Adapter with aperture (iris) for Pentax Auto 110 mount

glasslover · Expire: 2013-10-19

Hi!

I like the Pentax 110 lenses. The quality is surprisingly good on m43, and they are really tiny! But they are fixed at f2.8, which limits their use considerably. I was not the only one who noticed this issue, and in fact several people came up with DIY solutions to the problem. These showed the potential of the lenses to me, but the solutions were difficult to make, or fiddly or difficult to use, so I didn't go the DIY route. Now one of the Chinese manufacturers has made an adapter with a built-in iris, much line the Canon EF adapters that have been coming out recently.

The differences between putting a rear iris on an EF lens or a pa110 lens are important, though:
1. The Pentax Auto 110 camera had its iris behind the lens, so these lenses are presumably built to have an iris behind them, and so are likely to give good performance set up that way; and
2. Did I mention that the pa110 lenses are tiny? The "standard" kit of 18mm, 24mm, 50mm pa110 lenses, a (less-common) Soligor 1.4x teleconverter, and (non-irised) unbranded pa110->m43 adapter--all with lens caps--weighs only 155g. That's not much. The 70mm lens adds an additional 180. Just to put it in perspective, the Panasonic m43 14-42 kit lens--which people have complained is very plastic-y and insubstantial-feeling, weighs in at 195g.

Here is the new adapter. I have no idea what it weighs, but it can't be that much:

http://www.rjcamera.com/ocart/index.php?route=product/category&path=20_27

I'm very much looking forward to its arrival.

Cheers!
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DigiChromeEd · Joined: 29 Dec 2009 Posts: 3462 Location: Northern Ireland

http://forum.mflenses.com/pentax-110-adaptor-with-a-difference-t48915,highlight,%2Bpentax+%2B110.html

glasslover · Expire: 2013-10-19

Hi!

Yes, that was a great post, and it started me on this route. But nothing in it talked about the weight of the kit, which I think is critically important to thinking about these lenses.

glasslover · Expire: 2013-10-19

Hi!

The adapter showed up, but unfortunately it didn't allow my 18mm lens to focus to infinity. That same lens focuses just fine on the non-irised adapter I have. In fact, the lens wasn't able to focus beyond about 2m. After a little back-and-forth to verify the problem, the seller is sending me a new one, that he promises will work correctly. I'm hoping it does.

Cheers!

glasslover · Expire: 2013-10-19

Hi!

These shots were taken with the adapter with iris. They are all with the 18mm lens, scaled to exactly 1/4 size of the original photo, with screen sharpening set to "low" in Lightroom. All of the photos in this post are of the same scene, taken over a period of about two minutes. All are at ISO 400 on a Panasonic GH2, which is probably not the very best for showing absolute detail. I think that my focus wasn't perfect, however focus was always supposed to be on the dog on the sleeper on the clothesline, found in the center of each photo.

The adapter's iris has no click stops--of course--so I did f-stop approximation with shutter speeds in aperture priority mode. I do notice a bit of vignetting, clearly caused by the irised adapter, since the vignetting does not occur with my non-irised adapter. I think the vignetting will be fairly easy to fix in post-processing.

All in all, I'm satisfied. I think that this adapter allows me to carry a very small and low-weight prime lenses kit, have some fun, and perhaps take some good pictures.

#1 1/1600s (f2. Cool

(widest aperture available)

#2 1/1250s (~ f3.2)

#3 1/1000s (~f 3.5)

#4 1/800s (~ f4.0)

#5 1/500s (~ f5.0)

#6 1/320s (~f 6.3)

#7 1/200s (~ f8.0)

#8 1/125s (~ f10.0) (narrowest aperture available)

PS: I took the same shots also with the 24mm, the 50mm, and the 70mm. Posts, including 100% crop, will follow as time allows.

Cheers!