Sirui AF 75mm f/1.2 - Lightweight Portrait
Sirui have been making lenses for around a decade now and their trinity of f/1.2 APS-C auto focus "Sniper series" lenses (23, 33 & 56mm), which came out last year, just got expanded with a 16 and 75mm. The latter being the most interesting to me (for wildlife and bokeh panoramas) with its full frame equivalency of 113mm f/1.8. Weighing a mere 425g it's the lightest lens of its type by far (as well as amazing value - €300). Let's see how much I can cut the weight of camera down by and what impact it will have on image quality...
Sony A5100 | Ducati | 41 image Bokeh Pano
Size & Weight
I really like 135mm lenses for photographing friendly wildlife. They give me a little reach (to keep some distance), while having fast apertures (for poor light / good subject isolation) and being relatively small (compared to a 70-200mm). This Sirui lens provides very close results to the full frame setup I am used to, while cutting the weight of the system in half! Saving weight with smaller sensor cameras usually comes at the expense of subject isolation (depth of field) and noise, due to smaller entrance pupil lenses, but not here!
Lens Entrance Pupils Compared
Sirui has managed to get this lenses size and weight down to that of an 85mm f/1.8, which is especially impressive when you realize its entrance pupil is larger than an 85mm f/1.4. Being a crop lens this a closer to something like a 105mm f/1.8 on full frame. This is still an unusual lens, but Nikon used to make an AI-S version. Compared to that the Sirui 75mm is: Smaller, lighter, sharper and faster while adding good auto focus and costing less new than what the second hand Nikon lenses tend to in worn condition!
Read on and judge the images for yourself, but I feel like this Sirui lens is capable of some pretty impressive results that rival much larger modern optics. Never before has "Having your cake and eating it" been so achievable - losing the crop sensor penalties, but keeping the size, weight and cost advantages. What kind of wizardry is this?
Sony A1 (full frame) | Red Squirrel | f/1.2, ISO 800
Image Quality
The above full frame image (shot @ f/1.2) shows how much extra you can get from the crop lens and where where the vignette starts to creep in. Manually correcting this (on crop / wide open) required the lowest amount of adjustment that I have seen from a fast lens like this. Mechanical vignetting (cats eye shaped bokeh shapes in corners) was quite noticeable, but not worse than most fast full frame lenses. There is quite strong lens flare, but chromatic aberration is quite well controlled.
So, is the image quality any good? The short answer is yes, sharpness generally delivers. The first caveat is a technical one on my part - there are no high pixel density Sony APS-C cameras to properly test this. 26mp is the highest resolution and I only have a 24mp one. To get the above image I used a 50mp full frame Sony A1, which provides 21mp from the crop area. The lens seems to max all these sensors out, which is great, but I can't say how this would be on a modern 40mp Fuji APS-C sensor.
Sony A1 | Baby Squirrel | f/1.2, ISO 200
There is a drop in sharpness when focusing very close and the aperture is wide open, although this is quite normal. Any closer than 1m (MFD is 69cm) I found stopping the lens down to f/1.6 improved the results nicely. Very out of focus backgrounds look pretty good and clean, however the transition from in focus to slightly out of focus specular highlights can look rather busy and less smooth (see squirrel image below). It's worth noting that this was only observed on the full frame Sony with electronic shutter, so I will keep experimenting with this to see if that had a baring on the effect.
Sony ZV-E10 | Baby Woodpecker | f/1.2, ISO 1000
Focusing
The 69cm minimum focus distance is great for wildlife. Matching the Sony 135GM lens, while its shorter effective focal length means it is slightly less capable for moderate macro work. The STM focus motors are pretty quick and very quiet. On the Sony A5100 (now ten years old) I was using the focus tracking with reasonable success (see above and below). It only has 179 PDAF points, so it's not able to follow small details, but it does a vastly better job than my pro DSLRs or first generation full frame mirrorless cameras do. This €200 camera pairs pretty well with the lens to make an extreme lightweight bargain considering its depth of field and auto focus ability.
Stepping up to the three year old Sony ZV-E10 bumps the number of PDAF points up to 425 and enables eye-AF subject detection (human and animal eye-AF), as well as general object tracking. This has been really enjoyable to work with and again the lens feels like it holds up pretty well. The experience here reminds me a lot of that from the original Sony A9, just without the sheer number of PDAF points and not quite as responsive.
Sony ZV-E10 | Red Squirrel | f/1.2, ISO 320
Build & Design
I assumed the Sirui 75mm would need to cut a lot of corners in order to get its weight down below 450g (1lb). They have left off weather sealing, switches, custom buttons and an aperture ring to help reduce weight (and costs), but apart from that it's not obvious how they've managed it. The construction feels solid, more so than the Samyang 75mm (although that does have a switch). The design uses a nice mix of materials and looks interesting (plus there are three colour options), although I'm not so keen on the look of the text and large chrome logo.
The biggest issue I have with the design is the shape of the lens where it sticks out, near the mount. This does not leave much room for your fingers on the Sony ZV-E10 grip. Sony are also at fault for not having much grip space, but Sirui should have considered this too. There are two quite sharp corners that hit my fingers right on the cuticles and knuckles (see below). This can be downright painful to hold at times, so I really hope that Sirui can address this on a redesign.
The focus ring grip and turn smoothness feel really good (focus by wire of course). Firmware updates are accessible to everyone through a USB C port on the bottom, which is a nice touch and is a pleasantly simple process. To be honest the only issues I had were with the included lens cap and hood. These could have been better designed as they're quite difficult to get on/off. It's also not flat on the front and thus I can't reliably put the camera down on the lens, is it just me that does that? It feels like it will fall over.
Sony ZV-E10 | Woodpecker | f/1.4, ISO 800
Value
With Samyang, Viltrox, Meike, 7Artisans, TTArtisans, Laowa, Yongnuo, Tamron and Sirui (did I miss any?) it's easy to get overwhelmed by all the great value 3rd party auto focus lenses coming out of [mostly] China lately (Samyang is Korean). However, I would advise anyone ignoring them on the basis of quality to reconsider. These models are improving quickly and some are very interesting!
It is difficult to overstate this lenses performance in the value category. Image quality, speed, build quality, auto focus, size and weight. Usually, when the price is as reasonable (low) as this, at least one of those things has to give way. However, other than a rather uncomfortable grip experience on the smaller Sony cameras and a lack of weather sealing there are no huge issues here.
Sony A1 | "Tiger" Squizzel :P | f/1.2, ISO 100
Conclusion
Sirui are not the first to make an auto focus 75mm f/1.2. Viltrox have had one for about 18 months, but that is 50% heavier and nearly double the cost! This is a version of Sirui's manual focus Cine lens that came out a few months ago. The AF 75mm's image quality in combination with its subject isolation and size / weight is what I find most impressive. The fact that they have made other Asian lenses look large, heavy and expensive is rather mind blowing. Getting similar results to my full frame camera and lens while carrying around half the weight and costing about 40% is simply incredible! I wish there were higher resolution APS-C Sony sensors, but I am seeing some issues here so maybe it's lucky and just maxing out these 24mp sensors.
Despite a rather uncomfortable grip and a really annoying warning message every time I knock the zoom rocker on the Sony ZV-E10, I think I have found my new travel camera setup, since it weighs only 768g (1.7lbs), in testing.
Sony ZV-E10 | Squirrel | f/1.2, ISO 400
Bokeh Panos
This technique (A-K.A. The Brenizer Method) involves stitching multiple images (with the same settings) to achieve a wider angle image with otherwise impossibly shallow depth of field and extreme sharpness. I used to be convinced that full frame cameras and lenses were the best way to maximize this effect even considering that they weigh more, but this lens has largely changed my mind.
I made this chart and the mathematics behind it a while ago. It's rather complex as it takes the raw potential (a lenses entrance pupil size) and divides it by its kilogram weight (including a camera). This gives any score that weighs under 1KG a boost. It then takes the focal length into consideration and penalizes those scores based on how many images are required to reach a specific end angle of view. When I plotted the Sirui 75mm onto the chart it got the highest score. It gets close to the raw performance of the very best full frame bokeh pano lenses (85/1.2, 105/1.4 & 135/1.8), but it weighs less than half what most of those do, that is insane! Although it's true that the camera that helps get it that score is rather old, most of the samples below are from that combo. If you put it with the newer ZV-E10 its score only drops a few points. Combine it with the Sony A6700 however and you might as well use a full frame combo.
I really like the effective 113mm that you get here for bokeh panos. For a long time I have been hoping someone would make a full frame 105mm f/1.4, as it would have been a great sweet spot for effect, workflow and results. This lens gets very close to that. If I could convince Sirui to make a 70mm f/0.93, or a 90mm f/1.2 APS-C lens that weighs less than 700g I would buy them in a heartbeat!
