Media Technology

One of the most appealing features of the Sony NEX a7 a7R a6000 mirrorless cameras is the size. When you have a small camera body like that, you want to use a small and light camera lens with it. There are legacy film and DSLR prime lenses that are more than up for that small size challenge, but are there any really small zoom lenses?

Some of the smallest zooms ever built were the IX-Nikkor lenses, sold with the Nikon Pronea cameras, starting in about 1996 or so. The Pronea used APS film, which was a 23.4mm x 16.7mm format. That is comparable in size to the modern APS-C digital sensor size, but it's considerably smaller than the Sony a7 and a7R 35mm film full-frame size of 24mm x 36mm.

So if the IX-Nikkor lens could be mounted to an APS-C digital camera, it would cover the sensor size, but would it work for a full-frame sensor camera? The IX-Nikkor lenses use the standard Nikon F mount, but they protrude well into the camera body, which is fine for mirrorless cameras, but not so good for a DSLR.

The Sony NEX 7, NEX 6, a7, a7R, a6000, etc., use commonly available e-mount adapters for Nikon lenses. However, since modern Nikon lenses don't have aperture rings on the outside, you'll need a NEX e-mount adapter with a rotating collar, that has an internal pin attached to the inside of the collar. The pin actuates the aperture lever sticking out of the inside of the lens. Be aware that not all modern Nikon lenses have an accessible aperture lever, the lenses that you want are typically labeled by Nikon with a "G" nomenclature. Nikon started removing the aperture rings in about the year 2000.

The IX-Nikkor lenses that the Nikon Pronea used don't have aperture rings, and they aren't labled as "G" lenses, but since they have aperture levers sticking out of the lens mount, they work fine with the right NEX e-mount adapter. The biggest problem you'll have is trying to figure out where f8, f11, etc. are, because the rotating collars on the NEX e-mount adapters aren't usually labeled. You'll have to look into the lens to see how far the aperture is open, and then guess about what the aperture is.

Of course, that means full manual operation only. When the aperture is nearly closed(f11, for example), very little light is getting into the camera sensor, but the electronic viewfinder on the Sony a7R puts gain on the display you are looking at, and if you chose the correct setting in the a7R menu, what you'll see in the EVF is what the picture will look like.

The Nikon Pronea IX-Nikkor lenses were all zooms, with focal lengths ranging from 20-60mm, 24-70mm, 30-60mm, and 60-180mm. The black versions of the lenses were usually made in Japan, while the silver lenses were made in Thailand. The 20-60mm is reputed to have been the most expensive of the bunch. These lenses are incredibly light, because they were built with a lot of plastic. Unfortunately one of the things that was left off was a decent focus ring; on the 30-60mm lens, you can barely grip the end of the lens to focus, so if the lens you are testing is good, get a couple of step-up rings to screw into the end of the lens, so that you'll have something to grab for focusing.

How will IX-Nikkor lenses work for DSLR video use? They are plenty sharp enough, of course, given that video records far less resolution than still photographs capture. The NEX to Nikon-F adapter being used here is clickless, and so is the lens, so it's perfectly quiet, but you'll have to watch out, because you can't see what the aperture is really set at. These lenses do not have parfocal capability, which means that they have to be re-focused every time that you zoom, which is typical for DSLR lenses. Lenses are a lot cheaper to manufacture when you don't have to worry about holding focus through the zoom range.

At this point you're probably wondering why anyone would want to go through this hassle. The answer is that these lenses are dirt cheap, extremely light, very small, and sharper than you might imagine. In order to mount the lens to the Sony NEX e-mount adapter, you may have to first remove the backing plate and electronics from the lens. With the lens sitting upside down, on it's face, remove the screws from the lens mount, starting with the screws holding the electronic contacts mount. Pull the backing plate off, and cut the ribbon cable, if you don't want to tear it apart any further. See the picture below for details.

Since we know that these APS lenses will cover the APS-C sensor size, the real question is, will these lenses cover the full-frame sensor size on the Sony a7 and a7R? How much vignetting will there be? Imatest vignetting testing of the 30-60mm IX-Nikkor on the Sony a7R shows that the worst case scenario, of a wide open aperture and the widest zoom setting, is -3.2(EV) dark in the corners. That is very noticeable, but if you look at the Imatest results for the new and very expensive Sony FE 35mm 2.8 prime lens that was designed for the a7R, you'll see that it's at -2.6(EV): http://www.photozone.de/sonyalphaff/865-zeiss35f28ff?start=1

So the 30-60mm lens is fully usable on the full-frame sensor, depending on aperture, and how much corner correction you can live with in the edit suite. The pictures below show the Imatest.com vignetting test results for the 30-60mm IX-Nikkor lens. When you are looking at the colored circles, it's the numbers that matter, not the colors. The numbers indicate how dark the overall picture area is, since vignetting affects further into the frame than just the corners. Vignetting testing was done at the 30mm focal length.

What about picture quality? Sharp in the middle, but unfortunately the lens being evaluated was decentered, so we'll have to get another one to test. Not to worry, though, because the 20-60 lens shots are about ready to upload.

Dan Euritt

As a photographer, one of the worst things that you can do is to take a picture of someone who has their eyes closed. That is often caused by the preflash of your flashgun, which occurs right before the main flash. The camera is using preflash to test and calculate the amount of light that the flash needs to put out. When there is a long delay between the preflash and the actual flash used to take the photo, the subject will have time to close their eyes, which is a natural reaction to a flash(or preflash, in this case).

So the ideal situation is the shortest possible time between flash and preflash. Of course, you could eliminate the preflash entirely, by doing the flash calculation yourself, or by letting the flash itself do the calculation, in manual mode, but that's another post for another time. For now, we are looking at how long the Sony a7R takes between preflash and flash.

All cameras will have some kind of delay between the time that the button is pressed to take the picture, and when the picture actually gets shot, without using a flash. So how much no-flash delay does the a7R have, and how much time does the flash add to that delay? Imaging Resource has this to say about the no-flash delay: "When manually focused, the Sony A7R's lag time only dropped to 0.261 second, which is a bit on the slow side for manual focus shutter lag. The Sony A7R's prefocused shutter lag time was 0.163 second which while quick, is much slower than most DSLRs or CSCs." http://www.imaging-resource.com/camera-reviews/sony/a7r/sony-a7rA6.HTM

To give you an idea of how slow that is, they measured the mirrorless Sony NEX-5N prefocused time to capture at 0.022 second(no flash involved). The a7R, with it's mechanical shutter, is considerably slower, which is going to really increase the preflash to flash delay.

Measuring that delay can be done at home, by shooting video of the camera taking a picture, that uses the flash. It won't be totally accurate, but you'll get an approximate number. We already have video of that online, thanks to David Kilpatrick, over at http://www.photoclubalpha.com:  http://www.youtube.com/watch?v=yX9oXHnJZEs

In the screen capture below, you can see individual frames from the video, that barely shows just when the preflash started, and much more obviously, when the actual flash happened, five frames later. There are five clean frames in between those events, and at 25 frames per second, it's 5/25th of a second delay(two-tenths of a second). David shot several flash events in that tape, and the rest of them all had four clean frames between preflash/flash, which is 4/25th of a second, or .16 second delay. Compare that with the .163 second shutter delay that Imaging Resource measured, and you can see that the flash doesn't add too much to the overall time-to-capture delay. The worst case scenario for preflash/flash delay appears to be almost 1/25th of a second. The mechanical shutter is actually what's causing most of the delay.

Measuring the preflash-to-flash shutter delay, Sony a7R.

Dan Euritt

The Sony a7R is a 36MP full frame(35mm film size sensor) camera, that many photo enthusiasts purchased with the intention of mounting legacy and 3rd party camera lenses on. The picture quality is outstanding with just about any camera lens, but there can be issues with wide angle lenses, so we'll highlight that issue in this post. To be more specific, wide angle rangefinder lenses are generally the most problematic, but even some standard DSLR wide angle lenses don't work well on the Sony a7R. The focal ranges where these issues really show up is typically 24mm and wider, with the 35mm and up lens range being generally acceptable, with most lenses.

The problem can manifest itself as smeared corners, and/or out-of-focus blurry areas that cover the entire sides of the picture. The smeared corner issue will typically show up both before and after the infinity focus point. The OOF(out of focus) area problem is most noticeable after infinity focus, when shooting landscape pictures in particular. The OOF lens shots may look great when shooting subjects up close, but then be unacceptable for shooting big areas, that need sharp focus across the entire plane of the picture. The center of the picture is usually very sharp, in perfect focus, but then the picture falls apart gradually, starting about a third of the way in, from each side. This post will dwell on the latter problem in particular, using DSLR camera legacy lenses, because they are cheap and plentiful.

There are a number of examples of this OOF area problem on the internet, but it's not always noticeable, because the picture needs to be evaluated as it comes out of the camera, unprocessed, and at full size. Our first sample picture was taken by a Kiron 28mm f2.o lens, which is a nice piece of manual focus glass. This Colorado landscape shot was taken by uhoh7, who returned his Sony a7R, and purchased the Sony a7 instead. Look at the mountain range, and how only the middle third of it is in sharp focus, while the sides of the picture are very OOF.

If your bandwidth is limited, the thumbnail pic links to a 100% cropped version, edited down to three narrow strips, that illustrates the problem clearly. The full-sized 12MB version is linked below the thumbnail:

http://www.flickr.com/photos/55299472@N07/11769495364/sizes/o/in/photostream/

Here is another example of the blurry sides problem, shot at f8 with a Sigma 24mm f2.8. This lens is no slouch, it got a 4.0 rating at photodo, tested on a crop sensor camera. The center is sharp, but the sides are very blurry at this aperture, so the picture was also shot at f11 and f16. Notice how the telephone wires on the left hand side are much cleaner by f16, but at the expense of slightly less resolution in the center. The reeds along the lake are also a good basis for comparison. *Make sure that your browser is set to display pictures at full size*:

Lens diffraction testing on the Sony a7R, using a Sigma 24mm f2.8 lens.

Not all 24mm/28mm prime lenses that are put on the Sony a7R show such a wide disparity in resolution, between the center and the sides, so you'll have to evaluate your glass accordingly. You can find out more about when diffraction starts affecting resolution at http://www.cambridgeincolour.com/tutorials/diffraction-photography.htm Stay tuned to this website for further landscape lens testing, with a Pentax SMC 24mm 2.8 lens, and a Canon FDn 24mm 2.8.

Dan Euritt

Here is a quick post about mounting Canon FDn camera lenses to a Sony a7 a7R NEX e-mount adapter. The adapter being used is one of the cheap Fotasy units from overseas. Some of these NEX adapters have different labels on the adapter ring, for example, "lock" versus "close", but the functionality is generally similar. Fotodiox is another lens adapter vendor.

The rotating rings on these cheap Canon FD/FDn adapters don't necessarily lock the lens to the adapter flange, the lock function is actually done by the lock ring on the lens itself. For FDn lenses, there is a button on the lens ring that you have to push, before the lens can be rotated off of the adapter flange mount.

If you are new to Canon FD/FDn lenses, the first thing to know is that with an un-mounted FD/FDn lens, you can't always control the lens aperture by rotating the aperture ring on the lens. The lens has to be mounted first, which is not usually the case with camera lenses manufactured by other companies, like Pentax, Nikon, etc. So if you are evaluating a Canon FD/FDn lens for purchase, for instance, be sure and at least take one of these cheap adapters with you, so that you can confirm the condition and operation of the aperture blades. The blades need to be free of oil, and they need to move easily.

The second thing to look out for is to make sure that the lens pin is engaged properly on the Sony a7R NEX e-mount adapter. With the cheap adapter shown below, the lens can be mounted with the pin on the wrong side of the actuator lever in the adapter, which means that the blades won't move when you turn the aperture ring on the lens.

Dan Euritt