What is Focus By Wire

Let’s start with mechanical focus systems. They have a focus ring that is directly coupled to and moves the lens elements.

Focus by wire uses electronic signals to control focus. The photographer turns the focus ring but that doesn’t change the focus. Instead, turning the focus ring controls the motor(s) built into the lens. The motor(s) take their instruction from the movement of the focus ring, and the motor changes the focus.

Focus by wire gets its name from fly-by-wire systems used in aircraft. Except on small aircraft the pilot doesn’t move the control surfaces on the wings directly because it would be impossibly hard. Instead, the pilot presses a pedal or turns a dial and electronic motors move the control surfaces..

And because the aircraft is so big, any small errors are not relevant.

In cameras it is different because small movements can be seen and felt. This is true in still photography and in video.

And that has been the source of the criticism of focus by wire – that the systems are laggy and prone to overshoot.

The photographer turns the focus ring quickly, and the system plays catch-up.

Photographers report that they feel divorced from the focusing, which is the exact opposite of what one should feel when trying to take a photo that needs critical focusing. The pressure might be off in a studio or with landscapes, both of which are situations where the photographer has time to focus. But on the street or with any fast paced action, the photographer needs to feel that the response is immediate and consistent.

The situation is improving and some focus by wire systems have smooth focus changes.

It’s helpful to know how the focusing system is on a lens feels before you lay down money for it.

Wayne Avrili

Wayne Avrili performing outside Tate Modern
Wayne Avrili performing outside Tate Modern

He was performing, guitar and vocals, outside the Tate Modern. The song was Knocking On Heaven’s Door, a song that usually makes me see in my mind’s eye, the scene in Pat Garrett & Billy the Kid where Slim Pickens is shot and sits down on the river bank, dying. His wife or partner, played by Katy Jurado, sees he has been shot and she comes to comfort him. She is on her hands and knees, a respectful distance as he goes through what he is going through, and they look at each other with love and sadness.

Meanwhile, Pat Garrett is tackling another outlaw back at the cabin seventy yards away or so. So there’s a split narrative in the scene as it cuts back and forth – and it is full of love, regret, acceptance, and death.

Wayne’s card says he is available for gigs singling and playing classic pop from the 50’s to the present, including the Beatles, Oasis, Bob Marley.

Canon R6 and Canon RF 35mm lens

Camden People’s Theatre Thirty Years

Camden People’s Theatre in London celebrated its thirty years of existence with a private fundraiser and a show.

Performers who had been nurtured by CPT and gone on to fame in the wider world reprised the first part they performed when CPT gave them their start.

Before performing, each of them talked about the supportive atmosphere at CPT, where artistic expression was respected and valued. They said that that encouragement had given them the confidence to do things in public they never thought they could do.

Then the people behind the scenes outlined what CPT did, and asked the audience to give them money so they could continue doing it. Times are hard, they said, with ventures closing down. So it was all the more important to support CPT.

I was invited to photograph the evening, the social mixing before the show and then the show. I shot everything with the Canon RF 28-70mm f2.8 lens. The lighting was a real mix and low and I shot everything at 6400 ISO. It’s been a while since I have taken photos to someone’s requirements, and in such poor lighting.

Canon RF 28-70mm f2.8 IS STM Lens

A few days ago I tried the Canon RF 24-105mm f4L IS USM lens and I expected it to be great. The man in the shop let me to put the lens on my Canon R6 and I shot off a few frames inside the shop, so the light was mixed. Had the weather outside been better I might have asked to take a shot at least through the open door. But it was very dull and dark and raining so I didn’t.

Well, that and the fact that the man had told me the reason the cameras were behind glass in cases and not on the tables was because of theft. When I say the cameras could have been on the tables, I don’t mean loose on the tables but fastened down with a fixed white grip. Obviously it hadn’t been enough to protect them.

So I photographed one of the men serving in the shop. And when I put the images up on the screen I was shocked (that might be a bit strong of a word) to see that the images looked a bit lifeless. Desperate not to criticise the lens I put it down to the mixed lighting in the shop.

Then earlier today I watched a video of a photographer comparing various Canon RF lenses, and a couple of times he mentioned that the Canon RF 24-105mm f4L IS USM Lens lagged behind the others and that the shots seemed a bit flat and lacking contrast.

On the other hand, everyone says how lovely the Canon RF 28-70mm f2.8 IS STM Lens is.

I am not an impulse buyer when it comes to spending serious money. So I agonised and then agonised again and eventually bought a copy.

The photos that follow are substantial crops, and still you can tell what a good lens it is. This first crop is about one thirteenth of the total area of the frame. I shot the dancer at f/ 3.5, 1/1250 of a second at ISO 1000, and the man standing in the road at fl 2.8, 1/320 of a second atISO 200.

Hey, But

This is where some errant reader among my overwhelmingly intelligent readers thinks that primes are better than zooms so the results can’t be that good. The facts say otherwise.

Modern zoom lenses are not optically inferior to prime lenses, contrary to old beliefs. Primes still have advantages in size and weight, but then to cover the range of focal lengths that the zoom covers you need a bunch of primes. That fact is one of the compelling reason for zooms. The other reason is of course that it does away with having to switch primes all the time.

Maximum aperture, advancements in lens design and materials over the past 50 years have significantly improved zoom lens quality. That applies to primes and to zooms. Beyond a certain point the incremental differences show less and less significant results. The bottom line is that zooms and primes have converged in optical quality to the point that both of them are so good that the differences really don’t dictate one or the other.

Tests and discussions with experienced photographers confirm that, on average, zooms perform as well as primes—sometimes even better. That is not to say that someone might not have a bad copy.

It is an unpalatable fact thatIndividual lens performance varies, and you will only really know by testing to determine whether your lens is superior in quality. What you can do though is to narrow the field and choose a lens manufacturer known for consistent close tolerances.

Fine words, but the Canon RF 24-105mm f4L IS USM Lens disappointed me. Was it the copy I used in the shop? Who knows?

But the Canon RF 28-70mm f2.8 IS STM lens has not disappointed, at least not my copy.

Canon RF 28-70mm f2.8 IS STM Lens

Lilian Reading

Shot with an Olympus E-PM1 with an Olympus 45mm f1.8 at f1.8, 1/1250th of a second and
ISO 200