of using an LPR with camera lens would be to get a 2" mounted one, and the appropriate step ring for the front of your lens.

Thinking of doing just that with my H alpha filter.

TG

hey Tan Guan

is the 2" mounted one is the one that fits onto 2" eyepieces issit? the largest step ring seems to be 58mm. my lens is 67mm. anymore solutions?

Thanks again,
Colin

oxygn · Post by **oxygn** » Mon Mar 21, 2005 10:23 am

Hey Tan Guan

what does modifying your canon 300d do? does it improve the sensitivity to near IR range?? wouldn't i get a somewhat effect if i put an IR filter to let IR pass only, then i combine this frame with the visible spectrum frame??

do correct my ignorance.

Thanks,
Colin