Ha filter on DSLR for moonlit nights

[Magnus_e]

Hi.

Two nights ago i had perfect clear skies no haze, but a bright 100% full moon.

As the clear nights in periods are scarce i figured i should try to image. I pointed at heart nebula and collected about 4.5 hours of 7.5 minutes subs at iso 400.

I knew it would not be great data as the skyglow was real bright on the subs. I did manage to process the image so i could see the heart shape, but with that much data it could / would be one of my better ones if the moon was not there. In the beginning of the month with no moon there was not a single forecasted night of clear skies.

So, should i get a Ha filter for my DSLR? I know the scope will increase it's "theoretically" fstop about four times due to only a quarter of the pixels being used, but how will the images bee like? If in an entire month there will only be one or two clear nights and i can get 8+ hours on a Ha filtered DSLR with the moon up, then i have something? Or will the images be so faint that i wont be able to use it for a Luminance layer or to blend in to red if i get some rgb data?

As i wont get a great setup with Ha filter and DSLR like i would with a CCD, i would probably be loocking at the cheapest one i could find. Anyone know of any decent budget ones, or is it not a good idea to start with?

[geordie85]

With filters you really do get what you pay for. If you buy a cheap one then it's not going to perform very well at all. I have the 12nm ha astronomik clip in filter and I've never had a problem with DSO's being too dim even at 5 min exposures.

You will need alot of subs though as they always seem to come out quite noisy for me

[swag72]

I have learnt over time that full moon nights are for sitting on the sofa and spending time on something else. I use a mono camera with 3nm Ha filters and these struggle massively with the moon....... But I appreciate that clear nights often seem to coincide with that damn big blobby thing.... so what does one do?

[Magnus_e]

Hi, and tanks for the replies.

What i get from this is that it's doable to use Ha on a DSLR, but there still will be some affect by the moon. Also not by a cheap one

As i have been a student for four years and just about to start a job hunt my finances are a bit on the low side. After looking trough the webstores for a Ha filter yesterday, i realized how expensive they are if i dont buy a cheap one

Think it will be something to look for next year.

The beauty of this hobby is that its timeless. No need to rush things

I did at least get the outline of the Heart, despite full moon and poor guiding after the flip.

[wimvb]

That's still a good  image you have, with lots of detail in the nebula.

I haven't tried narrowband yet, but I guess:

as the moon reflects allmost all sunlight (wavelength-wise), my guess is that a narrowband filter won't work. The reflected Ha from the moon will interfere with the Ha from the object you're trying to capture. To capture the faint details of Ha-nebulae you'll still need a dark background; so, no moonlight.

Just my thoughts on this.

[ollypenrice]

That's still a good  image you have, with lots of detail in the nebula.

I haven't tried narrowband yet, but I guess:

as the moon reflects allmost all sunlight (wavelength-wise), my guess is that a narrowband filter won't work. The reflected Ha from the moon will interfere with the Ha from the object you're trying to capture. To capture the faint details of Ha-nebulae you'll still need a dark background; so, no moonlight.

Just my thoughts on this.

No, Ha is remarkably moon-proof, the narrower the bandpass the better. There is a huge difference in partial moonlight between our 3nm Astrodon and 7nm Baader. Other NB filters are hardly effective at all. (OIII is no good in the moon.) For all that, even with Ha the moon needs to be well away from full phase so I agree with Sara.

Olly

Edited December 31, 2015 by ollypenrice

[Magnus_e]

Thanks for the info Olly. I'm still considering it, but have to wait a while an see how the job situation works out. Think it was a 2" 3nm astrodon filter i found that cost almost as mutch as my scope :-))

Sent fra min D5803 via Tapatalk

[ollypenrice]

Thanks for the info Olly. I'm still considering it, but have to wait a while an see how the job situation works out. Think it was a 2" 3nm astrodon filter i found that cost almost as mutch as my scope :-))

Sent fra min D5803 via Tapatalk

Yes, I know, that's the one we have here. Terrifying!! 

Olly

[Jonk]

I'm looking at filters at the moment whilst compiling my unbearable shopping list!

Yes they're all expensive, but I want to buy the best I can while I can.

Is there a huge difference to a narrowband beginner between 5nm and 3nm Astrodons?

I mean mainly for the moonlight points above, at what phase of the moon are these filters usable worse case?

For full moon nights I will just play with lunar mosaics or plentary, or do something else!

[Davey-T]

Given the rubbish weather in the UK I found it hard to justify buying 3nm as opposed to 5nm so bought 5nm Astrodons back in September, so far I've used the HA for about an hour 

There are posts around advocating different wavelengths of NB filters in the f / wheel, so not necessarily all 3nm.

Dave

[Jonk]

Fair point Dave but these will be useable for hopefully many years to come.

I'm trying to decide on the 3nm or 5nm Astrodons (the moon point is in my mind too), and also which LRGB to go for - Baader or Astrodon?

Once they're bought that's it - money has gone, hence the need to get it right.

[ollypenrice]

It isn't a case of 'better or worse' between the 3 and 5 Astrodons. The 5 passes the NII line while the 3nm doesn't. I use NB to enhance broadband images so I went for the very high contrast offered by the 3. It's discussed here. http://stargazerslounge.com/topic/206268-astrodon-3nm-versus-5nm-ha-filter/

To be honest I'd have thought that the Astrodons would be a big investment to use on only a quarter of the pixels with a DSLR.

Olly

[Jonk]

They won't be on a DLSR, I'm upgrading to an 8300 CCD, so will be looking at LRGB and NB imaging.

From what I've read since, the general consensus is 'the narrower the better', especially for use during certain phases of the moon.

I can't find much on Baader vs AD RGBs though.....another topic.

[ollypenrice]

They won't be on a DLSR, I'm upgrading to an 8300 CCD, so will be looking at LRGB and NB imaging.

From what I've read since, the general consensus is 'the narrower the better', especially for use during certain phases of the moon.

I can't find much on Baader vs AD RGBs though.....another topic.

I use Baaders but have processed a couple of images with the Astrodon LRGB. I'm a fan of the AD narrowband but was slightly relieved to find myself vaguely preferring the Baader RGB set. This might be through familiarity but at least I didn't feel my Baaders had to go straight in the bin!! I like the Baader LRGB set.

Olly

Edited January 3, 2016 by ollypenrice

[Davey-T]

I bought the Baader LRGB to go with the Astrodons Jon but haven't used them at all yet 

Perhaps it will stop raining by March

I have a set of old Baader LRGB in the Atik EFW2 wheel that have been fine as far as I'm concerned, the new ones are supposed to be different / better ? I think.

Dave

[Jonk]

I think I'll get the Baader LRGBs, they're less than half the price of the Astrodons and hoefully won't be too different. The Astrodon NB will be later on.

The rain has just appeared here again, after 4 hours of clear-ness!

[mr saddo]

Hmm I have a dedicated canon 120d moded with a ha filter in it.. the red filter was takern out and s proper hA fitted, i shot Orion on my first go stacked 20 odd frames iso 1600 21 secs.. and it was a nice light purple nebula no moon was out, shot same exposure same time and very red! Moon was out quite bright,  had to drag the ISO  down to 800 and time down. Still red. So does the moon effect the HA? Yours paul.

Edited February 5, 2020 by mr saddo