Using Microscope Infinite Objective On DSLR Camera
TWO VERY IMPORTANT NOTES:
1. The tube lens (prime or zoom) MUST focus to infinity.
2. Keep the tube lens wide open to ensure highest quality.
This video shows how to mount a microscope infinite objective onto a DSLR camera. Infinite objective requires a tube lens that focuses parallel light ray from it on to an image plane, in this case, the image sensor of the DSLR.
You can use a zoom lens as tube lens as long as the zoom is set to the focal length of the required tube lens by the objective. Often, a prime lens of appropriate focal length is better choice as tube lens as some zoom lens does not provide good quality. If the focal length of the prime (or zoom) is different from the required tube lens focal length, magnification will change and it is possible to have vignetting if the prime (or zoom)'s focal length is much less than the required tube lens focal length. In this video, the particular objective requires 180mm tube lens focal length, therefore, the zoom is set to approximately 180mm.