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Narrowband

Narrowband Imaging and DSLR


NickMorris

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Thanks John,

appreciate the reply. From the little that I know so far, narrowband is good for imaging from light polluted areas. Bearing in mind that I live in London, would it make more sense for me to mod the camera and then use Ha, OIII and SII in a filter wheel in front of the EOS-350D?

cheers

photonboy

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I haven't tried OIII or SII but from the advice I've had they're just not worth it. A DSLR just isn't sensitive enough.

You'll get good results with a cls filter to kill light pollution for colour, Ha filter works pretty well too but you need long exposures - 10 mins +

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from the Astronomik site (about the OIII CCD filter)

Suitability

Visual observation (dark skies): Very good, huge contrast enhancement at O III-emission nebulas

Visual observation (urban skies): Very good, huge contrast enhancement at O III-emission nebulas

Film photography: It depends, very long exposure time

CCD photography: Very good, huge contrast enhancement at O III-emission nebulas

DSLR photography (original): Very good, huge contrast enhancement at O III-emission nebulas

DSLR photography (astro modified): Very good, huge contrast enhancement at O III-emission nebulas

DSLR photography (MC modified): Very good, huge contrast enhancement at O III-emission nebulas

Webcam / Video (Planets): Unsuitable

Webcam / Video (Deep Sky): Reasonable, if light pollution is a big problem and OIII Objects are beeing observed

and the SII

Suitability

Visual observation (dark skies): Unsuitable

Visual observation (urban skies): Unsuitable

Film photography: It depends, but very long exposure times

CCD photography: Very good, huge contrast enhancement at S II-emission nebulas

DSLR photography (original): Unsuitable

DSLR photography (astro modified): Very good, huge contrast enhancement at S II-emission nebulas

DSLR photography (MC modified): Very good, huge contrast enhancement at S II-emission nebulas

Webcam / Video (Planets): Unsuitable

Webcam / Video (Deep Sky): Unsuitable

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Hi John,

I am thinking of buying the EOS Ha 12nm clip for my un modded 1000d, would you mind posting a few examples of what I could expect from this filter.

I have been able to autoguide for over 40 mins so I think I have the tracking nailed down.

Acme

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Halpha narrowband imaging with an unmodded camera is like trying to run with your shoes tied together, surely?

Oh I didn't see that the camera stated was unmodded. Just as a point - the images above are with a modded camera.

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Be aware that an LX200 is maybe not the ideal tool for several reasons. I outline a problem and a solution here.

-It has a slow f ratio so will need very very long exposures. (Do you have the 6.3 reducer-flattener? This is a must in my view. The 3.3 is a horror aimed only at tiny chips).

-These long exposures will require acccurate guiding which my own LX200 never delivered. (Long exposures at long focal length require the best guiding.)

-Many of the Ha targets are large on the sky and a long focal length = a small field of view.

Solution; what I did quite successfully for a while was piggyback a small refractor on the LX200 (I used a William Optics ZS66 with flattener reducer) and this was faster, had a wider field and required less accurate tracking. I used the LX as guidescope. There are lots of small fast refractors out there and up to 80mm will not trouble the LX.

Ha season is anytime when the Milky Way is well placed. The emission nebulae which shine in Ha are mainly found in the galactic spiral arms - ie in the plane of the Milky Way - so any time the MW is up you have lots of Ha targets. The lean time is just the spring galaxy season when the MW is lying on the horizon and we see out of our own galaxy when looking high. But even then many imagers like to add an Ha layer to galaxy images in order to highlight starbirth regions in the arms.

This is a CCD Ha image taken with the 66/LX200 setup described.

Olly

617927496_Uccgo-X2.jpg

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