roll off or dome

[des anderson]

Well what a question?Roll off or dome,I`m thinking of getting an observatory,space has been agreed by the boss,at the back of the garden,max size is 8x8,so i could even get a Sky Pod.Can anyone help with the pros and cons......of each,no good at building my own, as my DIY sucks.

[laser_jock99]

I only went for a roll off because I could easily build it myself and I didn't want it to 'look like an observatory' for securtity reasons. To the casual passer-by my obsy looks like an average summer house, not like a dome full of expexpesive kit.....

[chrisvdberge]

With a dome you need to consider that you'll have a small slit. This means you'll have a longer cool down time and stronger air currents probably. Also, it might be a bit more complicated since you need the slit to follow the object you are imaging as well  

[ollypenrice]

Domes are good for combating dew and stray light. The slit gives a limited view of the sky and needs motorizing for imaging, as said above, with the potential complication of needing to be realigned after a meridian flip if the aperture isn't wide enough. Space inside is pretty tight in my view. I can't see myself wanting one for visual use because you see so little sky, which is part of the pleasure. To me a dome's advantages are for imagers (with the synchronized motorization proviso.)

I use only roll offs and am happy with them, but I have a dark site and, in general, low humidity for much of the year. Because I have clear horizons mine have rolling upper-roof-and-sides so I can image low down. Bear this in mind when looking at proprietory designs, some of which are very zenith-orientated. On one of mine the roof rolls back over the warm room.

I can't say I think much of the Pod. It's too much of a halfway house with the disadvantages of both dome and roll-off rolled into one. Also, I wouldn't buy one till you've seen one in the flesh. I'm aesthetically allergic to garden plastic and I have never seen anything which shouted 'plastic' as loudly as the Pod! But that may just be me. To get to the zenith you need a partial roll off device which is available.

Olly

[happy-kat]

If the dome is higher than a normal shed then may want to consider the impact on neighbours, their gardens and their views. Does a dome need planning permission.

[malc-c]

If the dome is higher than a normal shed then may want to consider the impact on neighbours, their gardens and their views. Does a dome need planning permission.

Depends on the size of the dome and where you intend to locate it.  Most planning regs relate to general outbuildings and seem to state that it can't be more than 2m to the eves, or 2.5m to the ridge if the building is sited a set distance from a boundary, 2m I beleive.  There are alos clauses regarding the percentage of your garden that is occupied by outbuildings, and if this is exceeded then permission is required.  It's worth checking with your local authority what the regulations are just to be on the safe side

[des anderson]

Hi,to you all,thanks for the advice,seems like a roll off is the way to go..The observatory will be at the back of the garden,nice and cosy,no stray light,from neighbours,who turn there lights off,without a a prompt from me,whenever they see me getting ready for a night stint.

[malc-c]

Both ROR and Domes have their advantages and disadvantages, but for me a ROR gave me more area for the same amount of money.  I have a warm room / office / man cave area where I can chill out, listen to music, build electronics projects etc, and a decent sized scope room.  The building looks like a large storage shed so isn't the attraction of the local youth.

One golden rule of building a DIY observatory though - Make sure you post up lots of pictures in your build thread !!

[steppenwolf]

Against the grain, me!

I'm on my second dome and would only consider a ROR now if I couldn't motorise the dome. Contrary to above, my gear is very quickly at ambient temperature and a further advantage is that I never suffer from dew on my gear during an imaging session - I do, however use a dehumidifier after the session to remove the dew that forms on the inside of the dome roof (I consider this to be a sacrificial dew magnet ). The dome also excludes extraneous light and wind. For imaging, it is a great solution although for observing, the ROR is far better as you get that great view!

[fondofchips]

Both ROR and Domes have their advantages and disadvantages, but for me a ROR gave me more area for the same amount of money.  I have a warm room / office / man cave area where I can chill out, listen to music, build electronics projects etc, and a decent sized scope room.  The building looks like a large storage shed so isn't the attraction of the local youth.

One golden rule of building a DIY observatory though - Make sure you post up lots of pictures in your build thread !!

Another obsy builder on here came up with this quote "design it to death before you put a spade in the ground" - really good advice.

Did a lot of drawings to scale before I started anything, and it paid off.

I re-stained my obsy a darker colour so it would blend in more.  Warm room is a real luxury, now getting much more use since I switched to Video Astronomy.

Cheers,

Fondofchips.

[r3i]

I only went for a roll off because I could easily build it myself and I didn't want it to 'look like an observatory' for securtity reasons. To the casual passer-by my obsy looks like an average summer house, not like a dome full of expexpesive kit.....

They're the same reasons why I went for a ROR, though I'm not sure if they do end up looking like just another garden shed. We had a carpet fitter in a while back - he looked out the window and said "Hmm, that's no ordinary shed, what's in there then?!"

[Gina]

With the roof closed my ROR obsy looks like two garden sheds joined together.

[Davey-T]

Ian King does nice roll off obsy's if you're not into DIY.

Dave

[mhard26339]

Against the grain, me!

I'm on my second dome and would only consider a ROR now if I couldn't motorise the dome. Contrary to above, my gear is very quickly at ambient temperature and a further advantage is that I never suffer from dew on my gear during an imaging session - I do, however use a dehumidifier after the session to remove the dew that forms on the inside of the dome roof (I consider this to be a sacrificial dew magnet ). The dome also excludes extraneous light and wind. For imaging, it is a great solution although for observing, the ROR is far better as you get that great view!

Hi, I fully support Steve's view, for observing ROR is possibly the best but for imaging a dome is most certainly its equal if not better IMHO. Very important is the fact that there is rarely wind disturbance and the shutter does offer a large "filter effect" for light pollution; regarding the security aspects, many people who I have spoken to do not even know what it is, strange but true! As with all things you pays your money and takes your choice, both will work but you state that you have limited DIY skills, buy a Pulsar and get them to erect it for you, job done.

[malc-c]

Hi, I fully support Steve's view, for observing ROR is possibly the best but for imaging a dome is most certainly its equal if not better IMHO.

Most people I know who image tend to do so remotely from the comfort of a warm room or their home, especially if the observatory is a dome as there is often less room compared to a ROR design.  If the dome isn't driven it requires the operator to leave the warm room, trape to the dome, and move it on regular intervals so that the scope can keep tracking the target.  If the dome is fully automated then I would agree that the advantages Steve mentioned such as dew prevention and light shielding would make a dome ideal for imaging.

Bottom line is that both types have their advantages and dis-advantages, and the choice of dome over ROR is down to location, cost, and individual preference of DIY skills over ready assembled.  The cost of a 2.2m dome, with full motorised option, and alarm system delivered in the UK and erected by Pulsar is £4839, and that excludes the cost of the base on which to place the observatory.  For half that money I built my 2.2m x 4.8m ROR with warm room observatory, so whilst domes have advantages over ROR, cost isn't one of them.  By comparison, a 15' x 10' ROR with motorised roof option from Ian King installed is £3700, still a grand less than the dome.

[ollypenrice]

My latest small robotic roll off has cost under 1000 euros. It's taken about three working weeks, including the base, though.

Olly

[BlueAstra]

One other advantage of a dome is that you don't have to park the scope to close the roof (unless its a really big shed!). I went for the roll off roof shed since I already had a shed to convert, and as I live in a built up area it looks less obvious. I also increased the fence height so you can't see it from the back.. My original build thread is here. I now have a different scope and mount.

[Mr Spock]

When I look up I like to see everything! Though I can see why a dome has appeal - the lack of dew, wind and stray light do make it tempting.

[des anderson]

Wow,lots to think about,roll off seems the way to go,but i do like the idea of a dome,i only try to image the solar system,and get most pleasure out of visual,I`ve got an 9.25 sct on AVX so really need a home for it. Des

[r3i]

Wow,lots to think about,roll off seems the way to go,but i do like the idea of a dome,i only try to image the solar system,and get most pleasure out of visual,I`ve got an 9.25 sct on AVX so really need a home for it. Des

Whichever you eventually choose, be assured that it will make a massive difference to your enjoyment of astronomy.

[ollypenrice]

Whichever you eventually choose, be assured that it will make a massive difference to your enjoyment of astronomy.

So true. An observatory really is a game changer.

Olly

[nytecam]

6 domes and counting down the decades (and never a RoR) for club/ friends/ self. Domes give complete protection of scope and observer/imager from local LP/wind/ dew. RoR do none of these - they're like standing on the patio. They only allow a permanent set-up.

As quoted most people don't know what a dome is for or what it contains or care. That's just astro-hype. And they are often lighter in construction than RoR and easier to build than popularly believed :-)

Nytecam

[mhard26339]

So true. An observatory really is a game changer.

Olly

Totally agree

Mike

[Gina]

Does a dome really solve the dew problem?  I'm thinking of a mini or micro dome to house a widefield imaging rig - DIY of course

[pmlogg]

Imaging with a non-driven dome is not as much of a problem as some have suggested.  My Pulsar dome has a good size slit and often only needs nudging around after 30 min or more.  Also, as you are not as exposed to the elements there is less need for a warm room.  Flooring is important though - normal garden decking never feels freezing cold the way concrete does, and I suspect that rubber matting, unless thick, would not be as insulating. 

Screening from light is excellent - other houses surround me but now don't really interfere at all, whereas before the dome doing anything before midnight was difficult.

The overall garden space required can be less too, not needing room for the rolled back roof.  Space inside is an important consideration, good planning is vital. The book I read before I started changed my plan - I went slightly bigger, to 2.7m, and I find that there is lots of room, including for storage of kit.

I enjoy it for visual use too - yes you don't see the whole sky but a better view is just 4 ft away at the slit, or outside the door.  If you are sitting in a warm room you are seeing no sky at all, just your computer screen's view of what you are imaging.