What does apo lens mean?

What does apo lens mean? Below is what I have compiled for everyone, for your reference! What does apo lens mean?

APO is the abbreviation of English Apochromatic. It means "apochromatic". APO lens is an apochromatic lens, which refers to a lens that can eliminate chromatic aberration for multiple colors of light (more than two). Introduction to apo lenses

The long working distance apochromatic objective lens, or APO objective lens, has an excellent optical system. This objective lens can provide flat, monochromatic (almost no chromatic aberration) images throughout the entire field of view. , it is suitable for various microscopes and can be combined with a series of Pomeas zoom lenses to form a high-performance zoom lens system, which is an ideal choice for semiconductor product inspection, flow cytometry or other efficient high-magnification applications. Its advanced design delivers very high resolution and outstanding contrast. Its resolution can be from 5 microns to 0.34 microns.

Features of APO lens

1: Apochromatic optical design; 2: Optional long working distance; 3: Ultra-fine resolution; 4: Parfocal distance 95mm; 5: Infinity Optical system, tube lens focal length 200mm; 6: Objective lens thread M26X0.705.

What is an APO lens?

APO means apochromatic, which reduces chromatic aberration through ultra-low dispersion lenses, etc. . Although many manufacturers currently produce APO lenses, APO is not a standard, but a term for reducing dispersion.

When white light passes through the lens, it is separated and focused due to the different refractive index of various colored lights. At different points, achromatic means that the colored light can be bridged again and focused on the same point. The original achromatic can only be used for certain two colors of light, but later it was improved to be able to work on certain three colors of light, which is called apochromatism. APO is just a meaning, not a specific object. In order to realize APO (apochromatic), many methods can be used.

The most common method of reducing chromatic aberration is to apply low dispersion lenses. This glass material has an ultra-low dispersion coefficient, which helps to reduce chromatic aberration. It is widely used in modern photography lenses, especially telephoto lenses. middle. In addition, some Canon telephoto L lenses also use fluorite, which has an abnormal dispersion coefficient and is used with optical glass with normal dispersion to correct chromatic aberration. In addition, low dispersion is also called ED, UD, SLD, etc. Different manufacturers have different names, and the lens materials and technologies may be different. However, any lens that adds low dispersion lenses is for the purpose of reducing dispersion and can be called It is an APO lens.

As early as 1800, people knew that natural fluorite had the effect of eliminating chromatic aberration, but natural fluorite crystals were too small, too brittle, and too expensive. It was not until the late 1960s that Canon mastered the technology of producing large artificial fluorite lenses, and launched two fluorite lenses in large quantities in 1969: FL-F300mmF5.6 and FL-F500mmF5.6. In 1973, Canon Launched the FL300mmF2.8 fluorite lens that shocked the world. Canon claims that fluorite lenses combined with other optical glasses can effectively eliminate all chromatic aberrations. Another type of low dispersion lens is called "UD" or "Super UD", which is made of optical glass mixed with special oxide. Its function is: 2 pieces of UD = 1 piece of super UD = 1 piece of fluorite.

The low dispersion lenses of Nikon and Benin are called ED lenses. Nikon said: Calcium fluoride lenses will cause deviations in the refractive index of the lens and seriously affect focus, while Nikon's ED lenses have extraordinary sharpness and extremely low chromatic aberration, and have none of the disadvantages of calcium fluoride glass. Note: The material Nikon calls "calcium fluoride" is "fluorite" (CaF2).

Tamron's low dispersion lenses are called "LD" lenses and "LD-Hybrid Aspherical Lenses". It is worth mentioning that "LD-Hybrid Aspherical Lenses" should be Tamron's first. Tamron said that it has developed a specially treated resin aspherical surface layer that is adhered to the formed LD glass lens, thus ensuring the perfect combination of the two lenses. Currently, both the Tamron 28-105mmF2.8 and AF28-300mmF3.5-6.3 lenses use this lens.

Sigma’s low dispersion lenses are called “SLD” extra-low dispersion lenses and “ELD” extra-low dispersion lenses. Currently, its "ELD" premium low dispersion lenses are only used in the latest three lenses: APO 500mmF4.5EX HSM, APO 300mmF2.8EX HSM, and APO 800mmF5.6EX HSM.

Minolta's low dispersion lenses are called "AD" lenses; Tokina's low dispersion lenses are called "SD" lenses; Mamiya's low dispersion lenses are called "ULD" lenses.

The number of low-dispersion lenses in a lens group and the size of the lenses are also determined by the design orientation of the lens. Generally speaking, the bigger the lenses in a lens group, the better, and the more the lenses, the better. However, since the manufacturing cost of low-dispersion lenses is higher than that of ordinary lenses, for products from the same manufacturer, you get what you pay for. As for the balance of "cost-effectiveness", it depends on your wallet.