OIII ON M42?????

Hi all, Well my 11 year old Caroline, went out and bought her self with her own money, an 1 1/4" OIII Orion filter for one of our 3 scopes . We had a ultra block but no, that was not good enough she need an OIII. So even with the temp. at 19.3 here in Warwick, NY we took her new starblast EQ ( the smallest of the 3 ) out so she could show my wife and I why she needed to have the filter. It only took but an instant for us to see the difference between the OIII and the ultra block, the OIII showed more of M42 out to the edge of the nebulae but what i found interesting was, that stars the make up the trapezium were at best very very faint if visible at all, but with the ultra block you could see the nebulae nicely along with the trapezium. We were using relatively low power a 24 mm and a 15mm panoptic's. So is my 11 year old wrong about the OIII or is M42 just the wrong nebulae for the OIII.

Thanks for any input

Bob & Caroline

Robert, M42 is fine with the OIII filter...

The OIII filter is a bit "narrower" than the Ultrablock, and that's why you'll see less STAR light, but you'll see more NEBULAE, which is WHY you get these filters in the first place...

You're 11 year old seems to be quite a smart girl! 8)


Clear skies!

Hi Bob,
I have had both and came to the same conclusions. I first had the ultrablock and then had the chance to buy a Televue OIII. The ultrablock was better in the city, but the OIII blew me away from a dark sky site. Try to get to some dark skies with that OIII to see M42 before spring to see for yourselves. The view of the Veil Nebula in the summer was much better in the OIII, too. All the OIII filters that I have I've looked through at club observing sessions had less light tranmission and higher contrast than the ultrablock. I've since sold the ultrablock, but I do miss having it my light polluted backyard.

Cheers,
Jim Moscheck
SE Michigan