Microscope objectives

Here are some microscope objectives that can be used for direct projection on the sensor using macro tubes. All of them are designed for 160 mm finite tube.

Left to right: Nikon E Plan 4x, LOMO 3,7x 0,11, LOMO PLAN-P 3,5x 0,10, LOMO PLAN 9x 0,20

Nikon E Plan 4x

Magnification: 4x
Type:
finite tube, 160 mm
NA: 0.10
Cover glass thickness:
Mount: RMS
Coverage: APS-C sensor (18 mm circle)
Working distance: 20 mm

LOMO 3,7x 0,11

Magnification: 3.7x
Type:
finite tube, 160 mm
NA: 0.11
Cover glass thickness: 0.17
Mount: RMS
Coverage: APS-C sensor (18 mm circle)
Working distance: 27 mm

Lens is either uncoated or single coated, but I suppose it is uncoated.

Robert OToole made a comprehensive review of this lens, which can be read here: https://www.closeuphotography.com/lomo-3-7x-objective

Also there is Flickr group: Lomo 3,7x 0,11 microscope lens

This is a very popular objective and Ebay prices can be up to $100 which is very expensive. In Russia typical prices are about $15-20 for the item in mint condition. 

LOMO PLAN-P 3,5x 0,10

Magnification: 3.5x
Type:
finite tube, 160 mm
NA: 0.10
Cover glass thickness: xxx
Mount: RMS
Coverage: APS-C sensor
Working distance: xx mm

Lens is either uncoated or single coated, but I suppose it is uncoated. Since this lens is a planachromat, its field is flatter than that of LOMO 3,7x 0,11.

“P” means polarized, this lens can be used for observation or taking photos in polarized light. From the point of view of optical design, this means fewer internal stresses in the lens glass. This does not affect use with normal lighting in any appreciable manner.

LOMO PLAN 9x 0,20

Magnification: 9x
Type:
finite tube, 160 mm
NA: 0.20
Mount: RMS

Planachromat. Fairly cheap, as well as PLAN-P 3,5x 0,10. Average prices for items in very good or mint condition are between $5 and $10. I think this is the cheapest way to get a 9x-10x magnification.