IC1805 Heart Nebula, with new Baader 35nm Ha filter

[SteveL]

One of the issues with imaging with the Hyperstar @ f/2 is that the wavelengths all get shifted by ~6nm, so doing narrowband with it can cause some real issues. A 13nm filter would appear to be OK, but in fact by the time (for example) Hydrogen Alpha is shifted by 6nm, its in the 30% or less bandpass section of the filter.

Then Baader released their new range of filters, including an oddity... a 35nm Ha filter. Is it a wide Ha or a narrow red? Who knows, but its use on the Hyperstar was obvious to me, keeping the peak Ha emision line well above the 90% transmission. It also seem to cope really well with the full f/2 shift at the outer egdes of the QHY8 APS size CCD. The only small downside is that because of the wide bandpass, its not quite as "contrasty" as you would expect from a narrowband filter.

So, here goes:

OTA: NS8GPS @ f/2 (Hyperstar v3)

Guiding: William Optics ZenithStar 66 SD + DSI-C + PHD

Imaging: QHY8 + MaximDL, 24×600s, Baader 35nm Ha

Stacked: DeepSkyStacker

Post Process: ImagesPlus + PSCS2 + Noel Carboni’s AstroTools

(Click on image for larger version)

[ngc2403]

that is a really nice image steve,

just wondering how does the hyperstar shift the wavelength of light????

i know that the things it does are out of this world but i didn't think that we needed to take relativity into account

ally

[SteveL]

The hyperstar is imaging at f/2, and so at the very outer edges of the available light cones, the effective wavelength is shifted by somewhere between 5-6nm. You know when you read that some filters are effective for imaging at f/5 or slower? Well, this is the reason. As the angle of incidence increases, so the effective wavelnegth shifts (towards the blue btw).

[ngc2403]

oh right pathlength through the filter got you.

i just thought it was across the whole filter. That would mean that you would get wavelength dependent vignetting, which could be a problem?

[FLO]

Blimey, that was quick, you only got it yesterday!

No flies on you

[moondog]

That's a super image with the new Baader filter Steve - seems to work well.

I brought the same filter with me to NZ to use with the QHY6 mono and the WO ZS66 @ F3. Not had a chance to try it out yet as I can't borrow a suitable mount.

8)

MD

[SteveL]

That would mean that you would get wavelength dependent vignetting, which could be a problem?

Exactly right, except for some reason this Baader 35nm doesnt appear to be causing any kind of problem like that. I know for sure that my IDAS filter does have this problem (with crazy colour shifting round the extreme edges of the CCD), and my 13nm Astronomik does to a lesser degree. Unsure about my CLS, its been so long since I had a chance to image with the Hyperstar under a moonless sky.

The other problem that may be showing up here is the ffects of the microlenses over the individual CCD pixels. At such extreme light angles, the microlenses can be less effective, which can cause vignetting... but the amount they are less effective by is dependant on the light wavelength. I believe that they become less effective for the red end of the spectrum, and so the outer edges can have a blue-green tint to them. I need to test this soon by not using any filter at all on a target, and inspecting the edges of the subs that I collect.

And many thanks to Steve @ FLO for getting me this filter so quickly

[LostNSpace]

Thats a lovely result all the same Steve......

Mark

[Whippy]

'tis a great shot mate, but I'm curious about the filter. 35Nm seems pretty wide in comparison to 'normal' narrowband filters, I'd be interested to see how it performs in a moonlit sky. Would I be right in guessing there's more testing in the works?

tony..

[SteveL]

yes, lots more testing with it... but i now have a dillema. Do I get the "soul" part of this mosaic, or do I play with the large black skywatcher mak newt that is sitting on the table next to me at work

Tough call.... if only I had two large format CCDs, eh? ;-)

[Whippy]

yes, lots more testing with it... but i now have a dillema. Do I get the "soul" part of this mosaic, or do I play with the large black skywatcher mak newt that is sitting on the table next to me at work

Tough call.... if only I had two large format CCDs, eh? ;-)

I'm just getting in the car with the Atik.... Not large format but better than nowt...

Tony..

[MartinB]

Great result with the new filter Steve, could have been made for your set up.

Love that tweak Rog. I've never tried that. Top tip.

[Psychobilly]

Decisions decisons... mine are made easier by the carp weather...

Nice Image Steve and cant wait to see the results with the new Mak-Newt...

Billy...

[Tim]

Looks like that may be well on the way to sorting it out for you Steve. Certainly seems to me that it has enabled the camera to make the most of the Ha on that shot.

PLAY WITH THE MAK NEWT ALREADY!!!!! Not that i'm interested in one or anything..........

TJ