Sky at Night Magazine

[daryl_lincoln1984]

I am heading to a metal fabricators tommorow to hopfully get my wedge made for my lx90

i have been 2 hours tonight making a blue peter type model as it hard to explain even with drawings so i thought i would post my sticky back and cardboard wedge




[image]local://3339/4321269077A44E93A58F6BE7648E1D71.jpg[/image]

[keithmorris]

Why not make one out of 15-18mm plywood. I know of a few people who have. Total cost is about £20. If you are not going to move you scopes home position then it does not need to be adjustable and you can make it rock solid with no play so your alignment won't change. Just give it a few good coats of varnish to weather proof it and you're away.

Keith

[daryl_lincoln1984]

Yeh that was a idea was just taking it to a fabricators to get a price and he going to get back to me today with a price we will see what i decide to do

[paull]

Sorry to appear thick but what is the wedge for....

[brianb]

[quote]Sorry to appear thick but what is the wedge for....
[/quote]
Converting a altaz fork mount to equatorial. So that it's possible to make exposures longer than 30 secs-1 minute without field rotation spoiling the image - especially in the critical "near overhead" zone where conditions are usually best. Usually improves tracking too since a steady rate in one axis only is required.

[keithmorris]

Hi Paull, not a thick question at all. If you don't know something, as, that's how we learn.

A wedge is used on a fork alt/az mount (Meade LX200, LX90 Celestron CPC etc) to turn the alt/az mount into an equatorial one. The wedge goes on top of the tripod/pier and then the fork driven mount goes onto the wedge. The mount is not held level with the ground anymore but at an inclined angle that is equal to your latituge.

Now when you mount moves because the azimuth drive turns the scope is actually moving in Right Ascention to follow stars and other things as they move across the sky.

This is essential for imageing especially long exposure imaging so you don't get star trails.


Keith

[daryl_lincoln1984]

lol M42 i might be going down the wood route as the price they cam back to me was a little steep £285+vatso even with vat at 15% i think that one big present that santa will have to bring.

B&Q here i come

[paull]

Thankyou Brian and Keith...but isn't that what my motordrive is supposed to do on my skywatcher 130mp....Paul

[psychobilly]

One off bespokes can be a PITA for engineering companies - I am fortunate that I have a couple of companies I work with that will do things for me at very good rates provided I supply them with cad modelsl for the parts.

have made various wedges starting in Plywood then "scrap" Aluminium plate which I machined myself and finaly a 10mm steel plate combined pier and wedge design which I had professionally made - laser cut and welded up for me : )

Billy....

[Chanctonbury]

[quote]skywatcher 130mp[/quote] [quote]ORIGINAL: paull

Thankyou Brian and Keith...but isn't that what my motordrive is supposed to do on my skywatcher 130mp....Paul

[/quote]

That is exactly what you 140 PM does but your mount is an equatorial mount so is already inclined at an angle - a standard Alt.Az is level hence is unsuitable for for astro-imaging purposes.