Which Filter for light Polution?

[Jgw]

Hi folks,

Where i stay is really quite close to the Airport, yes and you can quess,a lot of light polution...

A question to all the experts, is there any good light polution filters on the go ...?

Which one do you think would be good for Canon 350D...

Thanks for your Help...

Cu John

[Atlas]

Orion makes a ultra-block filter specifically for that use.

Orion UltraBlock Narrowband Filters | Orion Telescopes: Filters

[GlassWalker]

I use the Astronomik CLS for general purpose light pollution reduction. I got it in EOS-clip fit so it fits inside the camera body and can be use with most lenses except EF-S lenses. They do a slightly more expensive CCD version too which blocks IR contamination, which may be a consideration if you intend to modify the camera at a later date.

That Orion Ultrablock looks interesting too, if a bit less general in usage. It is comparatively narrowband around OIII and H-beta so my thought was it might be best for visible viewing or other broader spectrum subjects. No use if you're after H-alpha.

[malc-c]

+1 for the EOS CLS clip filter -

[rfdesigner]

take a look at this

Astronomical filter curves

the astronomik UHC and the lumicon deep sky filters are independantly, spectrally tested.

Derek

[Jgw]

Hi Folks

Many thanks for your help. I like the Idea of the Clip filter, as the sensor on the Camera, gathers a lot of dust Etc...

Btw. Thanks for the Link, some good info there!

Or maybe I could ask the Airport to turn of there lights?:D:D

Cu John

[Gina]

I'm using an Astronik CLS-CCD clip filter. I did a couple of test shots last night of the southern aspect from here with a number of orange street lights and several white house lights, firstly without then with the filter. The orange street lights disappeared completely and the white lights turned blueish and a bit dimmer. I got the CCD version to work with an 1100D with both filters removed. The CLS filter certainly removes street light pollution.

[Jgw]

Thanks Gina,

My problem is, that I can do no more than 180 Sec, and then too much light. I would like to capture with 5-10 min, so with so much light polution, forget it..

So I will just have to take the plunge...

Cu John

[rfdesigner]

So you're imaging.. I hadn't really twigged despite the 350D comment (doh!)

How about imaging in narrow band?.. if you're pushed for cash just go for a Ha filter. I've seen great Ha images from people even when it's a full moon.

The imaging band is ~300nm wide, Ha filters of 7nm mean about 98% glow reduction.. and with a 3nm wide filter you'll get 99% improvement.. assuming the unwanted light is 'white'. If it's spectral then it will be much better still.

Derek

[Viv]

another vote for the CLS CCD clip in

With a horrible street light right behind me, am getting 4 minutes ok. Not tried beyond that yet.

need to have a test evening, to see what I can push it to ........

[Jgw]

Sorry , I didnt mention that yes I,am imaging, well trying to..

Thanks for the idea about Ha filter, never thought about that...

Just being curious? Does anyone have a Foto of Orion in Ha?...

Here is a Foto I made last week, with 5 x Lights 180 Sec & Darks

Cu John

M42.bmp

[Gina]

Nice one

[GlassWalker]

Here's my attempt at Orion in Ha only, with the Astronomik Ha 12nm filter. Not going to be the best as no darks/flats applied.

Oh, one thing to be careful about. Unless the camera is modified for astro use, the standard sensitivity at Ha is relatively low.

[Jgw]

Hi Glasswalker,

Thanks for the Foto, looks very interessting..

Cu John

[Gina]

That's a rather different looking M42 from a full colour one. Great image