The question about what's better for an A7x user looking for more reach: to buy the Sigma lens or to grab the versatile RX10III, pops up every once in a while in the forums. Therefore here some thoughts and tests for those who evaluate which of the two would fit them better. An RX10III costs almost the same as the Sigma 150-600 C with a converter. That's why it's worth to think about it and compare the two.
But in the meantime the situation has changed. The Sony 100-400 GM hit the market. Therefore the question now should be: What's the better solution for Sony A7X owners looking for more reach? The Sony 100-400 GM, the Sigma 150-600 C or the RX10III/IV?
There's really only one answer: The Sony 100-400 GM with the TC 1.4! To learn more as to why I have sold my my RX10III as well as my Sigma 150-600 C and bought the Sony 100-400 GM instead please scroll down to Addendums 1+2. When I wrote the 1st version of the following article the GM was not available yet and once it came out I first thought that it is too expensive. But I changed my mind and happily can say: it's worth every penny!
From here down to the Addendums 1+2, this is my original article dealing with the comparison of the Sigma 150-600 C with the RX10III, not including the 100-400 GM yet:
Wanting more reach I bought the Sigma 150-600mm Contemporary for my Sony A7RII, especially for wildlife photography. Before buying the lens I had a hard time to decide whether to get this bulky and heavy lens. I asked myself time and again if I wouldn't be better off with the much smaller and lighter RX10III. Well, since I love my A7RII so much I went with the Sigma. But... Only a few months later I decided to add an RX10III to my collection. (Which turned out to be a mistake – further down, in the new Addendum 1 you can see why I already sold the RX10III after using it for 17 months).
So, to help those Sony A7x users who evaluate the two above solutions, I will share some of the experiences I made with these systems. Since many reviews were written and published about these cameras and lenses, I will not get into the technical details here, but talk about some real world differences. But one thing remains to be said: I use the Sigma (Canon mount) currently with the Metabones IV adapter. I also have the Sigma MC-11, but at the current state of the firmware (May 2017), the MB IV performs better for me. This might change again with future updates.
Test shots
The following screen shots are based on test photos ...and I was not trying to be "artistic". It's not a scientific test either. Due to the weight I did not take out both systems at the same days. Therefore there may be some differences due to the light and/or atmospheric interferences. But the indoor shots were taken under the exactly same conditions. This page should best be viewed on a large, calibrated monitor. Viewing it on cell-phones etc. is not recommended for a realistic comparison.
Since I use the A7RII with 42 MP and the RX has only 20 MP, the results are obviously very different. The full frame sensor of the A7RII plays an important role. The RX10III only has a one inch sensor. Above you see the proportional difference in size, if you shoot the subject from the same distance at 600 mm. Due to the higher resolution, the A7RII/Sigma combo is like having a 900 mm lens when compared to the RX10III. In other words: you have significantly more reach with the A7RII/Sigma combo. For those with 24 MP cameras this difference is smaller of course.
So especially if you have the A7RII, the significant difference in the resulting picture size (if taken from the same distance) should be considered in your evaluation as well. When camera makers talk about the "35 mm equivalent" it's sort of a marketing trick. The RX10III really has a 220 mm lens which results in the same field of view as that of a 600 mm lens on a full frame camera, due to the smaller sensor of the RX.
But the larger images of the A7RII are not the only advantage. To get the same size of the subject, you can move farther away from it with the A7RII/Sigma, which can make a huge difference in wildlife photography. Staying farther away reduces the risk of scaring the animal away! And, of course, you get plenty more room for cropping with the A7RII. Dynamic range, the rendering of fine details and ISO performance are also much better on the A7RII as we will see further down the page. And some more very important aspects are (shallow) depth of field and subject isolation, wich are far easier to achieve in cameras with a full frame sensor. On the other hand it's easier to get a deeper DOF with the RX10III. These factors should be taken into account as well, before deciding whether to get the Sigma lens for your A7x or to add an RX10III to your collection.
Remains to say that if I were forced to make a choice, it would clearly be the A7RII.
Direct comparison
The below picture was taken at a distance of 3 m with the RX10III. With the A7RII I could move back to 4.5 m to get the same size of the subject! Both were shot at 600 mm with the lens wide open. Both lenses deliver sharp images wide open, even at the long end. Of course the resolution of the finest details is better with the A7RII/Sigma.
The following test shots were taken on a tripod at ISO 100. The pictures taken with the A7RII/Sigma are always on the left/above, those from the RX10III on the right side/below.
The following comparison was taken from a distance of about 3.5 km. The A7RII shot clearly shows more details.
Following is an example shot from a distance of 600 m. The A7RII/Sigma combo is clearly better. Again both shot at 600 mm wide open. Both images scaled down to about 50% to get better quality (further down in Addendum 2 you can see the 100% crops of these images compared to the far superior result of the 100-400 GM with TC 1.4).
The next image was shot with the RX10III at 34 mm (image at the left). Comparing to the above shot gives you an impression of the magnification you get when zooming in to 600 mm. But it also reveals the lack of detail you get when shooting with a 1" sensor camera like the RX10III. For comparison (at the right) a shot of the same scene from a slightly different angle taken at 30 mm with the A7RII and the Sony 16-35 f4. Even in these examples of the small size of only 2560x1700 pixels the difference in IQ is apparent. No pixel-peeping necessary to see the difference...
ISO, noise and dynamic range
In the below tests I tried to simulate a little more difficult situations, instead of setting up ideal conditions. I did this because in reality we are often confronted with more challenging scenarios. We often read in forums that the difference in IQ between these cameras is minimal, which simply is not true. People making such statements usually refer to pictures taken in broad daylight under pretty much ideal conditions. In such pictures the difference may be smaller but nevertheless clearly visible. But as soon as we have to shoot under not so ideal conditions, the differences actually are substantial. Under less than optimal, difficult conditions you often can continue to shoot with the A7RII, and still produce very good results, while with the RX10III it's not even worth trying anymore. Again, I don't say this to put the RX down at all. It's simly a fact, based on the technical limitations of the camera., which really should not be a surprise for anyone.
I only used the relatively low ambient light for the following photos. The tests show what's to be expected when a little more post processing is required. How well can we overcome the shortcomings of some under- or overexposure? How easily can we cope with noise? To properly evaluate the two systems, we should be aware of the strenghts and limits of each of them.
1. Photos underexposed by two stops
The first series was taken at ISO 800, 1600, 3200 and 6400 to compare the ISO performance of the two systems. In this case the shots were deliberately under exposed by two stops, to push up the shadows in post. It happens time and again that we have to underexpose to prevent a very brightly lit background from clipping. Or we have to raise the ISO level and/or lightly underexpose to get an acceptable shutter speed. Underexposing and then pushing up the shadows in this test reveals more noise with both cameras of course, and we can compare how this affects the pictures from the two systems and how we can deal with it in post.
Like before the A7RII/Sigma images are at the left/above, the RX10III ones at the right/below.
2. Correctly exposed photos
3. Counter light shots at ISO 100
Next we examine some examples of counter light shots, all taken at ISO 100. The camera in this setup is rather weakly lit from a window at the left. I made two sets of pictures. At first I exposed for the highlights and pushed the shadows in post. In the second round I exposed for the subject, ignored the blown background and pulled the lights in post. With the A7RII I managed to get almost identical results in both scenarios, except for the blown background of course. Missing information cannot be recovered – not even in RAW – as we all know. In the case of the RX10III there were larger differences in the results from the two tests, and the IQ of the RX10III images suffered in both cases from these slightly more difficult conditions. Shots taken at 300 mm.
The same effect can of course be observed when shooting counter light outside. And it's not even direct counter light in this case but only shooting against a relatively bright background. The RX10III looses a significant amount of information. The following shots were not even shot in extreme conditions and the images were correctly exposed (no blown highlights) The light was not very harsh on this overcast day. In other words: a typical everyday situation. We face similar conditions very often when shooting landscapes. These were taken at 55 mm.
Auto focus
As to be expected, the auto focus of the A7RII is remarkably faster thanks to PDAF and it's easier to focus with it, despite the fact that the Sigma 150-600 is not a native, but an adapted lens. The RX10III auto-focus is slower, particularly at longer focal lengths, and continuous auto-focus often struggles with fast-moving subjects, which is clearly less the case with the A7RII. In low light the AF of both cameras becomes weaker and starts hunting, and with the RX10III it can get painfully slow, especially at the long end of the lens. This weakness in darker conditions kicks in a lot earlier with the RX10III, but in this respect I'm not totally happy with the A7RII/Sigma combo either. Shots of birds in flight are probably very difficult – but not impossible – with both cameras. So far I did not try it myself, but I saw corresponding images from other photographers.
I recently took both cameras to a darker part of the forest to test the AF in a real life situation. Hidden behind a tree I had enough time to take several images with both cameras, because the squirrel luckily took his time for the meal. While I was able to get several sharp shots with the A7RII, the RX10III failed under theses circumstances. It was a tough scenario due to low light and low contrast, and what made the situation even more challenging were some branches right in front of the squirrel. The RX10III would either catch one of these branches or hunt endlessly, but I was never able to catch the eye of the animal and not one RX10III-shot turned out to be in focus. Maybe the Mark IV would have worked better, but I doubt it. Comes to it that the necessary ISO 6400 would have ruined the RX shot for sure.
Apart from this test I would not choose the RX10III for this kind of shots anyway. I had to use ISO 6400 to get a reasonable shutter speed. As we have seen in the ISO-comparison the RX10III would deliver unusable results at such a high ISO-setting anyway.
A word about macro
The Sigma 150-600 mm can be ignored in this respect. Close-ups: yes, macros: no. The RX10III can get pretty close to the subject. The following images show a coin with a diametre of 20 mm, shot at the closest possible focusing distance of 3 cm at the short end, and at a distance of about 90 cm at 600 mm. At 600 mm you can also shoot lovely close-ups of flowers with a nicely blurred background, but this is what the Sigma also can do of course.
But – and there always seems to pop up a "but" – compared to the results of a dedicated macro lens on a A7RII, the magnification of the RX10III "macros" is much less impressing as we will see further down. Since I also have a good macro lens, I will definitely continue to take this kind of shots with the A7RII. Especially when it comes to macro, the higher resolution of the A7RII comes in handy and the results possible of course surpass those of the RX10III by far. But you need an additional macro lens.
I add one more picture here to show the difference to a dedicated macro lens on the A7RII, the FE 2.8 90 mm Macro G OSS in this case. Of course we go into totally different dimensions here. Anyhow, it's interesting to see how huge real macro images can be. The coin almost fills the frame of the A7RII and the cropped file is still 7473 x 4985 pixels large. One can see tiniest scratches on the coin. Therefore, if you want to get into real macro photography, the RX10III is certainly not the way to go.
A dedicated macro lens literally dwarfs the largest RX10III "macro":
Depth of field
As mentioned before, it’s easier to get a deep DOF with the RX10III, but it’s very difficult to get a shallow DOF. Shooting at 600 mm and by either getting really close to the subject or by choosing a background far away from the subject, it's easy even with the RX10III. But that's not the point. We can’t always – and often don’t want to – shoot at 600 mm. And more often than not we can neither move the subject (or ourselves) as much as we would like, nor can we move the background farther away. At shorter focal lenghts the RX10III totally fails to produce a shallow DOF. Therefore subject isolation becomes pretty much impossible with the RX10III under many different circumstances like portrais for example, as well as in many scenarios in wildlife photography, and so on. It's a well known fact that FF-sensors are far better in this respect. We may think that we can resort to add the blur in post production. But this is not easy to do at all, even for experienced retouchers. And it is very time consuming if we want it to look realistic. So far, most of what I saw in this regard looked rather unrealistic and artificial.
For the sake of completeness I therefore add a picture with two examples of each camera. All shots were taken at the lowest f-stop available at the corresponding focal length. The first shot was taken at 150 mm. At this focal length the difference already becomes apparent. The second picture was shot at 55 mm (in this case not the Sigma lens was used of course). This example strikingly shows what it's all about. One has not the slightest chance to get this kind of result with the RX10III at shorter focal lengths in a scenario like the below example. And that’s sure one of several good reasons to keep the FF-camera (and even an APS-C camera for that matter) and add the RX10III as a complement and not as a replacement, which it cannot be in many ways as we have seen in the comparison on this page.
When viewing the below examples be aware that these are heavily downsized. The 1:1 images reveal a even bigger difference of the DOF. On large prints the effect will also be much more prominent. But the below A7RII 55 mm sample shows what good subject isolation means – even at thumbnail size, while the 55 mm version of the RX10III image shows the opposite! As you can see, with the FF-sensor it's much easier to blur the background.
After pointing out several of the obvious technical limitations of the RX10III, it would not be fair to remain silent about it’s advantages. But frankly, wouldn’t it be kind of naive to expect the same performance from two cameras with such different price tags? And that’s the first big advantage of the RX10III: it’s lower price! For what it costs, you really get a fine tool to take beautiful photos.
It’s versatility, portability and it’s fantastic coverage of a range from 24-600 mm (35 mm equiv.) are some other advantages. The comfort of never having to change lenses adds positively to this list. No doubt, the RX10III can produce good photographs in good light. And, as shown above, the "macro" abilities of the RX10III are not too bad either!
As a travel camera the RX10III may be good enough for many. Overall you get a good tool for the money. When it comes to video the RX10III is good indeed.
All of these aspects can make it worth to add an RX10III to your bag if you are willing to live with a lower IQ. For some people it even might be the all-in-one solution they are looking for. For me it definitely is not. I really love my A7RII and my A7S ( and now A7RIII) and I would never give them up in favour of the RX10III. And when it comes to wildlife and landscape photography with lots of fine details the RX10III certainly cannot rival the A7RII/A7RIII at all. The RX is good if there is plenty of light, if you can get close to the subject and if there are not too many fine details.
When we talk about image quality we need to stay realistic. Of course the RX10III cannot compete with any FF cameras... and it was never meant to. I often read on the web that the difference in IQ between these very different camera systems is marginal, but that’s simply not based on facts. The difference very often is substantial as we have seen above. I also read comments like “no other camera could have taken this picture better than the RX10III” and similar statements... That’s rubbish to be honest... sheer emotionally colored opinion. I guess that in such cases psychology kicks in. We all tend to judge mildly about stuff we have paid for and, after all, we have to justify our own purchases. That’s understandable and normal!
But it’s not helpful when it comes to objectively compare two systems. Such statements are distracting us from making an educated decision! To find out what’s right, you first have to find out what you really need, and then solely rely on solid evidence in your evaluation. Did the person making the claim provide the pictures and/or proof to substantiate what he says? Is the reviewer of a product commercially linked to the manufacturer, and/or does he maybe only try to sell the product? These are questions which you should include in your evaluation. Also sleep over it and reconsider the facts the next day. This way you will be safe from disappointment.
Addendum 1
Meanwhile (in May 2018) I sold my RX10III because almost everytime I used it, I later regretted to not having carried my A7RII instead. I lost almost 50% of the money because in the meantime the RX10IV was released. But the following comparison shows so clearly that the A7RII is far superior, that I decided not to trade quality for convenience anymore! Now I always take my A7RII with me and did not regret selling the RX10III for one single moment.
The below photos were taken five days apart (but at the exact same time of the day). This explains the minor changes in the vegetation. The second day, when I took the A7RII image, was also a little hazier, but it should not matter much in this comparison.
1. Overview
2. 100% crops of the flowers near centre and at the bottom
3. Centre crops, both at 100%
4. A7RII photo resized to match RX10III image
One more example to show the dramatic difference between the two cameras when it comes to fine details when shooting from longer distances. In the following example the shooting distance is about 900 m, both photos taken handheld at the same time, both at ISO 100, 55mm, A7RII at 1/100 sec, f7.1, RX10 III at 1/400 sec, f3.2, both downscaled to the same size and same post processing for both images except more sharpening applied to the RX-image.
Addendum 2
I was pretty unhappy with the RX10III after using it for 17 months and I sold it as said above. But I hesitated to sell the Sigma and get the Sony 100-400 GM for several months due to it's relatively high price. As time passed by I grew more and more frustrated with the Sigma because the quality did not match to what I saw from the GM and the auto focus of the Sigma was unfortunately very limited when compared to native Sony lenses. Therefore I took the plunge, sold the Sigma too and bought the 100-400 GM with the TC 1.4. This was a real WOW experience. It's the best zoom lens I ever held in my hands. With the GM my good old A7RII feels like having a brand new camera. All of a sudden it's not a problem to focus and track moving subjects anymore, even at the long end and even with the TC 1.4! Using the Sony 100-400 GM is pure pleasure.
The following image is my first test shot taken with my brand new A7RIII. All other shots further down were taken with the A7RII.
The following image is a 1:1 crop taken at 400 mm without TC 1.4. I did not expect that a plane would suddenly show up. Acting fast was required. I only had a very short time window to catch it, but it worked out pretty well. It was my very first attempt to catch a plane in flight with the GM. To prevent clipping the clouds I had to underexpose and lift the shadows more than I normally do because the plane was not much more than a silhouette.
I could not have taken this shot with the Sigma or with the RX10III (of course I did try but never really succeded). The RX10IV, which I tested in the meantime, is clearly much better with it's improved AF and such a shot is of course possible with it. But the IQ is pretty much the same as it was with the RX10III. Therefore not an option for me.
Contrary to the Sigma where I used a monopod most of the time, I always use the 100-400 GM handheld. The lens is 500 grams lighter than the Sigma and it is more compact and far better balanced with the camera. Therefore I also don't need to carry the monopod and save another 700 grams of weight to carry around. The A7RII/100-400 combo (inkl. TC 1.4) is just about 2.3 kg which really is not a problem at all and not that much havier than the RX10III at 1.1 kg. I can easily carry it on my full day hikes in this steep mountain terrain (using a Black Rapid shoulder strap) even when I also carry my daypack.
Besides the image quality of the 100-400 GM being significantly better than that of the Sigma 150-600 C, another huge advantage is the far better AF and its tracking abilities. Additionally the minimum focusing distance is only 98 cm instead of 280 cm as it is with the Sigma. This allows stunning close-ups and leads to "macros" even better then what the RX10III/IV can deliver, especially when the GM is combined with the A7RII/III. Finally the OSS of the GM combined with the in camera IS of the A7RII is excellent and allows me to shoot handheld at slower speeds.
Remains to mention that contrast and colour-rendering of the GM are also excellent, better than what the Sigma on a A7RII and far better than what the RX10III/IV can deliver.
Even when photographing small birds from relatively far away (and even under difficult circumstances like backlit subjects) the GM-lens deliveres fine details:
With the A7RII/GM combo we get the same size of the subject at only 400 mm as with the RX10III at 600 mm (due to the larger pixel count) when shooting from the same distance, but the GM image shows significantly more details.
Some comparisons with the Sigma and with the RX10III at 600 mm resp. at 560 mm with the Sony GM + TC:
The 40 mm less reach of the GM with TC are more than compensated by the superiour IQ of the 100-400 GM. After using it for several months I never even felt the missing 40 mm of the GM.
Many users of the RX10III/IV in the forums say that they only need their images at 4K-size and that at this size the difference cannot be seen anymore. Well, allow me to prove the contrary. The following three examples were all downsized to 4K. The difference in IQ is smaller but still obvious. Despite downsizing to 4K especially the RX10III still lags behind in terms of IQ (no surprise considering the 1" sensor).
The marmot shots were taken at the following settings: ISO 1600 and 1/1250s A7RII/Sigma on the left. ISO 3200 and 1/500s A7RII/GM in the centre and low ISO 100 and 1/500s RX10III at the right. Same distance for all three marmot shots, focus on the eye. The GM shot also looks best at 4K, despite being shot in less favourable light and at the highest ISO of 3200 in this series (even better than the RX image despite it was taken at only ISO 100).
Four Sony 100-400 GM examples taken with the TC 1.4, all handheld at 560 mm from very close (1 m) to very far away (10 km +), first three are 1:1 crops:
Just a few days ago (April 26 2019) I upgraded my A7RII to the A7RIII because my local dealer made me an offer I could not resist, including a five years complete cover warranty. The A7RIII (now with firmware 3) offers better and faster AF than the Mark II and several other improvements like much longer battery life, two card slots, superb view finder, joystick and better ergonomics etc. Now I'm fully happy with my photo gear.
Some more examples taken with the A7RII/100-400 GM + TC 1.4
All handheld. The first six images were taken without the TC, all others were taken with the TC.
Some more real world examples of the Sigma and the RX10III
On top of the examples I added a panorama image in each section. The shot taken with the A7RII was of course not made with the Sigma 150-600 C but with the tiny, excellent Sony FE 35 F2.8.
It's in no way a scientific comparison and I only added these two panos for completeness to illustrate the different IQ and the different rendering of fine details of the two cameras when it comes to landscape photos. Obviously – as expected – the A7RII beats the RX10III clearly.
1. A7RII with Sigma 150-600 C
Only the following panorama was not taken with the Sigma lens.
Click photos for larger view.
2. RX10III samples
The RX10III examples are not all shot in the range of 150-600 mm (which would be the ragne of the Sigma lens). I used the entire range from 24-600 mm (35 mm equivalent) for the following images.
Click photos for larger view.
Conclusion
From my point of view the RX10III, IV cannot replace the A7RII/Sigma combo at all and by no means the combo with the Sony 100-400 GM! If you own the A7RII it's well worth to buy the Sony GM (or the Sigma if your budget does not allow the GM) and live with the a little heavier and bulkier combo. If you are serious about photography, you won't make any compromise concerning the image quality, just to get a little more convenience and save some money. And by shouldering a little more weight, you will be rewarded with far better IQ and will be much more flexible when it comes to more challenging scenarios.
Even if you have one of the other A7x models, getting the RX10III or the Sigma instead of the GM lens is not a good choice in my eyes. Be aware that especially when it comes to wildlife, you will not get the same quality with the RX10III or IV or the Sigma as with the A7x/100-400 GM. The test images on this page clearly show it. And don't give away or sell your A7x to replace it with a RX10III/IV! As said before: the RX10 cannot replace any of the A7 models from my point of view. The full frame sensor alone with it's obvious advantages is worth to keep your A7x. Some people will try to tell you otherwise. But look at the facts and don't let them talk you into something you probably will regret.
For me personally it's absolutely clear: I will never buy a small sensor camera again! The convenience may be tempting, but the lower image quality and – what's even more important – the far fewer photographic possibilities (low light, DOF etc.) are a too high prize to pay.
For those who still claim that the differences are marginal or cannot be seen without pixel peeping there are two options:
- you may have a problem with your eyes
- you may need to get a better monitor
I do understand that all the above shown flaws and limitations are not a problem for many and that for them convenience is more important than getting better IQ and having more creative options. What I do not understand is when people simply deny the obvious...
I hope this page was helpful for you to make the right decision. One often forgets to think about important details and only sees the temptation of the "600 mm reach". But as shown above 600 mm is not always 600 mm... Or is it?
© 2017/2018 by ReBaFoto
Credits:
All photos by ReBaFoto, shot in the Swiss mountains in Lower Engiadina.