that extra aperture ...

[johngccfc]

I'm still very much in the umming and arring stage and on a steep learning curve. One day i'm certain that i should go this way, then the next day i think instead that i should go that way.

So, if you'd be so kind, todays conundrum. ..

A 12" newton gives me more mount options for sure, but all portability issues aside, I'm wondering what a 16" dob would give me over a 12" newton. I'm really wondering about what extra 'reach' (?) the extra aperture delivers. very grateful, thx

[MatthewMarkWray]

iv got a 8'' dob and tbf its amazing was talking to a guy on here thats just got a 16'' and it has 4x as much light gathering power than my 8'' if you can afford it go for it but bare in mind the 8 only just fits in the car without the mount lol so transporting a 16'' will be a task

clear skys

matty

[MatthewMarkWray]

so ild say it would probably have about double the light gathering power off the 12''if its got 4x off the 8'' but am no expert

[johngccfc]

to throw another spanner in the works, and i'm sure there are many factors involved, how would a sct 8, 9.25, 11 compare?

sorry, i appreciate that its a bit of an apples and pears comparison

thx

[Moonshane]

I have both a 16" and a 12" dob and really enjoy both. there's a massive difference in size. see the pic below. the 12" is becoming my most used scope as it is quite light and easy to move, cools down quickly and is put away more easily. it gives a wider field too, although it is a f4. the whole pleiades is nice. from home there's not huge differences as there's a lot of light pollution but the aperture of the 16 is a noticeable step up in terms of how deep you can see and the fainter objects show more 'body' than with the 12". at a dark site the 16" comes into its own and is a wonderful instrument. if I could only have one larger aperture scope then I would definitely have the 16" but it's very useful having both. the 16" f4 I have just fits in my smallish hatchback. the 12" is definitely more portable though. I'd want to put neither on anything other than a dob mount. as I am solely visual though that's the best option anyway. for me, nothing beats a decent aperture, wide field lower power top quality eyepieces and dark skies.

[John]

It all depends what your interests are, what your viewing location is like and whether or not you need a scope to be portable or plan to keep in in an observatory of some sort. Are you more interested in the moon and planets or do deep sky objects draw you ?. Are you likely to be interested in taking images with the scope at some point and, if so, of the moon / planets or deep sky objects ?

I guess I'm saying we need some more information before we can give useful advice. As you are finding, there are very many options and all have their pros and cons.

Generally the more aperture you can get the better but it's not always the case and it's no use if the scope is so awkward to use that you find you just don't !

By the way, a dobsonian is a newtonian on a simple mount. Same optical layout, different approach to mounting it.

[Moonshane]

a 16" scope as 1.77x the light gathering of the 12" so not far off double.

[swamp thing]

Hi

What scope are you using at the moment, or is this your first one?

Not sure I'd recommend a huge 16" Dob as a first scope.

[Moonshane]

good points above. I was assuming from your comments that you had a scope already. if intent on a large visual scope a 10-12" dob is hard to go wrong with, especially if buying used but a 16" is very large comparatively as stated/shown above.

[johngccfc]

Guys, thanks so much for your comments. No I don't have a scope at the moment. I'm trying to learn about what scope gives what.

I am partially interested in AP but I don't think I'd ever trade to ability to see for the ability to photograph. I'm trying to do as much learning and research as I can before I start spending cash.

I'm probably already suffering from aperture fever but at the same time I'm trying to learn about what options i could stat with that may also be useful in the future, for example if i ever did decide to get into AP too.

My initial 16" x 12" question was geared around whether so much more would be available with a larger aperure. I have no real preference (well, knowledge) about planets v DSO but I think that of the images I see that nebula images blow my mind more than planets, but then I've never seen either so I guess both are interesting.

As a noob I'd be quite reliant on a GoTo and some tracking and my initial question was wondering whether I'd be missing out much by choosing a 12 newtonian that could be mounted on EQ6 type mount, which could double for AP at a later date, and if I chose a large Dob that couldn't fit on such a mount, thus wouldn't be futureproofed for AP, would such a large aperture give me so much more for visual only.

Anyway, again, thanks for all your comments. I shall continue with my reading, better informed.

[swamp thing]

TBH deep sky observing is often about contrast. How much one can see is therefore more linked to sky conditions than aperture alone. For example a 6" under a pristine dark sky will knock spots off a 12" used from centre of town.

A 12" scope on an EQ mount is huge. You won't set that up many times before growing very tired of doing so. It's not a portable option, so unless you have an observatory planned I should forget it.

For visual deep sky use the Dobsonian mount is as good as it gets. It helps keep large scopes manageable, transportable, stable, and fun to use.

AP is something personally I have no interest in, but most seem to find small fast Fracs work as good as anything. You certainly don't need a great big 12" on an EQ mount when starting down this road.

In summary. If you live in LP area, get a portable set up. You'll see much, much more from out of town. If you live under rural skies, remember you still have to get it outside to observe.

Personally I would go with an 8" or 10" Dob for now. See how you get on. You may find them big enough, if not make your second scope the big one.

[Moonshane]

excellent post Steve

[Jim Steele]

If you can pop over your local astronomy shop or club to see what the scopes look like in the flesh. Some of the pictures on the web don't give an appreciation of size.

The last thing you want to do is buy a scope that is too awkward or cumbersome to use

[sgazer]

....and the best scope, is the one you use!

[CSM]

If you are in Bristol then I think light pollution is going to be a problem and a GOTO scope very useful. I would suggest that you would be better off going for something relatively small and portable to start with - no more than a 6 inch - get used to that, discover what your interests really are - visual, astrophotography, planets, deep sky, Moon, nebulae, clusters, variables, etc.,etc., - and then think about what scope will best suit you. Aperture fever is something we all suffer from at times, but amazing things can be done with the smaller scopes.

[ollypenrice]

When experienced astronomers say that you can 'see far more' in a larger scope than a smaller one a beginner might not entirely agree with them. Yes, of course you see more, but when you compare the monstrous bulk of a 20 inch Dob with a little three inch refractor you might expect a similar leap in what is delivered at the eyepiece. You won't get it. There is more difference between the scopes, in other words, than there is in the view! That said, there IS a big difference but many beginners find it a little underwhelming relative to their expectation. As suggested, only a bit of 'hands on' at an astrosoc will really tell you what you want to know.

Personally, something I know I don't want in a small to medium scope is a long focal length. A long FL restricts your field of view so it deprives small scopes of something only small scopes can offer - a wide field of view. I don't call a degree wide. I can get that in our 20 inch. For me wide means four degrees, diminishing as scope size increases.

Olly

[nicks90]

absolutely agree with olly re: wide field of view.I have seen 'more' with my 70mm short refracter than I have with my 130mm newt - but thats because last year I was an absolute beginner and I found star hopping incredibly easy with my little scope. With a 25mm ep in it, I can get teh whole of the pliaedes in the field of view with space around it! it also meant finding globulars and open clusters very very easy under dark(ish) skies, as the 'steps' in turn left at orion where extremely easy to see and follow. The moon is absolutely resplendant in it too.

However you do need to set an expectation of what a glob will look like in a small frac. You will NOT be resolving stars to the centre of a glob in a 70mm in an area with any sort of light pollution. it will be a round grey / white splodge. Most other DSOs are also fairly underwhelming visually - but still a buzz that you found a galaxy!

In myback yard - thats a different story! bad LP means with such a small aperture it is difficult to see fainter stuff. but the advantage of the little frac and little tripod is it all fits in to a baby changing bag and I can take it anywhere!

In my larger newt, the field of view is alot smaller and I find star hopping harder to do, however when i do get the object - it does look better. But you do need to know the star hops much better and know where to look!

Now I know my way around the skies better, I can usually find things easier - and hence I now only use the 130. But as a first scope, I am glad I had such a wide view - as spending hours searching in vain would have been dismal and possibly put me off.

I am just about to take delivery of a 12" dob - my scope for life!!! - but I am fully aware that my lowest power EP in the new mega-dob will give me the same magnification as my highest power EP in my little refracter!!! hence it wont be as easy to just scan a section of sky to find my chosen object! For that reason I am modifying my little scope and turning it into a big finder for my dob, star hop with the little one and then 'zoom' in with the bigger one.

good luck with whatever you get.

Nick

[mitchelln]

I've got a SkyWatcher 12" FlexTube GOTO and it really is the maximum a single person can shift around and get through door ways. +1 on all the comments about the best scope is one you actually get to use!

[AlexB67]

Good luck with what you get , I see you are in Bristol too and you will know, depending where you are, skies are not the best around here. Many would argue, this is not just my view but commonly heard advice that the 8 inch Dob is the perfect starter and it is the most popular in the UK. According to many vendors it is most sold scope, even a 6 inch perhaps may not be a bad idea, both should be easy to set up, easy to carry round , not too much hassle with cooling down time, not needing regular collimation etc. offers good bang for buck as a first investment, and it offers a good overall balanced scope in terms of features.

No point buying a 12 inch DOB IMHO as s starter scope, the best scope to start with is the one you'll use the most, and between the good days of weather we get around here, if you have a big scope and cannot be bothered to get it out during the week, probably because you want a short session, tired form work and don't want too many of the overheads that come with a big scope.

In fact if you look at my sig I didn't even go that far. I find a 5.1 inch scope already to be a very useful instrument that I can see myself being happy with for at least a good year before the bigger light buckets will be ordered

In the end of the day there is much fun that can be had if you take to the hobby and like it, I believe no aperture can buy you that, if you really like it, you'll learn to appreciate what you see in a smaller scope in any case.

[Moonshane]

it all depends on what you consider portable/carry-able. personally I find my 12" dob easier to set up (or certainly as easy to set up) as my 6" was on a pedestal mount or my 6" f11 is on an eq mount. it takes me about two minutes and then about ten minutes before the scope is cool enough for low power. maybe 20-30 minutes for higher power 100x and above, or an hour for full equalisation. it is a home made base though and a f4 scope all of which make it more usable in my opinion. other people would find it heavy etc but the little extra effort is worth it to me.

[planet15]

I find portability issue as relative thing - I mean, when I had a 4.5", and got 8", I thought oh my god what on earth is that? Then I got used to it, then when I got 12", and I thought it was a monster of a scope, but got used to it as well. Now I feel 8" is real small toy. I would imagine it would be the same with 16", we all get used to them, and will feel the 12" is tiny compared to the 16".

What I really would like to know is, and feel this was what the original poster was about too - what is the optical capability and difference of 16" compared to the 12" under the same sky condition be it under LPed or pure dark sky forgetting portability and set up time issues.

[AlexB67]

When I was writing that I was pretty much considering what starters are likely to buy, probably a sky-watcher or something similar. Of course I don't know for sure not having owned a bigger scope such as a 12 inch, but I know the weight and size of it, and my own scope I can pick up in one hand, I'd only consider the latter to be really grab and go, but I am no popeye I would not have wanted a scope that I need to collimate pretty much every time starting out as well ... personally.

Just a hunch but I suspect the more seasoned observers such as yourself are always more likely to suggest something bigger when you have invested so much time and effort already, the same with eyepieces when you read that forum, how people often consider only the expensive when they have been at it for a while, whereas for me the new BST is basically more than adequate as far as I can see for a long time to come, I am stoked with it and can't see myself wanting something more.

In the end of the day it is all about how much spare cash you have and are willing to invest as well I guess. I Just fear that for many newcomers even if you did have the cash, digging too deep too soon is not necessarily the best way to start versus the risk of getting frustrated with the hobby given the technicalities that come with a bigger scope.

My two cents, from a non expert I hasten to add

[rowan46]

I come from the other end in terms of portabity to moonshane my instrument is a small refractor that can be carried along with a tripod eyepices and no car. i have had a larger scope and have to say that the 80mm is limiting and that i miss apparture. Having said that because the scope is so portable I use it a lot more than I did the last one. So the best scope is the biggest that you can comfortably handle in all the locations you are likely to use it.

[Moonshane]

I think broadly we are all saying the same thing really. buy the scope you can carry with relatively little effort, to the place you'll observe from most. if this is a mile hike down a country lane, your requirement will be different to someone carrying it from the garage 10 yards to the garden. big effort gets boring after a while.

in terms of eyepieces, I admit to recommending Televue almost without exception. the reasons for this is that as someone once said on the forum - I am not relatively well off so can only afford to buy quality. or another way with quality it only hurts once. you can buy TV eyepieces at between £40 and £800.

[AlexB67]

I think broadly we are all saying the same thing really. buy the scope you can carry with relatively little effort, to the place you'll observe from most. if this is a mile hike down a country lane, your requirement will be different to someone carrying it from the garage 10 yards to the garden. big effort gets boring after a while.

in terms of eyepieces, I admit to recommending Televue almost without exception. the reasons for this is that as someone once said on the forum - I am not relatively well off so can only afford to buy quality. or another way with quality it only hurts once. you can buy TV eyepieces at between £40 and £800.

Agreement that is what I like about the lounge, constructive discussion. Most forums that I recall in some other areas this could have heated up big time, for that reason I would not have even wasted my time posting in such a discussion, but here we can all express a point a view in a civilised manner. Hopefully it has been helpful to the OP.

So now you tell me I should have been buying the TVs , too late, BST already bought