Finding Polaris?

Started 9 months ago | Questions thread
tradesmith45 Senior Member • Posts: 2,138
Laser Pointer "Calibration"

landscaper1 wrote:

Alen K wrote:

landscaper1 wrote:

Of all the suggestions made in this thread, the idea of attaching a laser pointer to the SkyTracker Pro (probably right above its optical sight) seems the best of all. I'm going to try that.

Of course, my OP inquiry was based on a certain amount of optimism. I'm 74, have high BP, and live in what is expected to be a Covid-19 epicenter (Baltimore/Washington/Northern VA region). In all likelihood, it'll be some time before medical experts are likely to say it's safe for people like me to be getting out of our self-imposed quarantine.

I have seen low-power green laser pointers on Amazon for as low as $8, so it's an economical solution too. Just be mindful of airplanes and don't do it if you are anywhere near an airport.

Stay safe. We're going to get through this!

I've seen those as well. However, I wonder if their low price also correlates to not being as bright and less able to maintain a narrow beam at greater distance. They are, after all, intended for use in making presentations in a much smaller space.

Landscaper, mentioned in an earlier that I use a laser pointer w/ a Nanotracker w/ success up to 135mm @ 30".  Below is a photo showing the Nano, DIY adapter (not suggesting you make one) & the pencil style pointer.  As you questioned, @ $8, these are not precision devices.  Two things to know: from my 2 copies, these do not point exactly parallel to their body so aim calibration can improve accuracy & they eat AAA barrettes pretty fast especially in cold weather.

The form factor of the iOptron makes it harder to make an adapter so I'm assuming you'll simply hold the pointer in some reliably reproducible position on the tracker which requires a face on the tracker that's parallel to the drive shaft.  (BTW, I've used this pointer in this way on a friends iOptron when we're out to help him check alignment & it worked well.)

Of course your a clever guy & may come up with another approach to using the pointer but here's my suggestions.

Be sure to get a pointer that's round & has as few protrusions as possible.  When you get one, place it on a table, point it at a wall & rotate it around its axis to see how large a circle the pointer traces out on the wall.  If it traces a large circle, you'll not be able to accurately align your tracker w/ that one because it doesn't point straight enough- get another.

Next "calibrate" your pointer.  Set up your tracker w/ polar scope (but sans angle finder & adapter) & aim at an object some distance w/ the scope reticule on some specific point.  Now place the pointer in a reproducible position against the tracker & rotate the pointer until it points to the same position as polaris on the reticule.  Mark the pointer so you can place it in that position repeatedly.  In my case, I aimed the pointer so it pointed into the center of the peep hole FOV.  For my pointer, the correct position was w/ the on button pointing down.

When pointing at polaris at night, you need to get close behind the pointer when placing the green beam on the star to avoid parallax errors.  (Sorry, no rest from getting into a low position just as w/ the polar scope-:)  When aimed at polaris, you'll be 0.5-1º off the NCP but if you use an app showing the relationship of the star & NCP, you can aim more accurately at the NCP.  But none of that is needed for short FL lenses.

FWIW, ShoeGoo can glue anything to anything.  If interested, you could use that to attach part of the pointer to the tracker - just be sure you can change the batteries.  OTOH, w/ the right parts, might be able to place the pointer in the hole for the scope.  I used simple bands to adapt my pointer to a plastic clip for polar scope on an Omegon LX3.

I too am 74 & wish you the best with you health & safety.


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