Ha Imaging with DSLR

[gbeal]

OK you bright sparks, I need help.
After seeing Scotts fantastic images with a modded Canon and Ha filter, I am looking to try this. I have yet to hear back from him, but have tried a few things at home in the meantime.
I have a non-modified 20D. I also have a Schuler Ha (656mn??):help: filter in 1.25" size.
I reasoned that it would vignette, so slipped it into the front of my home made T ring to 2" adapter, which I use for prime focus imaging.
I shot a few pictures of the blank wall in the office, and sure enough they looked a little red, and without any real vignetting. So far so good.
I wondered if I was better off with the filter closer to the camera lens throat so undid a few sections (I told you it was home made), and in doing so screwed the filter in the other way around. Now the images are NOT red???
Why??? Is there a right way and a wrong way to use the Ha filter??
Gary

[Merlin66]

Good question!!! I've always assumed there was no difference??? How can it make a difference? The light still has to go through one way or other????

[gbeal]

Yep, that's what I thought Merlin, but the difference is significant.
Anyone else tried it, or am I just losing it??

[Striker]

Not that I know of Gary...the HA filter is very red as you know...you wouldn't think it make any difference which way it was threaded...but who knows.

I say your going mad.....I dont know how well your camera will image in HA unmodified....you may be better imaging in OIII with an unmodified camera.

[gbeal]

Nothing new Tony, I've been mad for years.
Worth a try, and if this doesn't work then the next step is to modify.