View Full Version here: : Pier height?
15-05-2011, 05:02 PM
I'm in the process of making my 'Covert Pier' to be fixed in the hole
prepared in the earlier thread, and am wondering how high I should
make the post.
Essentially I need to know at what the height above ground should be
for the centreline of the OTA at the top of the pier. Does this height
vary between scope types, ie would pier height be different for Newt
vs Refractor vs SCT/RC ?
EDIT: At the moment I'm using either an ED80 or an 8" f/6 Newt. Later
I am considering the 12" Newt or buying an RC, as big as will fit on an
15-05-2011, 05:11 PM
Most certainly. I use a portable pier, & my two main scopes are a C11 SCT & a 14" F4.5 newt. A 'one size fits all' in this respect just doesn't work for me.
EDIT: It seems you want to use your 10" newt for now..?
16-05-2011, 02:10 AM
Depends on the type of mount and also type and length of the scope plus it's dominant use. Diferent mounts are different heights.
Also, bear in mind that the same pier will probably have to serve your needs for some considerable time to come and this may well involve changing both your mount, your scope and your usage oatterns. You'll pprobably scale your equipment upwards as you get more and more into it and that will probably involve getting bigger not smaller. So future use is a factor also.
A long refractor and a newtonian used visually would require to be at different heights dependoing on how you want to use them - visual or imaging or a bit of both. Picture yourself in the middle of the night trying to look through an eyepiece and imagine the position you'd have to be in to do it comfortably for any length of time. Newtonians can put you in some odd positions and one too close to the ground will have you on your knees with your head cranked backwards and that can very quickly be a turn-off.
On the other hand, scopes being used for imaging are a bit different - apart from using the finder scope occasionally, your dominant concern is balancing the payload and making sure nothing fouls the mount as the scope slews and tracks.
You've referred to an ED80 and an 8" newtonian. Assuming the newtonian will be used both visually and for imaging, a compromise height seems to be a good idea so you don't have to spend time perched on a stool or on your knees to look through the newtonian eyepiece, I'd suggest a basic pier at about 800 mm high (floor level to the base of the mount).
16-05-2011, 02:37 AM
I kept banging my head against the camera when sneeking into my tiny dome so I put in one of those skywatcher extension tubes and pushed the mount up a couple of feet. All sweet now.
16-05-2011, 09:18 AM
Future changes have been allowed for in the design, it's
a two part pier allowing me to make longer or shorter main
sections to allow for different heights, it would just cost
me $400-$500 for a different section to be made.
The strength of the pier won't be an issue in the future, it
is being made strong enough for any equipment an amateur
would ever have.
I just want to know what a good height would be to start
out with using my current equipment. If I go for a big mount
and scope later, $400 for a new section of pier woudn't be a
huge outlay in the scheme of things.
17-05-2011, 11:18 PM
As well as being able to swap the pier extension (steel pipe section), I was able to lift the telescope by using the arrangement shown in the attached picture. It is very sturdy, and doesn't compromise the rigidity of the pier. the four threaded bolts are 3/4", and the fixed wedge base plate is 20 mm thick (Aluminium - to keep thermal mass down). This arrangement also provides a handy cubby hole for bits and pieces. It would be easy to shorten the bolts back, or use slightly longer ones if necessary, but this would also depend on the mass of the mount/scope.
For what it's worth, the top plate of the red pier is 820 mm above floor level, and the top of the base of the wedge (where the controller is resting) is 990 mm above floor level.
When observing, I nearly always use my adjustable observing stool (sold by Bintel), and for me, the comfortable range of eye piece heights achievable from the stool is 1040 mm (min) to 1640 (max).
If I were you and were contemplating visual observing, I would work out the range of eyepiece heights (for the scope and mount of choice), and then make the pier to suit. As others have noted, you don't want to be dragging yourself on the floor or have the EP so high that you unnecessarily need steps. There is no magic answer, but I've seen quite a few designs at around the 1200 mm mark.
17-05-2011, 11:54 PM
Great, thanks for the comprehensive reply Chris, much appreciated.
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