I finally bit the bullet and pulled my DSLR (300D) apart and modded it. Replaced the low-pass/IR filter with a MC Clear glass from Astronomik.
I was very relieved when reassembled and powered up with the narrow to full spectrum CMOS filter replaced that it actually powered up and worked. Now for some clear skies to test it out.
The last 4 pics are a quick infrared sensitivity test between my unmodded 7D and the modded 300D.
All pics are taken with daylight white balance, f4.0 1/20th shutter and ISO1600. I just held up the telescope 1.25" IR pass filter in front of the lens... I think the sensitivity to IR is quite evident.
Just to note, modding the 300D was not as daunting as I though it was going to be, it was actually quite simple... time consuming but simple. It took me about 3-4 hours all up, that is including the time waiting for the glue to dry (I did take my time, no point in rushing it).. I gave it about an hour to dry before I cleaned any blemishes of the glass and commenced reassembly.
I'll leave the installation of the cold finger until my pics are too noisy to accept, but with the multiple exposures and stacking I'm hopeful that it might be OK for at-least a while.
I feel like changing from a low-pass filter to unfiltered glass still leaves the camera how it was intended to be operated, just sensitive to more light frequencies.
Of course as my luck would have it, we had nothing but rain every day since the day I modified the camera... just a big middle finger from mother nature as I'm itching to take it for a test drive on the horse head.
Great work, the h alpha you will now get is mind blowing I've being loving the 1100D because You can just ditch the IR and Keep the LP ( 2 pieces of glass) which responds better then then baadar IR/UV replacement and saves you money buying one. Though full spec will be great for spectroscopy and you can wack a clip-in to cut IR for DSO ect. Yes TEC cool it lol, if not make a cooler box you know you want to
Yeah, I am tempted but I think I'll see what I get with it as it is first. I bought some IR filters of eBay, 720nm, 850nm and 950nm to see how sensitive it is on IR... even the 950nm filter can be used hend held now, and I'm talking 1/20th shutter and get good exposure in IR. By contrast the 7D through the 950nm filter needs about 15 seconds exposure to see anything on the photo. That gives me hope that I'll get heaps of HA & SII through the respective filters next imaging session.... still hangin, been overcast for a while but hopefully next day or two I'll have a horse head to be proud of.
I've being loving the 1100D because You can just ditch the IR and Keep the LP ( 2 pieces of glass) which responds better then then baadar IR/UV replacement and saves you money buying one. Though full spec will be great for spectroscopy and you can wack a clip-in to cut IR for DSO ect. Yes TEC cool it lol, if not make a cooler box you know you want to 
