"pollution solution"

[stan26]

Quite chuffed with that title

Following on from my "idea thread" in the imaging discussion section, in total stan26 el cheapo style I have successfully installed a skywatcher light pollution filter into the rear of my Canon 200mm USM L lens, and the results are looking good......

I have opted for the Skywatcher LP filter, as the cost and previous reviews suggest its great value for money, we like that. It comes in a nice little padded box, and overall quality seems very good. The coatings on the glass give the filter a purple tint. It also comes supplied with a little paper spectrum graph to show what the filter does between 200 - 1100 wavelength nm. It has many spikes and troughs with a big cut at around 580-600nm. Thats a very good thing because that area of the spectrum is street light LP territory, And that is the main problem I want to tackle.....

skywatcher lp filter by James stannard, on Flickr

To fit the filter in the rear of the Canon 200L, I simply used an O-ring around the filter housing to create a nice tight fit in the exit aperture of the lens, and used a 35mm internal circlip to hold it in place. The circlip bit is very important. I hate to think what would happen if the filter fell into the camera body whilst Imaging

filer by James stannard, on Flickr

filter in lens by James stannard, on Flickr

Total cost: Skywatcher LP filter £20. Circlip FOC from local bearing supplier (brammer UK), O-ring FOC from work. Total cost £20. VS astronomik clip filter....well..........:(

A quick test in between cloud I done earlier. These image's are totally un-edited crops. I think the results speak for themselves...

filter test by James stannard, on Flickr

I would like to mention First light optics for there excellent online ordering service. I ordered the filter late Sunday, received it Tuesday morning free delivery. Excellent service highly recommended!

stan

[Ags]

A very impressive result!

[wired2moon]

Wow, I didn't think a filter would make that much difference. Well done

[Chris]

I can't believe the difference it makes for 20 quid! I said you should be working for Skywatcher Stan:D they should at least give you commision I bet they sell like hot cakes now, I'm getting one:headbang:

And yes very clever title;)

[Gina]

Great solution - wonderful title

[terrym2002uk]

Very neat. Did you set a custom white balance in camera or just fix in processing?

[Sam]

That has made quite a difference, nicely done and a great idea.

[LukeSkywatcher]

Good to see your idea worked. Impressive results. I wonder if i can fit my filter into my lens. I'll have to check it out.

[Gonzo]

great results, off to buy the 2" one now

[stan26]

Very neat. Did you set a custom white balance in camera or just fix in processing?

The camera is set to auto white balance, neutral shooting mode. In fact I have used AWB for all my imaging. Absolutely NO adjustments have gone into the above pics, just cropped in PS and thats it, thats how they are completely raw off the memory card.

Would you guys recommend setting a custom WB for astro work..?

Stan

[terrym2002uk]

The camera is set to auto white balance, neutral shooting mode. In fact I have used AWB for all my imaging. Absolutely NO adjustments have gone into the above pics, just cropped in PS and thats it, thats how they are completely raw off the memory card.

Would you guys recommend setting a custom WB for astro work..?

Stan

To be honest I'm not sure if raw files take into account the white balance settings. I guess it depends on the software that you use to develop them.

But either way and excellent solution for doing wide field.

[LukeSkywatcher]

I just had a look at my camera lens' and i dnt think i can do this with my LPF. A better option for me would be stepdown rings on the front end of the lens. That could be expensive for something that really isnt that much of an issue?

[Psychobilly]

Step down ring should only be around £5-6

[Ags]

Yep, I think I will either get clipins or get step-down rings. The advantage of putting the filter on the front is that you can use filters with very narrow passbands - not possible with a rear-mounted filter at F rations below 4. Of course, front-mounting only works for lenses up to about 100mm