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Archive 2015 · Pentax 67 lenses on Sony A7r -- are you seeing shutter vibration?

  
 
rdeloe
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p.1 #1 · p.1 #1 · Pentax 67 lenses on Sony A7r -- are you seeing shutter vibration?


I'm looking for insights from people who are using Pentax 67 lenses on Sony A7r cameras (not A7, A7 II or A7r II). I'm specifically interested in how the 55mm f/4 Pentax 67 lens is affected by the A7r shutter vibration problem -- but experiences with other Pentax 67 lens are welcome (e.g., 75mm and 90mm primes, 55-100 mm zoom).

I won't be moving to an A7R II for a while, if ever, so I need to get the most from my A7r. That means managing shutter vibration. I've been testing extensively during the past week and now have a good idea how my own equipment is affected. All of the following results are in portrait orientation (which I find myself using very often). Note that with the Canon FD lenses, the camera mounts to the tripod on its L bracket. With the Pentax-A lenses, I'm using dual Mirex adapters, and the first Mirex adapter is mounted to the tripod; the camera hangs off the second adapter. This is of course the ideal "worst case" scenario for A7r shutter vibration!

* Among my Canon FD lenses, the FD L 20-25 f/3.5 and the FD 17mm f/4 are not subject to the vibration problem on my setup at any shutter speed. However, the 50mm f/1.4 and the 100 mm f/2 are extremely sensitive from 1/125 second to 1/4 second. All my FD lenses are perfectly fine on my Sony A7.

* I have three Pentax-A 645 lenses that I use on my A7r with dual Mirex adapters. (Results are the same on my Fotodiox P645-NEX adapter, so it's not the Mirex adapters.) The Pentax-A 35mm is totally immune to vibration problems based on my tests. The Pentax-A 45-85mm is fine at 45mm, but shows blur increasingly strongly towards 85mm in the range of 1/125 to 1/4 seconds. The 150mm shows it very strongly too.

For the lenses that show vibration issues, I use Joseph Holmes' "deadweight" solution; a deadweight clamps to the L-bracket and absorbs the virbration. It's a bit kludgy, but it works.

I'm intrigued though that the 35mm Pentax-A lens is not affected at all, whereas my Canon FD 50mm is severely effected. Would big, heavy Pentax 67 lenses (in particular the 55mm f/4) behave like my 645 35mm lens, in other words, focal length short enough and lens heavy enough that it's not affected by vibration. I use the 55mm focal length a lot; it would be nice to have one more lens where I don't need the deadweight. If the 75mm and the 90mm are also unaffected, I could avoid the deadweight most of the time...

Rob



Sep 14, 2015 at 03:13 PM
molson
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p.1 #2 · p.1 #2 · Pentax 67 lenses on Sony A7r -- are you seeing shutter vibration?


Hopefully you've changed out your camera's lens mount to a tough e-mount, or are using a lens adapter with a built-in tripod mount (or ideally, both...). Otherwise, you're likely to bend or tear out the lens mount by mounting those heavy 67 lenses on the camera.


Sep 16, 2015 at 07:21 AM
rdeloe
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p.1 #3 · p.1 #3 · Pentax 67 lenses on Sony A7r -- are you seeing shutter vibration?


Yes and Yes!

The camera has the Tough-E mount, and the whole assembly is attached to the tripod via the tripod foot on the P645-EOS Mirex adapter. The camera mount is therefore only carrying the weight of the camera and an aluminum L-bracket. The L-bracket is basically just a "roll cage" most of the time -- except when I have to attach a deadweight to absorb shutter vibration with certain lenses.

I'm with you on the risks of mounting the camera to the tripod with this kind of rig. I've seen it done, but I don't think it's a good idea to put that much load on the camera mount. It's also borderline too much weight for the Mirex adapter (which starts tilting on its own unless you tighten the screw all the way down).



Sep 16, 2015 at 08:40 AM
alwang
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p.1 #4 · p.1 #4 · Pentax 67 lenses on Sony A7r -- are you seeing shutter vibration?


I'd love to see some photos of this combination. I have a P67 with a 105/2.5 and 55/4, but I haven't tried shooting them much with my A7, other than a real quick test.


Sep 18, 2015 at 12:28 PM
jharter
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p.1 #5 · p.1 #5 · Pentax 67 lenses on Sony A7r -- are you seeing shutter vibration?


I used to have several Pentax 67 lenses: 45, 75, 90, 135 macro, and 200. They were excellent on the P67II. I bought an adapter for the A7r but the Pentax lenses were comparatively huge. Never had vibration issues but I did not check for every lens. Also, I tried them handheld because of the imbalance on a tripod. In then end, I sold them all. Would be nice to see photos on the A7r with those lenses. I don't think many people are using them with A7r.


Sep 20, 2015 at 09:40 PM
rdeloe
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p.1 #6 · p.1 #6 · Pentax 67 lenses on Sony A7r -- are you seeing shutter vibration?


Pictures of these lenses don't do justice to just how big they are! I keep reading how amazing the 55mm P67 lens is (late version). One of these days I may bite the bullet and try it out.

In the meantime, the more I use the P645 45-85mm f/4.5 the more impressed I am. It's a bit softer at the 85mm end than at the 45mm end -- but only in side-by-side comparisons of ISO charts. In real world shooting, it's a fantastic lens. Using it on the Mirex adapters gives me a huge amount of flexibility in terms of movements.

Incidentally, there are a lot of posts from people who use Mamiya 645 lenses with Mirex adapters, but not many with Pentax 645. If there's interest I was considering putting together a post with some images and notes for people who want to try out the Pentax route with dual Mirex adapters. I found it very hard to scrounge up detailed information about the adapters, especially some of their quirks.



Sep 21, 2015 at 08:17 AM





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