Levente,
I will probably get jumped on for contributing here because I have had issues with Siebert, but your post interests me as a binocular repairer (not as a Siebert critic).
Even if you can merge the images, your binocular or binoviewer can still be miscollimated. Especially at night, and with low magnifications, your eye/brain can compensate for a bit of miscollimation and merge images. The miscollimation still exists, however, and will manifest itself as a headache or tired feeling from the effort you are unconsciously making. To see if you do have a collimation problem, focus on an object in the middle distance (not at infinity) during the day. Concentrate on something right in the center of the field of view and then take turns closing each eye and looking through just one side in turn. The object should be stay centered in both sides, if not there is miscollimation.
This will be (in my experience) slightly more visible in daytime than at night - especially if the miscollimation is up/down, which the eye-brain resists compensating for more than left/right. It will also be more obvious at higher magnification, something you may have already noticed with your 15mm eyepieces. It is unlikely that the eyepieces are causing the problem.
Nils
I should note that this is binocular knowledge. I've never built a binoviewer or even taken one apart. Binoviewers are different of course in that you have one image that is being split in two, rather than two images. Still, it seems to me that the same test for collimation should work.
I will probably get jumped on for contributing here because I have had issues with Siebert, but your post interests me as a binocular repairer (not as a Siebert critic).
Even if you can merge the images, your binocular or binoviewer can still be miscollimated. Especially at night, and with low magnifications, your eye/brain can compensate for a bit of miscollimation and merge images. The miscollimation still exists, however, and will manifest itself as a headache or tired feeling from the effort you are unconsciously making. To see if you do have a collimation problem, focus on an object in the middle distance (not at infinity) during the day. Concentrate on something right in the center of the field of view and then take turns closing each eye and looking through just one side in turn. The object should be stay centered in both sides, if not there is miscollimation.
This will be (in my experience) slightly more visible in daytime than at night - especially if the miscollimation is up/down, which the eye-brain resists compensating for more than left/right. It will also be more obvious at higher magnification, something you may have already noticed with your 15mm eyepieces. It is unlikely that the eyepieces are causing the problem.
Nils
I should note that this is binocular knowledge. I've never built a binoviewer or even taken one apart. Binoviewers are different of course in that you have one image that is being split in two, rather than two images. Still, it seems to me that the same test for collimation should work.
