AstroSystems Laser Collimator with Barlow arrived...problems

[DJVege]

Omaroo...Now that I'm back in the country, I'm trying to collimate using this laser collimator. Using it is easy as, but in the end, using my cheshire piece, the collimation looks like the attached image. Any ideas why??? It's as if the secondary isn't centered....?? I'll try a star test tonight and report back as well, but I'm sure this isn't right.

Using the laser, I centre it on the mark on the middle of the primary, then go about collimating the primary...I think what I'm doing is correct.

[Omaroo]

DJ - is your 2" to 1.25" adapter (that you are mounting the Cheshire in) tight and free of slop? It sounds as though it may be de-centering the Cheshire as you tighten either the 2" focuser clamp or the 1.25" adapter clamp - or both. The new laser collimator is a 2" unit in itself - so it eliminates any misalignment in the second (1.25" adapter) unit as it doesn't use it. Overriding rule of thumb - make sure that you seat the collar around the collimator as FLAT as can on to the edge of the focuser.

If you loosen the clamp ring, how much slop is there if you jiggle the collimator with the laser on?

I'd be interested to see now the star test goes and we'll go from there. I've heard of people discovering that their secondary was way off due to the fact that they never got their Cheshire or other 1.25" devices to sit square in the first place. The secondary holder might actually be offset too - just because the 45° angle is correct (to get the spot hitting the target on the primary) doesn't mean that your spider is laterally centred - and this can be compounded if the clamps put the Cheshire out of centre as well.

Lemme know!

[PhilW]

I had this very problem a while back with a cheap adapter (well, it was free). I solved it by buying a nice snug adapter from Astrosystems.

Phil

[ballaratdragons]

It could also be that the Laser collimator is out of collimation.

[Omaroo]

Same here Phil.

My secondary was out by a fair whack because of the cheap and loose adapter.'

Ken - these are nothing like the design of the typical Orion/Bintel/etc laser collimators. :) They are non-adjustable. Discussion over this got a bit heated last time. See here: http://www.iceinspace.com.au/forum/showthread.php?t=24955&highlight=astrosystems

[DJVege]

Hmmm...I have the 10:1 focuser from Bintel. I removed the base, and attached it to the base of my old focuser cause that's the only way it would fit. I'm at work at the moment, but will have a closer look at this when I get home. If there are no clouds (doubtful), I'll give you the results of a star test as well.

I'll also take close up photos of the focuser and cheshire etc...

Thanks heaps guys.

Oh, and I don't have a spider. It's a Mak Newt or something. It's glass, with the secondary holder in the middle of the glass. All will be revealed in the photos tonight! :)

[Omaroo]

A Mac Newtonian! I see that in your sig now - an MN56. Gee... I dunno then. Don't you alter the collimation by screws on the outer meniscus ring or something? I've heard Mac Newts can be a real bear to collimate - so maybe this needs to be addressed by another MakNewt owner - and specifically an Intes one.

The biggest problem I see you having is having to un-clamp and withdraw the entire collimator to put the barlow attachment on and then re-insert - possibly to a different place. The spider on a standard Newtonian lets you reach through it and place the barlow on without having to touch anything else after centring the dot on the primary - giving you a better result I imagine. The fact that you have to remove the whole apparatus between aligning the secondary to the primary's centre dot and then the primary return image to the barlow gives us a new problem to contend with I guess.

[DJVege]

Umm.. What I'm wondering, is maybe my secondary needs to move a bit in (towards the primary - direction). When I put the cheshire in, and move the focus as far IN as I can, I can see there's something in the way of the image (at the top). Either focuser, or top of scope...dunno.

I was hoping my secondary wouldn't need to be moved, but maybe that's what it needs. In any case, I'll have a play with it tonight and post many pics so that you can see them.

The laser collimator itself is sweeeeeeeeeeeet!! :)

[DJVege]

Ok! Here are the pics!!

The first 3 are of the focusser!

The fourth is of the cheshire in the focuser.

The fifth is of the laser collimator in the focuser.

The sixth is what I can see through the cheshire at full IN focus (put the digital camera flush on the 1.25" adaptor).

Seventh is what I can see through the cheshire at full OUT focus.

What do you think? Maybe the secondary needs to move away from the primary a bit?? (In that direction...???)

Oh, when I collimated, I did so at full IN focus.

[Tannehill]

That straight edge on the full-in focus pic is the focuser drawtube encroaching into the light path. The fact that it's absent in the full-out pic cinches that, I think. That's normal, most newts look the same.

The last two photos are with the Chesire in the focuser tube, or just the appearance thru the focuser with nothing in the drawtube? I can’t see the typical concentric rings I’m used to seeing in a Chesire….just wanted to clarify this, because the last two photos look like simple shots thru an empty drawtube; we see the secondary mirror (no spider, as you say, in a Mak-Newt). Is your primary mirror marked with a donut? Could be the pics are just a bit dark to see all these things….

Can you see the back of the laser’s Barlow attachment thru the meniscus? Or are you just using the primary (without Barlow attachment) laser beam of the collimator to align the secondary, then using the chesire to align the primary? Or using the laser with-then-without Barlow attachment to do both, then checking it with the chesire?

As to that apparent eccentrically located center spot…It seems more like the upper right edge of the image is fuzzy, rather than eccentrically located…this raises the vignetting issue. At least that’s what your last photos suggest. And this fuzzy edge feature is MORE dramatic in the last pic, the full focuser-out version, and covers more than 180 degrees of the edge. Changes in the appearance of things as you rack your focuser in and out are almost always either focuser squaring problems or vignetting of the light cone somewhere along the way.

When you look thru the empty focuser tube in the full-in and full-out positions, centering your eye over the focuser tube as best you can, are you able to see the full circumference of your primary mirror both times? Can you see the full circumference of the secondary mirror itself, also?

S

[DJVege]

Hi Tannehill,

The last 2 photos are just with the digital camera sitting flush in on the tube (empty tube). I was just making the point that this is also what I see through my cheshire (except with crosshairs).

I use the laser without barlow to align the secondary. All i do is make sure the beam points directly at the circle in the middle of the primary. :)

I then use the barlow attachment to align the primary. Then I check with the cheshire.

As for your "squaring my eye over the focuser" question, I'm pretty sure that I can. But I'll confirm that tonight when I'm back at home.

One question...what's vignetting? (I'll google this).

Thanks a lot for your help/advice.

[Tannehill]

vignetting is some form of obstruction of the light cone. For example, if your secondary is not positioned correctly under the focuser, it would miss part of the light cone coming up from the primary. (I don't think that's it in your case). Or, if your tube diameter is just barely larger than your primary mirror and the optical axis is not exactly matched by the tube's axis, the tube itself could vignette the light cone. Or, if you focuser doesn't move straight in and out as it points at the center of the primary mirror; or, consider that the axis of the light coming into the focuser drawtube is at a different angle than the axis of the center of the focuser drawtube...basically means the focuser is not "squared" to the axis of light coming in from the secondary mirror.

The reason I suggested vignetting is that the fuzzy upper-right limb of your picture has that look. Your camera lens could be off-center a bit, but if that's what you see with your eye, it probably isn't just that simple, since most of us will automatically and unconsciously move our eyes to find the best image as we look down the tube...and rule out that as an explanation.

I'm sure I'm missing something b/c I don't know mak-newts well.

By moving your eye about as you look in the empty drawtube, can you make that fuzzy vignetting-like dark zone disappear...in other words, can your eye find any position in the drawtube that looks like a perfect circle with the center spot and primary center mark in the exact center of the view?

Did you have this same problem with the original focuser or did it start when you added the 10:1?

Try this: point the scope at some bright light in your house, and take the thru-the-focuser picture again. Hopefully we'll see more of the secondary assembly better illuminated, maybe even the bottom of the focuser drawtube. Or have someone shine a torch at an angle through the meniscus aimed at the back of focuser.

S

[DJVege]

I can use the cheshire to collimate the scope and all is good. (According to my amateur opinion, though). I've had everything centered when using just the cheshire...I'll report more when I get back home after work.

I've only just got the laser collimator, so the problem has only started now.

[Tannehill]

ok

the barlowed laser and a chesire assess the same thing, and should always agree, unless there some anomaly in how the device(s) fits into the drawtube. Even miscollimation of the laser beam shouldn't affect the laser when used in barlow mode....but miscollimation of the primary beam only (without barlow attachment) will affect how it enables you to align the secondary mirror. So, perhaps your primary laser is off collimation itself...Still doesn't handily explain everything....


s

[DJVege]

Ok, first image is of full IN focus.

Second image is full OUT focus, with the camera as far left (in the 1.25" adaptor) as possible.

Third image is full OUT focus with the camera as far right as possible.

I think maybe I just have to move the secondary a bit..

But then I'm missing something in my collimation process.

I thought, to fully collimate...you simply shine a laser, adjust the secondary so the laser hits the middle of the primary, then adjust the primary so the beam goes straight back to the source.

I must have to use the cheshire first...actually MOVE the secondary so that it's in the centre of the primary, THEN adjust the rotation of the secondary with the laser, etc...

I'll give that a go and report back.

[DJVege]

Ah...I think I need someone to show me how to collimate. LOL!

This is all I got when I collimated with just the cheshire. First is full IN focus. The second is full out focus.

When I put the laser in after collimating with the cheshire, it's a cm off to the left of the mark. (centre of primary).

I think I dunno what I'm doin. ;)

I don't think the images are showing it properly, either. The bottom of the image seems to be chopped off. (Bottom of the tube). The lens may not be exactly centred on the cam. ???

[Glenhuon]

I'm pretty new at collimating Newts but I'll give you my method.
(From reading the instruction book, what I've read on here and a bit of intuition.)
I first look straight down the focus tube and wind the adjustment out until I can no longer see the end of the tube in the mirror reflection. My main mirror has 4 clips holding it in place and if I cant see all of them evenly at the edge of the field of view I adjust the secondary till I can. This secondary adjustment has to be done rarely as once its set it will stay pretty well OK unless the tube or spider gets a hard knock. I then put the laser in and fine adjust the secondary so the dot is on the centre spot of the main mirror. The final stage is adjusting the main mirror so the reflected laser spot on the angled cut out on the side of the laser collimator disappears back down the central hole from whence it came.
I hope this helps, I had a hard time getting it right too, but once you've done it a couple of times its not so bad. I don't use the cheshire, just the laser.


Cheers
Bill

[DJVege]

Thanks Bill.

My problem is that I'm a bit worried about moving the secondary. With the focuser flush, I think I need to move the secondary out a bit. But, there is one middle screw for this (the three around are for optical alignment). So I'm not sure if all I have to do is play with that centre screw or not.

[Glenhuon]

The central screw is quite a long one to allow for some adjustment of up/down position. Then you have to adjust the others by the same amount. Its surprising how little adjustment of the screws it needs to get things in line. Probably best to adjust in small increments as slackening it right off will allow the secondary to spin on its axis and upset the perpendicular secondary/focus tube alignment. If you look down the focus tube or cheshire and the secondary is pretty round and in the middle of the field of view its probably OK for position in the tube.
My 6" was due for a check so here's a couple of pics. I checked the position of the 3 clips on the primary using the cheshire as its probably more accurate. Cheshire was removed for pic. Put in the laser, centred the spot and adjusted the primary till the dot disappeared down the hole. Re-check the spot center, as mine is incline to shift a tiny bit when I adjust the primary and tweak the primary again. You'll notice the focus tube is out a bit so the end of it doesn't show in the mirrors.
Took 30 mins all up, but I've had a bit of practice now.

Hope this helps

Bill

[DJVege]

Yeah, with this new focuser, I don't think the secondary is centered properly under it. It's the Bintel 10:1 focuser. However I had to remove the Bintel base, and screw the focuser onto my old focuser's base so that it would fit without having to drill any holes into the scope.

Hopefully I'll get some time this weekend to play with the secondary some more. I'm fairly sure this is all because the secondary is out...

Although...if my secondary is out...shouldn't the cheshire AND laser collimator give the same results???

Anyone in Brissy wanna test this laser collimator for me? And my cheshire while you're at it?

[Tannehill]

Well, that fuzzy edge seems intermittent and moving about, now. Perhaps that was due to slight off-centering of the camera lens in the focuser tube....

Now the main issue is that your chesire and laser technique don’t agree, right?

You say the laser mark is off after collimating with the chesire….a cm or so…Can you describe your steps exactly in order?

The primary or first-out laser beam of the collimator, and the chesire, assess different things. The former for secondary adjustment, the latter for primary mirror adjustment. One can be on while the other is off, actually. However, the return-beam adjustment and the chesire should agree….assuming your laser is collimated, that is.

If the laser is not collimated, that return beam method won't work right. That's the vulnerability of laser collimators. If the laser beam isn’t drilling right down – and co-incident with – the central axis of the focuser (which should be the same as the central axis of the collimator chasis) – then it’s cactus. An un-collimated laser collimator is good for lecturing and exercising cats…and that’s about all. Unless you have a barlow attachment, in which case it'll still work for primary collimation...but that isn't relevant in your case....

When in doubt here about your primary mirror’s collimation, of all the tools you have as you describe, believe your Chesire.

You likely don't have a V-block for testing your laser's collimation, but a second-best method is to put the laser into the focuser tube, and, with the set screw loosened obviously, spin the collimator in the focuser and watch the beam on the mirror. If it describes a circle on the mirror as you spin the collimator, your laser is not collimated and you should either return it or collimate it if you can.

But, I’m pretty sure that correctly centering your secondary mirror under the drawtube (adjusting the center screw) will not correct the problem you describe: that the chesire and your laser merge-the return-beam-method do not agree. Centering the secondary under the focuser is still valuable, but will not fix this part.

Secondary position - under the focuser correctly or up or down or over a bit - is not really a "collimation" issue, but rather a way to avoid missing some of the light cone (vignetting). Assuming of course that you have already dialed in the secondary’s collimation (that is, it’s “tilt”) using a collimated laser, adjusting the screws so the laser beam hits the primary mirror center mark. That IS a true collimation issue. We can (and many will) argue about the practical definition of collimation, but IF a flat diagonal mirror's "tilt" is correctly reflecting the center of the focuser axis to the center of the primary mirror, but is "shifted" a bit to miss some of the light, your star test will still be correct, but your image will be less bright, so a purist could argue this isn't a collimation issue but rather vignetting.

The next step is checking your laser’s collimation. The other (less likely) explanation is that the collimator is not sitting flush straight in the drawtube and when you tighten the set screw, it tilts off-axis….but that’s unlikely, unless there is some flawed lip on the collimator’s rim….

My two cents...

Cheers,

Scott

[DJVege]

Hi Scott,

Much appreciated!

I'm fairly sure the laser collimator is collimated as that is the whole point of getting this particular collimator. You aren't advised to ever collimate the laser yourself. It's supposed to keep it's collimation...if not, send it back and they'll recollimate it for you. However, I'll test this with the drawtube method when I get back home tonight. This laser collimator has a barlow attachment as well.

I'll test the laser's collimation and report back here tonight. Thanks a lot for your explanations and suggestions.

[matt]

DJ.

Those laser collimators can go quite easily out of collimation themselves.

When I used to have a newt I purchased a laser collimator and tested it 'out of the box' and it was a mile out.

It was one of these: http://myastroshop.com.au/products/details.asp?id=MAS-143

Although I purchased the unit from somewhere else, I think.

You can collimate it yourself. There are 3 little hex screws which are used for this purpose not too far from the grub screw which turns the laser light on and off.

You can make a simple tester from a block of wood and some screws.

By placing the colliamator horizontally in the tester, projecting the beam onto a distant wall and rotating the unit, you can tell whether your unit is out of collimation. If the dot on the wall stays in the same point while rotating...you are fine. Otherwise you need to adjust those screws until it doesn't form a looping sort of arc as you rotate the unit.

I'll try and find a link to the DIY tester for you.

[Omaroo]

DJ - test it easily yourself by laying it on a glass surface and turning the laser on. Draw a line on a piece of paper and aim the laser at that line. Roll the device along the table and see it it maintains the same dot height relative to the line or not.

Also, mount the laser in your focuser and nip the clamp up lightly so you can rotate the laser. If you rotate it, does the beam move relative to the primary's dot?

Although these are meant to be non-adjustable in day to day circumstances, a decent enough hit will knock it out of whack like any other. It isn't impervious to de-collimation, just more resistant than most.

[matt]

Chris.

This can also be a sign of poor machining in the focuser.

[Omaroo]

Matt - this is nothing like the typical laser collimator. Sorry to point this out, but everyone is assuming that it is. Go here to see that it is completely different:
http://www.astrosystems.biz/laser.htm

[matt]

Don't be sorry, mate. You've done nothing wrong.

My mistake. Came in on the discussion late and assumed we were talking about the more common laser unit.

However, is it still required to be inserted in a focuser?

[DJVege]

Yep. Thanks guys. Here's hoping the laser collimator is off. :) Then we'll have found the culprit, and it means my collimating techniques are wrong with the cheshire! LoL.

Omaroo..what do you mean nip the clamp up tightly so that I can rotate the laser? Which clamp? What am I rotating? I thought I just put the collimator in, don't screw in the collimator to the 2" tube...and simply turn the whole laser collimator in the tube. Not right?

Which screws/clamps on the laser collimator can I play with?

[DJVege]

You're right, Matt. Which is why I will perform both tests. Roll on floor, and twist in focuser. :)

[Omaroo]

LOL! No probs Matt. It's just that last time this unit was discussed someone refused to believe that it wasn't constructed the same as the type you've pointed out and added their argument based on that assumption. This unit, although technically able to be collimated, (set screws are glued in place) comes with a free "return to manufacturer" clause if it needs re-collimation. You are only up for postage - they do't charge anything for the service. Of course, if you want to break the warranty you could chip the glue away and collimate it if your really wanted to.

[Omaroo]

DJ - just insert the 2" collimator into the 2" focuser as per normal. GENTLY tighten the ring clamp on the focuser - barely tight enough to hold the collimator so that there's no obvious slop but so you can grab the collimator and twist it while it's sitting there. If you twist the collimator and the dot moves in a circle on the secondary then the beam isn't straight. So - in essence - do step 1 (adjust the secondary to get the dot in the primary's circle) and then twist the collimator gently. If the dot moves, let's discuss it at that point.

You've got a wee complex problem here because a) you have a MakNewt and b) you've replaced the focuser with a non-standard one. These two will add an extra dimension of variables for us to figure out.

[matt]

Chris......isn't there still room for machining error to enter into the equation if you are rotating the collimation unit inside the focuser?:shrug:

We're assuming all contacting surfaces are perfectly machined and the unit is perfectly centred.

[Tannehill]

Ah, you do have a barlow attachment, then.

Use that to adjust the primary mirror, not the return beam-only method. Get the shadow of the primary center mark centered around the hole in the back of the barlow attachment. In "barlow" mode, mis-collimation of the laser won't matter. Then, see if that agrees with the Chesire.

Then compare the agreement using the primary laser to align the secondary and the return-beam method to align the primary.

If the former method agrees, but the latter disagrees (as you say it does now) then I'll bet you it's the laser's collimation as the issue...

S

[Omaroo]

Absolutely Matt - it's only a rough indicator - but one that will work nontheless.

[DJVege]

Tannehill,

I've done that, and the barlowed laser doesn't agree with the cheshire. It's the same, about a cm off. But just to be sure, I'll perform this test as well tonight.

Thanks guys.

[matt]

I'd want to eliminate the machining of the focuser and the laser unit itself as factors before blaming the collimation of the laser.

But all things being equal...it's most likely the laser unit is out of collimation.:)

[DJVege]

haha. Well, place your bets gentlemen! Around midnight tonight, I shall post my results!

[Tannehill]

well, heck, I dunno then...

Hmm, well, if the telly has poor offerings I'll check in here then for the suspense-filled outcome...

s

[Omaroo]

Same here LOL! If the sky is CRYSTAL clear, I may be up.

Otherwise...sleepybyes....

[matt]

You really are short of excitement around your place.;):rofl:

[GeoffW1]

Hi,

If that's me you mean, you missed the point then, and you still are.

If not, I think it's an unnecessarily snide remark anyway.

Cheers

[Omaroo]

Geoff - I see we're at it again. http://www.iceinspace.com.au/forum/../vbiis/images/smilies/lol.gif

Again - with all due respect, have you yet directly and actually used one of these actual units in question? Have you had one in your hand? A simple question with a yes or no answer!

"you missed the point then, and you still are." - who's being snide?

Sorry DJVege - I've had enough of this subject - apparently there are experts who have never used one that will answer your questions, but what the hey!

Cio

[GeoffW1]

Chris,

We're only at it again if you want. I replied only under some provocation from you. I'd certainly like to move on, and I want you to also. I agree all this has definitely come to be a complete waste of space.

Whether or not I've had one of your favourite laser units in my hand has nothing to do with it - read my earlier posts. I am quite happy to accept the unit has any marvellous features you claim for it. Each to his own.

I have made no claims at all to being an expert, just someone with a bit of experience to share.

I'll repeat for your benefit (you seem to be the only one who needs this) -

I think it is really useful to be able to give your laser collimator a collimation check yourself.

If you cannot do that check, you may suspect the unit requires collimation, but how will you know for sure? Again, if you send it off for a fix, how will you know for sure it is now OK when you get it back, or indeed if it is any different at all? That's my perspective. No aspersions intended about this laser unit in particular.

There it is in a nutshell. Just my opinion, never was anything else.

Now, can we move on? Without further derogatory references to my opinions (the ones I am entitled to)? Please?

Cheers

[DJVege]

Hey guys,

Ease up GeoffW1 and Omaroo. No "war of opinions" required here.

MY RESULTS!!!

THE ASTRO SYSTEMS LASER COLLIMATOR IS COLLIMATED!!! :) It passed the straight line test, and the tube test. Well, I think it did. I put it in the tube, I didn't bother centering it, Omaroo. It was about a cm from the middle mark on the primary...I turned it in the focuser tube, and it stayed exactly there!!!

[Tannehill]

good, that's a relief.

Try collimating the secondary mirror with the primary laser beam, then the primary mirror with the barlow-attachment on the laser. Don't use that merge-the-return beam technique. See, then, if the chesire agrees with the barlowed laser re the primary mirror.

s

[Omaroo]

Good one DJ - and so it should be. That's what you pay for when you order one, a company-guaranteed instrument that is in alignment out of the box. Mine was the same - the beam is straight and well-defined. With the barlow on, my beam stays put when the unit is twisted - right back to the barlow on the diffused return beam - which is obviously double the distance.

[DJVege]

It doesn't. This is the techniqe i tried first when i got this astro systems laser collimator. I'm going try, hopefully this weekend, to move the secondary into the centre of the focuser, as I think this is the problem. Once that's done, I'll try the technique above, and see if the cheshire agrees. If not, I'll be back on here, asking someone to help me!! :)

Will report back once it's done!

Thanks guys!

[Omaroo]

DJ - are you sure you want to do that? Moving the secondary in relation to the focuser is going to also result in a shift between the secondary and primary... which you should not want.

Logic would state that you've replaced the focuser assembly with another - so any misalignment would more than likely be as a result of this exercise. Are you absolutely certain that the relationship between the focuser and the secondary's offset centre dot is still correct? The axial centre of the focuser should be pointing at a slightly-offset centre of the secondary - not the true centre. It will still work if it doesn't, but you may see an offset secondary (as you have). David Kriege's book explains it all if you have access to a copy.

Can you replace the new focuser with the original (accurately) and see if you get what you're used to in terms of cheshire alignment?

[Glenhuon]

Think I'll sit back and listen now, looks like you guys have a fair bit more experience than me. Probably learn something new :)

Bill

[DJVege]

Hmmm...In actual fact...i'm lost! :)

I thought, looking down through a cheschire, the secondary mirror should be centered under the focuser (or through the tube I'm looking through).

Maybe I should just wait till someone in the know can take a look. ??

I'll have another play/look tonight and report back.

[Omaroo]

DJ - start by going back to your original focuser for a bit. Go back to basics and see if you get the same collimation result that you expect. You've proven that the A/Systems unit is in collimation and its beam is straight - so there are other reasons why the two systems don't agree..... or do they? Maybe the new focuser tube placement has off-centered it in relation to the secondary, and it's only because you physically sight through the Cheshire that you're noticing it now.

[DJVege]

If the new focuser HAS off-centered it...what do I do? Don't I use the set screw and move the secondary back?

[Omaroo]

It'd be better to investigate why the new focuser centres in the tube opening differently. Did you use the original focuser base with the new 10:1?

[DJVege]

Sorry for the late reply, but I had a very busy weekend.

Yes, I used the old focuser base with the new 10:1 focuser from Bintel.

[DJVege]

Omaroo, sorry about not getting back to you yet. Have been very busy lately; getting between 3 - 5 hours of sleep a night. But will play with the focusers today and get back to you.

Thanks and sorry again.

[Omaroo]

All in your own time DJ - no worries here :)

[Tannehill]

I'm keen to learn if the secondary adjustment fixes the disagreement between barlowed laser collimator and chesire.

I took the liberty of generically describing your observation (the barlowed laser and chesire do not agree) to the gurus on the telescope collimation yahoo group. There was no easy explanation from them, either. One of the most experienced fellows did point out that the collimation of Mak-Newts is a bit specific; the corrector plate needs to be aligned as well as the primary mirror, and there was not (to his knowledge) a well described way to do this.

I'm sure there is some element of your observation that we're missing; hopefully your secondary adjustment resolves the problem. It's just that, as I continue to learn the optics of collimation, I can't figure out how the disagreement between the chesire and barlowed laser could be anything other than an odd flaw to the chesire, the focuser tube (piece is not sitting in straight), or what have you....and not the secondary.

Please keep us apprised...

regards

scott

[DJVege]

Uhhh!! You know what...my new theory is that I just don't know what to look for in collimation with this Mak-Newt, and I'm going to wait till I can get a pro to look at it for me...and tell me where I'm going wrong!!! :)

Phil, I find out today if I get that job or not...if I do, I'll be up your way in no time!!!!!!!!!!!!!!!!!! :)

[DJVege]

Unfortunately, I didn't get that job!! :(

Anyone in Brisbane who I can visit with my scope and who can tell me what I'm doin wrong? Pleeease?