sh2-157

[alacant]

Hi everyone

Full moon and faint target, the challenge being to try HOO from the UHC and IR filters screwed to the end of the coma corrector. At least the red stayed red but I'm not a fan of those false looking stars. We spend many hours and $ getting images of stars. And then obliterate them!

Any dslr users had a go at this? Please post your images too if so.

Thanks for looking and wishing clear skies to all.

700d @ ISO800

Edited August 22, 2021 by alacant

[Budgie1]

24 minutes ago, alacant said:

At least the red stayed red but I'm not a fan of those false looking stars. We spend many hours and $ getting images of stars. And then obliterate them!

There is a way around the false colour in the starts when using narrow band filters on DSLR's & OSC.

If you take your subs with the narrowband filters for the nebula and then take another set of standard broadband subs with just the UV/IR cut filter to get the correct colours for the stars. Because you're only trying to get the star colours, you don't need that many broadband subs.

Then in processing use something like Starnet++ to remove the stars from the stacked nebula image and replace them with the natural coloured stars from the stacked broadband image.

[almcl]

I did have a go at this a while back as a widefield Ha target using an Astronomik 12nm filter on a Canon 700d.  Maybe I should revisit it with the Lenhance and the ASI 2600

[alacant]

25 minutes ago, Budgie1 said:

false colour in the starts

Thanks. It was more the tiny false looking stars which looked wrong, But yeah, good idea for the colour with the non-filter layer.

[ollypenrice]

I like the image. I've tried this in HaLRGB and it was as dull as ditchwater,  just a uniformly red affair with one dimensional colour. I didn't even keep it, let alone post it.

Here, though, the upper claw, with a significant OIII component, has modelling and three dimensionality which make it very attractive.  Since HOO closely replicates RGB I agree with Martin that a handful of subs for RGB stars would be perfect. Alternatively you could just lose the greenish stars by lowering their saturation.

Olly

[alacant]

4 hours ago, Budgie1 said:

another set of standard broadband

Any guidelines as to exposure time for the set without filter?

We used 5 minutes with the UHC. With the full moon tonight, that's gonna be too much direct to camera.

Cheers and TIA.

[Budgie1]

1 hour ago, alacant said:

Any guidelines as to exposure time for the set without filter?

We used 5 minutes with the UHC. With the full moon tonight, that's gonna be too much direct to camera.

Cheers and TIA.

The good thing is, you're only looking to capture the stars on these so you don't need long exposures. Something between 45 & 90 seconds is going to give you the stars and their colour.

Run a couple of test frames to see what works best with the Moon. You could even bring that down to 30 seconds an just take more subs.

 

[alacant]

On 22/08/2021 at 17:53, Budgie1 said:

Something between 45 & 90 seconds

Thanks.

Used 6 x 60s. Perhaps not enough to make much difference. Overdid the saturation.

Not given up yet. Still thinking...

[ollypenrice]

6 hours ago, alacant said:

Thanks.

Used 6 x 60s. Perhaps not enough to make much difference. Overdid the saturation.

Not given up yet. Still thinking...

I think that worked well. You have have a distinction between red and blue stars which gives the image a more natural look and is truer to the target. Maybe the hue in the blues could have a tweak to make them slightly less green but being wary of going into magenta.

I reckon that, for star colour, less is more because too much signal burns everything to white.

This is the first image of the Lobster Claw which I've found engaging.

Olly

[gorann]

Nice, and you are well on the way but may need more data. I do not have any DSLR version of it but I have two HaOiii images, one up close with my Esprit 150 and ASI1600MM (7 hours w Baader filters), and one wide field with a RASA8 and ASI2600MC (6.5 hours with IDAS NBX dual band HaOiii filter).

Cheers, Göran