Mirror Cell Movement ??

[ronin]

Think I have been over complicating something.

Does a mirror cell ONLY adjust the tilt of a mirror in left/right and forward/back tilt.

I had the idea that it would also be moved it laterally left/right and forward/back, however reading something on Stellafane it says there is only tilt, not lateral movement.

Any insight ??

[andrew s]

29 minutes ago, ronin said:

Does a mirror cell ONLY adjust the tilt of a mirror in left/right and forward/back tilt.

Yes that is correct.

29 minutes ago, ronin said:

I had the idea that it would also be moved it laterally left/right and forward/back

You can sometimes move it backwards and forwards but it is best to keep any push pull screws / springs as short as workable.

Regards Andrew

[ronin]

That makes making one a lot easier - bit of a project in mind, just need a small mirror. Back to the Stellarfane site again then.

I had just assumed that they also were supposed to move in the horizontal plane in order to get the centre's aligned. Thoughts were getting a bit complicated. Now all I need is a new set of tires for the bandsaw - mine did a small bit of disintegrating a couple of weeks back. They have to come from the US it seems.

Sometimes all that effort the teachers put into learning me to read pays off.

[rl]

Some main mirror cells do offer a few millimetres of adjustment in the horizontal plane by three radial screws (usually nylon-tipped) but not all. If you can make the secondary centre move over the primary centre by adjusting the spider legs then primary adjustment  isn't really necessary, and primary adjustment will be difficult with the mirror in the tube unless you cut holes. 

RL

[Paz]

I've only seen cells that allow tilt on 3 screws, and by screwing all 3 the same way you can walk the mirror up and down the tube a bit.

[ronin]

For whatever reason I just expected them to have lateral movement - may be from the optical table mounts I have met. Getting my head around making one was making me think a bit too much. Then I read something that said sort of "tilt only" so I checked on Stallarfane and they basically said "tilt only", so asked here and it seems "tilt only" is normal.

When I get replacement tires for the bandsaw I will look into it as a project for the next few months. Better draw up a few plans and ideas I suppose.

[Dave In Vermont]

What variety, or model, of telescope are you talking about, Ronin? Newtonian vs. Catadioptric may have a different set of parameters, depending on model and sub-catagories, etc.

Dave

[ronin]

Decide I might try one of he ultra portable dobsonians, someone put up images of a small one they built about 8 months back and it looked really useful. Sat and thought about it several times but never quite got my head round the mirror cell - seems the reason for this was simply I was thinking of somethnig that would tilt in both planes and also move laterally in both. Case of me overcomplicating things it seems.

Today I search through the OOUK site for a small mirror, one of their150 f/8's looks good, and got back to thinking about it. Then read the sort of "tilt only" aspect. Now tilt only is easy. Present idea is build the box and rockers etc and when happy get a mirror.

Got to be honest, it may never reach completion. But the mirror cell was the aspect that kept me confused. Did keep an eye out for an "old" 150PL that I could cannabalise, never saw one appear on the used side as then I could have used the bits from that and rehoused it.

Not going to happen for a while as I need those bandsaw tires and the only souce I can track down is US based. Delivery on those is the first week in August. Then I need to pull it apart, clean the old ones off (seems they are glued on) so not going to be easy, and get the new ones on and reset the wheels.