Adjustable Brightness Laser

[Dave In Vermont]

I noticed this new offering from ScopeStuff.com in the US - they are probably the largest warehouse of astro-goodies on Earth. Well worth a visit, but I caution you: Pack a lunch, and hide your wallet - or let the dog bury it outside somewhere. You won't be back for awhile.....

If you've read any of my advice on collimation on the forum, then you know I'm a nut who actually enjoys this chore. So it stands to reason that a new laser-collimator would catch my eye. And noting this one proclaimed it had adjustable brightness - and laser's being too bright is a common complaint. So my resistance slowly wore down until I pulled the trigger.

I ordered this on Thursday night, and it arrived on Tuesday - Monday being a federal holiday - shipped first-class mail from ScopeStuff in Texas. Jim, the proprietor, is very good about speedy shipping. And the price, $44.00US, includes shipping in the US. The box was well-sealed and the box with the laser packed in styrofoam-chips. All was well within.

The box stated: Next Generation Laser Collimator, and a graphic. The laser, along with a 2" to 1.25" adapter with a screw-stop, was snug in a fuzzy-plastic cut-out. Nothing fancy. A simple, yet clear, instruction-sheet rounded out the contents. Now for the test-run:

The laser had a CR2032-battery in it. The top is marked with numbers, and I twisted it to it's first setting. One way was the dimmest, the other brightest. I hit the brightest by luck. A bright red dot appeared on my 200mm F/4 mirror's center-spot. I let-up slightly on the screw holding the laser in the focuser and slowly turned it around while watching the red dot. No movement was present. The laser had arrived well-collimated. Jim had informed me the guy who makes these is very conscientous about ensuring this. Jim's for real. Now I re-tightened the screw in my cheap focuser and clicked the twist-cap through the different levels of brightness - there are 8 of them, including OFF. The lowest-level is hardly visible, and the brightest is about what you get from the average laser-collimator: Very bright. And all points between are present with the range of the click-stop top.

The body of the laser has 3 small screws. These are recessed into the body and two are covered in a malleable glue-stuff. The third is under the ubiquitous WARNING! label. These are the collimation-screws to re-collimate the laser should you drop it down the stairs or some other Stupid-People-Trick.

The Last Analysis: I see a day when adjustable-brightness laser-collimators will be the norm, rather than the exception. If you want one now that works quite well - and at a quite reasonable price - by all means go for it. This one is fine.

Don't forget to pack lunch,

Dave

http://www.scopestuff.com/ss_lcol.htm

[mcolbert]

Dave thanks for this - I've been looking at lasers to use for a lighting source for macrostudiophotography, this may be a possible answer.

michael

[Psychobilly]

Dave thanks for this - I've been looking at lasers to use for a lighting source for macrostudiophotography, this may be a possible answer.

Michael

Sounds interesting.... especially if it needs to be illuminated by a laser 

I have used Cree LED light torches in the past the zoom types for this and coloured gel filters for "creative" effects... in the UK Lidl/Aldi often have them cheap around this time of year... I made some clamps for them and used cheap "gorilla pod"  clones as lighting stands...

Peter...

[triton1]

I have one of these next generation lasers but found it best to turn the on off brightness switch one way is switch on go to correct setting you want ie 3 then when finished go 4 5 6 and then off.I found the switch quiet stiff and ended undoing the end and breaking a wire which I had to resolder

[Dave In Vermont]

Sorry to hear you courted a disaster in trying to adjust the knob's tension, John. But glad you managed a solder-fix on the beast. The knob/switch is rather tight. I just use both hands to adjust it to where I like it and then leave it be. I find 4 or 5 on it does the trick for me. It's nice to actually see the area the red-dot occupies in full - instead of a non-descript blaze of red-light around it.

Collimation is fun!

Dave

[triton1]

Yes it is Dave!

[Mrbloke]

These are available in the UK at a well known auction site for the princely sum of about £18.59. I have one, but unfortunately it was somewhat less collimated out of the box. Once I had collimated my collimator it collimated my scope admirably and continues to do so.

[Jason D]

There is an old trick to reduce/eliminate the glare of the laser at the primary mirror. Point a flashlight at the primary mirror while looking down from the OTA opening. It will remove the glare and show the laser as a tiny dot on the primary mirror.

Jason

[bambuko]

I have got one as well (after resisting the temptation for so long... )

Started by testing the collimator, using my lathe as convenient and accurate device.

Secured it in the chuck

and allowed it to shine out of the rear (pardon the expression ) on a wall exactly 2mtrs away (red arrow marks the spot):

then rotated the chuck, noting the position of the laser spot on the target:

           

            

Smallest circle on the target is 4mm dia, so as you can see at the distance of approximately 2000mm the spot is rotating the circle about 8-12mm dia.

Personally I think it is not acceptable and I will have to have a go at collimating the collimator but what do you guys think?

BTW - I have repeated this test with the collimator secured in the chuck in the number of different positions - the results were always the same (not surprisingly ...)

[Mrbloke]

Yes, it is time to collimating the colimater. Start digging out the rubber on top of the grub screws...

[bambuko]

As far as I understand one of the three grubscrews is just for locking and other two are for adjusting.

Originally the trick to discover which is which was relying on the adjustment grubscrews being at 90 deg to each other, and the locking grubscrew at 135 deg to the adjusting ones.

Now Chinese manufacturers did their usual trick (I have personal experience in this field ) and simplified things - all three grubscrews are at 120 deg to each other...

So it seems that the only way to find locking grubscrew is to try adjusting all three - the one with no effect is likely to be locking screw   I guess...

unless this model doesn't have locking grubscrew???

see: Collimating the Laser - A Right Pain!

[Dave In Vermont]

I guess this explains why the owner of ScopeStuff, Jim, informed me that his friend collimated each one of these before boxing them up for shipping. Mine arrived perfectly collimated. I asked Jim about collimation-screws on these, and he told me where they were. I wanted to be certain they existed - unlike some lasers I've seen offered up for sale for collimation purposes.

Rather defeats the entire purpose of collimating the scope if your laser is out-of-whack.

Dave

[John]

I've owned a few laser collimators and they all needed their beam adjusting, even the more costly ones. I aim to get the beam to stay pretty much in exactly the same spot at a distance of around 5-6 metres when the collimator is rotated.

It can be tricky to achieve this though, especially with non-symetrical design collimators such as the Baader Laser-Colli.

The one I have at the moment is in pretty good adjustment now but I tend to prefer the cheshire eyepiece approach to collimation these days.

Using the barlowed laser collimation method can help here as I believe that it's less critical that the laser beam is directly on the optical axis for that. It just needs to be pointing down the scope so that the barlow can expand it's beam to cover the centre spot of the primary mirror. More info on that here:

http://www.smartavtweaks.com/RVBL.html

[bambuko]

To be honest I have bought laser collimator with only one job in mind - to check the tilt of secondary, to ensure, that the centre of focuser and the centre of primary are coincident (I am perfectly happy doing everything else without laser).

Laser collimator is ideal for that particular job, providing it is securely, precisely and repeatedly located in the drawtube (as both Nils and Steve make very clear in their articles).

Most (majority) of even very expensive focusers are not very good at that... so on top of problems with dodgy collimator, one also has to put up with wobbly collimator in the focuser

Focuser drawtube needs to use vee block or collet principle to make it reliable.

I have solved that problem with my focuser and tests with laser show that it is delightfully rock solid

[bambuko]

With OP permission? I will continue with some more info about this particular collimator.

I tried collimating the collimator, but it wasn't very satisfying experience (well... I've used different words in the workshop , but that's another story ), so as is my habit I took it apart:

Clockwise, starting from top LH we have 7 positions switch head, circlip that retains battery and brightness adjustment, battery holder, o-ring that secures the battery in the holder (plus 4 screws which secure laser contact pad, not shown in this photo), PCB with7 different resistors and "click" plate.

Aforementioned resistor PCB in close-up:

and, finally the rest of the collimator:

Couple of things to mention:

1. you can see "laser contact pad" mentioned previously

2. if you look carefully at the photo, you will see the answer to my question in previous post about the three collimating grub screws - one of them is actually a screw locking the spring (in the photo) which allows the other two screws to be used for adjustment.

Originally the two adjustment screws were at 90 deg and spring loaded/locking screw was at 135 deg to the other two. Sensible arrangement making collimation relatively easy.

But the "brains" in the factory simplified things and now all three screws are at 120 deg to each other.

This means that when using one of the two adjusting screws you are not only moving the laser up/down but also a bit left/right - making it a pig to adjust properly/easily. Same happens when you are using the other screw

Of course it can be collimated (eventually) but it is not as easy as it could/should be!

Your guess which one of the three is spring... (mine was under the label, but I guess this is not guaranteed?)

I think there is nothing left, but to rescue the laser bit and make better contraption out of it   (I can feel proper kinematic mount coming along.... but that will be another thread!)

[ChrisLX200]

How much do you trust that 3-Jaw chuck? Did you put a DTI on the collimator body to check?

ChrisH

[bambuko]

The chuck is Polish Bison on DIN mount - I trust it quite a lot

I didn't use DTI, but as I've said previously "...I have repeated this test with the collimator secured in the chuck in the number of different positions - the results were always the same..."

I am sure it is better than the usual arrangements for collimating the collimator

My main beef is with the way this collimator was "improved" from the original reasonably good design.

[ChrisLX200]

The chuck is Polish Bison on DIN mount - I trust it quite a lot

I didn't use DTI, but as I've said previously "...I have repeated this test with the collimator secured in the chuck in the number of different positions - the results were always the same..."

I am sure it is better than the usual arrangements for collimating the collimator

My main beef is with the way this collimator was "improved" from the original reasonably good design.

I have the Griptru version of that chuck, I wouldn't trust a standard version to run true unless proven otherwise:

The only chuck I have that I _know_ runs true is a 6-jaw:

For that particular test I would use a 2" collet and even then I would check the run-out using a DTI on the body before being confident the laser was not running true with the body.

ChrisH

[bambuko]

He, he, some nice lumps of iron in this workshop of yours

You are of course right about relative accuracy of standard ve griptrue ve six jaw etc

However... (within reason) regardless of the accuracy of the chuck, one should be able to collimate the laser once it is secured in the chuck. This particular model instead of having two adjusting screws at 90 deg (giving you straight up/down & left/right) has them at 120 deg which means that when you are adjusting for up/down you are also affecting left/right (similarly when you are adjusting left/right you are messing up up/down).

Like I said it can be done, but it is un-necessarily cumbersome, because somebody in China has "improved" original design.

[Reeny]

With OP permission? I will continue with some more info about this particular collimator.

I tried collimating the collimator, but it wasn't very satisfying experience (well... I've used different words in the workshop , but that's another story ), so as is my habit I took it apart:

That picture looks familiar.

The "locking" screw is a normal grub screw which holds a spring between it, and the laser housing (only adjust the 2x adjuster screws).

The non adjuster will be the screw next the warning label.

My spring must have slipped, because I lost all the adjustment to collimate the laser.

It needed to come to apart for repair / then I broke a wire, badly bent the retaining cir-clip, and flattened my last battery.

I ended up running it off 2x AA's in a battery pack attached to the side.

My Laser collimator was £26 from our regular Ebay seller of BST's.

I found out later that they were available for £17 direct from China.