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Issues with my new Takahashi FOA60Q

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#26 Lappe Lad

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Posted 22 May 2020 - 03:24 PM

Your supplied picture looks practically identical to what I saw with a Takahashi FS-60CB during daytime viewing. It is the lack of knife-edge baffles within the drawtube causing stray light to bounce off the drawtube interior and throwing a veil of glare across the field of view. Sometimes subtle, other times very much contrast-killing. When I looked obliquely through the eyepiece, the veil would shift out of sight, more easily achieved with larger exit pupils.

If the FOA-60 is similarly without at least one knife-edge baffle in the focuser drawtube, then it’s possible that’s what going on. At any rate, Takahashi’s standard blackened anti-reflection threading within the drawtube does a very satisfactory job of stray light control during astronomical observations.

Robert


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#27 senolite

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Posted 23 May 2020 - 01:26 AM

This sounds exactly like what I was seeing in the FOA 60 Q. Removing the Q extender made it less obvious which corresponds to a greater exit pupil with the same nagler 17 mm in it. If that were true I guess my expectations for daytime viewing were too high....

 

Thanks for the feedback Robert, that was very insightful for me.


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#28 Lappe Lad

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Posted 23 May 2020 - 12:06 PM

These days I accept what is basically a transient daytime artifact that comes and goes with changes in magnification, lighting direction and intensity. At one time, I considered the FOA-60 – a sort of Holy Grail of contemporary 60mm offerings. I do regret selling my FC-60 back in the early 90’s, though. That was extremely good for daytime viewing.

I wish you the best in your hobby; it sure is rewarding to examine the natural world through any kind of optical aid!

Robert


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