First M42 with 120ED and filters

[Sirius Bizness]

This it the first night I have looked at M42 with the 120ED (only used an ED80 previously) as its been out of view behind houses until now. It looked good with the 35mm Pan but really came to life with the UHC and OIII filters. A nice green tinge with far more nebula visible. Both filters gave the same improvement. The real surprise was when I switched to the 9mm Nagler with no filters to get a better look at the trapezium. The detail in the nebula was amazing. I hadn't expected it to get better with magnification!

[Pig]

I cant wait to se them with a filter.

I am still waiting for my UHC filter to arrive, the 1st oreder didnt turn up and they failed to mention it wasnt in stock so I had to cancel the order, hopefully I will have more luck with this one.

[John]

The central region of M42 does show some real detail when you apply magnification. I prefer the unfiltered view myself though. You should be able to make out the E & F Trapezium stars with your ED120. I can see E and I'm glimpsing F with my ED102 tonight. F is just a bit easier with the ED120 I find. I find around 100x magnification about right to pick out E & F. Much more or less and the task gets tougher.

[michael.h.f.wilkinson]

I find filter do bring out a lot of detail. The extra aperture of the 120 helps too, of course. I have also used high magnification on M42 (up to 254x to split the trapezium), and the centre part can take a lot.

[Sirius Bizness]

The jury is still out on filters for M42 for me. They certainly do bring out more detail but it gives it a more artificial feeling. I think I did prefer the unfiltered view at 100x.

John, not sure I could split E and F at 100x. Will have to check. I think I was only seeing E as a bit of elongation. I was going manual on the mount though as I couldn't be bothered with getting all the power bits out. There is something refreshing with just dropping the mount down and sticking on the scope for a quick 30 min session. The HEQ5 isn't ideal for nudging about though. I seem to remember the trapezium splitting well at 257x with the 3.5mm Nagler although I may have dreamt that. The 3.5mm is now gone so will be giving the zoom a go with some tracking on a longer session soon.

[John]

I too prefer the unfiltered view of M42. And most other brighter nebulae for that matter.

In spotting the E & F stars in the Trapezium (or Theta 1 as it's formally named) I find the right magnification is key. Thats not too much and not too little and this varies scope to scope, night to night as well.

E & F are not actually that close to the A and C stars but they are a lot fainter and this is the challenge. You need an eyepiece that gives you the tightest star images with minimal glare / light scatter from the A and C stars.

E is a little easier to spot than F because F's neighbour, C, is the brightest of the 4 main stars in this group.

Here is a diagram which may help pick out the E & F stars:

[Sirius Bizness]

Thank you for that John. Very useful. Will use that diagram next time I study it. Is it possible to cath a glimpse of G and H with a 120mm scope on a good night?

[Sirius Bizness]

*catch

[John]

Thank you for that John. Very useful. Will use that diagram next time I study it. Is it possible to cath a glimpse of G and H with a 120mm scope on a good night?

I've not managed to see G or H even with my 10" or 12" scopes and I've seen reports from folks failing to spot them even with a 16" scope from a good seeing location.

So I'm not holding out much hope for the 120mm !

[alan potts]

Interesting John,

I tried E and F last night with the GSO 150mm and saw both. Guess what the magnification was a 12mm Nagler on 1370mm F/L a Mag of X114, so looks like you fomular works. Switched to the 10mm Delos (Writing Review) and I couldn't see F any longer but could still see E, the Mag was X137, so again fitting in with what you said.

I will try G and H with the 12 inch my 10-11 degrees South of UK may make a difference.

Alan.

[michael.h.f.wilkinson]

The jury is still out on filters for M42 for me. They certainly do bring out more detail but it gives it a more artificial feeling. I think I did prefer the unfiltered view at 100x.

John, not sure I could split E and F at 100x. Will have to check. I think I was only seeing E as a bit of elongation. I was going manual on the mount though as I couldn't be bothered with getting all the power bits out. There is something refreshing with just dropping the mount down and sticking on the scope for a quick 30 min session. The HEQ5 isn't ideal for nudging about though. I seem to remember the trapezium splitting well at 257x with the 3.5mm Nagler although I may have dreamt that. The 3.5mm is now gone so will be giving the zoom a go with some tracking on a longer session soon.

Unfiltered is best from a really dark site with no moon (like I experienced in the Alps a few years ago). When there is a moon or LP, I like to use UHC on M42, but O-III is a bit too harsh, I feel

[Mike73]

Like Michael, I was really suprised to find that using filters on M42-43 actually harmed the view rather than enhanced it from a dark site, this only happened in the really faint wisps of nebulosity.

http://darkskysketches.blogspot.co.uk/2012/12/m42-m43.html

[Sirius Bizness]

Mike, fantastic sketch! After seeing that I really need to get the MN190 out to a dark site. It might be half the aperture but will be better than the 120mm and all the LP.

Out of interest did you see any colour at all?

[Mike73]

To be honest I cant say I've ever seen colour in DSO's, I know alot of people do but I guess my eyes just cant pick colour out for some reason?

[michael.h.f.wilkinson]

Filters block the reflection component of the nebula (reflection off the dust, rather than emission from the gas). In really dark sites this is a problem. With LP this component is usually so faint you do not notice it has gone.