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02-02-2019, 01:34 PM   #1
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Astrotrackers or barndoor trackers near the arctic circle.

Hello

I was wondering whether anyone here has used either an astrotracker or a barndoor tracker near the artic circle. + 62.5N

After having read a lot about them I decided to make diy barndoor tracker, only to find out that when I point it at the polaris it seems to form an angle of 70-80 to horizontal. (If I am reading the stellarium software correctly, the angle is 78) Which puts the ball head and camera close to horizontal. With all sorts of forces pulling in directions I'd rather avoid.

I wanted to use the barndoor tracker for budget reasons but I am starting to doubt whether this is at all useable.

The other option that exists is an Astrotracker, I suppose an astrotracker would solve this issue but I'd rather not spend 500$ on one to find out that I am wrong.

cheers.

02-02-2019, 02:36 PM - 1 Like   #2
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What are you pointing at polaris? It should be the axis of rotation of your tracker, and it should be highly inclined (tilted upward) at latitude 62.5 (in fact, 90-62.5 = 27.5 degrees away from vertical).

Imagine you were at the north pole itself. In that case, the rotation axis of the earth points straight up (the projection of the pole onto the sky).

Where your camera points depends on what celestial object you are trying to track. If you can attach a ball head to your tracker arm, you can aim at will.

Conversely, I was never impressed with my efforts (and I'm a reasonably good DIYer, and a professional astronomer, to boot) at making a useful barn door tracker.

If you can afford a real astrotracker, you will be much happier!

You may find it better to attach your ball head to the "side" of the tracker arm, rather than the usual idea of putting it on the "top" - then the the tip/tilt of your camera will be rotated 90 degrees and may not seem so perilous.

Last edited by AstroDave; 02-02-2019 at 02:39 PM. Reason: add attachment idea
02-02-2019, 03:43 PM   #3
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I've been pointing the hinge towards Polaris. I'm located at 64N so I guess I've been angling it closer to 60-70 rather than 70-80. (Assuming that I managed to aim correctly).

The idea of putting it on the side sounds good. I was thinking about extending the barndoor somehow so I would get more horizontal base for the ballhead (when in position) but wasn't sure whether that would work in practice.

I guess I'll try to make it out of more beam-like pieces rather than the flat pieces I used.

However I'd love to hear from others if they're near the arctic shooting astro or milky way.
02-03-2019, 03:37 AM   #4
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QuoteOriginally posted by krazny Quote
The other option that exists is an Astrotracker, I suppose an astrotracker would solve this issue but I'd rather not spend 500$ on one to find out that I am wrong.
You can take a series of shorter exposures with the 500/FL rule, at higher ISO, and use a software to stack them with alignment to reduce noise. That what Canon users are doing to cope with sensor noise and lack of astrotracer features. We Pentaxians are lucky to have in-camera astro tracer on some camera models so our workflow is simplified. The downside of stacking is you'll have to crop edges of the aligned stack.

02-03-2019, 10:13 AM - 1 Like   #5
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Do you have any optics support for aiming at the pole star? My aim varied with my barn door setup sometimes. It's not always easy to see without magnification. My buddies eyes are better and he would correct my positioning a few times. If I'd use mine more I'd add some magnification to aid aiming it.

When I did my barn door I wanted to make is smaller than most plans I found online. So I changed the pitch of the screw and made the barn door smaller and good for about 2 minutes of time tracking before too much error started creeping in. I also rotate it every 15-seconds and made a dial marks for that.

Here is the one I made.




02-04-2019, 08:39 AM   #6
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I haven't fitted any optics just been doing this by eye when I've tried.

I haven't actually taken any photos using the barndoor tracker because in the original setup the tracker would be pulled open when aimed at the polaris-ish.<

So I have no idea whether my aim is good or not.

I had some thoughts about adding some sort of "scope" or aimer. I guess the simplest solution is to attach a pvc pipe or two loops parallel to the hinge.

I've seen some recommend a laser as a pointer. Turns out some (or all?) lasers do not operate below freezing point so they're not much use.
02-04-2019, 08:48 AM   #7
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If buying something, either a compact tracker for widefield photography, or a larger counterweighted German Equatorial Mount (GEM), check the specs for the latitude range. Some designs don't work well near the poles or equator.
02-04-2019, 09:47 AM   #8
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QuoteOriginally posted by DeadJohn Quote
If buying something, either a compact tracker for widefield photography, or a larger counterweighted German Equatorial Mount (GEM), check the specs for the latitude range. Some designs don't work well near the poles or equator.
I was wondering about that.

I was watching some tutorial about the Star Adventurer which has a latitude base and it seemed to me that the latitude base only angled to 60 but I could be mistaken about this and there is no mention about this on the skywatcher.com.


I do not know this to be true for sure, haven't been able to confirm or deny this. Maybe they just figured that not that many people would be using one north of 60 (if true).

02-04-2019, 02:13 PM   #9
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QuoteOriginally posted by krazny Quote
I was wondering about that.

I was watching some tutorial about the Star Adventurer which has a latitude base and it seemed to me that the latitude base only angled to 60 but I could be mistaken about this and there is no mention about this on the skywatcher.com.

I do not know this to be true for sure, haven't been able to confirm or deny this. Maybe they just figured that not that many people would be using one north of 60 (if true).
The angle adjustment has physical limits. If you try pointing too far straight overhead, what started as the "back" of the tilting part becomes the "bottom", touches the base, and can't move any further.


Aiming devices (aka polar alignment scope) at polar latitudes get tricky because a human head can't fit between the tracker and the tripod. You can try a mirror to look through a built-in alignment scope, or use a removable bracket for your laser keeping it warm in a pocket when not aiming, or mount a 90 degree finder to put your head in a more convenient position Orion Black 6x30 Right-Angle Correct-Image Finder | Orion Telescopes to center Polaris.


iOptron's Skytracker Pro states a working latitude range between 30 and 65 degrees north. I have an older iteration of that product and it's worked well for me.
02-04-2019, 03:15 PM   #10
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Have you thought about making a simple turntable resting on a wedge? That might be an easier geometry for extreme latitudes.

A turntable also has the advantage of being able to track continuously 24 hours a day during those long winter nights above the Arctic circle.
02-04-2019, 03:59 PM   #11
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QuoteOriginally posted by DeadJohn Quote
The angle adjustment has physical limits. If you try pointing too far straight overhead, what started as the "back" of the tilting part becomes the "bottom", touches the base, and can't move any further.


Aiming devices (aka polar alignment scope) at polar latitudes get tricky because a human head can't fit between the tracker and the tripod. You can try a mirror to look through a built-in alignment scope, or use a removable bracket for your laser keeping it warm in a pocket when not aiming, or mount a 90 degree finder to put your head in a more convenient position Orion Black 6x30 Right-Angle Correct-Image Finder | Orion Telescopes to center Polaris.


iOptron's Skytracker Pro states a working latitude range between 30 and 65 degrees north. I have an older iteration of that product and it's worked well for me.
This makes sense.


QuoteOriginally posted by photoptimist Quote
Have you thought about making a simple turntable resting on a wedge? That might be an easier geometry for extreme latitudes.

A turntable also has the advantage of being able to track continuously 24 hours a day during those long winter nights above the Arctic circle.
I guess this follows the same principles as a barn door tracker? I've never heard of this before.

Last edited by krazny; 02-04-2019 at 04:04 PM.
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