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Field stop merging in BVs

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#1 Baatar

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Posted 25 June 2020 - 10:48 PM

I have Baader MaxBright II and use it with 26mm plossls and Baader MK4 zooms. When I looked at the moon, planets, stars and clusters, there are no merging issues at all and images are clean and focused.

Plossls' and zooms' field stops are smaller than the clear aperture of the MBII, thus no vignetting either. Eyepieces have sharp field stops, but when used with binos, the field stop edges are blurry and seem not to merge/overlap. And blackouts are easy too. These blurry and not perfectly overlapping edges create a slight discomfort and mild eye strain, which is a bit distracting and annoying.

Is this normal? Is this a collimation issue or something else? As said above, images in the center of the field of view are merged well.

Edit: I used binos in 10" Flextube SW dob without OGC at shorter preset, and with x2.6 OGC with poles fully extended. No issues reaching focus in both situations.

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Edited by Baatar, 25 June 2020 - 11:19 PM.


#2 decep

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Posted 26 June 2020 - 12:56 PM

You prisms are likely slightly out of alignment.  You are seeing a slightly different image in each eye.  It will not be as noticeable with lower magnifications, but it will get progressively worse as you increase magnification.



#3 Baatar

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Posted 26 June 2020 - 01:05 PM

Thanks for reply. With x2.6 Baader's optical corrector I observed the moon at over x350 magnification without any merging issues. It was really a wow experience.

It is just a blurry field stop that puzzles me, at any magnification. It is not vignetting either. I guess the field stops are not merging or overlapping perfectly, thus resulting in percieved blurriness, kind of similar to vignetting? Does anyone get sharp field stops in binos? Looked separately field stops are sharp, but with two eyes it is a bit straining. May be my eyes are at fault?

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Edited by Baatar, 26 June 2020 - 01:08 PM.


#4 decep

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Posted 26 June 2020 - 01:19 PM

Well... let me correct myself.  High magnifications will have a progressively larger image offset if the alignment is off, but you might not have a problem merging the images.  Your eyes will merge the images as long as the alignment is not too far off.

 

I suppose you will only have a big problem with low magnifications with having slightly different images.


Edited by decep, 26 June 2020 - 01:19 PM.



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