That'll be this one, then?:
For the 10x, NA 0.21 scope lens
the "f" number is about
So that looks very similar
to an Olympus 20mm F2.0, if (big "IF"!) there's one lying around.
I believe there's a test hereabouts showing the Oly isn't quite as sharp as a scope lens, even though its aperture is wider. *
doing the other sum, comparing the best ordinary 10x objective which has NA of 0.3,
Resolution being given by (0.61 *0.55)/2NA,
the SLWD comes out at 0.8 micron (μ)
versus for the NA0.3, 0.56μ.
Multiplying by the magnification gives 8μ and 5.6μ.
On Charles' excellent adventure with a spreadsheet **
he points out we really need 3 pixels to satisfactorily resolve a detail one pixel big.
SO to see the benefit of the difference in NA we need a pixel size smaller than, say two and a half microns.
The smallest-pixel DSLR sensor I'm aware of currently (4/3rds Olympus sensor) has pixels 4μ across, and mine are double that.
So it would seem from this alone
, that some of us might begin to see a difference in resolution, others wouldn't.
Other factors I can think of -
>>F numbers and NAs aren't all that they appear to be - where's that post where Rik shone lasers through his lenses...? ***
>>Something like an Olympus macro lens is designed to cover a 35mm frame - scope lenses aren't - but some do pretty well.
>>Something like a NCF 10x/0.3 scope lens for 160 tube is 16mm.
[Edit: That was wrong. Parfocal 45mm 160 tube length, FL = approx 20.5mm] We know that it can be wound out to give 15x magnification quite well. That's getting a bit long on the bellows for a 21mm [Edit: Wrong again, it would be longer] (210 tube length) lens such as the SLWD.
means I have to find a link )
The same vendor is currently offering NCF10x 0.3 infinity
objectives. Now I wonder how much difference that
Edited to correct errors in focal lengths of the scope objectives.