Best targets for a wide field scope

[Commanderfish]

Hi there guys,

My Explore Scientific ED80 Triplet has finally been delivered (Parcel Force took 8 days to deliver it on a 48 hour service )

With this scope I'll get the following views with my EPs:

6.1 degrees at x12

5 degrees at x16.5

4 degrees at x20

3 degrees at x28

2 degrees at x40

0.7 degrees at x80

I've been using a high focal length tight field SCT for so long that I can't imagine what targets would be best for a set up like this - other than the Milky Way of course. Any ideas?

After last night's session with my SCT, I'm guessing the Cygnus region is going to be tasty

There are big nebs like the Lagoon, Veil and North America that I've never seen in the SCT, though that is likely due to light pollution at home. I'm heading to a dark site tonight

[DirkSteele]

When you first get the benefit of really wide fields after being restricted to the drinking straw like fields of a long focal length scope like an SCT, it can be liberating.  As well as many of the larger DSOs such as M45, M33 and M31, you should try many other slightly smaller sized DSOs at lower powers and wider fields as well, as I find the extra sky around the object can help to provide a lot of context for its position in the night sky.  I would also recommend trying for more than one DSO at a time in the same field.  M8 and M20 are a good example of where that presents a striking view in the eyepiece.

[John]

4 degrees is enough to fit in both segments of the Veil Nebula. You will need an O-III filter to actually see it with an 80mm scope though. The same filter would make the North American Nebula a worthwhile prospect - thats another huge object.

The double cluster in Perseus is always a splendid sight at low power with any scope.

[Stu]

I don't think you'll quite get 6.1 degrees as at the extremes the calculation using field stop is more accurate. I think the field stop for the 42mm is 47mm so the calculation is 47/480 * 57.3 = 5.6 degrees. Still very nice

As John suggests, you might find that 4 degrees is nice, plenty big enough to fit the biggest objects in such as the Veil but with a smaller exit pupil so the sky background will be darker. It does depend which filter (if any) you have too.

Have a read of my Samos report and that will give you plenty of targets down in Sagittarius.

Cygnus will also be lovely, not sure if you will manage the Crescent, but certainly Veil and NAN are brilliant in a widefield scope.

[DemosL]

Just start doing sweeps of the sky near your prime meridian. Besides DSOs, you'll also come across some different colored individual stars or binaries and other apparent multiple star systems.

[Commanderfish]

Thanks for all the suggestions guys.  I haven't been able to view The Veil, North America or Crescent using a Broadband filter (Orion Sky glow).  Looks like I need to invest in an OIII.  Probably 2" so I can use my 17mm Nagler T4 with it as well

Any suggestions for best OIII filter?

[Commanderfish]

This seems unfeasibly cheap.  Anyone tried one?  http://www.rothervalleyoptics.co.uk/20196.html

]

[Commanderfish]

Hmm general opinion on other SGL posts suggest the Astronomik Oiii filter is the one to have.  Has anyone tried it?

[John]

I've seen decent feedback on the Skywatcher, Explore Scientific, Skies the Limit and Castell O-III filters. All are quite low cost but seem to do "what it says on the box".

I had an Orion Skyglow a while back and it did very little at all. It's a broadband filter though rather than a narrowband (ie: UHC) or line (ie: O-III) filter. The narrowband and line filters are the most effective on nebulae I've found.

Of the objects you list, the NA nebula is huge, the Veil massive and the Crescent smaller but can be tricky even with my 12" scope. The NA Nebula is so large that it's often better with binoculars rather than a scope although you can see it "a bit at a time" with a scope. Similarly for the Veil which comprises a number of segments which are overall nearly 4 degrees in extent, 8x the diameter of the full moon. I've found the Veil is the most interesting and engrossing of the three over the years.

I did own an Astronomik O-III for a few years and found it superb. I've now got a Lumicon O-III which is about the best of this type as well. Both cost considerably more than the ones I've listed in my 1st para though.

[Commanderfish]

 Thanks John.

I want a nebula filter, but am not certain whether to go for a narrowband "nebula" filter (Oiii and Ha) or just an Oiii.  I will mostly be looking at the big diffuse nebula mentioned in your post, with planetaries like the dumbbell being next on the list.

I've read that the narrowband nebula filters tend to be better on a higher number of nebs, whilst the Oiii can give slightly higher contrast, but with a darker image.  For context, I most often view from a moderate to low light polluted site (back garden in Surrey,where on a good night I can just about barely see the Milky Way), and sometimes form a dark site on the South Downs.  I'll be using an ED80mm for wide extended objects, and a 9.25" SCT for objects os 1 degree or less.  My Explore Scientific ED80 Triplet can produce a TFOV of 5.6 degrees using my 42mm EP, though at only x12 mag, so I tend to use the 30mm Moonfish at x16 and 5 degrees, or the 24mm Maxvision at x20 and 3.6 degrees.

I think I've got the choices down to the following:

Narrowband/Nebula filter - DGM Optics NPB

Oiii filter - Lumicon Oiii (or maybe Astronomik Oiii).

Thanks for any and all advice guys

[John]

Lots (and I mean lots !) of information on deep sky filters here:

http://freescruz.com/~4cygni/horsehead/NebulaFilters.htm#Intro

[Stu]

Dinesh, I have the Lumicon UHC and OIII, both of which work extremely well. You can perhaps try them tonight if you are coming, but they will be better with no moon obviously.

I would personally steer clear of the cheaper ones, I'm not convinced by the QC on them and I definitely get much better results with my Lumicons.

The results vary depending upon scope, and also getting the right exit pupil helps, but I use them both in a variety of scopes depending upon the object.

The Veil and NAN certain respond better to the OIII, I had lovely views in Devon of both, they fit in the fov of the Tak/31 nag no problem .

I'm interested too in the DGM John uses and may try one at some point.

I had lovely views of the Crescent at SGLX in the 16" but can't remember which filter worked best, probably the OIII as it gives better contrast.

[Commanderfish]

I thought there was no session tonight, silly me!  I'll clear it with the wife and hopefully should be ok to come along.  Yes would love to try the filters, thanks.

[Stu]

It's a bit of an extra, just thought we'd try if people are around. Just need this band of cloud to move in the right direction now!

[Commanderfish]

I'm up for it.  Clear outside says 50% cloud at 9pm, otherwise clear.