Pentax / Chinon 50mm Lens Test 4


Somewhere along the way, I’ve ended up with no less than FOUR 50mm lenses that mount on my Pentax K-3.

50mm Lenses

Two Chinon 50mm f/1.9, a Chinon 50mm f/1.7 and a Pentax 50mm f/1.4

50mm lenses

Four fifties

Three were older Chinon lenses: two copies of the f/1.9 (both the same model, but one more modern than the other) and one a f/1.7. I’d acquired these with old cameras, but they come up frequently on eBay, generally for less than £20.  These are all fully manual lenses (that is, manual aperture and manual focus). I also own a Pentax SMC FA 50mm f/1.4. This is far from Pentax’s most modern lens, but does at least have autofocus and the ability to set the aperture from the camera body.

Four 50mm lenses is, for me at least, at least two too many. I decided to carry out a quick test to compare them, and pick two of the manual lenses to sell. For interest, I also took the same shots with my two standard zoom lenses set at 50mm. These are a Sigma 17-70mm f/2.8-4.0, and a Pentax SMC DA 18-55mm f/3.5-5.6 AL WR. This latter came as a kit lens with my camera and I find handy to hold on to because of its excellent weather sealing.

Five scenes

Our five scenes (as shot with the Pentax 50mm f/1.4, at f/2.0 and ISO 400)

I shot the same five scenes, twice, with each lens. All handheld and in Av mode (as this is how I shoot general scenes). For the first time I set the aperture as close as the lens would let me get to f/2 and at ISO 400. For the f/1.9 lenses, this meant an aperture of f/1.9. For the Sigma and Pentax zooms at 50mm, this meant f/4.0 and f/5.6 respectively. For the second sets of shots, I stopped down to f/8 and set auto ISO. For the manual lenses, I relied on the K-3’s focus confirmation – but otherwise I used autofocus where it was available.

Exposure and Distortion

The first thing I noticed was that the Chinon scenes came out rather dark. The three modern lenses (the Pentax 50mm f/1.4 and the two zooms) exposed as expected, but the old Chinons all came out about two-thirds of a stop darker. To my eye, I couldn’t pick up distortion from any of the 50mm lenses, and only a little from the zooms. In this respect, the Sigma was probably a little worse than the kit lens. I didn’t note any vignetting with any of the lenses.

Sharpness

Despite the focus confirmation from the K-3, I did miss focus in a couple of cases – as is to be expected with a manual focus lens. Of course, under ideal circumstances this could be avoided – tripod-mounting the camera and focusing in live-view, fully zoomed in. However I wanted my test to reflect the way I usually shoot – and that generally means handheld.

We expect prime lenses to be sharper than all but the very best zooms, so it was no surprise that all four of the 50mm lenses gave sharper results than the zoom lenses here. Of the zooms, the Sigma was appreciably sharper than the Pentax kit lens.

While I’d heard that the Pentax 50mm f/1.4 was perhaps less sharp than its cheaper and newer 50mm f/1.8 SMC DA stablemate, I was a little surprised that it was the softest of the 50mm lenses I tested here. The Chinon 50mm f/1.7 was also slightly softer than the f/1.9 lenses. However, the differences are only really obvious at wider apertures and when viewing the images at a large size. By f/8 the differences had disappeared and all the lenses were extremely sharp.

detail levels

100% crop – The range of sharpness seen in the test at ‘close to f/2’

Other Issues

The bokeh (the quality of out-of-focus areas of the image) was generally pleasing in all the lenses, but the Pentax 50mm f/1.4 had slightly octagonal bokeh balls, while the  Chinon 50mm f/1.7 had quite mishapen balls of light. Shooting wide open, the two f/1.9 lenses showed the best characteristics (as the other 50mm lenses might have done had we shot been shooting wide open rather than at f/2. However, I only very rarely shoot wider than f/2 even on lenses that can do it, because of depth-of-field issues).

The worst of the bokeh - shown at 40% size

The worst of the bokeh – shown at 40% size

Three of the lenses – the Pentax f/1.4, ONE of the Chinon f/1.9 lenses, and the Pentax kit zoom exhibited colour fringing at high contrast areas. In the 50mm lenses, this behaviour was quickly eliminated by stopping down. However, in the kit lens it persisted at all apertures.

colour fringing

Lens Test Conclusion

While in some respects the Pentax 50mm f/1.4 appears the weakest of the 50mm lenses it’s still a keeper. The additional low-light performance of the wider aperture, and more importantly the added convenience of autofocus and camera-set aperture, outweigh the differences in sharpness for most situations. In addition, I’m holding on to the newer of the two 50mm f/1.9 lenses. It’s sharper than the other two Chinon lenses, and displayed no colour fringing.

The other two Chinon 50mm lenses, while extremely sharp and giving overall good image quality. are redundant and now heading for eBay.


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4 thoughts on “Pentax / Chinon 50mm Lens Test

  • John

    Hi Neil,

    I’m the chap that’s bought the aforementioned Chinon 50mm f1.7 off Ebay! Its intended purpose is for video work oddly enough, using my GH1. I have an M43-PK adapter, but also intending to get a speed booster to improve the focal length and increase the exposure for low light work. Anyway impressed with your blog anyhow, so thought it would be useful to sign up. If you have any more cheap primes you want to sell, especially with low f-value (I am looking for a 50mm f1.4 ideally), please get in touch.

    Thanks in advance,

    John

    • James Robins

      Given your setup, John, you should strongly consider going with the m-series Pentax 50mm f/1.4. Extremely smooth, and the center look for cine is absolutely great. I have no idea how well it will take to a speed booster. I’m not sure anything beyond 1.7 will perform great with those.

      Just to give you an idea about this lens – as shot on a Q (5.6x factor):
      http://albums.phanfare.com/isolated/Or4t8kw7/1/5972173#imageID=181775651

      Also, nicely done on the lens analyses. Also agree on the K-3. Family moved me off Pentax as a milestone gift – 20D and 5D later – but I came back mostly to Pentax for similar reasons as you post by the time of the K20D – and now the K-3 has finally caught up (surpassed) the 20D for AF capability. If only you could find anything comparable to the Canon 200/2.8 – that I miss shooting.

      • ngratton Post author

        Another comment to the above; I was shooting boxing last Saturday night. While boxers don’t move too far – I took over 1,500 frames and only missed focus on three (and they were probably down to user error). I’m pretty happy with the focus system.