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Hello all

Im about to do a Astro conversion on my Canon 550d so I can do the h alpha stuff better. I have a Astronomik CCD clip in filter with the IR cut already there. What do people think the main benefits are of full spectrum to one with just a IR cut off is. 

I know it will mean with full spectrum I can use only the filters that are made for that. Is it better in some ways to have a camera you can use without any filters. 

Thanks to all

Gerry

 

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Not sure what you mean here exactly...

full spectrum means that all light will pass to the sensor, so to Image you will need an IR filter in the Imaging train somewhere, or you will get star bloat and or halos around your stars, so the clip in you have would be ideal.

the Normal Astro mod, as I call it, means that one of the filters is left in the camera, as this filter gives very good IR cut, but does not affect the Ha signal passing, so an external one is then not needed, but as you already have a LP filter with IR cut then you may as well have the full spectrum mod.

as for only being able to use filters for full spectrum mod, well not sure what you mean here...!! :)

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It isnt a “full spectrum mod versus one with just IR cut off” as you say

its full spectrum mod (all light can pass through) versus the mod with IR cut left in the camera....so IR light will be blocked, which is really what you need, unless you plan on doing full spectrum imaging...which I doubt. :)

 

PS. Just re read your post, and made a bit more sense of it now, it was me being a little thick, but still think the above helps a little.. :)

Edited by LightBucket
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The IR cut filter that is in the Canons will be passing about 20% of the incident Ha at present, so the mod removes this IR cut filter to allow all the Ha wavelength through. You now get nice Ha enhanced images.

So now you have Ha @650nm (more ot less) but you now also have the other IR wavelengths at 700, 750, 800nm etc. Those are no use and cause problems in focus, so what people do is that slap a clip on filter over the sensor, or  have the removed IR cut filter replaced with another IR cut that cuts off wavelengths below say 700nm or below 680nm, but one that allows the Ha wavelength through.

That way you get the Ha through and cut off the longer unwanted IR.

What you have done is in a way simply change the IR cut filter for another that cuts off a bit further along the spectrum.

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You do need some sort of IR filter which you already have. I would just take out the canon filter and leave it empty and then just keep you clip in filter in place.

spill

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Hi yes 

I thought it could be misconstrued :) yes I just wondered if there was any benefits NOT doing the full spectrum mod. For example say I get a IR filter put into my camera instead of full spectrum and then I place my Astronomik Cls ccd clip which also has the 700nm cut off does that make a problem? As I'll be in effect doubling it. 

As I haven't done my camera yet and still choose I just wondered if there was someone there that got the full spectrum mod and then wished they didn't. 

Like if you replace the filter on the camera you can take photos of nebulas without any clip in filters in place but with a full spectrum your constrained to use the filters. 

Thanks for the help :)

Gerry

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I really am not 100% but am sure it would not make any difference. The only thing I can think of is if you replace the standard canon ir filter with a baader or similar then you can also use a Ha clip in filter if you wanted. Although again I am not sure how a Ha filter will perform without an ir filter in the train.

spill.

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4 hours ago, Gerry Casa Christiana said:

No I know you can use H alpha with a full spectrum mod no problem just wondering if people were happy with their full spectrum mods as opposed to a baader. 

I have a full spectrum mod, I chose it was there is a slight reduction in resolution if you leave the anti-aliasing filter in place and I have a UV/IR cut on my CLS filter anyway. 

Problem is that a lot of glass removed so it does shift the focal length slightly. So you probably do want the Clear Glass window to compensate for this if using a lens. If using a scope then its less of an issue but I did find I needed to tweak / reduce my CC separation my 1mm or so to get the best correction.  

Overall I would say that if you want an easy life then just go for the IR mod. 

So am I happy, yes, but then I did it myself so I cant complain too much. It seems to me that if a pro is doing it then you can expect a decent result either way but I do hear that the quality of the Astronomic MC Clear glass replacement is superior to the baader filter which can cause minor reflections / has been know to have some optical imperfections. Overall you will also need some kind of IR/UV cut of you go for a full spectrum so the cost of that is worth considering. 

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I have and use the FULL full Canon mod ( both the colour correction and the anti alias filters removed) for spectroscopy.

The Ha response is certainly enhanced by the removal of the colour correction filter and the remaining anti alias still acts as a UV IR filter.

I've uploaded previously the transmission graphs of both these filter elements in an attempt to show the differences.

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Two issues I can see is that you can't use the clip filter with Canon EF-S lenses (most EF are compatible) so if you ever intend on using one you will probably have to get a UV/IR filter in there somewhere.

Removing both filters could make achieving infinity focus difficult or impossible on some lenses (as already mentioned above).

 

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I'm toying with the idea of getting a full spectrum camera so I can also use it for IR or UV daytime photography with an appropriate filter in front of the lens, but I'd need to make sure it reaches infinity focus (I'm not sure the best way of achieving this). That's the only real advantage to full spectrum that I can think of.

Edited by Knight of Clear Skies

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To use the standard camera lenses with my FULL full mod I use an Astronomik clear clip in filter.

Works very well.

 

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The thing im not sure about is the anti antialiasing filter which softens the picture a lot on the Canon 550d. If I choose a ir cut leaving the LPF1 in the camera it will still have the anti aliasing filter in. If I do it full spectrum then I get bloated stars, but surely not with a filter like the Astronomik Cls? Which I have!

Not sure what route to go. 

Gerry

 

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You won’t get bloated stars as long as you have an IR filter somwhere in the imaging plane...

i would go for full spectrum and use your CLS CCD filter afterwards :)

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Nice thread or topic, i was planning to mod one of my DSLRs, but good i bought a cooled mono camera.

My question is, what about those CCD/CMOS mono astro cameras or even the color one whether cooled or not, are they modified already when purchase them? are they full spectrum already? example such as ZWO/QHY/ATIK/SBIG,...etc

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1 hour ago, TareqPhoto said:

Nice thread or topic, i was planning to mod one of my DSLRs, but good i bought a cooled mono camera.

My question is, what about those CCD/CMOS mono astro cameras or even the color one whether cooled or not, are they modified already when purchase them? are they full spectrum already? example such as ZWO/QHY/ATIK/SBIG,...etc

They are dedicated Astro cameras, of course they are full spectrum, that is the whole point of an Astro Camera, full spectrum mods only apply to daytime normal cameras...., I think you need to do some reading my friend.... :)

Edited by LightBucket

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6 minutes ago, LightBucket said:

They are dedicated Astro cameras, of course they are full spectrum, that is the whole point of an Astro Camera, full spectrum mods only apply to daytime normal cameras...., I think you need to do some reading my friend.... :)

I said i want to modify one of my DSLRs cameras, but i ignored this idea because i bought an astro camera, so i know that full spectrum modification is applying for non astro cameras, but i don't know if astro cameras themselves are modded as full spectrum or different modification.

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