Digz

Cheers mate.

Interesting thought about the relationship between focal length and effect of vibration.

Don't worry about it Coastliner, I was just the same. Mirror slap can be an issue and if your particular about the way you image (like I am) it can be an obsession trying to nail everything down.

Out of interest what will you be shooting through?

The best advice will be to try the Intervolometer without worrying about mirror slap and assess the results - you may be pleasantly surprised.

I have to admit that I don't use mirror lock-up unless I am using APT which is quite infrequent. At my focal length and exposure time I don't see any adverse effects. I can only imagine it affecting bright stars.

However if you can use it and it isn't a problem to do so, it won't do any harm to enable it.

Can you remind me of your longest focal length? Just curious as Im itching to see how long I can get on my AT...... :-)

A couple of years ago I was using my DSLR with my 250p ds at a focal length of 1200mm and mirror slap was an issue......it could, however, equally have been me getting something wrong

Mirror slap can be an issue in astro work and the higher the magnification the more of an issue it can be.

Scroll 2/3 of the way down, might be of use and took 5seconds to find

http://www.skiesunlimited.net/SPD/orion-xx16g-go-to-dobsonian--80001405-1356732243.jsp

Have you tried googling the measurements or looking at google images? That will be your best bet IMO unless someone with a 12" dob and same size living room as you can post a photo.....

Might still be useful as a guidescope Lee. Nice and light. :grin: .

Ron.

Lol, I think it would perform admirably next to no weight increase on the set up. Medium focal length and if the sky is cloudy I can just pop a slide in and guide on that.......

That's a nice bit of kit, Lee......Wonder how it would look on an eq3 mount?

Gary

The colour scheme might clash so you would have to pimp out the eq3 in a nice Matt red finish and gold decals

Getting this as a kid started it all for me

Fond memories of 'using' it.

Having recently decided to buy some new kit I pushed the button on Sunday on an Astrotrac. This was after a good round of email conversations with James whilst stock levels were checked and the battery holder was sourced from the supplier. All emails were quickly responded too and I was kept in the loop at all times.

I Received confirmation on Monday of the item being dispatched and by 9:00 Tuesday morning it was sat on my desk! Hows that for a slice of fried gold.

Good work FLO, from an all round happy bunny.

Just heard the news. Very sad indeed. Such an inspiration to many. May he rest in peace and enjoy being amongst the stars he so often gazed upon himself.

A great thread and one that I think should be maybe added to the sticky thread in the DIY obsy section.

I cant see much said about fire, so on that note there are a couple of things to consider. You could install a smoke and heat detector to give you warning of a fire. Another thing to consider is the cladding material and thickness. If you go with a certain section size for timbers then they will char thus inhibiting further flame spread. People I speak to about fire protection are often amazed when I mention that cavity stopping can be done with a timber block!

Security wise a good alarm and securely locking door will go a long way to helping deter wannabe thief's. Also some CCTV and or overt / covert monitoring will be good, if you can catch someone in the act then great.

Also marking kit with a postcode using a UV marker is a good idea (just don;t move house lol), but there is also something called smart water which might be something to consider.

What a great thread.

Id love for this to be a bit more organised and made a sticky, I think lots would find it very, very useful.

yes.....must.....see.....photos........

Thanks for the info

Hi Malc,

Got a question - sorry if its here on the thread somewhere, just cant see it. Which way does your roof slide off i.e. E-W or S-N? Im developing my second design based on a ROR and just wondered what you did.

Cheers

Looking great.

Gina if your going to do this either make sure they are treated or sat on a DPC of somesort. The last thing you want is for your corner posts to rot!

BTW, I was wondering how you did the corners. I was thinking of using square corner pieces to bolt the frames to. eg. 75mm fence posts.

Excuse the rather rough low quality sketch, but this shows two ways to handle corners.

This doesnt preclude your idea, I dont know how 75mm fence posts compare in price to the price you'd pay for timber for studs. Just bear in mind if you decide to do this, you need to decide how you will tie the post down to the base to avoid any weak areas.

I am getting soooo jealous now....cant wait to see how it progresses

Looking great

Sounds spot on to me

Indeed. It's the first rule of Obs building.

LOL, just got a soundbite of fight club now......

The first rule of observatory club.......

That's pretty handy. Nice one

They certainly are handy

Just one other thing, which may be useful in the future - span tables. These can be found on the internet and I've attached one below for reference.

KD C16 Softwood Span Tables.pdf

Regarding flooring, I was thinking of providing extra support in the middle of the span, particularly for the 8ft run of joists. I don't mind a bit of give but too much is rather disconcerting.

I would definitely provide central noggings on any span of flooring except relatively short spans, say 3ft or less. The centre of the span is where it is going to twist and deform.

Having said that if you plan to cover the joists with a sheet material, say ply, then providing adequate fixings to all joists, this will turn the floor structure into a diaphragm thus making the central noggings not as crucial.

One thing I am considering is making sure my floor is independent of my pier base. For example, the joist span either side of the concrete pier base (and don't touch it) and are trimmed around it, thus any movement, imposed or dead should not affect the pier and its base.

Just remember the maximum deflection along the length of a stud will be at the mid point of the span. This is where noggings should be placed.

Great sketch. I think 150 x 50 joists would be sufficient. Ive just used this size timber to frame out some oriel windows on a recent job and that was more than sufficient to cope with any flexure. Plus I plan on using this size timber in my design.