If you ever visited some industrial surplus shops, very often you would see some cameras and lenses used in industrial automation. But you probably do not know that these lenses can have very high optical performance and features we want: high resolving power, large image circle, low distortion, and often very long working distance compared to some of other lenses we use.
What is chromatic aberration for an optical system? Well, according to Wiki, it is the failure of a lens to focus all colors to the same convergence point. You usually see this effect when you have high contrast edges in your image. Well, it happens not just with microscope objectives, you will also see this effect with normal photographic lenses, for example along the edges of a mountain and the sky. But I will focus on this for microscope objectives as it is rather important.
Mitutoyo QV 2.5x 0.14, a 5x 0.15 “APO”, and a generic 4x PLAN objective. read more
Whenever you see a specification for a microscope objective, you will likely see the term NA, the numerical aperture value. Many people, particularly beginners in extreme macro photography, ignore or pay less attention to this parameter of an objective, and mainly focus on magnification and (eventually) working distance, but in actuality, the value of NA plays very important role.
When taking pictures using a macro lens, shallow depth of field usually mandates a rather small aperture to gain sharpness. With automatic lenses, stopping down is not a problem because the camera keeps the aperture wide open during view finding, unless you press the depth of field preview button. Only when camera is taking a picture, does it set the true aperture to whatever you set it to for exposure. However, if you ever used a manual macro lens, stopping down the lens cuts the light significantly, making it really hard to see through the view finder and focus. This is particularly hard for higher magnification macro lenses such as Canon MP-E 65mm f/2.8, Laowa 60mm f/2.8 2x and lenses on extension, etc, where it is almost impossible to focus even at f/11.
Good news is that there is a simple and easy to do DIY solution to this problem as shown above and the difference can be day and night. more …
When I first started doing macro photography back in late 2015, I have heard a lot of macro lenses, such as Canon EF 100mm f/2.8 macro lens, Canon EF 60mm f/2.8 macro lens, Nikon 105mm f/2.8 macro lens, and some third party macro lenses, such as Tamron 90mm f/2.8 macro lenses. However, these have maximum 1:1 magnification and because their focal length is fairly long, it is hard to get to, say 2:1. However around the same time, there is this lens, named Laowa (老蛙, old frog, in Chinese) 60mm f/2.8 with 2:1 magnification.
Laowa (老蛙， old frog) 60mm f/2.8 2:1 Macro Lens
I was a little skeptical as it is a Chinese lens and it sounded just too good to be true. Then again, being in China, I have seen enough of images taken with this lens and my curiosity grew and eventually bit the bullet last Feburary (2016). more …