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Astro modded DSLR - question for "les experts"


davefrance
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from what i understand its just the Ha that would improve which is red

Thanks Martin, that is what I thought but wanted to check.

Still playing with Pleiades but here is the latest attempt

post-34685-0-90463600-1423914982_thumb.j

Have left the satellite trail in for the moment

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  • 2 weeks later...

The LP2 filter in a Canon DSLR blocks IR and quite a lot of the Red" region. By removing this filter we let the Red and IR photons strike the sensor. However, letting the Red which is H-alpha onto the sensor is a good thing, whereas the IR is not so because it focuses differently in Refracting systems and thus produces "bloated" stars. A parabolic system like a good reflector will not have that issue. Blue and Green will remain the same regardless of the filter being there or not. In refracting systems one can use an IR/UV 2" filter with theT threaded  nose piece to cut off only the IR and UV and still allow H-alphs to pass.

I will be modding my camera tonight mostly and will post results in a new thread. 

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The LP2 filter in a Canon DSLR blocks IR and quite a lot of the Red" region. By removing this filter we let the Red and IR photons strike the sensor. However, letting the Red which is H-alpha onto the sensor is a good thing, whereas the IR is not so because it focuses differently in Refracting systems and thus produces "bloated" stars. A parabolic system like a good reflector will not have that issue. Blue and Green will remain the same regardless of the filter being there or not. In refracting systems one can use an IR/UV 2" filter with theT threaded  nose piece to cut off only the IR and UV and still allow H-alphs to pass.

I will be modding my camera tonight mostly and will post results in a new thread. 

Thanks, great explanation.

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Glad to hear that the IR problem is not so pronounced with reflectors. I was going to ask just that. Buying a used 500D tomorrow and will hopefully have it modded by tomorrow evening. For anyone who has done this before, how much time does it usually take and are there any common pitfalls? I've downloaded the Gary Honis guide but thought it still worth asking.

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It's worth noting that most of the common AP filters, including broad band LP filters, include some UV & IR cut-off. So using a 'full spectrum' modded camera is still possible with a refractor as the filter will stop out of focus wavelengths causing star bloat.

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Glad to hear that the IR problem is not so pronounced with reflectors. I was going to ask just that. Buying a used 500D tomorrow and will hopefully have it modded by tomorrow evening. For anyone who has done this before, how much time does it usually take and are there any common pitfalls? I've downloaded the Gary Honis guide but thought it still worth asking.

I tried modding my 500D yesterday. I used Gary Honi's instructions, but canon has design inconsistency issues. The three screws holding the circuit boars down were coated with a black rubbery glue that hinders the unscrewing. Its also difficult to scrape out with a blade. One of the screw heads got rounded in my effort to remove it and I then stopped the work to cool down my brain cells. Today morning i drilled out that one screw and hopefully by this evening the mod will be complete. Will post soon.

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