Hi,
I am having trouble with the optical assembly on the high resolution microscope. The print was reasonable successful and I have bought the correct spec lens on AliExpress (50mm focal length, 12.7mm diameter achromatic lens) It looks correct too.
The objective lens is from amazon and is listed as:
Objectives Lens,40X 185 Achromatic Microscope Objective, 40X Biological Microscope Magnifier Achromatic Objectives Lens,20mm Standard RMS Thread
185 achromatic microscope objective, if I understand the literature correctly, corresponds to a 45mm parfocal distance. I cannot find a single lens on amazon which actually directly specifies the parfocal distance - but I believe it is pretty normal. The actual length of the lens is 37.8mm, which suggests it is not a 35mm lens.
The focus point, however, is almost touching the lens. If I remove the optical assembly and place a prepared slide right next to the objective, I can get a reasonably clear image - but there is insufficient adjustment in the microscope to compensate for this.
The lens was very cheap - just £8.44 including delivery, so its possible its simply the wrong thing… or was mis-sold. But I would be interested in feedback from the helpful experts here before I try out a different (more expensive) lens.
I have attached a photo of the optical mount without the objectvie lens attached, showing the mounted PMMA lens.
BTW: I am using all standard parts, pi camera v2.1 (with lens removed).
3 posts - 3 participants