Kowa 99S Star test help (1 Viewer)

[Tmathews55]

New to this
I purchased this scope brand new. When I received it something was clearly wrong, could not get a sharp image at all. I sent it back and without much explanation they replaced the eyepiece and sent it back. This is when I got down the rabbit hole star testing and found out how many issues people are having with this particular scope..

These are the closest depiction I’ve been able to get of what my naked eye is actually seeing.


Second image goes blurry any further passed focus. No solid outer ring on this side of the focus. Had a hard time getting the right conditions for visible rings on this side of focus.

 

[Tmathews55]

Should mention this was indoors at 70x at a distance of about 12m

 

[henry link]

What are you using for an artificial star?

 

[Tmathews55]

What are you using for an artificial star?

This one I used a pinhole in foil over a flashlight

 

[jring]

Hi,

looks ok to me. A bit of astigmatism, nothing terrible. The undercorrection visible is sth often seen on fast and well color corrected refractors and it does not necessarily mean that there is SA in the objective but rather a limitation of the star test with these instruments.

I would expect this to deliver a usable image at 70x when the seeing allows...

Joachim

 

[Tmathews55]

Hi,

looks ok to me. A bit of astigmatism, nothing terrible. The undercorrection visible is sth often seen on fast and well color corrected refractors and it does not necessarily mean that there is SA in the objective but rather a limitation of the star test with these instruments.

I would expect this to deliver a usable image at 70x when the seeing allows...

Joachim

Thank you for the response

 

[BoldenEagle]

This sample seems to have better star test results than any 993 sample I have seen so far. None of them had that many and clear rings on both sides as for the correction of spherical aberration.

Is this straight model as there is no evident vertical prism line, which most angled models seem to have?

You should try to directly compare this sample to the Atx95 if you still have access to it. It may be very hard to tell which scope is sharper without direct comparison unless the other one is very bad sample and other is very good. Even then seeing may vary so much that it can affect the result.

Regards, Juhani

 

[Tmathews55]

This sample seems to have better star test results than any 993 sample I have seen so far. None of them had that many and clear rings on both sides as for the correction of spherical aberration.

Is this straight model as there is no evident vertical prism line, which most angled models seem to have?

You should try to directly compare this sample to the Atx95 if you still have access to it. It may be very hard to tell which scope is sharper without direct comparison unless the other one is very bad sample and other is very good. Even then seeing may vary so much that it can affect the result.

Regards, Juhani

This is a straight model. I’m going to compare it to a friends stx95 soon