Collimation

[WWPierre]

I am truly sorry for the misunderstanding. I am merely trying to get some advice on whether or not to bother trying to tune up my little mak. I am signed on to many groups, as many are, but I hang out at the forum linked above mostly, and I can't remember which forums I have posted to.

I thought to save a bit of time by simply linking my post at "home". Is this a breach of etiquette? If so, I apoligize, I can start another thread if necessary, and delete these posts.

This is the only place I have visited looking for the information I am seeking. Google led me here, and reading the posts, I thought, "these people know whereof they speak."

I mistakenly took Talitha's join date for the date of the thread start.

[John]

John, i don't think they want to ask anything, it's quite obvious what was done here.

WWPierre 1) joined SGL 4 months ago, 2) never posted anything till today, and then 3) suddenly decided to use my thread as a springboard to promote another group. Here's what came up when i Googled "collimating a 90mm mak". TBH i think the only reason my thread showed up is because it's recent, and my 90 Mak is listed in my signature line. Makes me wonder if they did the same thing to CN... they're #1 on the list.

I don't know where Admin stands on something like this, but as far as i'm concerned it's a pretty big slice of spam and i hope no one clicks on the links.

I'm sure you are right Carol - I was just giving him / her the "benefit of the doubt"

More to the point, how is the collimation of "Lurch" going ?. I looked through one of those at the SGL5 Star Party and had a great view of M51 - lovely dust lanes

[Talitha]

Hi John, the collimation's moving along quite nicely,thanks. I've had the scope out three times (will go again tonight), and haven't had any problems, which indicates things were done correctly. The three collimation locking screws on the bottom of the OTA proved to be more problematic than helpful though, so i removed them. It hasn't altered the performance any, and TBH it's made collimation less confusing because the only screws back there now are the ones i need to adjust the mirror. I'll post report(s) in the Observing zone as soon as time allows.

[Nick P]

Is there any way of doing a 'day light' star test?

Once everything is lined up it would be great to be able to confirm that collimation is correct!

[Doc]

I removed my locking screws as well Carol nothing but a pain. Everytime you locked the mirror it moved it, so I gave up.

[Jason D]

Locking screws are not a problem for me. I use them the same way I use the main collimation screws. That is, I tighten them carefully while keeping an eye on collimation to maintain it. It is not that bad.

[Talitha]

Nick, i'd seen a thingamabob somewhere that's used as a point source for daytime collimation but have no idea where i saw it, and obviously can't recall the proper name for it, lol. It probably needs to be done outside, because from what i remember it has to be placed a certain distance from the scope, and the distance is more than what a normal room size will allow, unless you happen to live in Windsor Castle.

[John]

I removed my locking screws as well Carol nothing but a pain. Everytime you locked the mirror it moved it, so I gave up.

I stopped using the locking screws on my Lightbridge 12" as well and for the same reason. I believe that the mirror cells of the LB's, while designed well enough, are made of metal that is a little on the thin side so the locking screws can "warp" the cell a little, which is not what you want.

[TopHouse]

@Carol, are you talking about an artificial star?

http://www.optcorp.com/product.aspx?pid=10823

[Talitha]

Jason, i tightened the mirror springs to the max after removing the locking screws, and the tension they provide seems to be holding the collimation quite well. I move the scope around the Starpad at least 4 times per session, and out of curiosity i test the laser collimation each time... it's always spot-on. The scope dolly's 10" tires are pneumatic, which helps a lot.

[Talitha]

Yep, that looks like the one, TH.

(artificial star sounds much better than thingamabob )

[TopHouse]

How posh is that??? A 'starpad' oooerrrr!

[Nick P]

Nick, i'd seen a thingamabob somewhere that's used as a point source for daytime collimation but have no idea where i saw it, and obviously can't recall the proper name for it, lol. It probably needs to be done outside, because from what i remember it has to be placed a certain distance from the scope, and the distance is more than what a normal room size will allow, unless you happen to live in Windsor Castle.

Carol, that's exactly the sort of thing I was thinking about, and from TH's link looks like it may be OK for normal indoor distances, although I expect a banqueting hall would be better. (Just noticed best used from about 100ft! and the Rigel one recommends 16 m for a 200mm scope`)

Now for what may be a really daft thought, how about a street light about 3 miles away? is it just that the test needs any point of light?

I have just noticed that the retaining screws on my Newtonian have all been totally loose and apart from my tinkering about, collimation hasn't shifted over the last couple of weeks, I'll just leave them fitted so they don't get lost!

[astromerlin]

A daytime point source of light for collimation could be a ball bearing glued on a piece of black card, bounce the sun off the ball bearing. I tried this a while ago and found it worked but I really needed to move the target further away and my garden isn't long enough and I didn't have an extension tube for the EP.

Oh yeah did I mention you need the sun, where's that been lately?

[TopHouse]

Ball bearings glued to cards and nailed to trees? I bet your neighbours love you!

[Talitha]

How posh is that??? A 'starpad' oooerrrr!

You wouldn't say that if you saw it.

The Starpad is just a 35'x35' area i cleared out of the old Christmas tree plantation on the eastern 1/2 of my 40 acre piece of land. I got tired of mowing the weeds out there all the time, so i sprayed it with a vegetation killer and then put outdoor carpeting down to keep the mud to a minimum. It's not much to look at, but it's my office... and i love the view.

[TopHouse]

Holy **** Carol!! How far away is your next door neighbour?

[Talitha]

Not far, actually. The further one is in the lower right corner of the pic, and the closer one is just to the left of that, on my side of the road (the closer one is a bit over 1/8 mile away). lots more room here than in Chicago where i was born and raised.

[Doc]

Slightly off topic Carol, but how much does land cost out there, to get 40 acres over here in England you need to be a multi millionaire.

I've always dreamt about moving to Canada or New Zealand and buying a big plot like yours, it really must be great especially if you have retired.

[Talitha]

I'm definitely not a multi millionaire, but it did take a solid, long-term plan and sensible money management. Not too sure about the current rates, but my land averaged around $1000 an acre back in 1996. Buying the land is only the first step, though. To that, add 1) the cost of building the house and garage, 2) having phone and electric lines ditched in from the road, 3) having a well and sceptic system installed, and 4) if you want gas you'll need an LP (liquid propane) tank installed and lines run to the house. Also add the cost of the usual permits and inspection fees for all of the above... the local gov't has to get their fingers in the pie, too.

[Doc]

But it's made you one very lucky and happy person, so it's money well spent

[Peter Drew]

Hello again Carol. Just to add my experiences with artificial "stars" for collimation. The battery illuminated versions are probably best as they can be used at night.Solar illuminated ones usually have the disadvantage of heat haze in the light path causing image distortion at the preferred long distance for the test. I am also always concerned that testing a large telescope in a relatively horizontal orientation might well present a different result at the higher elevations. It could be that Polaris will be your best friend when stable seeing allows.

[Talitha]

Hi Peter, thanks for your input. Logic says you're right about collimating on the horizontal. I'd read that it's best to collimate the scope on the angle it's most likely to be used, and it makes sense. Collimation is becoming quite a comfortable nightly ritual for me, much like polarizing the EQ mounts used to be in the past. Ah yes, good old Polaris... we've come to be very good friends through the years.

[ZOG]

Carol, collimation always seems like a dark art when you first try it but, honestly, once you have done it right a couple of times, it becomes second nature.

I see a couple of members have recommended the Hotech, and a fine tool it is. Can I also recommend the Glatter laser and blug. I can collimate my 12" in a few minutes and the results always agree with a cheshire. Thats another very handy tool to have, cheap, reliable, and lets you collimate it daylight.