Question about Bestwell Mini-Sight's reticle

[Paul Glover]

I just picked up a used Bestwell Mini-Sight 10x grain focuser. Looking at the wire which is strung across the focusing reticle, I notice it doesn't lie flat across the opening. It has a little slack in it and bows down in the middle by maybe 5mm.

It seems to me that this wire should be taut and flat from one side of the reticle to the other. I have no reservations about "fixing" this myself, assuming it needs fixed in the first place. Since I've never seen a grain focuser up until yesterday, I don't know if this is abnormal. But, my understanding of how these work suggests that the bowed wire is wrong.

Can anyone else who has one of these confirm that the wire should be flat? Thanks!

 

[tkamiya]

I have it's cousin, Microsight. In fact, I have two.

Looking at both, the strings are tight across the opening with no slack.

 

[TheFlyingCamera]

The wire should indeed be tight, not bowed.

 

[Paul Glover]

Thanks, that's what I figured.

I did get sent along a good description of how the aerial focusing works; the aerial image is always where it should be (assuming everything else is within spec) and will always appear at its sharpest when the enlarger is focused properly. However the eyepiece being set for a misplaced reticule will affect how sharp that "snap" into focus looks, like trying to focus a camera with the wrong diopter adjustment at the viewfinder. Get it far enough wrong and focusing would be a challenge, if not flat out impossible (as it is for me with an eye level viewfinder and no diopter correction, the image never snaps into focus, it just gets less fuzzy!)

I had always figured you focused your eye on the reticule and then brought the grain to focus matching that. Seems that the reticule is simply there to get the eyepiece diopter set appropriately.

Either way it's an easy enough thing to fix so that I can set the eyepiece correctly and not just "close enough".

Now if only my arms were a little longer. With the enlarger head all the way to the top it's quite a stretch to look into the focuser while reaching up to the focus knob on the 23CII-XL. Do-able, but a stretch!