Sony a7r … Houston, we have a problem!

A7R

I just recently learned that the Apollo 13 astronauts really didn’t say it this way, but it’s an adaptation in the movie Apollo 13 of something they sort of said. But it’s now a very common phrase which seems  appropriate … someone at Sony should be shouting to Japan “we have a problem”. Another common expression for situations like this derives from Watergate … this to me easily qualifies to be called shutter gate! Before diving in, some background info may be useful. Recently Sony introduced a couple of new cameras. Modeled physically after their NEX series of cameras, these cameras offered similar small sizes with something new and exciting … a full frame sensor.  The A7 contains a full frame 24mp sensor, and the the A7r contains a full frame 36mp sensor, the same sensor which is in Nikons d800. Two things peaked many photographers interest right away.  First was the small size.  These bodies are dramatically smaller than dSLR’s with equivalent sensor technology.

Sony_A7R_vs_Nikon_D800_Camera_Size_ComparisonCheck out this comparison yourself at camerasize.com!

Another feature which is intriguing to many photographers was the flange distance … the distance from the sensor to the the point the lens attaches to the body.  Because that distance is so small it opens the camera up to lens adaptors to allow other brands of lenses to be used.

As it turns out you can pretty much use any lens out there on these new cameras.  Love your Leica glass but can’t afford a Leica M? One of these bodies may be just the ticket.  One change to the Sony from the Nikon version is modifications of the on chip lenses, to accommodate lenses designed for non mirrored cameras (like Leica). Here’s how they describe it in their brochure:

“each on-chip lens is optimally positioned depending on its location to accommodate the sharper angle of light entering the periphery, which is caused by the larger sensor dimensions being teamed with the E-mount’s short flange-back distance.”

Pretty impressive considering there is a lens for every pixel – that’s 36 million micro lenses that have been tweaked.  Bottom line, a sensor doesn’t work quite the same way as film so when the light hits the outer edges of the sensor with various wider angle lenses, issues such as severe vignetting and color cast become problematic.  This technology is designed to help reduce that which makes lenses like those form Leica perhaps even more useful.

Does the camera live up to the hype?  I’ve had mine for a while now, and done some limited shooting with it.  So far nothing major, but my goal is to replace my d800 as a backup kit so I have something small and light enough to carry with my Arca Swiss kit. After all, the d800 setup is sitting in the car, because I can’t carry both – not very useful as a backup when you’ve just hiked for an hour to get a shot.  A Sony A7r with a couple of small primes would be small enough to fit in with the Arca.

This isn’t a review – there are hundreds of those out there. But a few comments about the camera in general before I get into the main purpose of the article.  I like the new menu system and the ergonomics of the camera … they did learn from mistakes of the NEX 7.  The eye level finder is very good and I like it’s positioning in the middle of the camera (Probably because I’m a left eye shooter).  Using manual focus is easy and effective, which is important as most 3rd party lenses will require manually focusing.  (I believe only Sony’s lenses and Canon lenses using a Metabones adaptor can autofocus.)  Image quality is pretty much the same as the d800 … until you start using telephoto lenses where you may run into some sharpness problems.

What does the shutter have to do with it?”

(For those of  you pretty familiar with focal plane shutters you may want to skip the next few paragraphs).

The issue is pretty simple.  Because this is a live view camera, the shutter is open.  To take a shot with any camera designed to use live view instead of an optical viewfinder, the camera can do one of two things when you take an exposure.

The simplest way is to close the shutter, clear the sensor, then open the shutter using what is referred to as a first curtain, and end the exposure by closing the second curtain.  This is how focal plane shutters have worked from the beginning. If you need a shutter speed faster than those two curtains can physically open and close, the second curtain begins closing before the first curtain is open.  You have a slit moving across the sensor, the narrower the slit the faster the “effective” shutter speed.  A focal plane shutter has a maximum flash sync speed, which is determined by the fastest time that can be used where the 1st curtain completely opens before the second one begins to close.  Since a typical flash duration is anywhere from 1/1000th to 1/10,000th of a second, any speed faster than the maximum sync speed will only expose whatever portion of the sensor isn’t covered – part of the image will be black. If you want to see this effect, take a flash shot at 1/2000th of a second … you’ll only get a slice of the image exposed.

The other option (which is used by most current interchangeable lens cameras)  is to  electronically clear the sensor and then simulate the opening of a curtain across the sensor by starting to measure light at the bottom, moving up to the top. This is referred to as an “electronic first curtain”.  A mechanical shutter then closes to complete the exposure, then immediately opens again to enable live view.

The A7 uses the second method to expose.  So there is no mechanical movement or vibration until the shutter closes.  Most of the vibration from this process is when the curtain hits the stop at the end, not when it begins moving.  Bottom line the shutter really can’t cause any vibrations until the exposure is finished.

So what’s the big deal? 

Unfortunatley the A7r shutter operates the other way. Because there is no delay in the closing of the shutter and then opening the first curtain to start the exposure, it means there is a lot of vibration going on … enough to blur the image under some circumstances.  If you are using wider angle lens, the blur isn’t easily detectable.  But if you need to use a longer lens, and thus mount the camera to a lens which is mounted to a tripod, the problem is immediately apparent.  Here are 4 shots taken with a Nikon 70-200 at 200mm, manually focused on the ink cartridges at 4 shutter speeds (I varied the ISO rather than the f stop to keep the exposures constant).

Nikon lens mounted to tripod horiz
Note: all images are shown without any sharpening being applied with CaptureOne

These are from a screen capture using CaptureOne Pro 7 at 1:1 pixel size.  The blur is obvious.  Notice the blur is more apparent on the vertical bar code because that is the direction the shutter travels.  If you swing the camera 90 degrees, the problem is even worse …

Nikon lens mounted to tripod vertHere you can easily see the blur problem.  Interesting here is the slower speed is better than the faster speed  Compare the single lines above the 87 on the left image which is 1/13th of a second to those of the right image which is at 1/1ooth of a second.  The slower the shutter speed the less apparent the blurring because not much light is captured before the camera stabilizes. The faster or slower the shutter, the less likely there is to be blurring.

The Nikon d800e I have can have issues with this as well.  But because the camera itself has more mass the shutter isn’t able to vibrate it as much.  Additionally with the d800 the shutter is closed, it doesn’t have to close before opening.  Even if you are using Live View on the d800 you can enable shutter delay which means the shutter will close but not take the picture for up to 3 seconds.

Many have been looking for a solution with varying degrees of success.  My main concern is the vertical position is quite bad, and I most likely would be shooting panos with this camera which is best done with the camera in vertical position.  A couple of thoughts are to add some weight to the camera … sort of self defeating because one of the main attractions to the camera is the small and light weight.  On the other hand there are many things to like about the camera which may make using such a weight less objectionable, as I mentioned pretty much every lens ever made will work on it.  Joseph Holmes shows this concept in an article which seems to eliminate most of the complaint.

I tried the same thing with the camera in vertical position, and just added a pano clamp and bracket from Really Right Stuff as a weight (you can see those pieces under the camera pictured later in this article). Not  as much weight as Joseph was using, but even adding this  amount made a big difference.  Here’s a side by side at 1/100th with the camera in vertical position (the speed which shows the problem most).

Vertical before after

I had a different idea to try, that of using a Really Right Stuff telephoto support bracket, which effectively adds the mass of the lens and tripod to the camera.  Here’s the setup I tested.

IMG_1138

There are a couple of extra pieces because the support is designed to be attached to the tripod foot of the lens, so a couple of parts are need to turn that 90 degrees to accommodate the camera.  Additionally, the camera is fitted with a RRS L bracket, something I install on every camera I use.  Because the camera itself is now securely mounted rather than just hanging off on the back of the lens this effectively increases the “mass” of the camera.  The lens support allows the weight of lens to be taken from the flange, a lens this size definitely stresses the flange more than it is designed. In fact on a tripod, there are many lenses designed for full frame dSLR’s that are probably too heavy and would be better off supported.  Even my Nikon 14-24mm falls in this category.

Does it work?  Here is a comparison of the 1/100th of a second shot without and then with the bracket…

Before after with bracket

Substantial improvement. Perhaps very slightly soft, but I don’t think the d800 would be any better (I’ll have to test that 🙂 )  Some of the softness is actually the camera resolving the bleed of the ink in the printing process.

If you turn the camera to vertical using the same setup the results are also much better …

Before after with bracket vert

Obvious improvement.  Is it good enough?  It is for me … I’m not sure the remaining softness isn’t due to the lens limitations and have nothing to do with shutter vibration.  I’ll have to test them against the d800.  One problem is anyone using a camera with this much resolution, meaning incredibly small pixels, has to be meticulous in their technique to maximize sharpness.

So is there a problem?  Pretty easy to prove, and you can see tests all over the internet showing it.  Sony won’t admit it, which to me seems a mistake – come on guys it is OBVIOUS and SIMPLE TO DEMONSTRATE. I didn’t discover this and several others have documented far better than I have, but I just wanted to show how easy it is to demonstrate. So denying it is just making Sony look completely foolish … (insert image of ostrich sticking it’s head in the ground here). Most think a delay mode added to the firmware, allowing the shutter to close and the camera to stabilize would help, but no one really knows because the opening of the shutter may be the main contributor to the vibration.  The best fix would be a new sensor with an electronic first curtain.  I’m not sure of the limitations that forced Sony to not use this for the 36mp sensor, but maybe some progress in that area would make it possible soon.

Why they refuse to address it I’m not sure, they have publicly denied the problem. I guess it’s a damned if they do, maybe damned if they don’t kind of thing.  Admit it and sales may  plummet (until they can re-engineer the shutter).   On the other hand if they don’t admit it they may get away with it, but it seems they  risk a possible class action lawsuit, because it definitely exists and if they sell enough of them, some lawyer some where would love a chance to go after them.

How do I feel?  I’ll keep the camera and switch from the Nikon.  Now I know about the problem, I’ll find ways around it.  Even if that means carrying around some dead weight I still see myself as better off.  I can use smaller lenses such as my Leica 28-35-50 tri-elmar.  I can use my Canon tilt shift 24, as well as my wonderful Nikon 14-24mm.  To me it’s about the glass and even if I end up not saving much weight on the camera body because I have to haul the long lens support or some extra weight, the trade off using the glass I want is worth it and some of that glass is much smaller.  The Zeiss 55 made for the camera is half the size and weight of the Zeiss 50 I have for the Nikon and appears to be every bit as good of a lens. Who knows, maybe Sony has a nice medium tele zoom that helps alleviate the problem, after all this is a body without much a lens line up – until you consider that pretty much any full frame lens (as well as some medium format lenses) out there will work on this camera.

So for now I’m OK with it. But that’s me …

I’ll post some direct comparisons against the d800e in a few days to see if the lens support allows the a7r to resolve as well as the Nikon.

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