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Kowa 883 with 25/60 and 1.6 Extender Center Shadow (1 Viewer)

wcerveny

New member
Please excuse me if this is a dumb question but I am very new to birding and spotting scopes. I just purchased a Kowa 883 with the 25-60 eyepiece and the 1.6 tele extender. When using the 25-60 without the extender I am having great results however when using the extender at about 70 or higher power I am seeing a circular shadow at the center of the eyepiece. It seems no matter where I place my eye at these higher magnifications I can not see an image without the circle shadow. I have adjusted the eye cup all the way down up and in between.
It almost seems like I can not get my eye close enough to the lens to get rid of the shadow.

Thanks in advance.

Bill
 

jring

Well-known member
Hi,

what you describe is called kidneybeaning and is usually caused by the eye being too close to the eyepiece. Can you try to fully extend the eyecup or position your eye even farther away?

Joachim
 

wcerveny

New member
Thank you for your response. I did a little reading on the kidney bean effect and please correct me if I am not properly informed. The effect can be kidney bean shaped or round and it can be from the eye being too close or also too far away. Mine appears to be too far away at higher magnification with the 1.6 extender. I can not get the eye close enough to eliminate the dark circular shadow. So perhaps the best thing is to return the 1.6 and be satisfied with the 25-60 Kowa unless you may have some other suggestions Joachim.

Thanks,

Bill
 

Alexis Powell

Natural history enthusiast
United States
I agree with Joachim, I think your eye is too close. I use the same equipment as you and I have no problems. I wear glasses, so my eye is not very close to the ocular.

--AP
 

mskb

Well-known member
Hey Bill, Congratulations on the scope. Did you figure this out? You do mention you have varied your eye cup height and still unable to resolve the shadow issue. So I wonder if it is something else other than the eye relief. Any chance you could post / link to an image of the shadow you are mentioning?
 
Last edited:

wcerveny

New member
Unfortunately I am unable to post any picture as I returned the scope and eyepiece.
I was still within the 30 day return period on the purchase.
I am happy to report that the new scope and eyepiece that were sent to replace the originals are working fine for me now.
 

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