ATIK CCD and Filters

[Tinker1947]

Is there a need to use filters like IR/UV when imagine with the CCD, my LP isn't very bad least ways there are no visible lights or light shadows in my garden.

[nytecam]

Is there a need to use filters like IR/UV when imagine with the CCD, my LP isn't very bad least ways there are no visible lights or light shadows in my garden.

I use a OSC cam unfiltered but unfiltered CCDs are very sensitive to near IR [beyond the visible spectrum]. With your 100% SW reflector you'll have no problem with bloated/defocused stars as this is usually associated with refractive optics, focal reducers etc so give it a go initially. Any IR/UV filter will reduce the sensitivity of the camera

[Martin-Devon]

If you use any LRGB or narrowband filters, then the cut is already built into these, so no need - but if you don't use one of these filters then yes you'll need a UV/IR filter

[rfdesigner]

I image with no filters at all for my mono shots and can get 2 arc second FWHM from the OTA. But then I have a reflector, it would look horrible with a refractor. If you want to get the very highest resolution then you will lose half an arc-second or so of sharpness on low down stars due to differential atmospheric refraction, but that's the worst of it.

It's also best to be careful what you mean by UV/IR filters, Baader do IR PASS filters, blocking everything except the IR. Astronomik do a set of three IR filters for NIR imaging too.

Derek

[ollypenrice]

Well now, I've always had a UV/IR in front of my OSC. It never occurred to me to try without one but perhaps I will, though I do use refractors.

Olly

[Bloom]

I recently (8 months ago or so) moved from dSLR to an OSC Atik 450L. I started imaging without any filter. While I got some very decent results, I noticed that the whole image had a look as if I had used a soft focus lens! The stars were not that bloated, so I did not immediately realise the problem. At the same time I was also having problems with colour balancing the new camera, so it took me some months to realise that the problem was that I was gathering IR signal along with RGB signal. The camera is sensitive to the IR, and it records it as "red". So you get more red colour than you should. The camera is also a little sensitive to the UV, but that is not so much of a problem. Two months ago I purchased a Baader UV/IR filter. Both the "soft focus" problem and the colour balance issues were solved.

IMHO since the CCD chips are quite sensitive to the IR, even in their colour versions, I think an IR blocking filter is sine qua non, if one wants to get the best out of the camera.

[Martin-Devon]

Interesting thread, I'd be keen to know if the IV/IR filters would give benefit only to OSC CCDs or whether they would add any advantages to mono CCD as well? Maybe I'll try it head-to-head and see the outcome with my Atik 460 mono

[Coco]

Interesting thread, I'd be keen to know if the IV/IR filters would give benefit only to OSC CCDs or whether they would add any advantages to mono CCD as well? Maybe I'll try it head-to-head and see the outcome with my Atik 460 mono

Ditto... I use an IDAS V2 and no IR, perhaps I should try one??

[Coco]

Ditto... I use an IDAS V2 and no IR, perhaps I should try one??

Never mind I found out I don't need one, its common question..

http://www.astromart.com/articles/article.asp?article_id=250

[FLO]

If you use any LRGB or narrowband filters, then the cut is already built into these, so no need - but if you don't use one of these filters then yes you'll need a UV/IR filter

Only the posh (expensive) RGB filters include UV/IR cut. If you use more affordable RGB filters you will probably need to include a separate UV/IR (L) cut filter.

HTH,

Steve

[FLO]

Interesting thread, I'd be keen to know if the IV/IR filters would give benefit only to OSC CCDs or whether they would add any advantages to mono CCD as well? Maybe I'll try it head-to-head and see the outcome with my Atik 460 mono

A One-Shot-Colour CCD camera will benefit from a UV/IR filter because it reduces star 'bloat' (the bloat is out of focus IR light).

Mono imaging sensors also benefit from a UV/IR for the same reason, it reduces star bloat. You should use one with your 460EX Mono.

An un-modded DSLR camera already has an IR cut filter over it's sensor but the UV/IR filter also cuts UV so you 'might' benefit from using one.

HTH,

Steve

[Earl]

A One-Shot-Colour CCD camera will benefit from a UV/IR filter because it reduces star 'bloat' (the bloat is out of focus IR light).

Steve

This is why when i used an OSC i had the IR blocking version of the CLS CCD Filters.

[FLO]

This is why when i used an OSC i had the IR blocking version of the CLS CCD Filters.

The IDAS LPS filter includes IR cut for the same reason

[Coco]

The IDAS LPS filter includes IR cut for the same reason

Thanks that was my next question

[Earl]

An IDAS will be on my shopping list it I do get a OSC again, not cast my vote yet.

[Coco]

I recently (8 months ago or so) moved from dSLR to an OSC Atik 450L. I started imaging without any filter. While I got some very decent results, I noticed that the whole image had a look as if I had used a soft focus lens! The stars were not that bloated, so I did not immediately realise the problem. At the same time I was also having problems with colour balancing the new camera, so it took me some months to realise that the problem was that I was gathering IR signal along with RGB signal. The camera is sensitive to the IR, and it records it as "red". So you get more red colour than you should. The camera is also a little sensitive to the UV, but that is not so much of a problem. Two months ago I purchased a Baader UV/IR filter. Both the "soft focus" problem and the colour balance issues were solved.

IMHO since the CCD chips are quite sensitive to the IR, even in their colour versions, I think an IR blocking filter is sine qua non, if one wants to get the best out of the camera.

How are you finding the 450?

[rsamuel]

Very interesting indeed! I bought an Atik 460EX OSC a little while ago, and wondered why I struggled to get decent colour out of it, even pushing the saturation to the max - images were always very yellow. Then after reading this thread, I realised my CLS filter was the one without the IR blocking, so did some experimenting with M42 last night - see http://www.rsamuel.me.uk/astroblog/archives/1014. I shall be using an IR blocking filter from now on!

Bob

[nytecam]

I recently (8 months ago or so) moved from dSLR to an OSC Atik 450L. I started imaging without any filter. While I got some very decent results, I noticed that the whole image had a look as if I had used a soft focus lens! The stars were not that bloated, so I did not immediately realise the problem. At the same time I was also having problems with colour balancing the new camera, so it took me some months to realise that the problem was that I was gathering IR signal along with RGB signal. The camera is sensitive to the IR, and it records it as "red". So you get more red colour than you should. The camera is also a little sensitive to the UV, but that is not so much of a problem. Two months ago I purchased a Baader UV/IR filter. Both the "soft focus" problem and the colour balance issues were solved.

IMHO since the CCD chips are quite sensitive to the IR, even in their colour versions, I think an IR blocking filter is sine qua non, if one wants to get the best out of the camera.

Interesting that your unwanted near-IR favours red?? Put my OSC cam on my stellar spectrograph and >1/3 of spectrum is in near-IR and recorded essentially colourless as you'd expect for invisible radiation Refractors can't [normally] bring invisible radiation to a common focus with visible [that the scope was designed for!] and hence the soft/bloated images from near-IR etc if not filtered out. In so doing the cam looses sensitivity recooped via longer exposures - if you're into that - I'm not and stick to reflectors

[Chris Rowland]

I thought that all the colour filters in an OSC camera were transparent to IR but maybe it depends on the device.