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Questions about Full Spectrum Mod

beamer3.6m

By beamer3.6m
in Discussions - Cameras

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beamer3.6m

beamer3.6m

Posted
Posted

In easy to understand terms can someone please clarify the following:

1. What is a Full spectrum mod

2. If I use a camera modded in this way with the 130pds (Newtonian) will any other filters be required etc.

3. Can you still use the camera live view

4. Can you still capture planets via the live view (admittedly this is not ideal)

5. Can it be used in daylight

6. If no to 5 why not and can this be corrected

7. Can you still capture images other than nebula (say clusters etc) and if so is there any degradation in the image.

8. Can you still use a lp filter to help with street lights.

9. Will the mod be affected by a coma corrector.

My intention is that this camera will hang on the back of my scope permanently in the Box Observatory.

I have been offered a camera modded in this manner so I don't need to know about the IR/UV mod.

Confused confused confused.

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Vox45

Vox45

Posted
Posted

I'll do my best :) feels like a Quizz ...

1. What is a Full spectrum mod

The act of removing both in camera filters (LPF1 and LPF2)

IR Filter

2. If I use a camera modded in this way with the 130pds (Newtonian) will any other filters be required etc.

arf, don't know for reflectors. For refractor you need to add an UV/IR filter to prevent star bloating as the IR does not focus at the same point.

3. Can you still use the camera live view

sure

4. Can you still capture planets via the live view (admittedly this is not ideal)

sure

5. Can it be used in daylight

no.. and yes ;) some people use their full spectrum camera for daylight photography but not the way we intend to do us mortals ...

6. If no to 5 why not and can this be corrected

you'll get all the IR light that is usually filtered out by both filters (LPF1 and LPF2) those are low pass filters responsible for filtering infrared light

Usually people just remove LPF2 to image Ha band. You do not need to remove both filter, although some people do for a couple of reasons. Removing LPF2 and replacing it by a clear glass will allow you to retain autofocus, you can then do a white balance to correct the extra red you will get and use you camera for 'normal' daytime photography.

7. Can you still capture images other than nebula (say clusters etc) and if so is there any degradation in the image.

image will be red, this can be corrected in the processing stage

8. Can you still use a lp filter to help with street lights.

sure, some CLS filter also include IR filtering (Astronomik CLS-CCD) Again, if you remove only LPF2 you still have infrared filtering inside the camera (LPF1) and this is only needed for refractrors, my understanding is that reflector will not be affected by star bloating (need some experts quote here) !

9. Will the mod be affected by a coma corrector.

don't know

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Vox45

Vox45

Posted
Posted

I simplified a bit, LPF1 is filtering IR and LPF2 is filtering 'red' to a certain frequency, and unfortunatly, it filters too much (the Ha we need) that is why we remove that filter.

To quote my mentor: "LPDF2 is the filter that "constricts" light to what we "see"...or what we want to see from our cameras(daytime users..obviously)..also known as the "color balance filter"

I'll let the expert expand on this ;)

If you leave LPF1 (the actual IR filter) you are filtering most of the IR so adding another IR filter in camera (Baader) or outside (IR cut lens) is not necessary. I am sure lots of people will disagree but I've read everything and the opposite on this so I cannot say for sure. LPF1 has also an antialiasing filter so removing that can be good.

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Vox45

Vox45

Posted
Posted

Ho, one more thing...if you don't put a clipin filter then your sensor is exposed to dust and debris.

That being said, I've read before that having a full sprectrum mode has another advantage: less glass surface where dust can cling ;)

(1) 2 sides of LPF1

(2) 2 sides of LPF2

(3) the coating over the actual sensor

So that's 5 piece of glass were dust can cling to. A full sprectrum has only 1 ...

Not sure if this is something I would feel comfortable with but it made me chuckle at the idea...

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Merlin66

Merlin66

Posted
Posted

Beamer,

Unless you really want to image faint Ha nebula then the stock 450D will work well.

I have and use both!

The modded 1000D, FULL spectrum mod, for spectroscopy and the 450D for everything else.

BTW on astro objects the mod doesn't give you red coloured images......only where there IS red emission (Ha) will it be accentuated. No impact on the rest of the colours... 

I added an Astronomik CLS (clear) clip in filter to the 1000D to allow std lenses to be focused.

Hope this helps.

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Thalestris24

Thalestris24

Posted
Posted

Louise,

I can only assume that you are using some refractive (lens) optics in the reflector - reducer? coma corrector?

It's certainly not coming from the mirrors.

Hi

Yeah, I have a coma corrector. In any case, I have very bad lp so need the lp filter.

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Vox45

Vox45

Posted
Posted

Louise,

I can only assume that you are using some refractive (lens) optics in the reflector - reducer? coma corrector?

It's certainly not coming from the mirrors.

Good point ! I was confused by this when I had my C6. I did not realise right away that even though my scope was a reflector, I was affected by this since I was using refractor elements... a reducer in my case.

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Thalestris24

Thalestris24

Posted
Posted

Good point ! I was confused by this when I had my C6. I did not realise right away that even though my scope was a reflector, I was affected by this since I was using refractor elements... a reducer in my case.

Hiya

I'm not sure if just having a coma corrector actually makes that much difference. To be honest, it's quite a while since I had the mod done and I can't remember whether or not I tried the camera on the 130pds without the cls-ccd... In fact, looking through the archives it doesn't look like I did, or didn't keep a record if I did. In that case I may be guilty of disinformation and I apologise! :embarrassed:  I was relying on my memory which isn't so good these days. I'll have to try the 130pds+fs mod without the cls-ccd one day. But, being close to the city centre, I suffer from bad lp.

Louise

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  • 5 weeks later...
MarsG76

MarsG76

Posted
Posted

In easy to understand terms can someone please clarify the following:

1. What is a Full spectrum mod

2. If I use a camera modded in this way with the 130pds (Newtonian) will any other filters be required etc.

3. Can you still use the camera live view

4. Can you still capture planets via the live view (admittedly this is not ideal)

5. Can it be used in daylight

6. If no to 5 why not and can this be corrected

7. Can you still capture images other than nebula (say clusters etc) and if so is there any degradation in the image.

8. Can you still use a lp filter to help with street lights.

9. Will the mod be affected by a coma corrector.

My intention is that this camera will hang on the back of my scope permanently in the Box Observatory.

I have been offered a camera modded in this manner so I don't need to know about the IR/UV mod.

Confused confused confused.

 Full frame mod means its a bare sensor that block no specturm.. effictively seeing all the way from 350nm - 850nm or so...

You should use filters with it, IR/UV Cut for RGB, IR Pass for NIR, Halpha for hydrogen alpha narrowband etc... otherwise you will have halos due to different focus point for different light, for example visible vs IR

LIve more works

Yes for planets, preferablt with filters,

Yes for day light but will need manual focus and custom white balance due to the red shifted sensitivity.

Yes for LP filters 

and

A corrector will not effect it at all negatively, will still be sensitive to full spectrum.

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