Image of the day

Captured by
Gary Taylor

M27 - Dumbell Nebula

My Account

New to Astromart?

Register an account...

Need Help?

hazy spots takahashi Fs102 lens

Started by esmuysimple, 12/25/2007 11:16AM
Posted 12/25/2007 11:16AM Opening Post
I think that my takahashi have PINCHED OPTICS. Pinched optics can also cause an aberration in a similar class as astigmatism. If a lens or mirror is too tight in its cell, the optic may get pinched enough to effect the optical figure. If that’s the case, the pinched optics can be spotted as triangular or
trapezoidal stars. It said that it could be from the cell too tight, or it may need longer cool down time
The optics are good, but again not perfect.In the daylight they look great, but at night when I shine a flashlight on the lens I can see some hazy spots in the inside of the lens. What is the problem?



Attached Image:

esmuysimple's attachment for post 40183
Posted 12/26/2007 01:03AM #1
Yes, the spots and a pinch are separate problems.

The spots appear to have a nucleus or center (perhaps
a bit of dirt), and then are spreading outward from
there. This spreading would worry me. It could just
be grease spreading. Or it could be something more
serious like a chemical reaction or fungus spreading.
I would get it professionally cleaned rather soon before
it spreads farther. It likely will come out perfectly
clean, but I would not let it progress farther.
Texas Nautical can do it.

Yes, pinching will appear in the star test (slightly out
of focus star) as non-circular or distorted rings.
It can be present at all temperatures if the retaining
ring is too tight. Or appear at cold temperatures as the
metal of the cell contracts more rapidly than glass.
Again these can be fixed. Call up TNR and talk to Art.
Posted 12/26/2007 03:22AM #2
I would get TNR to look at those sooner than later.