Roll off shed or roll off roof

[petejw]

I am about to set up a permanent site for my equipment. Skywatcher 200pds on HEQ5 on a concrete pier. It going to be for astrophotography and it will be controlled from the comfort of my front room.

I am unsure of the best option for the shed. What are the pros and cons of roll off roof vs roll off shed.

Can anyone offer any advice or their thoughts on the best route.

Thanks

 

Edited September 5, 2019 by petejw

[wimvb]

Depends on your intended use, space, and budget A roll off shed is easier and cheaper to build. Also smaller. A ror is more work, more expensive and (usually) larger. I used a roll off shed last season, but have now almost finished a ror. It's a LOT more work and expensive.

[gorann]

If you think you are into this for the long run, a roll of roof is the way to go. That will also keep winds off your scope, which should make a big difference especially with a Newton, My advice is to build for the future and make a pier with a top than can be used for any future mount. Then there are many different designs of a roll of roof . I have gone for a flat roof, and this summer I built a second one. Material costs were about 2000 GBP but then it is fully insulated so I can keep the mount and scope warm between imaging session (=less corrosion). Wim, who just responded, is building a similar one but with two piers.

Edited September 5, 2019 by gorann

[Carbon Brush]

If you are absolutely defintely certain that you will never want to join your scope for the evening, and you will never ever fit a bigger mount or bigger scope, the a roll off shed is the way to go.

However, if you have the space and money, or you want flexibility, build the biggest roll off roof structure you can. That way you are future proof.

I have never regretted my decision to go for a roll off roof vs other options.
Details in design, yes I made mistakes. But compared to a dome or roll off shed, no regrets.

Why not make a warm room next to the scope? That way it is easy enough to go out and give the scope a kick, waggle a connector, etc.

Just my thoughts. David.

 

[Gina]

Yep, nice big ROR with warm room was the way I went after considering many options.  Never regretted it - quite the opposite.  Yes, with hindsight I too might have made one or two changes.

[petejw]

Thanks for the thoughts everyone. I don't have a huge amount of room, I have a good southern view and will just about be able to polar align over an 7ft hedge to the north I was thinking of something about 4 foot Square and about 5 foot high and about 4 ft from the hedge. I don't plan to do any viewing at the equipment so I don't think I will need a warm room. Observing/imaging will just be remotely from the house but David makes a good point about future upgrades. 

Protection from winds is another good point.

Doesnt the height of the wall on the roll off roof method restrict viewing or is this below the good visibility level anyway?

[wimvb]

5 hours ago, petejw said:

 I was thinking of something about 4 foot Square and about 5 foot high and about 4 ft from the hedge.

That seems rather small for an 8" telescope. It's easy to measure how much space you need. Set up your scope and swing it around. Mark the positions on the ground that are furthest from the center. Also measure the highest point it will reach. This will give you the absolute minimum dimensions of any enclosure. Add some margin, and space to move around the scope if you plan for a ror.

The roll off shed that I used last season was about 3.5 x 4.2 x 7 ft, and had barely enough room for me to stand in an awkward position when needing to adjust the camera. And that was with a sw 150pds on an az-eq6.

As for the roof construction, there are several options besides a roll off roof. Eg, a clam shell design saves space. Google around.

[Gina]

Wall height with a ROR can be lower if part of the wall is attached to the roof and rolls off with it.  I do this as does Olly and some others here.

[Carbon Brush]

ROR can restrict views near the horizon.
In my build, I accepted the restriction. On the basis there are hedges and the like to contend with. Also low angle viewing tends to give a poor outcome.

My pier top height is set so the scope, when horizontal, just clears the roof.
This minimises the restriction caused by the wall height.

The pier top is adjustable so if in future I change mount, or scope, I can still set the horizontal OTA to just be below the roof.

HTH David.

[Gina]

3 hours ago, Carbon Brush said:

ROR can restrict views near the horizon.

Only if the wall are too high.

[petejw]

Thanks everyone, given me something to think about. I didn't realise that the roll off roof was such a big difference in cost but there are obviously advantages. Going to have to get the tape out again and see exactly what I can come up with. I may be able to get away with sliding the roof off over some raised borders next to my planned site. 

[old_eyes]

This link shows you how to calculate the swept volume or exclusion zone for a scope on a german equatorial mount.  https://www.blackwaterskies.co.uk/2013/12/observatory-planning-and-german-equatorial-mounts/.

I found it enormously useful in pondering various configurations for my roll-off roof observatory currently under construction. It means you can work out what the limits are for differnet scopes, cameras, piggyback or side-by-side arrangements.

I would also agree that 4 foot square is tiny. You will need to get at things to make adjustments, so you have to allow for your body to fit in beside the scope and still have enough space to actually use your arms and hands! The smallest scope enclosures are designed for remote operation and usually have very low walls, so that you can lean over the wall to make adjustments. Rules out visual use though.

[petejw]

Thanks for the link. Still in the pondering stage so this info will come in useful. I am thinking of remote operation and have recently come accross some sheds that not only slide the roof but part of the walls too and think that may be a good option for me.