Sony A7R Mark III Buying Guide

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So you can’t wait anymore. You have a big trip planned and you gave your other camera away. What should you get right now if you want great resolution. Here’s a list:

  1. Sony A7 Mark III. This is an expensive camera, but I do see that Adorama is at least offering bundles at the list price that takes a little sting out of it. So if you are for example going to shoot video and want a dedicated microphone, you can get one thrown in. (They do this a lot, for instance if you want an every day carry Sony RX-100 Mark VI, they have a bundle).
  2. Tripod. The Sony A7R is a 42MP camera, but you only get true 42 megapixel resolution if you shoot with a tripod. This is a light camera, so you can get away with an ultralight Gitzo Travel Tripod. Yes it’s super expensive at $680 and you also need a ballhead to go with it, but if you are going to spend that much for a 42MP sensor, you might as well get this. If you don’t want to then the 24MP A7 III is going to be just fine for you.

When it comes time to deciding what lenses to buy, you can literally spend $50K doing it, but from my friend Vlad, here are some recommendations for someone who wants the camera for travel, landscapes and the occasional portraits. These use opticallimits.com as the primary source of quality as he seems to do the best job with scientific results. I started with the lense lists from ephotozine.com, lensrentals.com, sonyphotorumors.net and Dxomark.com, but it is harder to assess their methods since they don’t document how they get their resolution figures for instance.

The Deep dark hole of Resolution

It turns out it is actually pretty hard to say what the actual resolution of a lens is. That’s because depending on whether you are talking about the center or the edges, resolution falls off, so you have to take some sort of rough average. Also, there is this transmission factor where some lenses (the Batis!) seem to just light up pictures because they are so efficient at transmitting light that being said, here are a stack rank of lenses to get the first sort was using DxOmark since it has the best ranking list and then cross checking with ephotozine.com, opticallimits.com, lensrentals.com and the-digital-life.com. The former use Imatest and the latter uses Olaf (which lensrentals.com pioneered). As an aside, note that the Olaf tests are done through the lens without a body, but the imatest uses a body, so the results will be different. The Olaf test is in some ways more pure and body independent, whereas imatest will tell you what you will get with a specific lense,
As an aside, the whole question of resolution is really complicated. There is something called the MTF. But to summarize, you basically take a photo of alternating white and black lines. So if you were just looking at the brightest of alternating black and then white, they would go up to the max then immediately fall to zero over and over.
Graph-of-Perfect-Bar-Chart.png
If you think about it, the result that you get out is a modulation transfer function (MTF), that is what comes out will be blurred. If it were perfect, then the MTF would be 1.0, but what happens is that you get a blurring of the lines (contrast reduction). As the lines get closer and closer together, eventually the lens just see a grey blob (the MTF is 0).
Now a bit on the common math. The distance between the lines is measured “line pairs per millimeter”. Obviously as you the lines get closer and closer together, they blur more, so say at 1lp/mm, you could nearly a perfect transfer, that is the blurring leads to MTF of 1.0, but at 20lp/mm, that is really dense, so the MTF can fall to 0.5. That is what MTF50 means, it’s the place where the basically 50% of the signal gets through. One way to think about this is this is the point where the light and dark are. Arbitrarily, MTF50 where the  black is half as much and white is half is what folks call the lp/ph the number of line pairs per picture height that is the resolution. In most cameras, with a full frame that “35mm” camera have an aspect ratio of 3:2  is 36mm width x 24mm of height. So if you have say 5,000 lw/ph, then the resolution would be 5K * (1.5*5K) = 37.5K megapixels.
Graph-of-Blurred-Bar-Chart.png
Thing gets even trickier though, because lenses have different resolutions depending on the orientation of the lines, so lines that are saggital (that is radiate out from the center) and meridian or tangential which are perpendicular. The resolution of the lense is different across these two diameters, so when someone says an MTF50 of 5,000, you have to ask for which kind of lines. Confused yet?
Meridian-Sagittal-Lines-Example-2.png
The last confusing thing is that these resolutions are actually different across the entire plane of the lense, so each spot no the lense has a different resolution. In general the center tends to be the best and the worst is at the edges, so a simplified 2D diagram of resolution will show the MTF value for different line widths as you go from the center to the edge. If you want to get even more complicated this resolution changes based on aperture (so wide open a lense has less resolution) and also if it is a zoom on focal length, you can see why it’s nearly impossible to say a lense has a resolution of 37MP, it’s really a figure of merit. The chart below for example shows that at 50lp/mm (which is a resolution of 50 line pairs x 2 lines/pair x 24mm/full frame sensor is 2400 lines or a camera that is resolving at 2400^2 * 1.5 or 8 megapixels). In this example, the tangential resolution that is at right angles to the center are much better at MTF above 0.5, whereas lines that a radiating out from the center are much worse. Dropping from 0.6 to 0.3
MTF-Chart-Sample-Average.png
As an aside, you can see how high resolution a 42MP sensor is, even with 100lp/mm, that works out to a 37MP resolution. so the charts you normally see really are at much lower resolutions. And you can see why need a tripod, 100 lp/mm means that each line pair is just 0.01mm or 10 microns wide! So a shake of just 5 microns would be catastrophic to picture quality.
Finally, what do these charts translate too. Well, turns out that the 10lp/mm is correlated with contrast. That is, how defined does an image look. You want figures about 0.9. And for sharpness, look at the 30lp/mm and make sure you are above MTF50 (0.5 transfer). Most folks just average the tangential and saggital even if they are very different. When the difference is high by the way, this is called astigmatism which you can have in human eyes, it means that some things are blurry and others are not.

Standard prime lens

This is perhaps the most use of all lenses and you want something that is going to really deliver on quality. Looking at ephotozine and DxoMark, we get While a kit Lense is nice, paying up for these monster primes will really be worth it particularly on a tripod:

  1. Sony FE Planar T* 50mm f/1.4 ZA. A remarkable lense, this one is $1,500 and is faster at f/1.4 (although its transmission is T/1.6, so not quite a perfect as the 55mm). It has a 41MP rating so a bit higher than the 55mm. There were not reviews at optical limits, but Lens Rentals which is another amazing site did a very complete set of testing.  Contradicting the DxOMark, they found that it is ? of a stop faster but is sharper at the center which is pretty incredible. Also the sample-to-sample variation was quite small (this is a big factor in lense testing). It actually has a DxOMark of 47 (but given that it is ? of a stop faster and we are not clear on methods), the Lens Rentals analysis is probably more accurate.
  2. Sony FE Zeiss Sonar T* 55mm f/1.8. At $1,000 this lense is super expensive and is a little more zoom than the typical 50mm, but DxOmark rates it a 48, so one of the highest rating. Mainly because it transmissions very good. The T-stop is a single sentence is the F-stop of the lense corrected for the actual light loss in the lense. So a f/1.4 lense will lose a bit and realy be a T/1.7 lense as an example. But in this case, there is essentially no light loss for this lense, so it is a f/1.8 T/1.8 lense which is pretty remarkable. They say the effective resolution is 40MP, but they don’t explain how they average. To get a sense of that, you have to go to Optical Limits to see the raw MTF measurement data. Vignetting wise, wide open there is a -2.6EV fall off, but this disappears when you get to f/2.8. But you can see why this is such an impressive lense at f/4 maximum resolution the center is a 5020lwph with the extremes dropping to 3620 lwph. As an aside, 5020 corresponds to 37MP effective maximum resolution, so it isn’t clear how DxOmark got to 40MP for the whole lense. The measurements across all three sites seem to vary and depends on how Imatest is used and what light conditions as well.

Wide Angle Prime Lense

Then the next lens to get for travel is probably a wide angle lense to take in all that beautiful scenery and cool street photography. So looking at ephotozine and Dxomark, here are the top choices:

  1. Carl Zeiss Batis 25mm f/2 Sony FE. This has a DxOMark of 46 and a resolution of 36MP and T-stop of 2 (so basically zero loss through the lense). Pretty incredible. Lens Rentals concurs that when compared with others, it is very sharp. It also has a 8″ minimum focus distance, so not bad for closeups that are also wide angle.
  2. Carl Zeiss Batis 18mm f/2.8. This is the only ultra wide angle tested by Optical Limits and it is quite a lense. Lots of vignetting, but incredible near center and center sharpness (5199 lp/ph at f/4 or 40MP+). This is really an ultra wide angle lense, but it is sharp if you need it. Lens Rentals concurs that this is really an incredible super wide angle. It’s great for astrophotography, indoor rooms and landscapes. My second wide angle after the 25mm.
  3. Carl Zeiss Loxia 21mm f/2.8. Rated at DxOMark of 42 with a 37mp resolution and a T-stop f 2.8, this is another great lense. The f/2 above is faster but not as wide of course.
  4. Sony FE 12-24 f/4 G. This is a zoom, so it is not going to be as high resolution, but definitely more versatile.
  5. Sony FE 16-35 f/2.8 G Master. Same issue but very versatile.

Macro, Portraits, Weddings

Then there are set of specialty lenses that come after this, for instance if you stay with primes, then there are choices for closeup, portraits and the classic wedding shoots

  1. Sony FE 90mm f/2.8 Macro G OSS ($1,098). This is a superb lense that does great close focusing. Optical Limits showed that is super sharp in the center with 5002 lw/ph at center and 3900 at the extremes. DxOMark agrees with a score of 47 and a resolution of 42 (so effectively they are saying no loss in image quality due to the lense) and no loss in transmission with a T-stop of 2.9. Pretty incredible but a pretty specialized Lense.
  2. Sony 70-200mm f/2.8 GM. This is the classic go everywhere zoom that is the standard Lense for close up wedding photography.
  3. Sony 100mm f/1.8 GM. This is a portrait Lense and by all reports one the sharpest made.
  4. Sony 100-400 GM. This is a the typical long zoom. It isn’t as sharp as the dedicated $10K lenses like the Sony 400 f/2.8, but this and 70-200 cover most outdoor travel photography.

Travel

If you just want one lense to use for all your travel, the 50mm listed above is a good choice. But if you do want to be able to zoom and so forth so that you carry just one zoom, you will give up somewhat on image quality, but it is convenient:

  1. Sony 24-70 f/2.8. This is the one Lense that is go anywhere. Of course with a 50mm f/1.4 that is two stops faster and a 42MP to work with, you can get quite a bit with the 50mm and cropping.

Accessories

If you get the body only then there are some accessories you really want to think about. Brian Smith has a great list:

  1. Sony NP-FZ100 Li-on Battery. Ok, you can’t really leave home with an extra
  2. Sony BC-QA1 Battery Charger. You can charge the battery from the camera, but that means you can’t use the Camera while charging 🙁
  3. Gitzo Traveler Alpha Tripod. Expensive but works really well and comes with a ball head.
  4. Sony PCK-LG1 Screen Protection Glass. Because the touchscreen is delicate.
  5. Sony SF-G 64-128GB SDXC Cards. You need at least a UHS-II card as Sony Rumors explains. The fastest one right now is the Sony with 300 MBps Read/Write to support burst shooting. And with video you need at least a 64GB card to shoot at the highest resolution this goes into Slot 1. The 128GB is a pricy $215 and the 64GB is $108.
  6. Sony UHS-1 64GB card. The second slot is slower, so these 95MBps cards will suffice. The 128GB one is $88 from Amazon. There are quite a few of these cards around, so for instance the SanDisk Extreme PRO UHS-I SDXC is one I’ve used, it’s a $95 for a 256GB card (but make sure to buy from a reputable seller as there are many counterfeits) which is a better value at Amazon. Alternatively the Transcend is a budget car
  7. Metabones Canon EF to Sony E-Mount T Smart Adapter V. Well this is $399, but let’s you use your old Canon lenses with your A7R III. It won’t have the resolution but not a bad choice to get a little more use. Brian has a complete guide to adapters for all other lenses too. As an example for $169, you ca get the Commlite CM-EF-E HS Lens Adapter, but you won’t get the firmware updates that Metabones is constantly doing to improve performance.

Video Accessories

If you are going to shoot some pro-level video, then you need still more gear:

  1. Sony ECM-XYST1M stereo microphone. There are many different versions, but it is a mike mounted on the hotspot.
  2. CAME-TV Single 3-Axis Handheld Camera Gimbal. This is a grown up version of the DJI Osmo. It is designed for smaller loads and is $988. It weighs 2.6 pounds It is a great way to shoot smooth handheld footage.

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