10 Lenses Compared at 5x - Stacked lens vs the Objectives

[RobertOToole]

The same dual flash set-up remained in place for all the lenses in the test.

Robert

Was the mag.x the limiting lens for lighting angle? Seems it is large in diameter and with short WD, so the lighting angle must be <<45-deg.

Yes, something like that, sounds about right.

Also I cut a small white disk and stuck that to the flat portion of the front of the lens to help get light on the subject.

Robert

[ray_parkhurst]

The same dual flash set-up remained in place for all the lenses in the test.

Robert

Was the mag.x the limiting lens for lighting angle? Seems it is large in diameter and with short WD, so the lighting angle must be <<45-deg.

Yes, something like that, sounds about right.

Also I cut a small white disk and stuck that to the flat portion of the front of the lens to help get light on the subject.

Robert

Thanks for the additional info. I was trying to figure out (in the remote possibility of ever finding one) if the objective could be used for stitching, but keeping the lighting constant relative to subject with such short WD seems to preclude this.

Lighting has been the biggest issue with my stitching efforts. Referencing the lights to the subject such that when it moves the lights move with it is a severe limitation and caused me to wait several years before going down the stitching path. Now that I've built a few lighting systems which move with the subject, I'm finding that WD is the next frontier. I attempted recently to stitch using a Lomo 3.7x, and although it has very good WD it is insufficient for maintaining the high lighting angle that is required for coin imaging. I find that that the requirement for telecentricity is minimized by high lighting angles, so I was hoping the Lomo could work, but so far no luck.

There is a possibility that a very small light, just larger than the diameter of the coin, and placed within the working distance of the objective, could work. This is exactly what I'm doing now for lower magnification, but on a larger scale.

There is also the possibility of coaxial lighting working, but it imparts an undesirable look to the images.

Bottom line, if I'm having trouble fixing the lighting with the Lomo 3.7x, I can't see how the mag.x could work with its 13mm WD. I guess this might make me feel a little better about not being able to find one!