Review of 7Artisans 7.5mm Fisheye Lens for Micro Four Thirds

A newcomer to the Micro Four Thirds scene, the Chinese lens manufacturer 7Artisans recently released two inexpensive manual-focus prime lenses for the system: a 7.5mm f/2.8 fisheye and a 25mm f/1.8 lens.

Today we will take a look at the 7.5mm fisheye.

Unboxing

The lens was well-packaged, in an understated black box with a coated-on-matte black print design. It comes with a carrying bag, front and rear slide-on lens caps, and instructions in Chinese.

Manual Focus

Manual focus is not really a detriment to this lens – it is probably the best choice for fisheyes anyway. When stopped down and set to the hyperfocal distance, fisheye lenses are pretty much “set it and forget it” as far as focusing goes. Also, there is typically so much information in a fisheye scene, most cameras would have difficulty deciding what to lock focus on.

Both the focus action and aperture adjustment are smooth and solid feeling.

Aperture Ring

The aperture ring has no hard stops – it can be adjusted from f/2.8 to f/22, but you must eyeball it when you line it up with the number markings.

Sharpness and Chromatic Aberration

To test the lens, I took a picture of a brick wall with sky and some leaves in the corner.

The pictures below are 50% out-of-camera JPEG crops at different apertures.

f/2.8 Corner

f/2.8 Center

f/4 Corner

f/4 Center

f/5.6 Corner

f/5.6 Center

At f/2.8 through f/5.6, the lens is somewhat soft in the center and there is quite a bit of chromatic aberration in the corners, although sharpness starts to improve as you stop down.

f/8 Corner

f/8 Center

At f/8, chromatic aberration slightly improves and the center becomes the sharpest.

f/11 Corner

f/11 Center

By f/11, the center loses perhaps a little sharpness but the corners look the sharpest yet. Some of this could be attributed to the characteristics of the lens, but it could also be the result of increased DOF. The corners of a fisheye can end up resolving objects in widely varying focal planes, even when shooting a relatively flat scene. Chromatic aberration is also best controlled here.

f/22 Corner

f/22 Center

By f/22, refraction kicks in badly and everything loses sharpness across the board.

I would guess the sweet spot of this lens to be somewhere between f/8 and f/11, which is surprisingly high for a Micro Four Thirds lens. Since there are no hard aperture stops, you could simply eyeball the spot between the f/8 and f/11 markings on the lens (approximately f/9.5), set focus to the hyperfocal distance, and leave it there for everyday shooting.

At f/9.5 on a Micro Four Thirds sensor, the hyperfocal distance is 0.4m, or 1′ 4″.

Lens Flare

Pointing directly into the sun, this lens controls flare quite well, with minimal loss of contrast.

I did notice some internal reflections (red and cyan spots, perhaps from the lens coatings) in certain situations involving bright overhead sunlight. See the image below for an example.

More Sample Images

These images have undergone some minimal post-processing in Lightroom, mostly to demonstrate how much CA could be cleaned up (answer: quite a bit, but you will need to push the sliders to their maximum value).

Conclusions

This lens is not for everybody. If you are looking to get a wide fisheye at an inexpensive price point, and can look past its flaws, it could be for you. It works best under bright yet well-controlled lighting conditions.

With so much chromatic aberration at the corners wide open, this lens is probably of limited use for astrophotography — unless you are willing to stop it down, give up much of its light gathering abilities, and use it with a star tracker.

While it may not be able to compete with more expensive fisheye lenses, the 7Artisans 7.5mm f/2.8 is a decent value for the money. I did have more fun shooting with it than expected. At some point down the road, I may try the Rokinon 8mm f/3.5 or step up to the Olympus 8mm f/1.8 Fisheye PRO. For now, I plan to keep the 7Artisans lens in my bag – I expect I’ll see more opportunities to take advantage of its unique perspective in the future.

The 7Artisans 7.5mm Fisheye Lens for Micro Four Thirds is available on Amazon.com

5 thoughts on “Review of 7Artisans 7.5mm Fisheye Lens for Micro Four Thirds

  1. Thanks – I liked this review.

    Can I point out the problem with common complaint of “out of focus edges” in fisheye pictures – such as the shot of the wall. The distance from the lens to the image centre is significantly closer than to the image edges. On a M4/3 camera this lens would cover a 160 degree field of view, on a APS about 180 degrees. This effect is geometrically larger for wider angle lenses and is inherent in all optical designs. This is why moderate telephotos make better macro-lenses than wideangles.

    If you focus for the edges with this fisheye – they will sharpen up – but of course the centre is then out of focus.

    The fisheye lens design was developed originally for astrophotography – where this is no problem. Now that such lenses are affordable we use them in different settings for an artistic effect.

    So – when using this lens – remember:
    [1] curved settings will focus well across the frame.
    [2] When shooting close up – focus on the object itself – not just the field centre.
    [3] Use the lens stopped down to its limit before diffraction steps in (between F8 and F11 for this lens).
    [4] For distant images such as landscapes – worry less about focus points across the field of view.
    [5] For close ups – put the object in the field centre if you want the best image effect. Placing the object at the field edges may work artistically – but don’t expect sharpness across the frame.

    I have just bought this in its “generic” chinese version (&-Artisans seems to be one of about 6 “brands” this lens is sold under. Each version has a small dofference in detail but not lens and diaphragm arrangement or overall dimensions. Can I recommend that readers try out the free “Hugin” software for panoramas – which also works to “de-fish” this lens to turn it into a 160mm wide rectiliner lens. Just google for instructions – and trust me, it turns out to be simpler than it looks. Just type in 160 degrees if you use a M4/3 camera, and 180% if you use an APS one.

    best wishes to you all – Paul C

    • Paul, thanks for the reply! The point you bring up about out of focus edges is what I was trying to allude to when I said “The corners of a fisheye can end up resolving objects in widely varying focal planes, even when shooting a relatively flat scene”—but you explained it better 🙂

      Perhaps I should say because it’s a flat scene, the corners are more likely to be out of focus.

      Thanks for the Hugin suggestions, as well. I have used it for panos in the past, but not defishing yet. I’m looking forward to giving it a try.

Leave a Comment

This site uses Akismet to reduce spam. Learn how your comment data is processed.