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Digitec laser collimator

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#1 Guest_**DONOTDELETE**_*

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Posted 21 June 2004 - 05:37 PM

I just ordered one of the "blem" units that digitec is offering through CN classifieds. I don't know if anyone here is using one, but i figured i'd give it a go. I guess i'm one of those people that will try anything to avoid spending one of those "perfect" nights collimating. I'd rather be observing... if anyone has experience with one of these units, let me know; i'd like to know what to expect.

#2 Rusty

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Posted 21 June 2004 - 10:02 PM

I have it - and I also evaluated a prototype. It works very well. You'll need a "target" (I can email you one I made). Get your hiking boots on, because with the C11, the distance to the target will be about 135'. With a homemade extension tube, I reduced that to 65'. Nevertheless, correlation with star collimation is quite tight.

It it for everyone? No. But was worth it to me because I got two or three fair observing sessions before I was able to tweak collimation on a star? Yep - and there was very little final adjustment left to be made.

#3 Guest_**DONOTDELETE**_*

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Posted 21 June 2004 - 10:10 PM

Thanks for the great answer rusty! Yeah, i'll go ahead and pm you my email address. Fortunatly, i have a little space to work with so its not a problem.

#4 Rusty

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Posted 21 June 2004 - 10:31 PM

Let me know what format works - I can export into several... (.dxf works most often).

#5 Guest_**DONOTDELETE**_*

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Posted 22 June 2004 - 07:36 AM

Correct me if I'm wrong (and most likely, I am), but isn't a laser collimator supposed to do away with the need to view from the front of the scope a great distance? Or for that matter, even need a distant target?

#6 Guest_**DONOTDELETE**_*

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Posted 22 June 2004 - 07:55 AM

On a Newtonian you only have one optical element that has any power, so all you need to do is align the focuser with the optical axis of that one mirror. With a laser collimator you can do the alignment without a distant target.

An SCT is different; it has a concave primary and convex secondary, so the alignment of both are critical. Not only that, but the primary is fixed and the secondary is adjusted to compensate for any misalignment of the primary. So you can't align the mirrors to each other with a laser collimator. The only way to collimate it correctly is to measure the end-to-end performance, either with a star test or by shooting a laser from the focuser and to a distant screen.

#7 Guest_**DONOTDELETE**_*

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Posted 22 June 2004 - 08:47 AM

Ahhhh. So I'm guessing if I need to align my scope, no matter what it would be a major pain in the rump. :mad:

I hope it travels well in my motorcycles topcase. :o

#8 Aquarianperry

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Posted 22 June 2004 - 11:52 AM

Ahhhh. So I'm guessing if I need to align my scope, no matter what it would be a major pain in the rump. :mad:

I hope it travels well in my motorcycles topcase. :o


You don't need to worry as much, since your using a Mak with a very long F ratio your collimation does not have to be as perfect as with an SCT. Plus on the bright side Mak's seem to hold their collimation very well and are pretty easy to collimate if you ever need to (just don't screw in the screws too much or you will mess up the O-ring around the back plate of the Mak).

#9 Rusty

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Posted 22 June 2004 - 09:37 PM

The Digitec Laser Collimator works in reverse on the scope. Attached to the visual back (2"), it projects an image onto the target. Unlike Newtonian collimators (point source), it provides a scattered source over the entire secondary. The only thing that's a surprise is that it emphasizes tube currents, although that won't affect the actual collimation process.

Very useful is an extender tube (I made one out of specialized thinwall PVC), which cuts down the distance to closest focus (135' without, 65' with).

The Digitec collimator won't replace star collimation, but it served me well for months until seeing conditions were clean enough to tweak collimation - and then, only a minor adjustment was needed.

For anyone with less than 8 or better seeing, it works well; with more experience, I might have been able to do the final tweak with the Digitec.


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