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Pincushion Distortion in Sony’s E 18-105mm f/4 – and Other E-mount Lens Musings

This is a guest post from Hugh Brownstone. To write a guest post follow the instructions on that page. Thanks!

6/21/16 UPDATEhttps://youtu.be/cMJLXqtR7HQ

Sony’s 18-105 f/4 did the business for me at a recent presidential campaign rally, but when I used it to shoot my latest review (first time I’ve ever used it for this purpose: a tightly controlled, familiar environment), I noticed significant pincushion distortion. Whaaat?

The Lenses

The kit lens for Sony’s FS5 is this Sony E PZ 18-105mm f/4 G OSS.  Excellent range — wide enough at the low end to be the full-frame equivalent of a 27mm, long enough at the top end to be the full frame equivalent of 158mm. Of course, the full-frame equivalent maximum aperture is f/6 — but you can get surprisingly good results across the board. Except…

I’m already on record as a fan of Sony’s E PZ 18-105mm G OSS f/4 [B&H|Amazon] – not a raving fan, mind you (the way I am of Sony’s new 85mm f/1.4 G-Master  [B&H|Amazon] or even my favorite daily shooter, Sony’s $248 E 50mm f/1.8 OSS  [B&H|Amazon]) — but as a pragmatic, straightforward choice when covering live events.

The new Sony FE 85mm f/1.4 G-Master [B&H|Amazon] is the sharpest, most bokehlicious lens at I’ve ever used. Other than high price (an issue for many) and lack of image stabilization (not much of an issue for the a7r II [B&H|Amazon] or a7s II [B&H|Amazon], but an issue for every other non-IBIS Sony body) it’s just about perfect.
Incredible lens for the price (less than $250 at [B&H|Amazon]), the Sony E 50mm f/1.8 OSS is the single lens I use most often.
On the other hand, the 85mm f/1.4 doesn’t have lens image stabilization. But in a rare instance where Zeiss is a relative bargain, you can get the image-stabilized Batis 85mm f/1.8 [B&H|Amazon] — another fantastically sharp, not-quite-as-but-still-bokelicious prime — for a third less than the G-Master. I think the Batis is a better choice for the FS5, FS7 and a6300, since they don’t have in-body-image stabilization like the a7x II series.
With my  a6300 [B&H|Amazon] mounted on the gimbal I was reviewing a few days ago, I decided I’d use the Sony FS5 [B&H|Amazon] loaner I have on hand with the PZ for the talking head portion of the review. That’s when I was astonished to see what I can only call severe pincushion distortion, something I hadn’t experienced with Sony’s E 50mm f/1.8.

Seeing the Problem for the First Time

My typical set-up is the Sony a6300 with Sony E 50mm f/1.8. Notice the table top – you have to look very hard to spot any pincushion distortion – I’m not sure I see any (I may not have gotten the tripod precisely level).
On the other hand, this was shot with the FS5 and the PZ 18-105mm f/4. Look at that table edge again. Crikey! Yes, I used a different lighting set up, and no, I’m not noticing the pincushion distortion in this shot – that reaction is really my fear that the gimbal I was reviewing might topple over.

I decided to shoot a different subject to replicate the issue (an incredibly photogenic mid-century garage door which looks like it hasn’t been painted since 1954 – I think maybe that’s right) and compare the result with Sony’s 90mm f/2.8 Macro G OSS [B&H|Amazon].

 

This Sony FE 90mm f/2.8 G Macro OSS is what I bought with my own money. Sharp, close-focusing and just about half the price of the 85/1.4 GM [B&H|Amazon]. No, it doesn’t have the bokeh. But it has image stabilization.
Results

Even if it’s 60+ years old, I’m telling you: the garage door doesn’t look like this. It’s square.

WHOA! Screen grab from Sony FS5 with Sony E PZ 18-105mm f/4 at about 50mm. I ‘m amazed at the level of pincushion distortion. I suspect this is a design issue, rather than copy-to-copy variation. I hope I’m wrong.
Screen grab from Sony FS5 with Sony E PZ 18-105mm f/4 somewhere between 90 and 100mm (I wish the FS5 would display the focal length, rather than percentage or simple bar). It’s less obvious, but the pincushion distortion is plainly visible. On the other hand, it’s nice and sharp at the center.
Screen grab from Sony FS5 with Sony FE 90mm f/2.8 G OSS has no visible distortion and great edge to edge sharpness. I tried these at a couple of different apertures – this happens to be wide open at f/2.8. Yum. Internal neutral density filters are wonderful!

Yes, in this day and age it’s often the case that lens imperfections can be corrected in-camera through software, but the PZ didn’t give me that option when I mounted it on the a6300 (the E 50mm f/1.8 did). If the FS5 has lens compensation, I couldn’t find it. In this quick test it was therefore native lens performance vs. native lens performance, 18-105 vs 90.

Would you expect to see differences?

Of COURSE!

The 90 is a macro, after all, and it is an optimized single focal length lens twice the price of the 18-105. Again, to my eye, the 90 exhibited absolutely no distortion. On the other hand, to the 18-105’s credit, there was little to set them apart for center sharpness.

I just didn’t expect to see this much curvature.

Takeway

Sony’s E PZ 18-105mm f/4 has a much more useful zoom range for APS-C and Super35 cameras than another Sony lens I do love, the FE PZ 28-135mm f/4. It’s also much lighter, much less conspicuous, and 1/4 the price of its much bigger brother. In a live, fast-moving event, I didn’t even see this imperfection and hope it’s a copy-to-copy variation. I suspect it is not. I do have a note into Sony about it.

I loved Sony’s FE PZ 28-135mm f/4 G OSS. It’s the nicest manual focusing autofocus lens I’ve ever had in hand. [B&H|Amazon]
Even so, I’ll keep my “it does the business for live events” recommendation for the 18-105 because out in the real world of people, I didn’t notice the distortion at all.Still, I also wanted to share with you this new learning — and maintain my “I’m a prime kinda guy” bias.

Oh – one other thing: even though the Sony 90mm f/2.8 G Macro OSS is magnificent, sliding the focusing ring into manual focus mode doesn’t change the fact that it’s fly-by-wire with a very short throw. It isn’t an alternative to Veydra’s silky smooth 85mm T2.2 Mini Prime in E-mount  [B&H|Amazon] — though on the flip side, the Sony doesn’t have the minor-but-visible-without-pixel-peeping lateral chromatic aberration I saw. Again, I hope this was the result of copy-to-copy variation, but without additional samples, I can’t tell.

The Veydra 85mm T2.2 is a real, beautifully weighted, creamy, long-throw geared cine lens for Sony Super35 E-mount and Micro Four Thirds mount cameras for less than $1,000 
Closing Thoughts

Fascinating. With Sony’s current line-up, their absolutely best glass (e.g., FE G-Master series, 90mm f/2.8 Macro, FE 28mm f/2.0) is optimized for their full frame cameras rather than their more expensive dedicated video cams.

And their best sensors are in their hybrid cameras (the a7 series and the a6300).

Gawd, I’d love to be a fly on the wall of their product roadmap and long-term strategy sessions. I think lighter weight, high-quality crop sensor primes would sell like hotcakes, but maybe that’s not the goal.

What do YOU think?

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