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ZEISS DTI thermal imaging cameras. For more discoveries at night, and during the day.

Needed - easy way to check collimation (11 Viewers)

Allen

Well-known member
Hi all. I have recently picked up a good priced pair of Swarovski EL 8x32 but feel they are out of collimation. My eyes feel like they are really having to 'reset' after looking through which I am not getting when compared side by side to my Zeiss Conquest 8x32. Before I send them off to Swarovski, what's the easiest way to technically check this?

Thanks
 
Hi,

search a bright star on the night sky, focus on it (or two, if things are really bad) and turn the diopter to the end of its range. So you will have a bright dot (the in-focus tube) and a large disc (the out of focus tube). The dot should be in the center of the disc if the instrument is correctly collimated.

The idea is to prevent the brain from merging the images of the tubes... since there is no star but a diffraction disc, it doesn't merge...

Joachim
 
Well i tried this and the in focus star is outside the blurry disc. So as I suspected out of collimation. I shall send to Swarovski but just out of interest what can cause this. I would assume knock damage but any other possible causes?
 
Thanks. Purely for my own interest, how does this get corrected then by an engineer? What do they adjust?
 
Porro design prisms can adjust prism angle or the slight tilt of the objective lenses. I would expect the latter are also used with roof prisms, but there may also be internal adjustable bits…. Swaro will know and be able to fix hopefully.

Peter
 
Thanks for all replies. I have the option to return these to the seller but as the SV ones don't seem to come up that often I wonder if it's worth keeping and getting Swarovski to sort them. My only concern being if they can't leaving me with a pair of unusable bins and a out of pocket.
 
From what I understand with the star test , as long as the focused star is inside the unfocused star (blob) collimation is acceptable although perfect center is ideal .
 
From what I understand with the star test , as long as the focused star is inside the unfocused star (blob) collimation is acceptable although perfect center is ideal .
It may depend.

Horizontal misalignment is much easier to tolerate than vertical.
 
From what I understand with the star test , as long as the focused star is inside the unfocused star (blob) collimation is acceptable although perfect center is ideal .
The focusaes star was right on the edge or just outside the edge of the blurry circle about 4 on the clock. It's gone off the Swarovski now.
 
You would be advised to have a full eye test before making collimation adjustments. You may have mild misalignment of the eyes themselves which will produce double images in the bins but possibly not while terrestial viewing. If Swarovski say there's nothing amiss with it then you will have to do the adjustment yourself (Youtube etc). Good luck.
 
The light source has to be far away? We don't see any stars here in the city. Do I have to wait until I'm in a nature reserve far from the city? Or can I do the same with a light from a high tower or so?
 
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The light source has to be far away? We don't see any stars here in the city. Do I have to wait until I'm in a nature reserve far from the city? Or can I do the same with a light from a high tower or so?
As far as you can get I think. You need a small bright object with relatively dark surroundings, like trees. I used an outdoor light on the house about 30 yards away. It helps to move your eyes back about 3" from the EP. Then you will see the double image more clearly. You could make use of sun reflection from a small piece of glass or ball bearing balanced on a wall perhaps.
 
agreed on most of the above. if you're checking collimation with a star and judging not just the merging of the star images but the quality of the diffraction pattern, be sure to place your target star in the center fov.

one quick daytime test for vertical collimation is to focus on a horizontal line, say a roofline, powerline or fence. slowly move the binoculars away from your eyes, keeping the eyepieces aligned with your eyes. observe how well the images maintain alignment. poor vertical collimation reveals itself very quickly this way as lines of uneven heights.
 
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The light source has to be far away? We don't see any stars here in the city. Do I have to wait until I'm in a nature reserve far from the city? Or can I do the same with a light from a high tower or so?

Hi,

infinity is not needed as has been mentioned but a point source or close to it would be good and it should be a few hundred meters or more in distance.

As for you can't see stars in the city... I am quite astonished. I live in a large city too and have one of Europe's largest airports (FRA) close by to the south... and with bins, quite a few stars can be seen. It's certainly not great for astro (at least visually), but when you just have a few minutes on the balcony with a spotter on a clear day there's usually sth visible

PS: I'll eat my words... after a quick look at a light pollution map, there is a huge blob of light pollution as bad or worse as right in the middle of the FRA airport but it's like 20-30km around Den Haag and Rotterdam... but still I'll bet you beer that stuff like Sirius, Arcturus or Vega should be visible there...

Joachim
 

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