Eric F wrote:I would like to find microlenses that could approximate the results of an objective lens -- at 1/5 to 1/10 the time & effort.
That's a very ambitious goal. I gather you're not intimate with the issue of diffraction, so let me walk through the basics using some of the numbers that you've given.
As background, bear in mind that to a good approximation DOF, diffraction, and aperture size have a very simple relationship: doubling the f-number doubles the DOF but also doubles the size of the diffraction blur. The size of the diffraction blur places a strict bound on how large an f-number you can use and still get the resolution you need.
You've mentioned making a 6-inch print for a journal article. I'll presume that means an image to be reproduced as 6 inches in its long dimension. The journal will impose some resolution requirement appropriate for their printing process. For example, the journal Science
currently says "Grayscale and color artwork should have a minimum resolution of 400 dpi, and a higher resolution if possible."
6 inches at 400 dpi is 2400 pixels, so what you need (for a 6 inch image in Science) is a lens that can resolve detail at the level of 2400 pixels.
Your sensor is around 22 mm across, conveniently the same width as a field number 22 microscope eyepiece. That means we can use Nikon's calculator "Digital Camera Resolution Requirements for Optical Microscopy"
to work the relationship between magnification, aperture, and pixel counts.
The trick to using that calculator for this purpose is to set FN=22, set CCD Format of 1", and adjust the slider for Video Coupler Magnification until the selection rectangle is the same width as the eyepiece circle. Then you just select an objective and read off the pixel count requirements.
For a 10X NA 0.25 objective, the calculator says you need 4000 pixels across that 22 mm field.
But looking at it the other way around, the calculator is also telling you that at 10X you need NA 0.25 to give you detail for 4000 pixels.
If you need fewer pixels, you can get by with a smaller aperture, but only in the same proportion. For your example, that's 2400:4000, less than a factor of 2 reduction and far less than the factor of 5 to 10 that you've indicated you want.
The bottom line is that you're bound by the physics of image formation. To get by with 1/5 to 1/10 the effort of shooting with microscope objectives, you'll have to settle for images that have 1/5 to 1/10 the resolution of microscope objectives. That can be done for very small reproduction formats, but it's not practical for 6 inch prints or even for modern wide-screen computer monitors.