Ha filter with modded DSLR?

[Beardy Bob]

Hi folks. I've been using a modded 350d for DSO imaging for a while now and wanted to experiment with a Ha filter to see what things look like.

Whilst I appreciate the very poor response I'll get, I'm interested in what I'll pick up (and at best am hoping that I might see some finer lines and traces in certain DSOs akin to the narrowband images taken with CCDs).

Has anyone tried this before? And how do I go about adding a filter to my existing 'DSLR-adapter/extender-scope' setup? I currently don't use any kind of filter at all.

[Psychobilly]

I have used a 2" Baader Planetarium 30-35nm HA filter with a modded 1000D

I used to use it to grab some Ha on night when Luna was around...

I normally used to combine the Ha data with the OSC images...

I am thinking of getting a Narrower BAndwidth (12nm) clip in filter as more and more of my imaging will be with Camera Lenses rather than scopes...

Peter...

[SamAndrew]

Also interested in this as i'm looking fot a Ha filter for my 450D.

Not sure if i should go for the clip in filter or a 2"; the 2 inch would be useful for when I upgrade to a CCD, but then the clip in can be used with camera lenses :|

[swag72]

I have a 12nm Astronomik clip in filter for my modded 1000D. Works a treat and I love the images from it. The only issue is that it really is difficult to focus. Definitely a good thing to have in your arsenal for when the moon is about.

Minimum exposures I used to go for was 10 minutes, but more often 15-20 mins.

[Shibby]

I've just bought an ha filter to try with my 450d, so about to find out first hand. Great results Sara, are they single subs??

[Psychobilly]

You can still use a bahtinov for focusing on a bright star but you will probably end up with dashed rather than solid lines...

FWHM measurements make it easier.

I would usually run 15 and 30 min subs.

Peter...

[swag72]

IGreat results Sara, are they single subs??

No these are stacks of a number of subs. The Heart and soul was 49 x 603s (8hrs 12 mins) and the other was 27 x 1200s (9 hours)

[SamAndrew]

Wow Sara, nice pics, and those are some long exposures for an SLR !?

What focal ratio is the heart and souls nebula one taken at ? I can see from your flickr the other is taken at around f/6 ?

So hopefully with the quattro I could get a similar amount of data with a 10 minute sub.

[swag72]

I think that the Heart and soul was taken at between f4 and f5 as I used my 300mm lens, not the scope.

[Beardy Bob]

It definitely looks worthwhile trying then. How do you attach the filter? Where does it go in the train of parts from camera to adapter? I've never been exposed to filters of any kind before.

[swag72]

I have the Astronomik clip in filter U.K. Astronomy Buy & Sell which fits directly into the camera before attaching the lens or scope. Fit the camera to the scope in the normal way and ....... voila! The only thing with this is that if you are doing any widefield stuff you can not use EF-S lens's with it. Also, there's some camera's that it's not compatible with. The list is towards the bottom of that page I think.

[Pomerol]

Why are the Ha images Black and White if taken with a DSLR?? Is it only the Red channel you are showing?

Ian Smith

[swag72]

I covert them to mono! Can't remember if they come out red prior to that or not!

[Psychobilly]

Yep they are red and you pull out just the R channel form the RGB image...

[Flea77]

You might be suprised how much response you get, here is the Spider and the Fly NGC1931 and IC417 with a Baader 7nm Ha filter on an UNMODDED Nikon D7000.....

and here is NGC2244 with a 35nm Baader Ha filter using the exact same 480sec exposure I used for the RGB image on the unmodded D7000 (converted to B&W)

Allan

[Beardy Bob]

Not being able to use EF-S lenses with the clip-in filter in place isn't a problem. I assume the filter just pops straight out again when I need to...

[Beardy Bob]

Also, one thing I don't understand - why does using a Ha filter allow you to shoot on moonlit nights? Doesn't the moon reflect Ha the same as every other wavelength?

[Psychobilly]

With the Ha filter your only allowing through a small part of the spectrum of moonlight... so yes some gets through but a lot more doesn't dramatically increasing the contrast...

[ollypenrice]

It has to be worth a go because the addition of Ha to the red channel in a final image is transforming on emission nebulae. My favourite example is this one, on the left without Ha and on an the right with!

Olly

[Beardy Bob]

Well, that's decided it then. Now I just need to find a clip-in filter. Either that or just go straight to ccd and filters. Anyone know of any reliable second hand ones about?

[SamAndrew]

I Decided to go for the astronomik 12nm clip in filter,

Here's my first light with it, a single 10min sub (no flats or darks) of a chunk of the california nebula taken a few days ago. I'll get more use with it this week now that the moon is coming back around.

I'm very happy with this ; it should produce excellent results if I can get a good stack together. This is my first 10 minute exposure

[Shibby]

Finally tried out my new filter (7nm Baader) with my 450D as SGL and the results are very exciting Needs some more data yet so think I'll resist posting for now..!

[themos]

An OIII should be even better as you have twice as many green pixels.

[Beardy Bob]

Good point on the OIII. I was thinking that myself actually! But I'm guessing that the most abundant emissions are Ha. Would be interesting to see if anyone has tried other filters with a DSLR. Maybe even a full hubble palette image!

[Beardy Bob]

Oh, and Sam, that image is most encouraging for a single 10min exposure. Show me the Astronomik 12nm clip-in filters!! I'm sold!