Astronomik CLS Light Pollution Clip Filter for Canon Cameras

[bamus]

its 5 minutes each, iso 400

[swag72]

Surely if you take them at the same exposure you are going to 'see' less with the filter. As I understand it (or certainly how I use it) is it allows me to go for much longer exposures than without and so catching more data. Not sure what an experiment such as this one proves really.

Give it a go in real life with 10 min exposures and see how you feel about it then.

[Psychobilly]

I agree with Sara... the filter should allow you to dramatically increase the exposure time .. then you will start to see the benefit of using it...

Peter...

[bamus]

maybe you are right. would lowering iso and increasing time not give you same result?

other night I have done 5 minutes and 10 minutes exposures, both with filter. you can see slightly better nebula in second (10 minutes) one, but is it such a big improvement?

[Psychobilly]

When I started using LP filters, I found that I could then increase exposure time and ISO.. the mount and tracking then became and issue...

Peter...

[Vega]

Thats strange, my CLS works wonders. I presume you have Custom White Balance turned off with the new filter?

Matt

[bamus]

I am using custom white balans set on artificial light long time ago when I didnt have filter. Perhaps I should set it again with filter in. What While Balance are you using, Matt? Shuld it matter when I shot in RAW anyway?

[Rossco72]

What have you done with the white balance?

[bamus]

What have you done with the white balance?

I have changed my DSLR camera customs white balance settings manually in order to have nice dark blue sky on night pictures. Don’t remember where I have seen my method, but it works rather well. Anyway, it should not matter at all, as processing is done on RAW files. Is it not right?

[malc-c]

One thing I've noticed when using my CLS clip filter is that it gives everything a greenish blue tinge. I have the 400D set to manual, so I'm guessing its the filter that's affecting the white balance ?

For example. Here is a straight export from nebulosity of a RAW image taken with the filter, then the processed one which has been de-bayered , and stretched. As soon as any image is de-bayered all stars are blue !

[mattias]

I have a EOS 600d and I was thinking if it's possible to use the clip filter with the camera unmodified, just to get the light pollution filtering?

How does the clip filter affect the WB in daylight use? If I do not remove the blocking filter, could it work transparently with the addition of removing the unwanted wavelenghts?

[bamus]

One thing I've noticed when using my CLS clip filter is that it gives everything a greenish blue tinge. I have the 400D set to manual, so I'm guessing its the filter that's affecting the white balance ?

For example. Here is a straight export from nebulosity of a RAW image taken with the filter, then the processed one which has been de-bayered , and stretched. As soon as any image is de-bayered all stars are blue !

I also have got same problem. i find it verry hard to do proper RGB balance on final pictures.

[malc-c]

I have a EOS 600d and I was thinking if it's possible to use the clip filter with the camera unmodified, just to get the light pollution filtering?

How does the clip filter affect the WB in daylight use?

I've always removed my clip filter for normal use of the camera. I only fit it when the camera body is attached to the scope

[malc-c]

I also have got same problem. i find it verry hard to do proper RGB balance on final pictures.

Yup, trying to adjust the sliders to remove the blue / green tinge on colour balancing without affecting the image is a pain. It also loses a lot of the colour definition of the stars, so every one looks that same, rather than the yellow and orange that you get under clear un-polluted skies.

But, it at least does allow us to get results from areas that are LP

[mattias]

I've always removed my clip filter for normal use of the camera. I only fit it when the camera body is attached to the scope

How much does the Clip-filter affect the image when the IR filter is still in place?

Do you find it useful "enough"?

[Rossco72]

I also have got same problem. i find it verry hard to do proper RGB balance on final pictures.

On my unfiltered 450D with the CLS I simply leave the camera to AWB or automatic and although everything looks green through the view finder, the final images all come out correct.

The camera seems pretty smart at working it all out for itself...

Cheers

[studdedsole]

I leave white balance as automatic in camera and then colour balance images after stretching in PS. Select each of the RGB channels individually in levels and move the black points to the start of the histogram peak. Using the colour balance sliders in PS is more subjective and prone to colour balance "errors".

The CLS filter works well with and without the IR filter in camera but as has been mentioned, the CLS allows longer exposures before LP becomes a factor. IR filter removal improves Ha response.

[bamus]

CLS allows longer exposures before LP becomes a factor. IR filter removal improves Ha response.

Ok then. My worry is fact, that I am not getting any more useful signal on 5 minutes subs with filter comparing to the subs without.

I can push for 10 minutes if I have to, but noise is drastically increasing in longer subs when DSRL is used.

I might wait with sale of this filter for few more weeks perhaps and try longer subs and change ABW balance to see if there is any noticeable improvement.

[swag72]

Ok then. My worry is fact, that I am not getting any more useful signal on 5 minutes subs with filter comparing to the subs without.

You won't get any more useful signal on a 5 minute subs with the filter compared to without. The whole point is that you can get longer subs, not use the same exposure time and get more signal.

I can push for 10 minutes if I have to, but noise is drastically increasing in longer subs when DSRL is used.

You will get more noise on a 10 minute sub, but to cancel that out you take a number of them and also dark frames so that a lot of the noise can be subtracted.

Regarding WB - I have used my CLS clip filter on both modded and unmodded camera's. I shoot in raw and leave WB to auto.

Hope that helps.

[studdedsole]

Remember that a filter will reduce your "useful signal" capture rate by its very nature. A LPR filter will aim to reduce the signal from light pollution by blocking these wavelengths and minimise the loss of "useful signal" with a rejection bandwidth which is sufficiently broad so as to block sodium and mercury street light outputs but trading off the width so as not to impact wavelengths of light close to sodium and mercury.

The whole point is to allow you longer to collect the "useful signal" without washing out the image with orange glow.

Find the point where LP just becomes obtrusive in the subs, back off a little and collect many images at the same ISO and exposure time and stack as is usual.

Noise will reduce with the inverse square root of the stacked images. so 4 stacked images will result in half the noise and 100 stacked images will reduce the noise to a tenth of a single image

[Rossco72]

Here's a 5 minute ISO 800 sub using my Canon 450D and a CLS filter from fairly light polluted Glasgow.

I think the CLS with AWB works quite well.....

Cheers

[dark knight]

Bamus, try changing the ISO from 400 to 800 and see what difference it makes.

[fielderda]

Very interesting study for the Astronomik CLS filter. 

While there's been some threads related to the types of lens used, I presume  the CLS filter should work well with my Canon 60D attached to my Celestron SCT EDGE HD 8" with 0.7x focal reducer should work very well?

Any comments are welcome

Another recent Newbie!