SingAstro

I am here to ask for your opinions on filter that will enhance the view of nebulas. I am currently planning to get a celestron oIII narrowband filter. What are some of the pros and cons and what other alternatives are there. Thanks for looking.

Hi dysam. Welcome to the forum. If you exceed, the objects you are trying to look at will get dimmer and dimmer. You may then not be able to see it clearly or at all, let alone trying to focus it. But do have fun trying that slowly on a bright Moon.

You will have the same effect as over-magnifying a digital photo: The image will become blur, seemingly difficult to focus because the resolution of the image at your eye will exceed either the resolving power of the telescope or the atmospheric seeing. Also in the case of telescopes, dimmer because the brightness of the image is related to the aperture of the telescope and the magnification used. (more correctly, its related to the exit pupil, which is a function of the two: Aperture divided by magnification = exit pupil)
Also, as you increase the magnification (hence decreasing the exit pupil), irregularities and floaters in your own eyes will become more obvious. This is increases as your exit pupil goes below 1mm and is very prominent below 0.5mm.
So unless you have quality optics on hand, try not to exceed 50x per inch of magnification (and often, use less)

Hi,
The maximum useful magnification is determine by the aperture of the telescope... the larger the telescope aperture, the higher the magnification the telescope can support before the image become too dim to see... The bad news is the atmospheric turbulent will usually limit the maximum useful magnification to 300x regardless of the aperture of your telescope. In short, atmospheric turbulent will blur your image and as your magnification goes higher, the effect of the atmospheric turbulent will become more obvious. So the use of magnification higher than 300x and still get a sharp, detail and stable image is few and far apart.

Have a nice day.

need help.

dysam wrote:I am here to ask for your opinions on filter that will enhance the view of nebulas. I am currently planning to get a celestron oIII narrowband filter. What are some of the pros and cons and what other alternatives are there. Thanks for looking.

Refer to these useful reviews by David Knisely.

http://www.cloudynights.com/item.php?item_id=63

http://www.cloudynights.com/item.php?item_id=1520

Hi Dysam. If you are asking a new question, you may start a new thread instead of editing the original post. Else the the subsequent replies from us will be no head no tail.

I second Mariners links of filter articles by David Knisely.

Start a new thread, friend. Its free to post ;)
If you're getting a first filter, I recommend a good narrowband UHC filter such as the Astronomik or Lumicon UHC. (Note: the Celestron UHC is a BROADBAND filter, equal to the Lumicon or Orion Skyglow)
A broadband filter is often too weak to be of much benefit in Singapore and an OIII filter is specifically for Veil and other planetary nebulas, which will also be well served by a UHC, perhaps just a little less so.
Do note though that stars will become dimmer and to a small extent, less pin-point. The image will be darker although the contrast will increase.

I am gonna throw in a nay here.

I have the DGM NPB narrowband that Dave Knisely loves so much.

The effect, even on bright emission nebulae like M42, in Singapore skies - is minimal.

Yes contrast is increased. Yes the sky background is darker. But everything is MUCH darker. I wasn't too thrilled with it on my C9.25, I suspect smaller scopes would suffer even more.

Maybe in darker (but not Mersing/Sedili level) skies the benefit would be greater.

orly_andico wrote:I am gonna throw in a nay here.

I have the DGM NPB narrowband that Dave Knisely loves so much.

The effect, even on bright emission nebulae like M42, in Singapore skies - is minimal.

Yes contrast is increased. Yes the sky background is darker. But everything is MUCH darker. I wasn't too thrilled with it on my C9.25, I suspect smaller scopes would suffer even more.

Maybe in darker (but not Mersing/Sedili level) skies the benefit would be greater.

I was leaning towards the NPB filter for my choice of narrowband. Anyone has the Lumicon or Orion UHC to review for our skies?