Eta Carina with infrared added >720nm

cometcatcher (Kevin) · #1 24-04-2017, 03:31 PM

The el-cheapo Chinese 720nm infrared filter arrived in the mail so thought I'd have a much about with Eta Carina since it's bright. I took 100x30 seconds at >720nm and 21x30 seconds with a UV / IR cut filter and combined them, using a Canon full spectrum 1100D. I used two different combining methods, one with the IR batch stacked onto the er.. luminance frame as luminance, and another with the IR batch added to the red channel.

I suspect there is some Ha bleed through in the IR filter as it cost a whopping $10, including freight.

But not that much as it's much weaker in Ha than my Ha filter.

Through the GSO 10" F4.

Edit... Added the IR stack alone for comparison.

Andy01 (Andy) · #2 24-04-2017, 03:50 PM

Pretty cool, Kevin - er did i read correctly that you used an IR cut filter in combination with an IR filter? Won't they cancel one another out?
Looks good anyway, but I'm curious...

cometcatcher (Kevin) · #3 24-04-2017, 06:12 PM

Quote:

Originally Posted by Andy01

Pretty cool, Kevin - er did i read correctly that you used an IR cut filter in combination with an IR filter? Won't they cancel one another out?
Looks good anyway, but I'm curious...

Hi Andy, I made two separate stacks of exposures. One lot with the IR filter and a second stack with the IR cut filter. The two stacks were then combined in photoshop. Otherwise, yes, they would cancel each other out.

cazza132 (Troy Casswell) · #4 25-04-2017, 06:04 AM

Nice Eta Carina! Ha bleed would be minimal though. By adding IR to the red channel, you are seeing more reflection in nebulae from IR cutting through passive clouds (not fluorescence that gives Ha response). Note the cooler red stars having a strong response.
What if you add green to the IR channel?
Love this stuff! I do a lot of IR work with my full spectrum 6D (day and night), but haven't tried it for deep astro. I will have to give it a go!
Love this sort of progressive experimentation!

SimmoW (SIMON) · #5 25-04-2017, 07:19 AM

Yes, thanks for posting, good comparo though ill need to download to review better. What brand/model of filter did you buy?

cometcatcher (Kevin) · #6 25-04-2017, 09:09 AM

Quote:

Originally Posted by cazza132

Nice Eta Carina! Ha bleed would be minimal though. By adding IR to the red channel, you are seeing more reflection in nebulae from IR cutting through passive clouds (not fluorescence that gives Ha response). Note the cooler red stars having a strong response.
What if you add green to the IR channel?
Love this stuff! I do a lot of IR work with my full spectrum 6D (day and night), but haven't tried it for deep astro. I will have to give it a go!
Love this sort of progressive experimentation!

Thanks Troy! I also have been doing a lot of daytime infrared. I have 590 / 650 / 720 and 850nm filters. I can only use the 650nm and 720nm "through the scope", as I adapt 46mm to 48mm and 48mm just screws in to the focuser.

Quote:

Originally Posted by SimmoW

Yes, thanks for posting, good comparo though ill need to download to review better. What brand/model of filter did you buy?

Thanks Simmo! It says on the plastic container "dHD". I also have a much more expensive Hoya R72 for daylight infrared. I can't really tell the difference between the Hoya and the dHD.