How Many Angels

How many angels fit in between a sensor and its protective glass cover?

I've learned over the past few days that there is a fair amount of disputation and conflicting opinion over the matter of whether the protective glass covering the sensors in various cameras makes a difference optically, and if it does, which lenses it affects and in what ways. Facts are in dispute, never mind their significance.

I have to reveal that it's not an issue that keeps me up nights, although I understand and sympathize if you're in a position to want to know about it. It's not like it's a small matter to everyone to drop multiple thousands of dollars on a camera. You want to know what you're in for and I get that.

My personal position, and hence, TOP's recommendation, has been that it's best to use lenses for any camera that the manufacturer intended for that camera. That was true 29 years ago when I started writing about photographic equipment. Things have changed a lot since then. In 1988, Sigma lenses had one single good property: they were cheap to buy. I was pretty convinced that a Sigma zoom could actively deteriorate just sitting on a shelf, never mind when it was being used hard. Now, Sigma is one of the world's best lensmakers, making lenses better than many of the lenses Nikon, Canon, Zeiss and Leica were making in 1988. So things do change. Also, of course, mirrorless came along and suddenly we have a situation we hadn't really seen since the days of Pentax (M42) screwmount and Leica screwmount (which Marc James Small dubbed "LTM" for Leica thread mount): we can use any (or many) lenses on any (many) bodies.

This spells f-u-n, and I know a number of photographers are happily exploring the look of old and odd lenses on their newfangled "digital backs" (mirrorless bodies).

I'd never discourage that. But I think as a recommendation it's still best to counsel potential camera buyers to plan on using whatever lenses each manufacturers makes for a particular body. The exception might be Micro 4/3 lenses, but in that case they're planned to be interchangeable and, because it's a shared standard, nobody in the consortium has to reverse engineer anything.

If Fuji doesn't make the lenses you want for the GFX-50S yet, wait 24 months. Fuji has a great track record of filling in its product lines; it's highly unlikely that waiting for them will be like waiting for APS-C primes or the D300 replacement from Nikon or more dedicated NEX-compatible lenses from Sony.

If you want to experiment with adapted lenses, that's great, but don't expect me to join you in fretting about the effects of sensor glass. It is what it is, the pictures will look like they look, and if you're reasonably flexible in applying optical aesthetics to real pics you'll appreciate what you get or move on.

And by the way: the answer to how many angels can dance on the head of a pin is however many God wants. It ain't up to us.

Mike

Original contents copyright 2017 by Michael C. Johnston and/or the bylined author. All Rights Reserved. Links in this post may be to our affiliates; sales through affiliate links may benefit this site.

/rant
Give Mike a “Like” or Buy yourself an adapter for your mirrorless camera

(To see all the comments, click on the "Comments" link below.)
Featured Comments from:

Bill Bresler: "I've used a Sony a6000 and NEX-6 for a couple of years now. Most of my work is made with the Sony-Zeiss 16–70mm. I have adapters for Nikon glass and shoot with older 24mm, 35mm, 85mm, and 180mm Nikon lenses. A Canon FD adapter is used to mount a Canon 50mm macro. I've had no problems with image quality and am pleased that focus peaking allows me to focus manually with my 62-year-old eyeballs. Whatever works."

Wayne: "It is not only low-priced lenses that actively deteriorate while not being used. I recall sitting in garage, looking at my Norton Combat Commando (motorcycle), when it sprung an oil leak right there in front of my eyes...I had to laugh."

Bill Owens: "Is there any evidence that the lens designers are optimizing their designs for the specific sensor (including the optical characteristics of whatever covering it has) or simply for the physical aspects of the camera, obvious things like focus distance and sensor size?

"I have no dog in this hunt, owning a single DSLR that in these parts would be considered worthy only to prop open a door; every other camera I have takes film (and many of them are M42). None of my lenses were manufactured in this century, much less matched to a specific camera."

Thom Hogan replies to Bill: "Yes, there is evidence that the lens designers are optimizing their designs for specific sensors. As I pointed out way back in 2003, both Canon and Nikon have patents regarding the 'optical characteristics of the sensor ensemble.' Film wasn't an infinitely thin film plane, nor were colors registered at all layers. Digital is actually an optical smorgasbord that attempts to deliver light focused on an infinitely thin plane to a deepish well in the sensor (at least pre-BSI; BSI is a bit different and really needs to be treated differently optically). Thing is, that 'plane' is often forward of the sensor's photo diode. What the Canon and Nikon designs attempted to do was realign the light so it hit the photo diode more telecentrically. Since those early optical systems in front of the sensor, things have gotten more complicated, with UVIR filtering, low pass filtering, microlenses, BSI, and photo diode walls all having some impacts on how the light rays behave before and at the sensing point. The Kodak SLR/14n was one of the first to really show what happens when optics aren't matched between lens and sensor: it had very visible side-to-side color variation on some lenses, mostly because of light pollution on adjacent photosites as you moved towards the edges with lenses that provide light at steep angles."

Comments

[Speed]

The set of picture I can't take because of the limitations of my hardware is very small (vanishingly small) compared to the set of pictures I haven't taken because I haven't got 'round to it.

[k4kafka]

Mike,
Have you ever calculated how many times "Fuji" has appeared in your hundreds (thousands?) of posts ? Might be fun to find out...just sayin'

[Kenneth Tanaka]

"My personal position, and hence, TOP's recommendation, has been that it's best to use lenses for any camera that the manufacturer intended for that camera."

My own experience across the 4-5 platforms I've used most over the past 10+ years leads me to concur with you. Leica M lenses perfom their best on Leica M cameras. Canon EF lenses do their best on Canon cameras. And so on.

But there are two "but"s. Requirements for x-platform adaptations or 3rd party products are sometimes unavoidable. Fuji doesn't make a t/s lens so you'll have to use a Hartblei, for example.

But perhaps the biggest "but" ('scuse me for that) is how you FEEL. The enjoyment of photography for a great many enthusiasts is at least as dependent on process as it is on product. The photo fora are crammed with testimonials for the merits of various old lens adaptations. Lots of guys are absolutely convinced that their 50 year old Pentax lens outrenders anything on their Sony A7. And that's just fine. It's part of the fun 👍

But in today's world of electronic photography lenses are very active partners with cameras. There's more processing power in a current-day lens than in the first Mercury space capsule. (OK, I made that up. But it might be true.) Cameras are truly "systems" that are designed to perform best when they can speak amongst their components. So no wonder same-brand lenses tend to perform best on their cameras!

[Darlene]

I find playing with an older Nikon 50 f/1.2 with my Fuji XP2 and cats surprisingly fun. The challenge of nailing the focus with the thinnest dof keeps me on my toes. :=)

[John Wilson]

Roger Cicala from Lens Rentals did some testing and thinks it does make a difference https://www.lensrentals.com/blog/2014/06/the-glass-in-the-path-sensor-stacks-and-adapted-lenses/

[Roger Bradbury]

I couldn't work out how to give you a "Like", and if I bought an adaptor for my mirrorless camera, I'd have to buy a mirrorless camera for my adaptor.

Instead I posted a couple of photos to your Patreon page. You lucky people can now look in horror at the maniac who comments here under the byline of Roger Bradbury. : ]

[Fazal Majid]

There are subtle second-order effects one must be aware of. The relatively thick "optical stack" (all the filters and protective glass in front of the sensor) on Sony mirrorless cameras means rangefinder lenses with their high angle of incidence do not perform as well as on the Leica digital Ms which have a thinner optical stack for precisely that reason.

[Jeff Clevenger]

No need for a mirrorless camera to explore Pentax M-42 screwmount lenses, Mike - just get a Pentax DSLR and the genuine Pentax adapter and you're all set. I have an armload of Takumar and Carl Zeiss screwmount lenses that I use on a Pentax K3-II with no problems and lots of excellent results. For those who like using manual focus lenses as I do, this is ideal. I look forward to getting a full-frame K-1 before too long so I can get the whole visual "story" that these lenses were originally designed to convey - that is, the full original image frame, with the digital sensor substituted for film.

[Tom Hassler]

Micro Four-Thirds is indeed a standard but regarding one manufacturer's lenses performing equally well on another's body, it ain't necessarily so. Experience has shown me that Panasonic lenses have certain quirks (both optical and mechanical) when used on Olympus bodies, while Olympus mFT lenses perform perfectly. One well-documented case relates to the whole image stack/sensor glass debate directly (the Panny 7-14mm f4 and a dreaded "purple haze" effect when shot on the Olympus EM-1.) The Olympus wide zoom has no such problem. There's also a funny but apparently harmless "chatter" when the Pana-Leica 25mm f1.4 is mounted on the EM-1. It's an otherwise outstanding lens but the noise is a bit alarming until you get used to it.

The only thing that can be said with certainty about some standards is, "They aren't... "

[Scarlatti24]

Sony system cameras, for me they are a revolution! For the first time in camera history, one is not obliged to invest into the foreseen manufacturer mount (E and FE) and -its a joy- to find the adequate workaround for what one intends to shoot (with abundance of former lens jewels). Thanks Sony, I love your E-Mount cameras; but I will not invest in your lensline! (I would feel robbed)

[Bear.]

It depends on the size of the pin, Mike.

[Oskar Ojala]

Whether or not a cover glass affects the optical properties of camera and lens combination is not in dispute: it does if the lens is not image-space telecentric. Regular photography lenses are not. The practical matter is then how big the impact on the image is with a particular camera and sensor combination at given apertures and focus distances. Sometimes the effect is large, sometimes irrelevant.

I agree that lenses designed for a particular cameras are those that work best. But adapting can be very useful for various reasons, e.g. macro work doesn't require autofocus and cover glass thickness tends not to be an issue there, so adaptation is the way to go. In everyday shooting I've managed to get great results using Zeiss ZM lenses on Sony APS-C cameras. What works for one's own application is what's important.

[Landsknecht]

> Is there any evidence that the lens designers are optimizing
> their designs for the specific sensor

Yes. Zeiss says that the optical characteristics of the sensor's cover glass is the reason why the optical formulas of their ZM lenses — designed for Leica-mount film cameras — could not be transferred unchanged to the Loxia series of lenses for the Sont E-mount cameras.

http://www.verybiglobo.com/photokina-2014-zeiss-loxia-story/