I don't know about amp glow in the 450D, probably someone else can help there. Whether it's amp glow or something else, the builtin noise reduction (dark frame subtraction) will definitely remove it. If you can, you're better off taking a few dark frames and processing these later on your PC.
Being the consumer model, the 450D I'd assume will show amp glow - some worse than others. For 2 minutes, yours is pretty prevalent. I have a 350D and a Nikon D40 and neither generate appreciable amp glow until they've run 8-10 minutes. It isn't to be confused with thermally-induced CCD readout noise (which ICNR will remove most of) either - it's different. The higher end 40/50D 1D, etc, bodies turn the readout amplifiers (at the edge of the sensor) off during exposure, and only initialise them on read-out at the end of the exposure, so they don't suffer from it. You pays your money, you get better results, like with anything I guess. Whether the exposure your doing is a light or dark, I think that the amps are kept on regardless - so ICNR won't remove it. Can someone correct me here?
The best way to get rid of it is take a few dark frames with the same exposure details as your lights and get your stacking program to process them out in one hit.
Chris ICNR is the way to go, I never image with out it and never take seprate darks, and expose up to 7-9 minutes with out any AMP glow at all.
My image runs are doubles of coarse, but that suits me fine.
Chris ICNR is the way to go, I never image with out it and never take seprate darks, and expose up to 7-9 minutes with out any AMP glow at all.
My image runs are doubles of coarse, but that suits me fine.
But then others here do it differently.
Leon
I think that the 5D also turns off the amplifiers during the exposure cycle Leon, as opposed to the 450D which does not - which is why you don't get amp glow and Chris would even with ICNR set on. Doing ICNR on the5D would leave your images pretty clean I'd imagine!
I got caught out on this recently. My camera battery run out before I took my darks (and I only have one battery - new one is on order!). By the time the battery was recharged, the camera had cooled down too much, and the darks did not match the images any more
I think I'll try ICNR next time. I guess it would give a better correlation between the light and the dark.
You might find an "off amp" (during exposures) mod for the 450D on the net. I did this mod on my 300D, but it was pretty tricky, youd need tech skills for that.
It might be worth trying flats of the same exposure time, but you would have to dark subract them and use a very dim light scource
Is there any body on this forum that has a 450D canon???,surly their must be someone with one,
Hi Chris,
I have a Canon 450D that I use for Astrophotography. 5 minute to 10 minute subs show no sign of amp glow. The 450D and newer models of cameras turn off amp glow during long exposures so you will definitely not have a problem with the newer models of these cameras.
Live view is a great feature especially for focusing with the 450D.
I used to get plenty of amp glow from my old 350D.. anything over say, 2 minutes and I'd get a rather large glow in one corner of my images..
I found darks would remove it. however the darks had to be taken at a similar temperature to the lights...
From my knowledge of how ICNR works, it should remove amp glow if its present. Being that it is noise generated by heat of the amp during the exposures, it should show up in an ICNR "dark"
Give ICNR a go, failing that, darks is the way to go...