Small Scope Observing - what do YOU observe?

[digitaldave]

I'm currently in the process of trying to sell my large SCT, and my plan is to replace it with a smaller refractor on a simple alt-az mount that I can observe with at a moments notice. However, I'm well aware that the reduced aperture will limit how deep I can see compared to the SCT, but I'm also aware that the wider field of view will mean that I can get larger objects completely in view. So this has led me to have a rethink of what I will actually try to observe. I've had a few thoughts so far:

1) Lunar/planetary observing - being relatively bright (at least as far out as Saturn I guess), these should be easy targets for pretty much any scope. however, I've been ignoring them on my SCT, perhaps because the larger aperture subconsciously makes me want to track down faint objects...

2) Open clusters - the narrow field of the SCT is a distinct disadvantage here, so the wider field of a refractor will be very handy. Again, this is a group of objects that I've largely skipped over so far.

3) Globular clusters - I'm well aware that they won't be particularly impressive in a small refractor, but I should be able to see the good ones. However, I think with a smaller refractor, the challenge won't necessarily be finding them, but seeing if I can resolve any individual stars.

4) Galaxies - pretty much the same here as with globs I guess - there should be quite a few still within the range of the refractors I'm looking at, so the challenge will be trying to detect structure and details.

5) The Messier Objects - I guess these are some of the most observed objects, especially for northern hemisphere observers, and I plan on hunting down as many of them as I can. I'll be using a 4" refractor, and apparently so did Messier, so it should be something I can do .

6) Doubles - I observed some doubles for the first time at the weekend at my club's observing session. Previously, this is something I'd ignored, because I'd thought it sounded boring, but it was surprisingly interesting .

7) I'm also hoping that by removing GOTO from my setup, I'll be forced to learn my way around the sky, and hopefully learn were some major attractions are located.

So, that's my plan. What do YOU do when using a smaller aperture (or even binoculars)?

Regards,

Dave.

[jgs001]

Dave, I've written up all my astro work on my blog. But using my 3" refractor I look at the Moon and planets and widefield stuff mainly. I have "seen" things like some of the galaxies, M51 I think springs to mind, but see is a very loose term. I spotted a very faint, and tiny grey smudge. For me that counts as seeing it (for the purposes of recording I found it). I've only seen a couple of globs and that's just what they looked like. Larger blobs of light. It really works very well on the open clusters.

[peeceeTal2M]

Hi Dave, "Turn Left at Orion" was written specifically with small scopes in mind,(around 3" diameter i believe) so anything in the book you'll be able to see with your 4"

[russ]

Loads to see in a 4" Apo. Had some great visual sessions with my ED100.

The planets are fantastic for a start. You'll immediately notice how little cool down the refractor needs to turn in extraordinary views. I just how favourably those views compare to a big SCT. This is one area where i don't think you'll miss your big SCT too much.

Lunar - you simply won't miss that SCT at all for this subject

Deepsky - again i think you'll be surprised just how capable a 4" refractor can be. i was certainly surprised with my ED100 when viewing things like M51, M13 and Eskimo etc.

Solar - pin sharp views with a white light solar filter.

All bases covered

[digitaldave]

I ahve a copy of Turn Left at Orion, and intend to make good use of it.

Rus - solar, that's something I'd completely forgotten about!

So, what do you guys do with a small scope or bins?

Dave.

[James]

I'll second Russ' comments (not least as I now own the ED100 he's mentioned!).

If you get a chance to go to dark skies you will be in for a surprise at just how much you see with a 4" scope. Several globulars will resolve some stars around the periphery like M13, M3, M5.

James

[russ]

I no longer have a refractor but if we are just talking small scopes then my ETX 90 qualifies.

I use that with a sturdy camera tripod for quick grab'n'go sessions. It cools a lot quicker than the 6" Mak. Main targets for me with that scope are:

Lunar - great views and not much to be gained by dragging out the bigger scope

Solar - as above

Planets - the 90 performs quite well, its worth the effort. Your frac would be a lot better to be honest

DSO - i did use it for a while when it was my only scope but 90mm and f13.8 don't make a good combo for this, unlike your frac.

Terrestial - it's a good daytime scope too, as would be your refractor. If that sort of thing floats your boat of course.

Russ

[scotastro]

I would echo James' (FLO) comments

I own an ST102 and fitted with a 2" diagonal and use either 1.25" or 2" wide angle EPs. In our dark sky it is easy to pick up loads of faint objects as at 15x you can get a 3^o FOV (hardly need a finder). Things like the Leo triplet (M65, M66 & NGC 3628) are smudges but with a bit of definition as Globulars would be. I can only think that an equivalent ED scope would give that little bit extra.

A solid mount is essential - at least an EQ3-2 for a short tube 102mm - as it allows higher magnification (160x) for the planets.

Mike

GAC

Galloway Astronomy Centre

www.gallowayastro.com

[Helen]

I've got a copy of Stephen O'Meara's book on Messier Objects. Its great, includes sketches as seen from a small scope (Ok, so he used a small Televue and has amazing skies in Hawaii I think), and loads of information about each object.

Helen

[digitaldave]

I've got a copy of Stephen O'Meara's book on Messier Objects. Its great, includes sketches as seen from a small scope (Ok, so he used a small Televue and has amazing skies in Hawaii I think), and loads of information about each object.

Helen

Helen,

I've been thinking about getting that book, I think I'll have to actually pull my finger out and order it - it sounds like a good book to have, and I quite like O'Meara's columns in Astronomy magazine. Sketches/images of the object as seen through a similar sized scope are always useful - Sue French's Celestial Sampler has sketches of many of the objects in the book, and it gives a good idea of what to expect at the eyepiece.

Dave.

[scotastro]

Dave

Saw this ED100 on astrobuysell - might be of interest.

http://www.astrobuysell.com/uk/propview.php?view=20516

Mike

[Whippy]

I've got a 110mm APO and even in moderately light polluted skies like mine, there's plenty to look at. I have used mine on my AZ3 alt-az mount and it just about takes the weight so it's not really suited to high power magnification that'd be good for planetary detail and splitting close(ish) double stars. You might want to check the weight of your prospective purchase and match the mount accordingly. I've managed to resolve some outer stars on the bigger globs like M13 but TBH the wider doubles, open clusters, brighter nebulae and of course the Moon all look gorgeous.

Tony..

[glennbech]

Contrast is king; Poor sky, poor night. In Stephen O'Meara's book I think there is a sketch that he has done over several nights that maps out the dust lanes of the Andromeda Galaxy... Imagine to be able to see them through a 4" ?! That must be some skies. From downtown Oslo; where I used to live, M51 wasn't within reach of my 8" Newtonian.

The advantage with a small scope is of course that you can visit dark skies :-) But then again; think about having a large dobsonian out there in the forest :-)

[russ]

M51 wasn't within reach of my 8" Newtonian.

i had that problem too from our old old house. I also couldn't see M45 naked eye :? The LP extended up 70 degrees from the horizon, just left with a tiny port hole overhead where i could see a couple of stars. Most nights i could count the stars visible on both hands.

Russ

[glennbech]

... Forgot to answer you question!

I hava 90mm Megrez 90 doublet.

- The moon is amzing.

- I can see 2 belts on jupiter and all the major moons.

- My best view ever of the double cluster was done in this scope mainly due to the perfect sized field of view with a 20mm EP. The scope also shows pinpoint stars on clear nights where my (badly collimated?) newt would have shown softer stars.

- M13 Wasn't that good

- I can easily see M57 and the ring shape in it.

When It comes to "Turn left" at Orion; I find it very good... BUT! It is not written with modern skies in mind. You should be on a mountain top with a red flashlight when you read it.

I also find the "directions" a bit confusing from time from time. Instructions like "move two finder scope lengths east" easily pushes me off track. But then again; I was never very good at getting directions .-) .-)

[glennbech]

i had that problem too from our old old house. I also couldn't see M45 naked eye The LP extended up 70 degrees from the horizon, just left with a tiny port hole overhead where i could see a couple of stars. Most nights i could count the stars visible on both hands.

Argh!!! From my horrible previous location the entire southern skies were pink. I lived a few kilometers north of the city core. Like you said; only the brightest constellation stars managed to punch throgh.

And I tell you; Trying to follow "Turn left" at Orion under those conditions; even with an 8" Newt (!!) can be very frustrating. I think that pretty much sums up the point of good skies. What you can "see" / find in a 3" can be totally invisible to a 8" Newtonian from washed out ligth polluted location...

[acey]

Dave, your wishlist sounds good - as others have said, there's loads you can do with a small refractor. I use an 80mm f5 as a deep-sky travel scope - I've seen lots of Messiers and Caldwells with it. Galaxies are interesting even in small aperture - they're little fuzzy blobs, just like through large aperture... Amazing how much detail you can tease out of the fuzz with a little patience and perseverance. The other night I had a quick look with 10x50 binos and had no trouble seeing M81/82, and lots of other stuff (in a mag 6 sky).

Like you I've never been into doubles and have always thought that maybe I should give it a go - they were a major pursuit in the days when small refractors were the only thing most amateurs had.

Star fields and large nebulae/galaxies also come to mind (M24, Helix nebula, Barnard's galaxy etc), where short f-ratio is more important than aperture.

O'Meara's books are well worth reading - but his site is mag 7.5 (I think), making his 4-inch equivalent to an 8-inch under a mag-6 sky. Lucky him. I just wonder why he doesn't use a 12-inch.

Andrew

[glennbech]

O'Meara's books are well worth reading - but his site is mag 7.5 (I think), making his 4-inch equivalent to an 8-inch under a mag-6 sky. Lucky him. I just wonder why he doesn't use a 12-inch.

I think the optics of the 4" described in the books is also a bit more than most people will put into a 4" .-)

How do you calculate the "mag" of your sky? dark adapt and find the dimmest star you can see with direct vision?

[acey]

How do you calculate the "mag" of your sky? dark adapt and find the dimmest star you can see with direct vision?

I use the stars of Ursa Minor (because they don't change too much in altitude). Zeta and Eta are mags 4.3. and 5.0 - if you can see them (with dark-adapted eyes) then look for the one halfway between them, which is 5.6. If I can see that one with direct vision then I'm prepared to call it a mag 6 sky.

You can get the data e.g. from http://www.wikisky.org/