A short while ago, we reviewed the Viltrox AF 28mm f/4.5 in Sony E-mount. The lens has just been released in Nikon Z mount, so let’s give it a quick revisit here.
As you may spot from the product images, we are talking about a full format pancake lens here. It offers both autofocus and electronic coupling, but it also has a fixed aperture. f/4.5 it is. No more, no less.
The build quality of the Viltrox AF 28mm f/4.5 VCM is fine, although you can feel that it was made to a budget. It does, however, feature a metal mount, whereas the tiny lens body is made of plastic. Another oddity besides the lack of a (changeable) aperture is the lack of a focus ring – AF is all that you’ve got here. The threaded part on the barrel is only meant to support you with the mounting/unmounting of the lens. You may also spot a USB-C port on the rear of the lens – meant for firmware updates.
Despite the tiny size, Viltrox managed to add a sliding lens cap that you can engage via a lever. The lever doesn’t feel super sturdy, but it does the job. As you may imagine, a lens hood is not provided because it somewhat contradicts the concept of a pancake lens. There’s also no filter thread.
Typical for most pancake lenses, the AF uses an extension system to shift the “whole” optics for focusing. It’s not a speed demon on our oldish Z7, but it does the job.
| Specifications | |
|---|---|
| Optical construction | 6 elements in 6 groups (2x ED, 2x aspherical) |
| Number of aperture blades | Fixed (7 edges) |
| min. focus distance | 0.32m (max. magnification 1:9.1) |
| Dimensions | φ60.3 × 15.3mm |
| Weight | 60g |
| Filter size | – |
| Hood | – |
| Other features | Lens cap slider |
Distortions
Let’s start with something positive—image distortions. Unlike the Japanese manufacturers, Viltrox is (almost) fully correcting its lenses (to date, at least), so image auto-correction isn’t necessary. This is good because distortion correction is a lossy procedure. The 28mm f/4.5 has a slightly wavy distortion, which Imatest identified as pincushion distortion – which you can debate or not. In any case – it’s not much.
Vignetting
The vignetting is quite heavy in RAW images with a light falloff of 2.4 EV (f-stops). Surprisingly, Viltrox walked the extra mile here and implemented a correction profile, which cuts this down by almost 50%. Stopping down is not supported, so that’s a short chapter here.
Please note that the values are slight lower compared to our Sony E-mount review. This relates to the different tone curve used by Nikon.
MTF (resolution) at 45 megapixels
The resolution characteristic of the VIltrox lens is mixed on a high-resolution sensor. The broader center performance is surprisingly high, with very good results in the dead center and just a little less near the center. However, there’s a sharp drop beyond. The border quality is lower – albeit still quite decent- whereas the extreme corners are soft. It’s a bit of a pity that you can’t stop down the lens here – because it would certainly be much sharper at f/8.
The centering quality of the tested sample wasn’t great. A better sample could have produced higher results.
Please note that the MTF results are not directly comparable across the different systems!
Below is a simplified summary of the formal findings. The chart shows line widths per picture height (LW/PH) which can be taken as a measure of sharpness. If you want to know more about the MTF50 figures, you may check out the corresponding Imatest Explanations.
Chromatic Aberrations (CAs)
Lateral CAs are reasonably well managed at the image borders, but they do increase in the image corners. A good RAW converter should be able to handle this, though.
The values are somewhat different compared to our Sony E-mount review. This relates to sample variations.
Sample Images
The related Sony review of this lens has some further sample images. Due to the bad weather that we had lately, there wasn’t enough time to produce more on Nikon.
The Viltrox AF 28mm f/4.5 VCM Z takes the pancake concept to the extreme. Short of the infamous "lens caps" that incorporate a tiny lens, we haven't seen another lens this small. However, the small size does come with some compromises. Performance-wise, it can't compete with conventional lenses on a high-resolution sensor. The broader center quality is actually pretty good, and the borders are quite acceptable, but the extreme corners are soft. Image distortions are surprisingly low, whereas vignetting does benefit from auto-correction. Lateral CAs are fairly high in the image corners as well. Stray light can be an issue in scenes with bright light sources.
The build quality is generally good. Surprisingly there's a metal mount and the quality of the plastic for the body is decent. The tiny built-in lens cap mechanism feels a bit flimsy, but it's good to have it on board. Other than that, there isn't much to report here. There are no buttons nor control rings on the lens. The AF is works fine without excelling. Manual focusing is not supported.
A fixed aperture of f/4.5 is quite exotic for a 28mm lens. As such, it's certainly not meant for landscape photographers because at f/4.5 the foreground just won't be sharp in infinity focus scenes. If you want high corner-to-corner quality, it's also not for you. There are, however, scenarios where this lens could be useful - 4K video is just about 8 megapixels and the Viltrox lens can do that. If you are looking for a lightweight lens for "talking & walking head"-style YouTube videos could be another one. f/4.5 won't matter much here. And, of course, there's street and social photography, where you tend to shoot quickly just to capture the moment. So if it fits with your shooting style, the Viltrox AF 28mm f/4.5 VCM Z could be a fun option - especially at this price point.
Viltrox lenses can be purchased via the Viltrox online store (enter KS28CHIPZ5 for a little discount) or the usual suspects such as Amazon or B&H.
The Good
- It's cute
- It's fun
The Bad
- The extreme corners
- No focus ring
- Fixed aperture
- Flare issues in certain scenes
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Optical Quality
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Build Quality
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Price / Performance