Leica microscope objective lenses are designed and made by our optics specialists to have the highest performance with a minimum of aberrations. The objectives help to deliver superior microscope image quality for many applications, such as life science and materials research, industrial quality control and failure analysis, and medical and surgical imaging.

Objective lenstelescope

Instead, what I got was one of these milquetoast clickbait articles whose headline poses a legitimate question that a reasonably sized audience would be interested to learn the answer to, but whose body contains literally no answer at all and instead rehashes facts that nearly any literate person probably already knows and defers to the reader’s personal judgment.

For me, that extra few stops of light wasn’t worth $1,100. Plus, the f/2.8 is much heavier, which is true of all f/2.8 lenses thanks to the number of lens elements required to make that wide-open aperture sharp and consistent. Believe me, the f/4 is heavy enough after you’ve been carrying it around all day.

The optics of the most basic microscope includes an objective lens and ocular or eyepiece. The objective lens is closest to the sample, specimen, or object being observed with the microscope (see the schematic diagram below). For more information, refer to the article: Optical Microscopes – Some Basics Show schematic diagram

What is an objective lensin microscope

As a concrete point of comparison, let’s look at the Sony Vario-Tessar T* FE 16-35mm f/4 ZA OSS (a lens with a completely ridiculous name) versus the Sony FE 16-35 f/2.8 GM. These lenses are both very well-reviewed and are equivalent in nearly all performance aspects, but the f/4 sells right now on B&H for $1,350 while the f/2.8 goes for $2,200.

Low powerobjective lens

All Leica objectives are marked with codes and labels. These identify the objective, its most important optical performance properties, and the main applications it can be used for. For more information, refer to: Labeling of Objectives

To make it easier for you to find which Leica objectives work best for your microscope and application, you can take advantage of the Objective Finder

Ocularlens

For some lenses, the f/2.8 version is sharper or has better color or autofocus overall. That is not the case with the Sony models I listed, but may be true for others, so do your research. Whether those differences matter to you depend a lot on the style of photography you’re into.

Eyepiecelens

In my opinion, the majority of people don’t actually need an f/2.8 (or faster) lens. The chances are pretty good that even if you have one, you shoot wide open with it pretty infrequently. If your particular business or artistic interest lives in that zone of luscious bokeh or low-light performance, you already know that and nothing I say should change your mind here.

Leica achromats are powerful objectives for standard applications in the visual spectral range, offering field flatness (OFN) up to 25 mm. The absolute value of the focus differences between red wavelength and blue wavelength (2 colors) is ≤ 2x depth of field of the objective.

Is that additional aperture worth $850 to you? Perhaps it is. In the 70-200mm focal length the difference is even more stark: the Sony FE 70-200mm f/4 G sells now for $1,500 while the Sony FE 70-200mm f/2.8 GM is a whopping $2,600.

Objective lensmagnification

That Fstoppers article appeared in one of my headline feeds and, as someone who has struggled with this question himself, and who carries with him most of the time an f/4 lens, I wanted to be convinced one way or the other.

So that’s my take; I really don’t think most people actually need apertures wider than f/4, and I would encourage anyone on the fence about it to just save the cash and spend it on something else that you know you’ll use.

My catalog contains a total of 53,794 photos. Of those, 41,090 were shot at f/4 or higher (that’s 76%)! The number of photos I’ve shot at f/2.8 exactly is only 4,811.

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What is an objective lensused for

Well, sorry to let you down, but I won’t be breaking any laws of physics today. But if you’re here because you’re actually not sure if you should spring for that fancy and expensive f/2.8 lens, I think I can talk you out of it, unlike Nando Harmsen of Fstoppers, who decidedly expressed almost no opinion at all.

Leica apochromats are objectives for applications with highest specifications in the visual range and beyond, offering field flatness up to 25 mm. The absolute values of the focus differences for the red wavelength and the blue wavelength to green wavelength (3 colors) are ≤ 1.0 x depth of field of the objective.

For some lenses, the f/2.8 version is weather-sealed and the others are not. This does tend to be the case with ones like the Sony where the f/2.8 is their “G Master” version (equivalent to Canon “L” or Nikon “Nikkor”). Again, do your research. I’ve taken non-weather-sealed cameras and lenses under the base of waterfalls and been fine, but it depends on the kind of work you do.

Do you need an individual objective for your application? Then contact our Leica OEM Optic Center so that we can offer you a customized solution.

I have gone on a great many trips with f/2.8 lenses and mostly stopped them down to somewhere between f/2.8 and f/4, or beyond f/4. In my catalog I have only 1,378 photos shot between f/2.8 and f/4 (exclusive), which is only 2.5% of all of my photos, almost a statistical anomaly.

Here’s the thing, guys, if you need a lens with an f/2.8 or larger aperture, you already know it, so why are you reading this article? Perhaps you suspect that I’ll talk you out of it somehow, teach you something you don’t know about the fundamental physics of light and save you a few bucks.

Types ofobjectivelenses

The objective lens of a microscope forms a magnified, real, intermediate image of the sample or specimen which is then magnified further by the eyepieces or oculars and observed by the user as a virtual image. When a camera is used to observe the sample, then a phototube lens is installed after the objective in addition to, or even in place of, the eyepieces. The phototube lens forms a real image of the sample onto the camera sensor. The objective’s numerical aperture (NA), its ability to gather light, largely determines the microscope’s resolution or resolving power to distinguish fine details of the sample. Also, the working distance, the distance between the sample and objective, and the depth of field, the depth of the space in the field of view within which the sample can be moved without noticeable loss of image sharpness, both greatly depend on the properties of the objective lens. For more information, refer to: Collecting Light: The Importance of Numerical Aperture in Microscopy, How Sharp Images Are Formed, & Optical Microscopes – Some Basics & Labeling of Objectives

The point that I’m trying to get across here is that if you are unsure whether you should spring for that f/2.8 lens, which in many cases may cost twice as much as the f/4 version of the same lens, because you are concerned that without that range of aperture wider than f/4 there will be shots you will miss, I think you should save the money.

For standard applications, Leica Microsystems offers an extensive range of top-class microscope objectives. There are also Leica objectives which have been optimized for special applications. The highest-performance Leica objectives feature maximum correction and optical efficiency and have won several awards. All over the world, scientists are relying on Leica microscope objectives to gain insights into their area of research.

Leica semi-apochromats are objectives for applications in the visual spectral range with higher specifications, offering field flatness up to 25 mm. The absolute values of the focus differences for the red wavelength and the blue wavelength to green wavelength (3 colors) are ≤ 2.5x depth of field of the objective.

But, if you shoot a variety of subjects, and mostly during the day, and you have a camera made in the last five or even ten years, you probably can get by with f/4. Again, if you’re someone who is absolutely obsessed with that luxuriously smooth bokeh, then you know this already and you should stop reading.

If you are deeply into portraiture or astrophotography, you need that huge light opening or the soft bokeh. Again, I think you probably know that already and wouldn’t be reading this if you were sure, but I mention it for maximum clarity.

There are a couple of reasons you may want to pick up the f/2.8 version of a lens, and it’s up to you to determine whether it’s worth the extra cost:

I have owned a good number of f/2.8 (and wider) lenses in my life, so I wanted to put this to a statistical test. Fortunately, I have also used Lightroom since it was in beta, and I have one giant catalog, so this is an answer that I can get.