EM-5, Lumix 20/1.7, ISO 3200, VSCO Ilford HP5 preset

Started Nov 8, 2012 | Discussions thread
Anders W
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Re: EM-5, Lumix 20/1.7, ISO 3200, VSCO Ilford HP5 preset
In reply to Bob Tullis, Nov 9, 2012

Bob Tullis wrote:

Anders W wrote:

Nice shots Bob. I especially like the first and last.

As to banding with the 20/1.7 on the E-M5: Did you see this?

http://forums.dpreview.com/forums/thread/3285963

Yes, and let me start by saying I really do appreciate what you people ([g] the more technically adept with electronics) bring to the table. But when it got to oscilloscopes and PCBs, I gloss over (Bear Of Little Brain syndrome).

Well that thread turned into more of a dissection of the problem that I had anticipated. Thanks to excellent help from people who know more about electronics than I do (especially Detail Man and thinkfat) as well as from Roger Cicala of LensRentals, whose generosity is as boundless as his expertise with lenses (he volunteered to take the 20 and the 14 apart for us just so that we could have a look at their PCBs and AF mechanisms), I think we actually got some distance towards a better understanding of the cause. But I can certainly understand that digesting the full content of our discussions is not for everyone.

I thought I got from all that what I suspected anyway - the build of the 20/1.7 causes the problem, and for whatever the reason it can be compensated for by having the lens AF a half a minute or so. And it became clear last night (using a MF lens) that there is banding in the EM-5, but this is the only lens that commonly encourages the camera to exhibit it.

My problem is the habit to leave the camera off when not composing for an exposure. I just don't care to have the EVF keep the camera on when at my side or in the bag. But for the snow walk, and because the 20mm was oh-so appropriate (less lens mass to collect snow, small front element that's not as quick to get 'snowflaked' as a larger element), AND the fact I wasn't going to be out for hours and hours, I did leave the camera on. And for that the 20 performed well. I did have banding when I thought I was done and pulled it out to turn it on for a quick shot on the walk back.

Anyway - I read through more of your topic before responding, if there was anything else of significance then I missed it (I laid that all out to see if the summary in my mind was accurate).

My original intent was primarily practical: To help people find a useful work-around. And despite the fact that the best work-around is now scattered across several posts, you have found the essence of it.

Yes, exercising the AF mechanism a bit before shooting eliminates the banding, at least with my specific copies of lens and camera. This is not, we think, because the AF mechanism is the root cause on the lens side. Rather, we think it is some component on the PCB, most likely the voltage regulator. But using the AF motor draws current which in turn warms up the voltage regulator which in turn reduces or eliminates the problem. At least that's our idea at the moment.

If you start from room temperature, as I have so far done in my testing, this "warming up" period can be made quite short. Just let the lens go through five to ten ordinary AF cycles. And once "warmed up" it takes a while, in room temperature, before you need to repeat the exercise. I wouldn't think you need to do it again unless you have let the lens "cool down" for at least half an hour.

Disclaimer: All of the above is to be regarded as provisional knowledge at the moment. I provide no guarantees whatsoever that it will work with other people's equipment both because different copies of the lens and/or camera might conceivably behave in slightly different ways and because my testing or understanding might be in error and/or incomplete. All I can say is that it's worth trying or I wouldn't have bothered to post my findings.

I'd rather have a fast lens w/a 35mm FOV, though, and with the advent of one due soon I'm looking forward to not having to compensate for this issue. But thanks to you people, I was able to get satisfaction from the endeavor on that night.

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...Bob, NYC
http://www.bobtullis.com
/"Well, sometimes the magic works. . . Sometimes, it doesn't."/ - Little Big Man
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 Anders W's gear list:Anders W's gear list
Panasonic Lumix DMC-G1 Olympus OM-D E-M5 Panasonic Lumix G Vario 14-45mm F3.5-5.6 ASPH OIS Panasonic Lumix G Vario 7-14mm F4 ASPH Panasonic Lumix G 20mm F1.7 ASPH +18 more
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