Tag Archives: lens

Samyang launches 50mm Cine Lens

New Samyang 50mm T1.5 vDSLR lens.
New Samyang 50mm T1.5 vDSLR lens.

At long last Samyang have filled the gap in their vDSLR lens line up! It was crazy not to have a 50mm lens. Finally they are launching a 50mm T1.5 lens with pitch gears etc. This lens will be available next month (September) so not too long to wait. It’s full frame so should work great with the A7s as well as all your Super35 and APS-C cameras.

Hop over to the Samyang web site for sample images and further information. I have one on pre-order as as soon as I can I will check it out.

 

Scheider Xenon FF Prime Lenses.

Schneider Xenon 50mm FF lens on the Sony A7s
Schneider Xenon 50mm FF lens on the Sony A7s

When you think of cine lenses then there are several brands that immediately come to mind. Zeiss, Arri, Cooke and Angenieux are probably the most familiar names but there are many others too. One brand I have been looking at more and more recently is Schneider.
Schneider Kreuznach have been making lenses since 1913. Based in Kreuznach in Germany they have long been know for their innovative designs and they won an Oscar in 2001 for Technical Achievement for their Super-Cinelux motion picture lenses.
A few years ago I met one of their lens engineers at NAB. I don’t think I have ever met a man as passionate about a lens design before or since. Every Schneider lens that I have ever used has been brilliant. They always seem to have near zero breathing, are always extremely solidly built and produce great images. So when I got a call from Manfrotto, the UK distributor to see if I would like a chance to play with some of the new Xenon FF (Full Frame) lenses I grabbed the opportunity.

Another view of the 50mm Schneider Xenon FF lens.
Another view of the 50mm Schneider Xenon FF lens.

The Xenon FF lenses are cine style lenses available with either Canon, Nikon or PL mounts. The mounts can be changed should you need to switch mounts at a later date. They are priced to directly compete with the Zeiss compact primes. At the moment there are only 3 lenses available, a 35mm, 50mm and 75mm, all are T2.1. In the near future there will also be a 25mm and 100mm T2.1 as well as an 18mm T2.4 Yum Yum! I’d love to have one of those for my Northern Lights or Storm Chasing expeditions. They are all the same size, have a 100mm front diameter, all have a 95mm lens thread. This means that swapping lenses during a shoot is straight forward as you don’t have to change Matte Box donuts or re-position the follow focus if you’re using one. Being Full Frame lenses and rated for 4K these should be a great match with the Sony A7s.

I got to play with a 35mm and 50mm with EF mount and decided to try them on my full frame A7s shooting in HD as well as taking a few still photos (which are the equivalent to 4.5K) on a cloudy and rainy day.

14 blade iris and EF mount on the 35mm Xenon FF.
14 blade iris and EF mount on the 35mm Xenon FF.

Straight out of the box you cannot help but be impressed by the build quality. These are substantial lenses, weighing in at around 1.25kg each with the EF mount. I could not find any plastic on these lenses, they look built to last.

The focus scale is large and easy to read, each lens being individually calibrated. Focus travel is a full 300 degrees. Even as you get to the far end of the focus ring the distances are still nicely spaced. From 9ft(3m) to infinity is around 100 degrees. Compare that to most DSLR lenses where the same focus range might be compressed into just  5 or 10 degrees and you can see that precise focus is much easier. Although sometimes  a very large focus travel can make focus pulls a little harder simply because or the large distance the focus ring has to be turned. But I’ll take a big focus throw lens over small throw any day.
The lenses have 14 curved iris blades giving a very round aperture even when stopped right down. I love peering into these lenses at the aperture blades as they are a work of art (but really hard to take a photo of). You can also see in the photo that the coatings of the lens are a distinct orange colour.

Photo taken with the 50mm Xenon FF.
Photo taken with the 50mm Xenon FF. Click on the image to enlarge or view at original resolution.

In practice the lenses did not disappoint. It did seem a bit odd to have such a large and heavy lens on the diminutive A7s, but as image quality starts with the lens a good lens can make all the difference. I shot at various apertures from wide open at T2.1 down to about T8 and didn’t notice any significant change in resolution across the range (I took photos as well as video to check the lens performance).

The lenses do tend to flare a little bit, the 35mm more than the 50mm, but I thought the flares were quite pleasing, others may disagree. Take a look at the video to get an idea of what they are like. There was a bit more flare at T2.1 compared to T2.8 or T4 on both lenses.
I did some big focus pulls to see how much breathing there was and as with all the Schneider lenses I’ve used breathing was very minimal. There is some breathing, these are not like the Cine-Xenars which have virtually zero breathing, but the breathing really is small.

Frame grab, shooting through trees. 35mm Xenon FF and A7s.
Frame grab, shooting through trees. 35mm Xenon FF and A7s.

Another test shot was to shoot some tree branches silhouetted against the sky to check for CA and colour fringing. Basically I can’t see any. Maybe right out in the very corners of the frame there is the tiniest bit of CA, but you really have to hunt for it.

Shopping basket frame grab. 35mm Xenon FF. I love the smoothness to the highlights.
Shopping basket frame grab. 35mm Xenon FF. I love the smoothness to the highlights.

Colour wise there is no obvious colour shift, if anything perhaps very, very slightly warm. As expected the lenses are very sharp and crisp, from corner to corner, but not excessively so. I found that the images contained a lot of detail but had a pleasing roundness too them that I really like. I shot a chrome shopping basket and the reflections of the bright chrome look really nice. I think this is a combination of a little bit of flare without excessive sharpness. I think it’s a very nice natural look. This can be one of the benefits of a video lens over a stills lens. Stills lenses must be incredibly sharp to work with 24 or 36 mega pixel sensors. Sometimes this results is a super sharp image that lacks character. Arguably if you start with a very sharp image you can always soften it a bit in post, but sometimes it’s nice to start off with a more rounded image. Look at how popular Cooke lenses are, they are well known for their rounded rather than super sharp images.

As expected from a 14 blade iris the bokeh is very creamy and smooth. Both near and far out of focus areas look very good indeed. Out of focus edges are smooth and don’t show any obvious double edges or other distortions.

It's really easy to get a very shallow DoF with a full frame sensor. Xenon FF 50mm and A7s.
It’s really easy to get a very shallow DoF with a full frame sensor. Xenon FF 50mm and A7s.

Take a look at the video for a better idea of the lens flares and the overall image quality. I really like the look you get from these lenses and wouldn’t mind a set of them for myself. I feel they have a lot in common with Cooke lenses, but at a much more affordable price. I hope to test them further in the near future and to a wider variety of scenes. I suspect they will be very good on skin tones and faces.

 

Quick test of the CommLite EF to NEX lens adapter. CN-EF-NEX

Commlite full frame EF to NEX lens mount adapter.
Commlite full frame EF to NEX lens mount adapter.

My old Metabones MK1 adapter is not suitable for full frame lenses on the new Sony A7s. So in anticipation of the arrival of my A7s I ordered a cheap CommLite full frame autofocus ready adapter on ebay. This adapter (CN-EF-NEX) was only $90 USD so I thought I would give it a try, much cheaper than the metabones.

To be honest I wasn’t expecting much, but now I have the adapter in my hands I am pleasantly surprised. It appears well made and very solid. It even carries a CE mark. It works just fine on my NEX5N and FS700. On the NEX5N I have working autofocus. If the lens has image stabilisation this works too. I have tried a wide variety of Sigma and Tamron Canon EF lenses with it and they all work. Even my new Tamron 16-300mm works with this adapter, this lens doesn’t work with a number of other adapter.

Autofocus is a little slow, especially if the light is bad. Having not used the MK3 Metabones I don’t know how this compares but certainly this adapter works and is quite useable. It’s said to be compatible with full frame lenses on the A7, but as yet I have not been able to test this. The little mounting post is easily and quickly removable, but a real boon on the NEX5N with bigger lenses. For the price, you can’t go far wrong, really quite impressed considering how little it cost.

What causes CA or Purple and Blue fringes in my videos?

Blue and purple fringes around edges in photos and videos are nothing new. Its a problem we have always had. telescopes and binoculars can also suffer. It’s normally called chromatic aberration or CA. When we were all shooting in standard definition it wasn’t something that created too many issues, but with HD cameras and 4K cameras it’s a much bigger issue because as you increase the resolution of the system (camera + lens) generally speaking, CA becomes much worse.

As light passes through a glass lens the different wavelengths that result in the different colours we see are diffracted and bet by different amounts. So the point behind the lens where the light comes into sharp focus will be different for red light to blue light.

A simple glass lens will bend red, green and blue wavelengths by different amounts, so the focus point will be slightly different for each.
A simple glass lens will bend red, green and blue wavelengths by different amounts, so the focus point will be slightly different for each.

The larger the pixels on your sensor the less of an issue this will be. Lets say for example that on an SD sensor with big pixels, when the blue light is brought to best focus the red light is out of focus by 1/2 a pixel width. All you will see is the very slightest red tint to edges as a small bit of out of focus red spills on to the adjacent pixel. Now consider what happens if you increase the resolution of the sensor. If you go from SD to HD the pixels need to made much smaller to fit them all on to the same size sensor. HD pixels are around half the size of SD pixels (for the same size sensor). So now that out of focus red light that was only half the width of an SD pixel will completely fill the adjacent pixels so the CA becomes more noticeable.

In addition as you increase the resolution of the lens you need to make the focus of the light “tighter” and less blurred to increase the lenses resolving power. This has the effect of making the difference between the focus points of the red and blue light more distinct, there is less blurring of each colour, so less bleed of one colour into the other and as a result more CA as the focus point for each wavelength becomes more distinct. When each focus point is more distinct the difference between the in focus and out of focus light becomes more obvious, so the colour fringing becomes more obvious.

This is why SD lenses very often show less CA than HD lenses, a softer more blurry SD lens will have less distinct CA. Lens manufacturers will use exotic types of glass to try to combat CA. Some types of glass have a negative index so blue may focus closer than red and then other types of glass may have a positive index so red may focus closer than blue. By mixing positive and negative glass elements within the lens you can cancel out some of the colour shift. But this is very difficult to get right across all focal lengths in zoom lenses so some CA almost always remains. The exotic glass used in some of the lens elements can be incredibly expensive to produce and is one of the reasons why good lenses don’t come cheap.

Rather than trying to eliminate every last bit of CA optically the other approach is to electronically reduce the CA by either shifting the R G B channels in the camera electronically or reducing the saturation around high contrast edges. This is what ALAC or CAC does. It’s easier to get a better result from these systems when the lens is precisely matched to the camera and I think this is why the CA correction on the Sony kit lenses tends to be more effective than that of the 3rd party lenses.

Sony recently released firmware updates for the PMW200 and PMW300 cameras that improves the performance of the electronic CA reduction of these cameras when using the supplied kit lenses.

Alphatron ProPull mini follow focus.

Alphatron MiniPull follow focus.
Alphatron MiniPull follow focus.

Over the years I’ve used many different follow focus units. Some better than others, but the majority of them a similar size. I recently got one of the new compact Alphatron Pro-Pull follow focusses to play with. The first and most obvious thing about the Pro-Pull is it’s size. It is very compact. At first I thought this might be an issue as the smaller knob requires more effort to turn than a more conventional larger knob, but in reality it’s not a problem. If you need more torque you can use either a whip or slot in hand grip.

IMG_1724
MiniPull on an F5 working with a Samyang/Rokinon Cine lens.

The Mini-Pull has some really cool features. For a start you can reverse the focus direction by swapping the gear drive from one side of the unit to the other. But the one I really like is the adjustable, locking end stops. This makes it really easy to pull focus from one distance to another. You simply set the stops at your near and far focus positions and then turn the focus wheel between the two stops. If you then need to focus beyond the end stops you simply flip up the latching stop pin and you can focus beyond the end stops. Want to return back to the end stops then simply flip the stop pin back down again. Very clever, very simple and very effective.

The focus marking ring is magnetic so if you need to change or replace this it pulls off easily, yet is very secure when in place. The MiniPull is attached using a simple bracket that attaches to a single 15mm rail. This makes it very easy to adjust the MiniPulls position if your changing lenses and going between different sized lenses. This bracket also makes the MiniPull very compact, which for me as a very frequent traveller is a real bonus.

I used the MiniPull extensively on my recent shoot for the short film “Inviolate” to easily execute a large number of focus pulls. I rate it very highly if you need a compact and easy to use follow focus. It’s supplied with everything you need to get going including a nice flexible lens gear ring and the screw driver needed to attach it. Also included as well as the 0.8 pitch gear drive is a drive wheel with a rubber edge that can be used with lenses without a pitch gear.

HD lenses for 1/2″ Cameras like the EX3, PMW-320 and new PMW-300.

Some people are struggling with lens options for the Sony half inch interchangeable lens cameras. Many try to use 2/3″ lenses via the ACM-21 with disappointing results. Lenses are designed to meet certain criterion. The lenses for the PMW-EX3 and PMW-320 actually perform very well, yet these are inexpensive lenses, so why when you use a much more expensive 2/3″ ENG zoom lens can the results be disappointing?

There is a very big difference between the way most typical ENG lens focus and the way an EX1/3, PMW-320 or PMW-200 lens focusses. An ENG lens will be a Par Focal lens, a lens that maintains constant focus throughout the zoom range. This is incredibly difficult to design especially with large zoom ranges and is one of the reasons ENG zooms are normally expensive pieces of glass.
The lenses used on the EX1/EX3, PMW-320 are not Par Focal, this makes them much cheaper, the focus shifts and changes as you zoom….. But clever electronics inside the camera and lens compensates for this by adjusting the lenses focus as you zoom so that in practice the lens appears to stay in perfect focus. An electronically compensated lens like this is lower cost to produce than a sophisticated typical ENG type zoom and makes the lens compact and lightweight as well as much cheaper.
Another factor is that as you increase the resolution of a lens, trying to bring everything in to focus on an ever smaller point, you run in to more and more problems with chromatic aberrations. Different wavelengths (and thus colours) of light get bent by different amounts when they pass through a glass lens. As you make the focussed light for one single colour smaller and sharper, the other colours of the spectrum become more dispersed. As a result, generally a softer lens, for example an SD lens (lower MTF) will exhibit fewer colour aberrations than a sharper HD lens. To compensate for these aberrations lens manufactures use very exotic types of glass with different refraction indexes to try to cancel out or at least minimise CA (chromatic aberration), but this glass is extremely expensive. The higher the resolution of the lens, the more expensive the glass gets.
With a camera like the EX1/EX3, PMW-320, PMW-200 when you know the exact characteristics of the lens (as they all use essentially the same lens) instead of employing exotic glass, you can program the camera to electronically remove or reduce the appearance of the CA and this happens inside the EX1/EX3, 320 and PMW-200 etc.
Next you must take in to account pixel size. In simple terms to work with the resolution of the cameras sensor, the lens has to be able to focus a point of light small enough to hit only one pixel. A typical 2/3″ HD camera has much bigger pixels that the pixels on the 1/2″ sensor of the PMW-320. As a result a lens that is only just able to achieve HD resolution on a 2/3″ camera, will not achieve HD resolution on the PMW-320 with it’s smaller pixels, it’s simply not designed to work with such small pixels. This means that you really need an HD lens designed for the 1/2″ sensor size and the corresponding pixel size.
These factors combined mean that the standard kit lens on the EX3, PMW-320 etc appears to perform very well and it takes a much more expensive, designed for 1/2″ lens to even match this apparent performance in most cases. Perhaps the new 16x lens coming for the PMW-300 will be available to purchase on it’s own. This would offer EX3 and PMW-320 owners the option of a high performing lens with a greater zoom range, probably for less than a similar performance conventional lens.

How big a compromise is using a DSLR zoom on a 4K camera?

This came up as a question in response to the post about my prototype lens adapter. The adapter is based around an electronic Canon EF mount and the question was, what do I think about DSLR zooms?

There is a lot of variation between lenses when it comes to sharpness, contrast and distortions. A zoom will always be a compromise compared to a prime lens. DSLR lenses are designed to work with 24MP sensors. A 4K camera only has around 9MP, so your working well within the design limits of the lens even at 4K. While a dedicated PL mount zoom like an Angenieux Optimo will most likely out perform a similar DSLR zoom. The difference at like for like apertures will not be huge when using smaller zoom ratios (say 4x). But 10x and 14x zooms make more compromises in image quality, perhaps a bit of corner softness or more CA and these imperfections will be better or worse at different focal lengths and apertures. At the end of the day zooms are compromises but for many shoots it may simply be that it is only by accepting some small compromises that you will get the shots you want. Take my storm chasing shoots. I could use primes and get better image quality, but when you only have 90 seconds to get a shot there simply isn’t time to swap lenses, so if you end up with a wide on the camera when a long lens is what is really needed, your just not going to get the shot. Using a zoom means I will get the shot. It might not be the very best quality possible but it will look good. It is going to be better than I could get with an HD camera and a very slightly compromised shot is better than no shot at all.
If the budget would allow I would have a couple of cameras with different prime lenses ready to go. Or I would use a big, heavy and expensive PL zoom and have an assistant or team tasked solely with getting the tripod set up and ready asap. But my budget isn’t that big. I could spend weeks out storm chasing before I get a decent shot, so anything I can do to minimise costs is important.
It’s all about checks and balances. It is a compromise, but a necessary one. It’s not a huge compromise as I suspect the end viewer is not going to look at the shot and say “why is that so soft” unless they have a side by side, like for like shot to compare. DSLR zooms are not that bad! So yes, using a DSLR zoom is not going to deliver quality to match that of a similar dedicated PL zoom in most cases, but the difference is likely to be so small that the end viewer will never notice and thats a compromise I’m prepared to accept in order to get a portable camera that shoots 4K with a 14x zoom lens.

What about DSLR primes and why have I chosen the Canon Mount?

This is where the image performance gap gets even narrower. A high quality DSLR prime can perform just as well as many much more expensive PL mount lenses. The difference here is more about the usability of the lens. Some DSLR lenses can be tiny and this makes them fiddly to use. They are all All sorts of sizes, so swapping lenses may mean swapping Matte boxes or follow focus positions etc. Talking of focus, very often the focus travel on a DSLR lens is very, very short so focussing is fiddly. If the lens has an aperture ring it will probably have click stops making smooth aperture changes mid shot difficult. My prime lenses are de-clicked or never had clicks in the first place (like the Samyang Cine Primes). It’s not so much the issue of requiring a finer step than the one stop click, but more the ability to pull aperture during the shot. It’s not something I need to do often, but if I suddenly find I need to do it, I want a smooth aperture change. That being said, one of the issues with using Canon EF lenses with their electronic iris is that they operate in 1/8th stop steps and this is visible in any footage. Ultimately I am still committed to using the Canon mount lenses simply because there are so many to choose from and they focus in the right direction unlike Nikon lenses which focus back to front. For primes I’m using the excellent and fully manual Samyang T1.5 Cine Primes. I really like these lenses and they produce beautiful images at a fraction of the price of a PL mount lens. My zoom selection is a bit of a mish-mash. One thing about having a Canon mount on the camera is that I can still use Nikon lenses if I fit the lens with a low cost Nikon to Canon adapter ring. If you do this you can only use lenses with an actual iris ring, so generally these are slightly older lenses, but for example I have a nice Sigma 24-70mm f2.8 with a manual iris ring (and it focusses the RIGHT way, like most Sigmas but unlike most Nikon mount lenses). In addition I have a 70-300mm f4 Nikon mount Sigma as well as an Old Tokina 28-70mm f2.6 (lovely lens, a little soft but very nice warm colour). One thing I have found is that most of the Nikon to Canon adapter rings are little bit on the thin side. This prevents any zooms from being Parfocal as it puts the back focus out. Most of the adpaters are made in two parts and it’s quite easy to take the front and back parts apart and add shims made out of of thin plastic sheet or even card between the two halves to correct the back focus distance.

So there you have it. Overall DSLR lenses are not a huge compromise. Of course I would love to own a flight case full of good quality PL mount, 4K ready, glass. Perhaps one day I will, but it’s a serious investment. Currently I use DSLR lenses for my own projects and then hire in better glass where the budget will allow. For any commercials or features this normally means renting in a set of Ultra Primes or similar.  I am keeping a close eye on the developments from Zunow. I like their 16-28mm f2.8 and the prototype PL primes I saw at NAB look very good. I also like the look of the Zeiss 15.5 to 45 light weight zoom. Then of course there is the excellent Fujinon 19-90mm Cabrio servo zoom, but these are all big bucks. Hopefully I’ll get some nice big projects to work on this year that will allow me to invest in some top end lenses.

Video overview of MTF Services B4 2/3″ to super35mm adapter.

In this video I take a look at the MTF Services (http://www.lensadapter.com) B4 2/3″ to super35 mm lens adapter. This adapter allows you to use a conventional 2/3″ ENG zoom lens on most video capable cameras that have a Super35 sized sensor or APS-C sized sensor. It comes in two parts, the optical converter (the expensive bit) and a simple low cost lens mount adapter ring. Adapters are available to work with the Sony PMW-F3, Sony E-Mount (FS100, FS700, EA50, NEX5 etc) as well as Canon EF (C100, C300, C500, 7D, 550D etc). To work correctly the lens must have a 2x extender. All is explained in the video.

 

Metabones EF to E-Mount smart adapter.

Metabone EF to E Mount adapter on Sony NEX-FS700

The new $400 Metabones EF to E-Mount smart adapter allows you to use Canon EF mount lenses on almost any camera with an E-Mount. So that means cameras like the FS100, VG10, VG20 and the NEX series stills cameras. I’ve been trying to get hold of one of these for some time, but they have always been out of stock due to popular demand. However I was lucky enough to track one down from a UK dealer a couple of weeks ago. It is a small compact device, there are no wires, cables or remote control boxes so it couldn’t be simpler to use. Simply attach it to the Sony E-Mount and then attach your Canon EF lenses to the adapter. The camera will then control the iris just as it would with a Sony lens. So in the case of a FS100 or FS700 the iris wheel will control the iris with an accurate display of the iris setting on the cameras LCD screen. You can also use the auto iris functions. For quick focus checks there is a small button on the barrel of the adapter that momentarily fully opens the iris so you have minimum depth of field, which makes it easier to see if you are in focus. The adapter doesn’t work with auto focus so no focus functions, but it does allow any image stabilisation built into the lens to work. It works with the vast majority of lenses although there are a few that don’t work or have some limitations, best to check the Metabones web site for details. I really like this adapter for it’s simplicity and transparent operation, you really don’t know it’s there. Just wish they could do one for the Sony F3.

Coming Soon: A review of the new Transvideo PMW-F3 base plate that completely replaces the underside of the F3 with a really nice bottom end and of course the Alphatron EVF-035W review.

Triad PL to E-Mount Adapter. A PL adapter for the FS100 and FS700.

Triad E-Mount to PL adapter

A little while back I was loaned a Triad PL to E-Mount adapter for review. E-Mount is the Sony mount used on the NEX-FS100, NEX-FS700 as well as The VG10, VG20 and NEX stills cameras. While more and more E-Mount lenses are becoming available from Sony and other DSLR lens manufacturers there will be many times when something more suitable for video work might be needed. One of the big issues with DSLR lenses is the very small amount of rotation on the focus ring to go from near to far, often only 45 degrees which makes accurate focus tricky. A good PL mount lens will have over 180 degrees of rotation. PL has been the industry standard for movie cameras for years and most rental companies have large ranges of PL lenses to choose from. So the ability to be able to use a PL lens on any super 35mm camcorder is always welcome. While I use DSLR lenses on my cameras for my day to day shoots, if I am doing a high end production such as a commercial then I will hire in the appropriate PL lenses for the job. Sony’s soon to be released FS700 is a camera that will, I’m sure end up getting used for many commercials as slow motion is a technique widely used to show off new products or ideas. As a result there will be many time in the future where I will need a PL adapter.

The Triad adapter showing the Flange Back adjustment ring.

The Triad adapter is very solidly made, machined from high grade alloy with stainless steel and chrome plated steel inserts. One of the very nice features is that the adapter has a built in adjustment for the back focus distance. A locking outer ring on the adapter can be rotated to alter the physical distance between the PL receptor and the E-Mount bayonet. This will allow the user to calibrate the back focus or flange back distance so that the focus witness marks on any PL lenses will be 100% accurate. It will also ensure that PL zooms will track focus correctly through the entire zoom range. As the FS100 and FS700 don’t have built in back focus adjustments this really is a vital thing to have. The Sony E-mount was only designed to support the weight of light weight DSLR type lenses so the Triad adapter has a support post that can be attached to 15mm or 19mm rails (via a suitable bracket) to help carry the weight of heavy PL lenses without over-stressing the cameras E-Mount. One note from Triad is that the Sony PL lenses supplied with the kit that comes with the PMW-F3 do not fit this adapter. There are quite a few PL mounts that don’t accept the Sony PL lenses without shaving a bit of metal from the Sony lenses mount. So this isn’t a flaw with the Triad adapter, it’s a non standard quirk of the Sony PL lenses.
There’s really not much more to say about this mount. It’s well made and does what it designed to do.