November 10, 2019 - 2 zoom lenses posted from Handbook of Optics
February 8, 2017 - 59 zoom lens designs posted, including 5 by Obama
The patent literature is full of zoom lenses. In January 2017 alone, at least 17 zoom lens patents were issued. The posted files are a sampling of some of the subcategories I've been interested in, including compact zooms for DSC cameras, high quality zooms for full-frame photography, and lenses for television cameras with large zoom ratios.
April 8, 2015 - 55 zoom lens designs posted
Today I posted 56 zoom lens files. All are for folded zooms, which provide an interesting study. As I described in a paper at the 2014International Optical Design Conference, this class of optics is interesting be they are of a reasonable complexity that the designs are likely to be instructive, they offer a small range of design constraints because of the standardization of CMOS imager sizes and the mechanical constraints imposed on DSC cameras, and there is enough recent activity in awarded patents that a representative sample of contemporary designs can be collected. You can find the design files and some analysis on the page for zoom lenses.
Some of the interesting conclusions from the IODC paper include:
- An analysis of the most-common glass types for this application.
The most-frequently disclosed glass type is n=1.855, V = 24, which corresponds to glasses such as FDS90 and N-SF57; its prevalence suggests the adoption of high index glasses despite their coloration and workability. The next most-widely disclosed glass type is n= 1.505, V = 82, which corresponds to glasses such as MC-FCD1-M20; its prevalence suggests widespread use of glass molding, which is consistent with the high volumes in this application. The most-common glass types are listed in the table below:
- Even for the designs with the most-similar paraxial properties, and, probably, the most-similar design constraints, the resultant designs are quite different.
US Pat# 7,193,786 and US Pat# 7,417,800 have almost identical in terms of f/#, image size, focal length, zoom ratio, length, # of zoom groups, # of elements, and # of aspheres; however, the designers arrived at quite different solutions for what was apparently the same set of design constraints. Differences between the two designs include: 1) The third group in the ‘786 design, is a doublet, while the third group in the design disclosed in the ‘800 design, is a singlet. 2) The front element in the ‘786 design is meniscus, while the front surface of the ‘800 design is nearly planar. This difference is significant in a functional sense in that the nearly-planar front surface might offer some attractive packaging options. 3) The bi-aspheric element in the ‘800 design is nearly at the stop, while the bi-aspheric element in the ‘786 design is at the far side of the group from the stop. 4) Although the total number of elements is the same, the number of elements in groups two and three aren’t the same for the two designs. 5) Group 2 in the ‘800 design includes a particularly low-index material.
I found it interesting that these differences weren’t reflected in the patent claims. The key differentiator in the patents is the power across the various zoom groups.
Listing of design files: