One of the things I was looking for the other night was M16.  I failed to find it.  I had a good alignment on the scope as my goto took me to several other DSO's with no issues.  I started with a 21mm unfiltered just trying to find it.  I could not so I added the OIII filter to the 21 mm and tried and still nothing.  I was using my 11" sct.  Is this target so faint that maybe I missed it?  I am in a fairly light polluted area but compared to other times I had an easy go of M81, M82, and M64.  Anythoughts would be appreaciated.  Thanks.

With a C-11 you might have looked right through it.

M16 is the open cluster than illuminates the Eagle Nebula. If you use an OIII filter, you'll darken everything in the field of view, including the cluster.

With a focal length of about 2,800mm you will need a widefield eyepiece to start with ... something in the range of 32mm and up. I use a 40mm eyepiece when finding a target, then get closer using a shorter-focal-length eyepiece if necessary.

A good method is to start with M17, the Swan (or Omega) Nebula nearby. Frame that using an eyepiece that will show the whole thing. Then go to M16 and you'll see the cluster. Once you have the cluster, you can use an eyepiece that increases magnification if you like. M17 is much larger (about 3X) in apparent angular diameter than M16.

Wait until after you can see the cluster before applying an OIII filter.

  I live in fairly light polluted suburb of Detroit.   I cannot see M16 at virtually any magnification--only the stars associated with it.   I caught a glimpse of the swan nebula through a pair of 15x70 binos, and only becuase of the concentration of the light at this low mag, and will averted vision.

  M16 is a georgeous sight, but I doubt that you will be able to view it, or if you can, it will only be a shadow if its full glory.  This goes for most reflection/emssion nebula.

   For me, the prime disadvantage of urban observing...

 Thanks guys,  cyber I hope you are wrong but I have noticed that nebulas are very hard to see for me.  I had a real hard time picking up M27 the same night.  I never thought to go lower power to spot M16.  I usually start with my 21 just because I really like the view I get through it.  I will have to try the lower power next time the weather and my work schedule cooperate.

Detecting the bright nebulosity associated with M16 is going to be tough from a light-polluted location and the dark nebulosity (the so-called Pillars of God) will most likely be impossible to discern. 

http://www.blountk12.org/Planetweb/ser.html 

However, you should easily be able to see M8 and M17 in Sagittarius.  Your nebula filter will improve the views somewhat.

http://www.seds.org/Maps/Stars_en/Fig/sagittarius.html

Dave Mitsky

   I wish you the best, but if M27 is faint--and this is a fairly pronounced planetary---you are in for some rough sailing.  M27 shows up rather well above 60 degrees here (in the 8" and 12", and I've spotted it in the 6" once upon a time).  My skies have a limiting visual magnitude of about 3.5, for comparison.   My limiting magnitude at the scope is about Mag 12-13 for stars and  SB 11.5 for extended objects.

   M16 is one of the few objects that I recommend a road trip (to the country) for.   I'm planning one in a few weeks at new moon to get an eyeful of various nebula and galaxies that I don't usually get a chance to see.

  I saw M16 with My 15x70s in Armada, Mich. (about 30 miles north fo Detroit) in Mag 5.5 skies, and it was AWESOME, in the full juvenile use of the term!--quite extended even at that low mag.  I'm hoping to repeat this year but using my 30x100s following the July 4th festivities at a family friend's.

  May the Force be With You, but eye some prospective farmlands...

 It's a good thing I do not mind a challenge from the sound of it.  Thanks for the information.  Dave, thanks for the links, I saved those, it looks like both sites have a lot of good information in them.