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Aperture Fever!


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I'm just throwing this one out there. At what point do you stop seeking more and more Aperture? I'm at the beginning of my Astro journey                        (5 months) and as yet only have a measly 5.1 inches Aperture. I'm obsessed with bigger and bigger already! lol But i was wondering, what point (if any?) do you get to where more aperture isn't really necessary? I'm thinking of saving for a 20inch dob, as they just look so desirable! All that light gathering ability! Imagine what Jupiter would look like through that! (compared to my measly 5.1 inch Newtonian! lol) I was thinking buy a 8inch dob next, but then i thought "but i'll only then want a 10inch, then a 12inch...and so on and so forth! so i might as well skip all the middle sizes and go as large as i can afford! lol Basically whats the best aperture that "will do" for many years of satisfying star/planet/DSO gazing...?

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There are two main constraints, money and practicality (size and weight).

In reality it depends on what you want to do and how you intend to do it. Visual v imaging , permanent obs v travel to dark sight etc.

We all suffer. Find the type of observing you want to do and see what most use succesfully in that field.

Regards Andrew 

PS then take the tablets

Edited by andrew s
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I tend to be a sensible sort of person who thinks things through before acting, ie. not impulsive, so my decision to buy my 12 inch Dobsonian was based on the two main criteria mentioned above - cost and practicality.

I bought the very biggest scope I could afford and also the biggest I could sensibly handle, and I'm very pleased I did! ?

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I have had my 8" SCT for 22+ years now. Must be doing something right. A key point in its favour is that it is very light and compact, so is easy to set up. I am considering getting a big Dobson as well. That won't replace the C8, merely complement it (and the 80mm triplet refractor, and 16x80 bins, and the solar scope ;) )

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Just wondering why you think a 5 inch reflector is "measly", lots of people on here don't use anything bigger, they provide a fabulous middle ground between seeing and usability.

Generally speaking in UK skies a 10 inch is roundabout the point where atmospheric seeing begins to limit the true potential of a system and then you begin to get diminishing returns as the aperture increases (yes bigger is better but the opportunity to use it to its potential decreases and the setup time becomes such that real planning is required for sessions).

You can find massive systems for sale second hand all the time, often bought by people who considerably misunderestimated the amount of time and effort and money involved in setup and ownership. 

 

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When I got back into this hobby, I did a lot of reading before taking the leap. I decided on an 8" dob because of ease in handling. But now that I've built an observatory, I wish I had gone 10" or 12".

So yes, I'm still suffering the fever and it's not letting up.

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Hi,

I settled (for visual) at 18" (Dobson) and 4" (Refractor). The 4" is very portable, super optics and not much influenced by bad seeing as scopes with more aperture. And 4" is for me the minimum aperture. I tried 85mm two times and it was to less for me.

The 18" Dobson is the maximum aperture for me concerning handling (weight, bulkyness) and shows already a lot. I have observed through bigger scopes already, but these where always to heavy for me to handle it personally. 

There is no use in a big scope which stays indoors because it is too heavy. ?

cs,

Uli

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Practicality is most important for me. I have a lot of light pollution and need to carry my telescope several times around the garden to dodge lights. And when I'm finished, I have to carry it inside over a small step. I can't imagine doing this with a 20 inch dobson, so for the moment I'm stuck with a 100mm refractor and a 15x70 binocular. I am looking at something bigger and I have the impression that a 8 to 10 inch dobson is the sweet spot between cost, size and weight. Especially the 8inch is remarkable portable for such a aperture!
But I'm rather immune for aperture fever and my next scope will probably be a 150mm refractor, which is less practical than a 8 inch dobson, so I'm contradicting myself ;-)
But try to see a 12 inch dobson in person. They are rather hefty pieces of equipment and a online picture just do them any justice.

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9 hours ago, wesdon1 said:

I'm just throwing this one out there. At what point do you stop seeking more and more Aperture? I'm at the beginning of my Astro journey                        (5 months) and as yet only have a measly 5.1 inches Aperture. I'm obsessed with bigger and bigger already! lol But i was wondering, what point (if any?) do you get to where more aperture isn't really necessary? I'm thinking of saving for a 20inch dob, as they just look so desirable! All that light gathering ability! Imagine what Jupiter would look like through that! (compared to my measly 5.1 inch Newtonian! lol) I was thinking buy a 8inch dob next, but then i thought "but i'll only then want a 10inch, then a 12inch...and so on and so forth! so i might as well skip all the middle sizes and go as large as i can afford! lol Basically whats the best aperture that "will do" for many years of satisfying star/planet/DSO gazing...?

Personally, I'd rather go for better than bigger. A 5" telescope of top quality will be much less of a hand full when compared to a 20", yet can deliver some of the finest (though not necessarily the brightest) views, if you're reasonably well dark adapted. I'd much prefer a 5" apochromat such as my Takahashi FS128.

 

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2019-04-21 17.56.17.png

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I started with a 10" Skywatcher, and then went for a 15" Obsession after several years.  It's better for every type of target, within max fov constraints.  In addition to DSOs, it's very good on planets, but note that they will be at low altitude from Ireland/UK for the next couple of years, so views will suffer unfortunately. 

I was kinda thinking that I should have gone bigger, then saw a 20" Obsession being set up, and saw it drop a couple of feet as the ramps collapsed as it was being wheeled out of the back of an estate car at a star party.

I still of course lust after bigger, but I know that 15" is a good, practical no fuss size for me at the moment.

What I really lust after now are dark skies, good seeing and transparency... and it all to come together at weekends and to get the opportunity to get out there ;)

You only live once: enjoy researching your options, and go for it when ready!

PS I'd suggest considering say a 12"...

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Practicality is the most important aspect for me.  Due to my somewhat hectic life, if I owned one, a really big scope just wouldn't get the attention it deserves.  It would find itself sitting there woefully, waiting.  I used to think that this hobby was all about aperture - granted that is extremely important, but you have to balance that with observing opportunities, lifestyle and storage space.  For me, it's these that actually win!

Portability is key for someone like me.  I used to have five scopes, but now whittled down to just two that actually get used.  I find my C8 wonderfully practical, it is just so short but still packs in enough aperture to satisfy me personally at a dark site.  When I am at home in the city, it's very good on moon / planets too.

I often take the smaller C6N on camping trips - a mere 6" at a dark sky site can deliver some pretty good views.

Provided you have the time and storage space for using a large aperture regularly, by all means go for it though!

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20 hours ago, mikeDnight said:

I'd rather go for better than bigger

And I'd go for bigger ....

18" is perfect for me, lift into the back of a Corsa if I wanted, image scale, wow views....and 20mins set up...go as big as you can, nobody was disappointed with a big dob.

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I went for the biggest scope I could set up and take down and move around on my own. When I was looking it was either going to be a 14" solid tube reflector or a 16"-18" truss tube reflector. In the end I landed a 14" solid tube and I'm very happy with it still and enjoying the advantages a solid tube provides.

I'd love to have somethung bigger but I dont envy bigger scopes as I know I couldnt handle them so easily and so wouldn't use them enough.

Aperture fever is a common feeling, and so is regret getting something too hard to handle or set up.

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It's always difficult as a newcomer to get to grips with what is right for you. If you get the chance to go to a star party or a local astronomical society observing meet-up do it. You will get a chance to see all kinds of different instruments in the flesh. Only then will you get an idea of how they perform, how much effort is involved in set up and how easy they are to transport and store. I see that you are in Liverpool. The Liverpool Astronomical Society would be worth contacting if you haven't already. Great bunch of guys.

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Much depends how often you want to observe and what sort of astronomy really interests you. Big dobs tend to excel at the fainter deep sky objects and benefit from the darkest skies you can find. That means observing at new moon only and making the commitment to get to those dark sites, often many hours drive away.

I wouldn't choose an 20" dob as an ideal planetary scope. They are more likely to require excellent seeing conditions to get the best high power views from, and those dont happen very often. There are other, smaller scopes which will more reliably give you good planetary views. Ultimately a large scope has better resolution, but you can end up waiting quite a while to make the most of that resolution when the seeing steadies.

Personally, I prefer to get out more often and for shorter sessions, otherwise I feel too removed from the hobby. As you will see from another recent post of mine, I enjoy a challenge in what ever scope I'm using, even my 65mm Newt :)

I owned a 16" Sumerian Dob for a while, which I enjoyed a few wonderful sessions with, but given that I have a dodgy back, found that I didnt use it as much as I had hoped, even though it was a compact truss design. Lifting a 16" mirror box into the car boot didn't really work for me.

The solution I have now is one which I believe I will stick with. It is a 14" 'dob in a box' from Sumerian with a very nice John Nichol mirror in it. In many ways it is quite compromised, not as stiff as the larger designs, but it suits me just fine. I can carry it with one hand very easily and it does not strain my back at all. It is very easy to get away to dark sites and I will use it often in future.

Everything is a compromise and it takes time and experience to work out where your preferences lie.

Sorry about the random order of the images.

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You can go bigger and bigger and bigger for as long as you like but this comes at a price. Your focal length also goes up and so your field of view comes down. Very soon you can forget the Pleiades. They won't fit. M31? You'll only see small fragments but, yes, you'll see them well.

Don't make the mistake of assuming the moon and planets will be best seen in a very big scope. I ran a 20 inch Dob here for about 14 years but it was F4.1 and didn't give anything like as good a planetary image as our TEC140 Apo or 14 inch Meade SCT. On the Veil it was fantastic (you could move it along and trace the filaments) but on the Rosette it simply didn't have the field of view. Don't forget all those targets which are best in binoculars...

The man who has seen everything will need a bigger scope to see new things. But in this scope he may no longer be able to see things he could see before... I think that's my key point.

Olly

 

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Hi,

I cant truly say ive ever suffered from aperture fever, but I did suffer from the more rare but arguably more dangerous mount size fever a while ago. Thankfully budget restrictions stopped me at an NEQ6. :D 

My message to anyone thinking of "going big" is really, really really think about weight and physical size. Its easy to say, "ill carry 25kg easy!", and no doubt most of us would be quite able to do so. However if you're getting out of bed on a cold night to do that, it really puts a fresh light (sorry :D) on the entire situation. Also, if you aren't feeling well or are worn out, a weight-lifting session prior to observing is irritating. ;) If you're a setup-each-time sufferer like myself, breaking up a setup and putting it back together again uses up valuable time! This will apply to dob users too, no doubt.

I can say quite honestly that my favourite setup of all time was an alt-az AT Voyager with a 90mm achro on. I could go out at any sign of clear skies, and literally carry the entire setup in one hand. Sometimes convenience truly is better than performance. 

John :) 

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 On the Veil it was fantastic (you could move it along and tracethe filaments)

Agree with you there Olly,  I see  both eastern and western veil through a 16 inch dob and was supprised how big and bright they was..that's now etched in the memory bank now

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1 hour ago, Mr niall said:

Well having poo-poo'd the practicality of big scopes as recently as 48 hours ago, I've just gone and bought a 300p flextube... I hate this forum sometimes... ??

:headbang: Congrats!! :grin:

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