Media Technology

The goal of this comparison is to see how multiple copies from two different brands compare. We are looking at how the sides of the lenses compare in particular, since wide angle DSLR lenses are problematic on the 36mp sensor in the Sony a7R.

Since we only have six lenses total to compare, on one camera, using two different cheap adapters, it won’t be possible to draw any statistically significant conclusions. The best that can be hoped for is for the viewer to see possible trends, and to get a good idea of what to look for when evaluating an image.

Sigma 24mm f/2.8 SuperWide II: If you have a Pentax background, you’ll probably know that this lens is legendary. It was highly rated in the photozone.de crop sensor camera test, and it has a 4.0 rating on the old Photodo testing site. We are comparing two autofocus versions and one manual focus version, all with the Pentax k-mount flange. This prime lens was sold in just about every mount option that was popular at the time.

Canon FDn 24mm f/2.8: You won’t have any problem locating one of these lenses, because Canon made a whole lot of them. Since there are so many, the pricing is fairly good, especially when you compare it to the astronomical cost of, say, some versions of the Minolta 24mm f/2.8 lens. All three of the lenses being tested here use the same Canon FDn mount, so they are the later versions, but this glass is also available in the earlier FD mount.

Results: Compare the “5610” street number on the back of the center building. On the left side of the images, look at the street sign hanging on the steet light. For the right side, perhaps the “USED CARS” sign on the side of the building. Canon wins for consistency here, the left side is basically the same in all three FDn 24mm images. The center varies somewhat, while the right side is perhaps the weakest for all three copies of the lens. That kind of consistency begs the question of whether there could be a Sony NEX to FDn adapter issue, or perhaps the a7R sensor isn’t perfectly parallel to the lens mounting flange on the camera. Copy “B” will be used for further 24mm lens comparison testing.

The Sigma 24mm lens group generated mixed results, with “B” winning on the left side. “C” wins on the right side, but there was a thin cloud overhead, which cut the sunlight down over most of the image, changing the contrast. “B” advances to the consolation round, but just barely. The Sigma 24mm f/2.8 appears to have more vignetting issues than the Canon FDn 24mm f/2.8 lens does.

https://www.codectest.com/images/24mmLensComparisonThreeCopiesOfCanonFDn24mm.jpg

https://www.codectest.com/images/24mmLensComparisonThreeCopiesOfSigma24mmSuperWide2.jpg

Dan Euritt

24mm camera lens shootout, on the Sony a7R: first round

24mm camera lens shootout, on the Sony a7R: second round

24mm camera lens shootout on the Sony a7R: third round, Konica 24mm

24mm SLR prime lens test, fourth round, shot on the Sony a7R

This second round of 24mm legacy camera lens testing will continue to focus on picture quality at the sides of the image, by comparing wide landscape test photos. As we saw in the first round of 24mm lens testing, there can be a huge disparity in picture quality at the sides, with the Sony a7R, to the degree that it overwhelms just about any other aspect of image quality. This issue with picture quality at the sides of the a7R images is far less of a problem at focal lengths of 35mm and longer.

A second copy of the Canon Fdn 24mm f/2.8 lens makes an appearance in this round, mounted on a different adapter, this time it’s a black no-name Ebay adapter. The lens has a light haze over about a third of the front glass, and a sticky aperture ring. The other two lenses being tested are the Kiron 24mm f/2.0(Pentax k-mount), and the Olympus 24mm f/2.8. All shots were taken with the Sony a7R, on a monopod, at f/8, iso200-250. Both of those lenses are nearly perfect in appearance; no haze, no fungus, and clean snappy aperture blades.

Ease of focus at long distances: The Canon FDn 24mm lens has a significantly longer focus throw than both the Kiron 24mm and the Olympus 24mm, and it’s noticeably easier to turn. Contrast is important for focusing wide lenses at extreme distances like this, and the Olympus 24mm may have a slight edge there. The Kiron 24mm optic is legendary, when you hold it in your hand, and marvel at how big the front and rear glass is, it’s hard to be subjective. The diminutive Olympus 24mm lens is perhaps the best match for the small a7R, depending on what your preferences are. In the end, none of them had quite the same pop that the 24mm smc Pentax did in the first round, so it’s two points for each camera lens.

Lens contrast: The test target being photographed in this round wasn’t as helpful for looking at contrast. The “5610” number from the first round was at a closer distance, and the thin lines of that number, against the light background, made a decision about lens contrast seem easier. In this case, the focus point was on the highway sign, and it’s numbers are unreadable, against a green background. We are left with looking at bushes on the hillside to the left of the sign, and the trees far away in the distance. The Olympus 24mm seems to handle vertical telephone and street light poles with slightly better clarity, in the center of the image, so 2 points for it. The Canon FDn 24mm may edge the Kiron 24mm out slightly for contrast, but since there aren’t any half points available, 1 point for each.

Sides of the images: This is where the differences are much more noticeable, which is why it’s so important. The second copy of the Canon FDn 24mm, with all of it’s issues, still clearly wins by a long shot on the right hand side. The Kiron 24mm goes down hard on the left hand side, bringing up the question of whether or not it’s decentered in that area. The Olympus 24mm could have issues on the right hand side, but it’s fairly solid on the left hand side. If you look at the rocks under the bridge, on the left side side, the Canon FDn edges the Olympus lens out slightly, so it’s the winner. Canon FDn 3 points, Olympus 24mm 1 point, Kiron 24mm(disqualified) zero points, it never won on any side.

Center of the images: Possibly the Olympus 24mm, but you’d have to analyze the RAW images to be sure. What you are looking at are cropped then recompressed camera original JPEGs, so it’s difficult to be sure. The Kiron 24mm might be the weakest of the three here, but is it enough to hand out points on?

Summary: The Kiron 24mm(3 points) is out, but can it’s sides be salvaged at f11? What about slight front focusing? Those are questions for the consolation rounds. The Olympus 24mm(5 points) moves forward, even with it’s possible weaknesses on the right side. Out of the five lens designs tested so far, the Canon FDn 24mm(6 points) is showing signs of being the most compatible with the Sony a7R.

Here is the test image for this round, it’s nearly 12mb in size, **be sure and view it at 100% size**:

https://www.codectest.com/images/24mmCanonFDnOlympusKiron.jpg

Dan Euritt

24mm camera lens shootout, on the Sony a7R: first round

24mm camera lens shootout on the Sony a7R: third round, Konica 24mm

24mm SLR prime lens test, fourth round, shot on the Sony a7R

Finding a clean 24mm prime camera lens that won’t cost you an arm and a leg is difficult, but finding one that works well on the Sony a7R camera can be a real battle.

That’s due in part to the demands that the 36mp sensor in the a7R places on things like field curvature of the lens. A 24mm lens on the full-frame sensor in the a7R is roughly comparable to a 15mm lens on an APS-C crop sensor camera, so it’s a pretty wide view.

This 24mm lens shootout will give you a good idea of what 24mm glass works best on the a7R, and to some extent, even how those lenses will work on DSLR or mirrorless camera bodies. This first test session covers the Canon FDn 24mm f/2.8, the Sigma 24mm f/2.8, and the smc Pentax 24mm f/2.8(K-mount). The test image is a group of medium distance landscape shots, because landscape shots are helpful for evaluating how flat the lens image field is, at infinity focus. All shots were taken at f/8, with the obvious question being, why not follow conventional wisdom for landscape shooting, and use f/11, f/16, or even f/22? The answer is that previous testing with 24mm DSLR lenses on the a7R didn’t always show enough image improvement on the sides, at smaller apertures, to make the tradeoff in center resolution loss worthwhile: Wide angle lenses on the Sony a7R However, since this should be evaluated for each lens design, some of the lenses that lose because of lens curvature issues will get re-tested in a consolation round.

Ease of focus at long distances: Pentax 24mm(3 points) wins by a landslide, it’s a dream to handle, followed by the Sigma 24mm(2 points), with the Canon FDn 24mm(2 points) slightly behind, but close enough to call it a tie. The Sigma 24mm being tested is an autofocus lens, which is difficult to manually focus, but the contrast is perhaps higher, so it’s slightly easier to get focused at long distances.

Lens contrast: look at how dark and contrasted the “5610” number is on the side of the building, dead center of each image: Pentax 24mm(3 points), Sigma 24mm(2 points), Canon FDn 24mm(1 point). Exposures varied in these images, even though they were all shot at “0” on the in-camera exposure meter. Download the jpegs from the link, make your own determination.

Sides of the images: On the left side, compare the text in the street signs, hanging from the traffic lights. The right side has several areas to compare. Canon FDn(3 points) wins on one side, Sigma 24mm(3 points) wins on the other side, while the Pentax 24mm(disqualified) simply fails in a blurry haze.

Center of the images: They all look good, take your pick. Keep in mind that what the Sony a7R giveth, it also taketh away. Resolution testing at lensrentals.com shows that the a7R sensor increases resolution in the center of a lens, in a manner that is probably unmatched by any other camera on the market. The flip side is that these test images show how tough the a7R can be on glass that doesn’t have a flat image field, like the Pentax 24mm lens.

Summary:  Sigma 24mm(7 points) and Canon FDn 24mm(6 points) both advance to the next round, due to possible slight sample variation issues on the sides, that needs to be investigated further. The smc Pentax 24mm lens would be fun to use on a crop sensor camera, and it might even be worth looking at for a 24mp full-frame sensor, as long as you don’t expect too much from the sides. The smc Pentax 24mm will get re-tested at other apertures in the consolation round.

Here is the test image, it’s nearly 20mb in size, **be sure and view it at 100% size**:

https://www.codectest.com/images/24mmfdnsigmapentax.jpg

Dan Euritt

24mm camera lens shootout, on the Sony a7R: second round

24mm camera lens shootout on the Sony a7R: third round, Konica 24mm

24mm SLR prime lens test, fourth round, shot on the Sony a7R

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