aperture and fuzzies im more confused than ever

[icebergahed]

Ok i know that nothing will get views of deep space objects like galaxies and nebulas like what you see in magazines. i know the couple exceptional bright one may get close. but if for visual use only is a 10 inch telescope gonna give me JUST a brighter fuzzy object compared to a 5 inch dimmer version fuzzy. maybe i will see more stars in a cluster but when it comes to fuzzys, is that all you get.....fuzzys.....?????

Sorry for over using the word fuzzys:)

[crashtestdummy]

From a dark site i can get faint spiral arms in m51 so no,you dont.just get fuzzies but still its never going to be like a photo.

[rowan46]

to some extent it depends on what the fuzzie is and your location eg how dark your sky is. but under city skies many fuzzies remain just that. fuzzy. However some of the brighter fuzzies definitely become unfuzzy under darker sky especially with more apparture so it could be said that larger appartures will make more fuzzies unfuzzy(The technical term is resolve)

[cotterless45]

It's a great sense of acheivement and excitement to go deep sky hunting. An 8" aperture will get you most reasonable observed targets.

The seeing conditions will dictate what detail you can see, with pristine dark sky providing optimum observing. You will not be getting astounding photographic views if you are a visual observer.

In the same way that travel broadens the mind, so does every view through a scope, bins or eye. Especially if you can share and show and enthuse others. For which you'll be needing

clear skies,

Nick.

[Imd]

I once got the amazing opportunity to look through a 24" telescope at kelling heath. I recall looking at m51 and m101. The view was breathtaking its a long way from a 10" but I thought I would share as the view was as good as many of the photos I have seen and when you are looking through an eyepiece and see so much detail it's extraordinary.

I hope I see him and his scope again one day if only to thank him again

[John]

I think that 10" or 12" is the aperture where deep sky objects start to show a little more in the way of features / form / shape. There are a few exceptions that show well in smaller apertures but generally I feel that 10" / 12" marks a sort of watershed in light gathering.

On a dark night globular clusters do start to look like their photos with a 10" / 12" scope.

One thing that can't be overstated though is the difference that getting whatever scope you have under dark skies to observe DSO's, makes. I was really impressed with the views that my 6" scope was giving under good skies at the SGL star party a couple of years ago. The views of many deep sky objects were better than my 10" scope could give at home so you could say that dark skies in effect nearly doubled the aperture of the scope.

I've seen M13 and M51 through a 20" scope and they were certainly anything but faint and fuzzy then

[stevepeverall]

It's a great sense of acheivement and excitement to go deep sky hunting. An 8" aperture will get you most reasonable observed targets.

The seeing conditions will dictate what detail you can see, with pristine dark sky providing optimum observing. You will not be getting astounding photographic views if you are a visual observer.

In the same way that travel broadens the mind, so does every view through a scope, bins or eye. Especially if you can share and show and enthuse others. For which you'll be needing

clear skies,

Nick.

Wise words. I don't remember Worzel coming out with that kind of stuff when I was a kid!

[Moonshane]

I agree with the 10/12" watershed and with 16" a lot of things look a lot better from dark skies and LP sites. at home where LP is bad, most galaxies are small and fuzzy even with my 16" scope. at a dark site, spiral arms and some details is visible.

globulars are great anywhere with my 12-16" scopes, open clusters are the same and planetary nebulae are good too and relatively unaffected by LP (the right ones anyway). nebulae are badly affected by LP but can look almost photographic. the orion nebula looks photographic with my 16" from home.

all that said, it's uncommon to see an object (other than solar system objects) which look like photos as it's a different light gathering process.

[AlexB67]

I think that 10" or 12" is the aperture where deep sky objects start to show a little more in the way of features / form / shape. There are a few exceptions that show well in smaller apertures but generally I feel that 10" / 12" marks a sort of watershed in light gathering.

On a dark night globular clusters do start to look like their photos with a 10" / 12" scope.

One thing that can't be overstated though is the difference that getting whatever scope you have under dark skies to observe DSO's, makes. I was really impressed with the views that my 6" scope was giving under good skies at the SGL star party a couple of years ago. The views of many deep sky objects were better than my 10" scope could give at home so you could say that dark skies in effect nearly doubled the aperture of the scope.

I've seen M13 and M51 through a 20" scope and they were certainly anything but faint and fuzzy then

I posted this little concise summary once before and found it ever so useful. It sums it up nicely and agrees with what you say, the link also mentions that it is really at the upper end, 10 inch and up you got to have any hope of seeing colour as well.

https://www.astronomics.com/what-can-you-expect-to-see-in-a-telescope_t.aspx

[NGC 1502]

Definitely pays dividends to get to a dark site. But most of the faint stuff will still be an unresolved patch with the following exceptions (for me) with a 10" at various dark sites.

M51, faint spiral arms (confirmed by fellow observers)

M31, main dust lane (..............ditto............................)

Veil Nebular, thread like extensions to main curving arcs of nebulosity

(..............ditto............................)

M33, main spiral arms (not confirmed by others, but definitely seen)

If you go larger, more can be seen with greater certainty.

Regards, Ed.

[Qualia]

A good source to appreciate what kind of thing may be possible to see with different sized scopes is to check out sketches.

For example, this is M 51 as seen by an experienced observer through a 4" frac under good sky conditions. Here is the same object through a 5" reflector under fair conditions. Again, here is M 51 through the eyes of an experienced observer with an 8" Newt. Here's another with an 8" SGT. Here's another through an 8". And so on.

From this kind of research amalgamated with knowledge of your own viewing, the sites viewed from and sky conditions and any sketches you have made, I think we can draw a number of conclusions. With all other things being equal,

• aperture really does help in getting to see more detail. Minimally it makes everything so much brighter and more spell binding.
  
• dark skies do magic, better the darkness better the magic and really will augment your telescope's aperture.
  

But these factors do not necessarily have the final word.

• training the eye and brain to tweak out detail is equally as important. An experienced observer will see so much more. This requires keeping your eye dark adapted, patience, repetition (returning time and time again to the object itself), actively asking yourself questions about what is actually being seen and if you can, practicing your own hand at sketching.
  
• sitting comfortably to conduct these exercises will add a good inch to your aperture.
  

[jetstream]

Qualia those sketches are great,they give us a realistic expectation under exceptional skies.My best view of M51 looked similar to the 4" sketch,but there was some "colour" connecting them,with both clearly separate.This was in very dark skies with Milky Way bright & Whirlpool high in the sky.Great post & replies.

[sgazer]

the closest thing to colour in a DSO I saw was with a 10" dob in a country location about 5 miles south of Coventry. I'm sure I saw a brief green hue in the Orion nebula. For that reason, I quickly moved to imaging which will capture the same nebula in glorious colour with just a 30s exposure. Large aperture and dark skies help significantly for DSOs.

[andrew63]

Very informative thread. M51 sketch is pretty much as i see it through a 4"

andrew

[swamp thing]

1371675854[/url'>' post='1967736']

is a 10 inch telescope gonna give me JUST a brighter fuzzy object compared to a 5 inch dimmer version fuzzy.

Let me try and use an analogy to explain how aperture works.

Suppose we walk outside at night, and we look at a far off tree under a street light. We get the rough shape but detail like leaves, branches etc aren't discernible. Now, walk nearer to the tree, we start to see detail. The nearer we get the more we can pick out. The tree gets no brighter it just gets bigger so our eyes can pick out more. This is how aperture works.

I find big scopes tend to "pick us up and put us closer to the object", the bigger the scope the closer we get.

I know the above sounds like we could simply magnify the tree to have the same effect, but when we magnify, the image gets darker. So using a small scope and magnifying is like making the featureless tree into a larger featureless tree. We need aperture to put us nearer to get detail.

[cotterless45]

Yep, I get green from M42. Tight planetary nebulae will give you stunning blue to blue green colours.

There's a lot of expectation of seeing Hubble type images visually. Often I get an " oh, is that it ".

Often it's not until you've explained the object or shown them Saturn that you get a "wow ! "

Nick.

[jimmyjamjoejoe]

If you go larger, more can be seen with greater certainty.

I think this whole thread could be condensed into the above sentence. Its not so much about seeing more of an object, just seeing it easier. Unless you go REALLY large, details like spiral arms etc will always be a kind of "ooohhh yeah i think i see it now", and essentially, fuzzies will always be fuzzy.

[michael.h.f.wilkinson]

I think apart from aperture, experience is essential. I can pick out detail in certain nebulae in my 8" that an inexperienced observer would struggle to see in a 16" scope (I remember picking out a tiny planetary with Olly's 20" dob, which he had never spotted, I later spotted it from home with my C8 as well, most people would have considered it a faint star). If you just look at the physics, the surface brightness of objects is given by the exit pupil. This means that a fuzzy in my 8" SCT at 64x has the same surface brightness as in a 10" at 80x, or a 12" at 96x. So if the surface brightness is the same, why would it be easier to spot?

This seems like a bit of a paradox, until you take into account the image processing that goes on in the brain. The brain does not register every variation in brightness in the image. Evolution has tuned it to detecting those that are meaningful in some way. Photon noise is not meaningful, so the brain tries to filter that out. In the 12", the object is 1.5x as large, linearly, and 2.25x larger in surface area (and therefore 2.25x the number of photons are involved). This larger area adds up to more evidence for the brain that that fluctuation is statistically above the noise, which is why you spot it more easily.

As you get more experience, you find that you can spot more detail. Averted vision and various other tricks become second nature.

[chiltonstar]

Worth remembering though that Messier observed all of his objects with a small (3" I think) long focal length refractor. Presumably though, he would have done far better with a 10" newt (if he'd managed to get it collimated!).

chris

[michael.h.f.wilkinson]

Worth remembering though that Messier observed all of his objects with a small (3" I think) long focal length refractor. Presumably though, he would have done far better with a 10" newt (if he'd managed to get it collimated!).

chris

He would have had a servant to collimate it, I presume

[Naemeth]

Worth remembering though that Messier observed all of his objects with a small (3" I think) long focal length refractor. Presumably though, he would have done far better with a 10" newt (if he'd managed to get it collimated!).

chris

I'm sure he would have been perfectly happy even having the coatings that modern lenses have. He would have seen far more with a modern refractor than he did with his refractor, but he didn't have light pollution.

[michael.h.f.wilkinson]

I'm sure he would have been perfectly happy even having the coatings that modern lenses have. He would have seen far more with a modern refractor than he did with his refractor, but he didn't have light pollution.

He would have seen even more with all the fancy star charts we have now

[OneEyedSam]

and he didnt have to contend with sodium lights !

[jetstream]

The colour I saw in M51 was just a whitish glow between the two,I may have implied something different.My scope shows some nebulosity as green-M42,& some in Sagittarius.What is interesting is that observation agrees with the science of object detection.Another poster referred to the Clarkvision site,very interesting.I guess data has been seriously been assembled during-after- WW2 & offers some interesting conclusions to visual observation.I like the conclusion....keep trying magnifications in steps around 1.5 or so.He says that an object of around 100 arc-minutes may show the most detail.When I'm bored I will figure out magnification needed to get different objects to this size & compare with more or less magnification.And also keeping in mind the exit pupil..... and if seeing can support the xtra mag.... &....?!!I need a bigger scope for this....another good excuse for one!That site also shows a realistic visual expectation under the best of skies.Its going to rain for 3 days so maybe I'll get the calculator out.....

[bish]

Very informative thread. M51 sketch is pretty much as i see it through a 4"

andrew

The sketch through a 4" is just like using a 10" from my light polluted sky (on really good nights)