GH2 12-35mm X - Constant Aperture through Video Zoom?

Actually 12-35's price is pretty decent. It may seem 'expensive' but compare it to other lenses with the same comparable focal length, and its fairly priced.

Can anybody post a really good zoom that has the same focal length, constant aperture and parfocal? Then compare how much that is compared to this lens.
 
dcloud said:
Can anybody post a really good zoom that has the same focal length, constant aperture and parfocal? Then compare how much that is compared to this lens.
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The discontinued Sigma 15-30mm f3.5-4.5 is about as close as you can get with a Nikon-mount lens that has a manual aperture ring. Among lenses without aperture rings, the Nikon 14-24mm f2.8 is around $2000. Slower and cheaper alternatives are the Nikon ($1100) and Tokina ($600) 12-24mm f4 zooms, which likewise have no aperture rings.

The iris flickering that you see when zooming the Lumix 12-35mm is an inherent aspect of its electronic design. Unlike manual-focus parfocal zooms, Lumix and Zuiko electronic lenses have no physical mechanisms to maintain a constant f-stop as the lens is focused and zoomed. Lumix lenses rely on the camera to continuously monitor and adjust the iris of the lens to simulate the selected aperture setting. Unfortunately, the camera often fails to do this seamlessly in real time, and transient glitches may appear as a result.
 
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Lpowell said:
The iris flickering that you see when zooming the Lumix 12-35mm is an inherent aspect of its electronic design. Unlike manual-focus parfocal zooms, Lumix and Zuiko electronic lenses have no physical mechanisms to maintain a constant f-stop as the lens is focused and zoomed. Lumix lenses rely on the camera to continuously monitor and adjust the iris of the lens to simulate the selected aperture setting. Unfortunately, the camera often fails to do this seamlessly in real time, and transient glitches may appear as a result.
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Even with a fixed focal length legacy lens, with mechanical (not electronic) aperture ring and therefore fixed lens aperture, with the GH-2 set on supposedly locked aperture, camera itself changes exposure if I simply pan through differently lit parts of a scene. So it does seem, as Lpowell suggests, that this undesirable (for video) flickering effect may indeed be a flaw, where video is concerned, in the camera itself. That is, it seems as if there is not really any lens that can cure the problem. Is there no patch or fix that can defeat this, or instruct or fool the camera into knocking off these automatic adjustments? If not, it would be great if somebody - Panasonic, ideally, but failing that, somebody else with the programming skills, if this dynamic isn't in effect hardwired into the camera - would come up with a cure.

This auto-adjust-type flicker effect reveals the still picture bias of the camera's design. I'm loving the GH-2 for video despite this - it's a powerful tool for video recording, especially for the price, but it's a silly design flaw that I would've thought could be designed to allow for exposure-locking override.
 
WhatAndGiveUpShowBusiness said:
Even with a fixed focal length legacy lens, with mechanical (not electronic) aperture ring and therefore fixed lens aperture, with the GH-2 set on supposedly locked aperture, camera itself changes exposure if I simply pan through differently lit parts of a scene.
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Really? I've never seen that with my legacy lenses. (Depending on setting the viewfinder may adjust, but my footage itself stays constant.)
 
GrahamH said:
Really? I've never seen that with my legacy lenses. (Depending on setting the viewfinder may adjust, but my footage itself stays constant.)
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Dude, thank you so much for that post. It made me go back to testing this again by recording video with an old 50mm (100mm, in effect) Nikor lens, fully expecting I would report that yup, still getting flicker. And initially, was getting the flicker as I panned from the interior of my living room up to the windows (more luminous than interior lighting, even on this overcast day). But then it occurred to me to hit the "AF/AE lock" button on the back of the camera, and lo and behold, no flicker. Exposure in the viewfinder (and in in-camera playback) steady as she goes.

Although I have not yet been able to find any AE lock and/or manual aperture control setting configuration that will prevent the flickering adjustment from happening with my Panasonic 14-140mm lens -- the one designed for GH-2 compatibility -- you've now given me hope that I may be able to eliminate flicker in video recording forever, for example by as simple a move as buying an adapter for my wife's 28-75mm (which would become 56-150mm) legacy lens! That would be totally awesome! I'll be sorry that it will probably motivate me to use the 14-140mm lens less and less, and I'll lose OIS capability, but so be it. Just gotta have that steady exposure for video.

Nice avatar, BTW.
 
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Glad to help. I have the 28-75 Tamron, which I like using on sticks for interviews. The lens I prefer, though, is the 17-50mm Tamron - a bit sharper, a bit less flare, easier to hand-hold.
 
Just got my 12-35 and am sadly going to have to return it too due to the flickering during zooms. Happens on GH3 and AF100. I do fair amount of "Office" style interviews with snap zooms with my Nikon 17-35 2.8. I was hoping to sell that lens in favor of the Lumix. Oh well.
 
Okay, been playing with a legacy (non-electronic) 28-80mm zoom lens, and though I love being able to eliminate exposure flicker, I've continued playing with my kit Panasonic 14-140 lens. Because the 10:1 zoom range on that thing is so useful (and buying a legacy lens with comparable range is out of my current budget), I hate to have to give up on doing live zooms while recording video with it due to the nasty flicker effect. And I just wonder whether (as I've mentioned in this thread before) a software hack is possible. Something somewhere is telling the lens or camera to change some exposure setting; since that flicker doesn't happen with legacy lenses with mechanical aperture rings and aperture set on "AE lock" in the camera, in theory there ought to be a way to tell the camera to treat the kit lens the same way, or to let the two work together to choose an aperture setting and stick with it. I don't write code and so cannot begin to create such a hack, but perhaps someone else (or Panasonic) can. We'd all be grateful.

And finally, I notice that some of my recorded video zooms even with the kit 14-140 do NOT have any flicker. I suspect that may be because lighting in those shots is relatively uniform. Will be testing this some more; most of my testing of zoom flicker lately has only been on the LCD viewfinder playback. Need to see if flicker is also present on playback after file download to computer.

Pans and tilts don't seem to activate the flicker effect as much as zooming. Perhaps this is related to zoom lenses' tendency to stop down when zooming in?

Just groping, stubbornly, for a workaround that will enable the 14-140 to do acceptable video zooms.

Edit: I wonder whether the trick of putting tape between the lens-camera contacts (see au8ust post, above) would help here. Or would that make it impossible to set aperture, since, as someone also posted above, it seems like camera is talking to the kit lens to set aperture.
 
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Update on taping over various lens-camera contacts: covering all 11 pin contacts on the lens stops the flicker effect but is not a usable tactic, as it also completely disables focus and aperture setting capability.

Covering over selected contacts only (haven't tried all of them so far, but a fair number) has not let me, so far, disable flicker adjustment while maintaining ability to focus even manually or set an aperture setting.

I'm going to be looking into deflicker software for post-production possibilities.
 
Weird additional update on the Lumix 14-140mm zoom flicker saga: found last night recording test video indoors in available room incandescent lighting that if I set aperture to widest setting (4.0), ISO to 2000, exposure control to "S" (for manual shutter setting) and shutter to 60 (i.e. 1/60 sec), exposure compensation scale set all the way up at +3, AE (automatic exposure) locked, all of which produced a fairly bright image for the lighting conditions, there was no apparent zoom flicker either on record or playback throughout slow zooming and throughout zoom range. I have no idea whether camera was doing any seamless f/stop adjustments, as f/stop readings were not visible in S setting, but no flicker. Also, didn't test a faster zoom action, just a slow creep. However, when setting was exposure "A" (aperture set to "manual") and ISO 1000 or 2000 (not sure which), frankly not sure what my shutter speed was at that point, AE lock on, not sure where exposure compensation was set to (will re-do the test later) - all of which produced a much darker image - lots of flicker throught the zoom range.

I realize it's only a limited workaround for the GH-2 video zoom flicker problem to have to, in effect, walk on eggshells to find a stable set of exposure-related settings. For one thing, I'm not sure those settings will even be usable in all lighting conditions (haven't done much outdoor shooting with the GH-2 yet, for example). For another, it's less than ideal, photographically, to have zoom exposure stability dictate exposure settings. Much better for Panasonic to just write some code to allow the user to enable an override to these exposure adjustments that happen during zooming. AE lock does seem to hold exposure quite steady during pans and tilts; it's only the change of focal length during zooming with my Lumix 14-140 that generates the problem in the first place.
 
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GrahamH said:
Glad to help. I have the 28-75 Tamron, which I like using on sticks for interviews. The lens I prefer, though, is the 17-50mm Tamron - a bit sharper, a bit less flare, easier to hand-hold.
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Graham, are you saying that you shoot video on the GH-2 using these Tamron lenses, and if so that you avoid the zoom flicker? If that's the case, am I right to guess that the lenses are not the versions I've looked at on ebay, B&H etc. sites, which seem to have electronic (camera dependent) aperture settings, but rather, older, truly manual aperture ring lenses?

My understanding is that any lens with electronic aperture set by communication between camera body and lens won't provide a workaround to avoid the GH-2 flicker. For that reason, I've been assuming that only lenses with a manual aperture ring are contenders for this workaround (and I've also assumed it's safest to look for lenses that also have manual, in-lens focusing, in case automatic electronic focus, especially for a third party lens, is incompatible with GH-2 camera-driven focus.) If these assumptions are faulty, somebody please let me know. Easy enough to answer the question by trying lots of lenses on the GH-2, of course, and I probably will eventually, just looking for shortcut to knowledge from this knowledge base.
 
@What..., Whether or not lenses like these Tamrons have manual aperture rings (my 28-75 does, my 17-50 doesn't), they function as purely mechanical/manual on a GH2 because the adapters are "dumb" (i.e. non-electronic). The only exception being 4/3rds lenses adapted to Micro4/3 ... those adapters do pass electronic control. Consequently, there is no iris flicker.

In the case of the aperture-ringless 17-50mm, I have a Pentax mount version and there are Pentax-to-M4/3 adapters that include a simple 'open-close' mechanical ring that provides manual aperture control. The same is available for Nikon mount. For example: http://www.ebay.com/itm/Pentax-K-le...ens_Adapters_Mounts_Tubes&hash=item5640282ead

Hope that helps.
 
Once again, very helpful. Moves me along the adapter learning curve yet again. The adapters I've gotten so far (Fotodiox Nikon F-to-micro 4/3 and Pentax KF to micro 4/3) are simple metal adapter collars, so naturally there is no electronic connection to the camera for any lenses I might use them with. What I had not known before your post was that there are adapters that can supply the aperture ring control for lenses from which that ring has been gelded (nice term) from the lens by the lens manufacturer, which seems to be the standard current lens configuration.

Well, here's another basic Lens Course 101 type question: Recently bought a used 28-200mm nikkor lens with manual focus and aperture ring, and I'm wondering whether a wide angle converter lens (in this case, 75mm, nikkor zoom compatible, say somewhere around .5x to .7x) could possibly provide usable shift of the zoom range of the 28-200 toward the wide angle end of things.

The few reviews I've been able to find for various wide angle lens converters (there don't seem to be many that are 72mm mount) vary quite a lot, with some commenters saying these converters produce uniformly horrible images, others saying that this can be a great way to save the expense of a wide angle zoom like the Tamron 17-50. I do realize that the Tamron would be a far higher quality way to go, and also that converter performance will depend on the specs of the particular converter and lens involved. What intrigues me about this is that, with the wide range of 28-200mm lens, a shift to the wide angle via converter lens -- if image quality doesn't suffer too badly -- would give me both the flicker workaround I've been looking for and a pretty good zoom range, at low cost. If this ends up being a lousy way to go because the converter produces lousy images, sounds like best route to go is to save up for that Tamron 17-50 to take care of wide angle shooting needs, and in the meantime do the little exposure setting dance (and maybe even look into post-production deflicker software) to keep the 14-140mm as flicker-free as possible in those shooting situations.
 
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Took a look at that speed booster article. But the $600.00 price tag has me wondering whether I would be just a well off going for something like a Tamron 18-270mm. Used, on e-bay, it'd cost less. I know a super zoom like an 18-270 would come with distortion at some focal lengths. (Or in fact I wonder whether the G3 has eliminated the video zoom flicker problem. No idea, haven't looked into it.)

Can't have it both ways (could if the darn 14-140mm was video zoom functional on my GH-2). Looks like the most likely choices for something like 17-140mm MFT video zoom range capability for the GH-2 are either two zoom lenses (say, 17-50mm or so and 28 (or higher)-to-whatever) or a superzoom like the 18-270 that may sacrifice some optical qualities. And add the speed booster plus 28-200 combo option when that's available - but that doesn't seem like a cost-saving option.
 
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WhatAndGiveUpShowBusiness said:
Weird additional update on the Lumix 14-140mm zoom flicker saga: found last night recording test video indoors in available room incandescent lighting that if I set aperture to widest setting (4.0), ISO to 2000, exposure control to "S" (for manual shutter setting) and shutter to 60 (i.e. 1/60 sec), exposure compensation scale set all the way up at +3, AE (automatic exposure) locked, all of which produced a fairly bright image for the lighting conditions, there was no apparent zoom flicker either on record or playback throughout slow zooming and throughout zoom range. I have no idea whether camera was doing any seamless f/stop adjustments, as f/stop readings were not visible in S setting, but no flicker. Also, didn't test a faster zoom action, just a slow creep.
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Posting reply to my own post certainly rates as "yapping dog," to use another dvxuser's apt phrase. Nevertheless, here's a correction on optimum exposure-related settings to eliminate zoom flicker, at least under indoor incandescent lighting conditions. I reported the settings that I quoted above, incorrectly. Actually, the worst thing to do is to set AE lock to "on." You want to leave that lock off. Set exposure controls to "S" (manual shutter; I set shutter to 60, shooting Cinema 24p in the test at the link below); set exposure compensation scale all the way up to +3. Good news is, it doesn't matter where you set ISO (I think I set it around 640 in the test linked to below); that doesn't effect zoom flicker (also, zoom speed doesn't seem to matter), so you can set ISO where you like, in order to work towards the exposure look you like. Then -- wallah, Lumix 14-140 zoom with no flicker. Here's a test: http://youtu.be/fUV-aEAcM-w

Same thing but with AE set to lock "on" (not in the test video) produces nasty flicker during zoom.

My guess is that under these settings, assuming that some type of exposure adjustments are even happening, camera and lens must be working in tandem to change aperture seamlessly. Either that or perhaps aperture really isn't changing, though that would surprise me if light admitted to the sensor varies with varying focal length, which I'm guessing is usually the case during zooms with most zoom lens optics. Plus you can hear lens adjust during the test.

Haven't tried juggling settings this way in outdoor lighting conditions yet, but you can bet I will ASAP.

Could this be a useful workaround???
 
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I think something might be screwed up with your lens. I own that lens and it's my number one go-to lens, shoot with it all the time, and I've never seen that effect. Call them Panasonic boys I'm thinking.
good luck.
 
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