Ha filter + Question

Ric · #1 24-07-2007, 01:57 PM

I recieved my 13nm Astronomiks Ha filter yesterday followed closely by the clouds.

Oh well I suppose that it was predictable.

I'm really looking forward to imaging with filter and seeing the results it produces.

I would like to thank Bintel for their speedy delivery, posted Friday afternoon and arrived on Monday morning.

Following some discussion on another thread, my stars in my first image looked a bit blobby (technical term

). I was wondering when imaging in Ha do you use an IR or IR/UV filter as well as in image through both at the same time. The info I have been finding on the net is some what confusing.

All advice appreciated

Cheers all

gbeal · #2 26-07-2007, 12:46 PM

I doubt the need for the IR/UV is that critical if you are imaging with the Ha, but I am guessing.
In my case I use a one shot colour camera, and ST2000XCM, and when using an Ha filter, that is all I use, just the Ha. If normal OSC RGB imaging I use a Baader IR/UV. Best option is to try both scenarios, and that will tell you (and others who I am sure also are interested) what the answer is.

Ric · #3 26-07-2007, 02:18 PM

Thanks gbeal for your thoughts. I think as you say I shall have a play with both scenarios and post the outcomes. and right on cue the bureau is predicting clouds and rain until next Tuesday, hope they are wrong.

Another thought is that my Hartmann mask is not the most accurate design either, this may be affecting my fine focus so I am making a new one this weekend following Baz's design.

Cheers

ballaratdragons (Ken) · #4 26-07-2007, 02:36 PM

Ric, my solution to questions like this is: Just try it and see what happens

Ric · #5 26-07-2007, 02:48 PM

Very true Ken, that usually is my philosophy. I also like hear thoughts and opinions from our learned collegues as well. It gives me a better understanding of the bigger picture as they say.

Cheers

jase (Jason) · #6 26-07-2007, 03:08 PM

Ric,
The Astronomik Ha (type II) filters have an IR blocking coating/film. There is no need to couple a separate IR blocking filter to the Ha filter. In fact, doing so is likely to slightly reduce the quantity of light reaching the chip. I wouldn't be concerned about UV as the filter has such a narrowband pass centered around the 656.3nm. UV is down the other end of the spectrum , around the ~310nm mark which the filter is already blocking.

pvelez (Pete) · #7 26-07-2007, 04:06 PM

I understand most people use a Ha filter on a regular CCD camera.

How will it go with my humble 350D?

Pete

Ric · #8 26-07-2007, 04:29 PM

Thanks Jase, I think in that light I should probably have a closer look at my focusing techniques.

Hi Pete, I dont own a digital camera but I think they may have a built in IR filter so you may encounter the problem that Jase was talking about with combining the two filters. But no doubt someone will have the answer.

Cheers

seeker372011 (Narayan) · #9 26-07-2007, 10:35 PM

Quote:

Originally Posted by pvelez

I understand most people use a Ha filter on a regular CCD camera.

How will it go with my humble 350D?

Pete

The astronomik 13 nm works well with a modified Canon but I doubt that you will get anything worthwhile as long as the standard IR filter is there

you can image in OIII with a standard Canon and an Astronomik OIII filter though