Aperture Fever?

[Raph-in-the-sky]

1 hour ago, Piero said:

Thanks John.

Anyway, my point is just that I don't consider aperture fever the purchase of a 200-300 Dobsonian. That's just a telescope that does a good job and all targets. To me aperture fever is an impulse purchase of larger telescopes without understanding why they are there for. I think SGL members are quite responsible on this actually. 

Beeing responsible is for adults! I'm just a 33 year-old kid with a big toy...and I want a bigger one!

[Guest]

I appreciate everyone's input. Whilst I enjoy the views from the old Meade 114-900, I'd like to see the moon's features with better resolution. That's why I was asking about the larger aperture Newtonians. 

I have a cheap 2x Barlow and a 9mm MA EP to call upon. I was wondering if going to a decent 4.5mm Plossl would be work better, on a bright object like the moon (as it's close in astronomical terms)? 

[Piero]

10 minutes ago, merlin100 said:

I appreciate everyone's input. Whilst I enjoy the views from the old Meade 114-900, I'd like to see the moon's features with better resolution. That's why I was asking about the larger aperture Newtonians. 

I have a cheap 2x Barlow and a 9mm MA EP to call upon. I was wondering if going to a decent 4.5mm Plossl would be work better, on a bright object like the moon (as it's close in astronomical terms)? 

Any 200-300mm dobson can reveal outstanding views of the lunar surface, with a plethora of details.   It will show you plenty of details on planets, and DSO under reasonably decent skies. 

If you decide to go for a dobson, make sure to get a decent collimator.

[Raph-in-the-sky]

19 minutes ago, merlin100 said:

I appreciate everyone's input. Whilst I enjoy the views from the old Meade 114-900, I'd like to see the moon's features with better resolution. That's why I was asking about the larger aperture Newtonians. 

I have a cheap 2x Barlow and a 9mm MA EP to call upon. I was wondering if going to a decent 4.5mm Plossl would be work better, on a bright object like the moon (as it's close in astronomical terms)? 

Actually if you plan to do lunar or planetary, refractors are often considered supperior. Big Dobs are really more suited for deep sky... I will leave advice regarding refractors to those who know what they are talking about.

Regarding eyepiece, short focal lenght plossl (ie less then 10mm) have a very short eye releif thus you would have to really jam your eye in the eyepiece to see anything. With a 114mm your maximum theoretical magnification is x228. More realistically you should look at a 5mm eyepiece as your most powerfull eyepiece (giving you x180). 

Reasonably priced eyepiece that don't suffer from short eyereleif and are all round very good (actually amazing for the price) are BST Stargiuders

https://www.firstlightoptics.com/bst-starguider-eyepieces/bst-starguider-60-5mm-ed-eyepiece.html

If you re patient you can find those second hand for about £30/piece.

Edited March 10, 2020 by Raph-in-the-sky

[Louis D]

5 hours ago, Raph-in-the-sky said:

Actually if you plan to do lunar or planetary, refractors are often considered supperior. Big Dobs are really more suited for deep sky... I will leave advice regarding refractors to those who know what they are talking about.

Regarding eyepiece, short focal lenght plossl (ie less then 10mm) have a very short eye releif thus you would have to really jam your eye in the eyepiece to see anything. With a 114mm your maximum theoretical magnification is x228. More realistically you should look at a 5mm eyepiece as your most powerfull eyepiece (giving you x180). 

Reasonably priced eyepiece that don't suffer from short eyereleif and are all round very good (actually amazing for the price) are BST Stargiuders

https://www.firstlightoptics.com/bst-starguider-eyepieces/bst-starguider-60-5mm-ed-eyepiece.html

If you re patient you can find those second hand for about £30/piece.

If you have a premium mirror in your Dob with an undersized secondary and low profile focuser, lunar views are every bit as good as through an APO of a couple inches less diameter.  Read this comparison review.  Lumping all Dobs together isn't really fair.  Also, the planetary views through 12"+ Dobs with Zambuto mirrors blow away any 6" or less APO that I've ever seen, at least under Texas seeing conditions.

I've found that separating tight doubles of uneven brightness is where refractors tend to shine because of the lack of any obstruction at all.  Stars have less bloat than in Newtonians, and thus close companions are easier to pick out.

[Guest]

I've taken the plunge and ordered a Sky-Watcher Skyliner 200P Dobsonian from FLO.  It should be here tomorrow.  Now, hopefully the weather will play along nicely...

[Louis D]

Sounds good.  Way to keep the economy moving along as well. 😉

Let us know your impressions of it once you get settled in with it.

[Raph-in-the-sky]

I Just took my 250px on the balcony and I was able to see M81 and M82 for the first time. I never thought I would be able to see those despite the light pollution!

The 200p is basically the same but a bit smaller. It's a great scope

 

Edited March 18, 2020 by Raph-in-the-sky

[Whistlin Bob]

6 hours ago, merlin100 said:

I've taken the plunge and ordered a Sky-Watcher Skyliner 200P Dobsonian from FLO

An excellent choice- they're wonderful all round scopes. It will give you superb views of the moon, planets are great in it and it has enough light grasp to get you going with DSOs. 

[Guest]

On 08/03/2020 at 11:42, Ships and Stars said:

I'm someone with a severe case of permanent 'Dobsonian Aperture Fever' aka 'DAF', so please take my views with a grain of salt. My first scope in March last year was a 20" dob which is frequently mind-blowing under dark skies, and I take it to dark sites every chance I get, but I quickly started looking for something smaller to play with when time was limited or I wanted a quick peek from home.

All except one of my scopes (300p flextube) were bought second-hand for what I think were good prices and I didn't lose any money on them, so I view then as investments that might take a little time to sell if I want the money back, kind of like a savings account with rapid withdrawal restrictions in place.

When I accumulate enough second-hand scopes and EPs, I can sell the part/whole lot and afford to jump up in aperture (the entire meaning of life for someone afflicted with DAF).

I don't know if you want to do imaging, so a lot of this won't apply, but next was a 130PDS on an AZ4, a fine scope, very sharp optically, easy to use, but at the end of the day lacked enough aperture to keep me interested, as my main area of interest are nebulae and galaxies. More for AP in my still-novice opinion, but also still reasonably good for very widefield views under darker conditions.

Then I went to a 200p on EQ5, a big step up from the 130p in the aperture department and thought 'now we're back in the game', but didn't get on with the EQ mount at all, and after a while the 8" aperture of the 200p was a bit ho-hum, but still, a leap up from the 130PDS. The 8" will start to show some objects very well like M57 and I even caught a whiff of the Veil Nebula from under moderate LP.

So I sold the 130PDS and 200p/EQ5 and went for a 12" 300p flextube, non-GOTO a few months ago for my 'grab and go scope'. I absolutely 100% love it. Fits in a normal car, is light-weight in the grand scheme of things, sets up in literally about 3-4 minutes and will happily go 250-300x magnification when conditions are good. Just set base down, lower tube gently in the cradle and extend flextube, tighten handles, pop on the finderscope/telrad, remove mirror covers, insert eyepiece, aim and start viewing. I 'detected' the Horsehead nebula from a dark site with it quite easily, though of course it didn't compete with the 20", which just shows the HH every time with direct vision. So the 300p passes my 'horsehead test'.

Diminishing returns is harder to pin down. I'd put it somewhere around the 12" to 14" mark. The 300p is a big step up in price from a 10" dob (£835 vs £439) which is arguably the standard for most amateur visual astronomers, the perfect point between size, price and aperture. The 14" is another £450 jump on the 300p, and it gets exponentially more expensive from there. 

So in my opinion, depending on what you can lift comfortably, how much room you have to store it, budget etc, I'd hold out for at least a 200p or better yet, a 10" dob secondhand and just skip the incremental upgrades. A 12" 300p flextube with homemade dobson mount was just online for £350, a bit tatty cosmetically, but the mirrors were reputedly sound. A nice second-hand 10" dob can be easily had for a bit less if you keep your eyes open and are prepared to wait a little bit. A second-hand 350p was just online for £700 and I'm pretty sure it went for closer to £600. That's a scope to last a lifetime. Unless you have DAF of course!

PS - I'd imagine even moving up to an 8" from a 114mm reflector will be a wow moment, so you have lots of goods times ahead no matter which way you go. Have fun!

 

Old thread revisit...

I admire those who move up to the 300P, but for me the diminishing returns are also in the big jump in financial cost and weight.  I can lift my 200P out the back door from my flat in one go, but couldn't with a larger one.  Yes, I could split it, but couldn't justify the cost, especially in such a light polluted area.  Perhaps I'm reading this all wrong, but aren't larger Dobs better suited to dark sky locations and not urban areas?  If so, that would seriously reduce to viewing abilities if I needed to go outside my domicile..

[Louis D]

13 hours ago, merlin100 said:

Old thread revisit...

I admire those who move up to the 300P, but for me the diminishing returns are also in the big jump in financial cost and weight.  I can lift my 200P out the back door from my flat in one go, but couldn't with a larger one.  Yes, I could split it, but couldn't justify the cost, especially in such a light polluted area.  Perhaps I'm reading this all wrong, but aren't larger Dobs better suited to dark sky locations and not urban areas?  If so, that would seriously reduce to viewing abilities if I needed to go outside my domicile..

They're also good at resolving more details in planets and globular clusters at higher powers, both of which are doable under light polluted skies.  However, weight and bulk do figure prominently into the trade-off equation.

[John]

My 12 inch dobsonian is the probably my most used scope. I observe 99% of the time from my back yard under moderately light polluted skies in the outskirts of a large town.

Mine 12 inch weighs around the same as a Skywatcher 10 inch though which helps a lot with portability. I had a 12 inch Meade Lightbridge a few years ago which was very heavy and unwieldy.

I'm not likely to go any larger though, unless we move house and I can setup an observatory or roll-off shed.

If I lived in a flat / apartment with no easy and level access to a garden I might well have settled for something smaller. Where I observe is just a few paces out through the door from the room where my scopes are stored. I can have my 12 inch dob outside and cooling in about 1 minute.

Knowing where to stop for your observing circumstances is the trick I think. Nothing worse than a fine large scope that is not getting used because it is impractical