How much magnification for M13

[mih]

Hi, i have a 6 inch newtonian, 150mm focal length(f/5), 25mm and 9mm eyepieces. I currently have observed M13(Great hercules cluster), but you know, its a fuzz. i have a 2x barlow on the way. Will that 2x magnification(83x -> 167x) make any difference?

[Ags]

I have a C6 (same aperture as yours) and used to own a 6 inch newtonian. At low magnification you can't pick out the faint stars against the general glow of the cluster and the light pollution. As you increase the magnification, the background glow gets stretched out by the magnification and gets dimmer, but the stars remain points and don't dim much if at all. So more magnification helps resolve the stars - but too much magnification loses the fuzzy structure of the cluster, so it's a balance. I get best results at 100 to 150 magnification with my 6 inch aperture.

It's also worth noting you don't just need magnification, you need good magnification to tease out these delicate stars. So get collimation right, and make sure your barlow and eyepiece are up to the task.

Edited May 28, 2020 by Ags

[John]

If you use careful focusing, cooled and collimated scope and study for a period of time under a dark sky M13 will show quite a lot of resolution into stars with a 6 inch scope. 100x should be enough but experiment and see what works best for you. 167x might be a bit much unless the seeing and optics are on song but give it a try.

If the seeing is a bit unsteady then the resolution into stars does not jump out at you - you need to carefully observe the cluster to pick it out.

It is not resolved to the core with a 6 inch aperture but the outer parts should certainly be resolved into a speckling of stars against an unresolved backdrop. I first got resolution of this cluster with a 6 inch scope many years ago. The jump from my 60mm refractor was substantial to say the least !

With my 12 inch dob I find 150x - 200x ideal and the view is spectacular but I have 4x as much light and 2x the resolution to play with.

 

 

[Louis D]

Definitely by 200x M13 starts to resolve in an 8", not sure about a 6", in Texas seeing conditions.

[mih]

Ok, then i want to ask about the Orion Nebula. Is that easier to observe?

[John]

55 minutes ago, mih said:

Ok, then i want to ask about the Orion Nebula. Is that easier to observe?

Yes but Orion needs to be visible of course !

Messier 42 (the Orion Nebula) is an entirely different type of object from Messier 13 though. Low to medium magnifications are usually used on this target.

Don't give up on bright globular clusters such as M13 though. With a 6 inch scope they are rather nice as you develop your observing skills. I often observe them with smaller scopes than you have and enjoy the views.

The visual views of deep sky objects such as the above won't rival the images that you see of them though, even those made using scopes similar to yours. Modern cameras, long exposure times and processing can produce results that far exceed what our eye can see though a scope.

 

[Trikeflyer]

I don’t think it’s as simple. There are many factors involved in your comment “easier to observe” it’s not just related to magnification. As others have said, scope collimation with Newtonian, aperture and light grasp, focal length and the ability to use longer focal length eye eyepieces to get the same magnification as short ones do in short scopes - generally longer focal length scopes are more forgiving when it comes to optical aberrations, eyepiece quality, scope cooling. Then there are factors you cannot control - sky darkness - all objects are easier under a dark sky, seeing and transparency - local atmospheric disturbances can cause degraded observing, altitude of the object - Lower elevation means more atmosphere to see through - making the object ‘worse’.  With these many factors. Involved, it’s not straightforward as it might seem. Make sure the factors you can control are sorted and get to dark sky if you can. Then it’s down to ‘how the atmosphere is on the night’

Steve
 

 

[Ags]

M13 is not hard to observe, it looks good in all telescopes. I enjoyed the views of it for many years with a telescope with half the light gathering power of yours and even at that aperture (4 inches) could resolve some of the stars in M13 with averted vision. At 6 inches the stars are still quite faint but I don't need to use averted vision any more. I think what John and I were trying to say is you can get a good view of M13 (and indeed many other objects) with your telescope, but you need to spend a little time observing it to see the details the telescope can reveal. Another target worth looking at right now is the Ring Nebula in Lyra, and pay a visit to the colorful double star Albireo (the head of the swan in Cygnus). 

Edited May 29, 2020 by Ags

[Louis D]

5 hours ago, mih said:

Ok, then i want to ask about the Orion Nebula. Is that easier to observe?

Being the brightest nebula in the sky from our perspective, it's pretty easy to see in just about anything.  However, late May is not the right time of the year to view it.  If anything, adding an OIII nebula filter can help bring out the fainter details in light polluted skies once winter rolls around again.

[michael.h.f.wilkinson]

I used to have a homemade 6" F/8 Newtonian, and M13 was generally visible as a bright glow, with what I like to call "diamond dust" sprinkled over it. Faint pinpricks of stars best seen in averted vision. A really beautiful sight, both at just 48x and at 133x

When I got my 8" Schmidt-Cassegrain, I turned it immediately to M13, and the view was jaw dropping, with a myriad stars visible.