Question about the Gain Display

T

Turbodog

Active member
I know that this topic has been discussed, & everyone said that there is no Auto Gain (Auto ISO) mode in the AF-100. However, in the Operating Instructions, Vol. 2 page 46, it states the following about the Gain Display on the LCD:

"17. Gain Display
Displays the gain value of the image amplifier configured. (During the auto mode, AGC is displayed)"

This indicates that there IS an Auto Gain Control mode! But nowhere else anywhere in the instructions or in the menus is there any mention or any setting to put the gain in "auto mode". What am I missing here? How do you set "auto mode" so that "AGC" is displayed instead of ISO xxx, as stated in the instructions?

Auto gain control is a really useful feature to have, particularly in low light where you're always shooting wide open. I'm coming from the GH2 which you can set in aperture priority, set the ISO to Auto and then if light levels drop, you keep your exposure while maintaining constant DOF and motion blur. You get some increase in grain, but that is acceptable for what I'm shooting.

So questions:
1. Anyone know how to set that "auto mode" for gain, mentioned in the instructions? Or is that, as I suspect, an error?

2. If there is no auto gain mode, then how do you maintain proper exposure if you're shooting with a manual aperture lens wide open and the light level drops? How do you adjust the camera to vary either the gain or shutter speed for changing light conditions, without a stepwise change that would be noticeable and ruin the footage?

For instance, say you're shooting 24p at 1/60 second. Subject is a singer lit by spotlight and the exposure is correct. Then you pan to the guitarist who is not in the spotlight and the light levels drop. How do you smoothly correct the exposure on the fly without an obvious stepwise change that would be caused by flipping the gain switch??
 
Well I guess I have to answer my own question.

I contacted Panasonic... it took them a week to get back to me. Chris in the broadcast camera division confirmed that there is absolutely NO auto gain on the AF100 and concluded after we tried every setting on the camera over the phone, that the only "auto mode" is "auto iris" and that the Gain Display will never display "AGC". So he concluded that it's a typo in the instructions (darn it).

I also complained to him about the fact that the "auto iris" is completely useless because it changes the exposure in obvious steps rather than smoothly like a video lens should. He said that he had replicated the problem in the lab and that other people had already complained about it and that he was forwarding the issue on to the engineers (good luck, right?). I complained that even cheap consumer camcorders have stepless aperture control and I asked him in what situation would ANYONE want stepped aperture and he admitted that in no situation would anyone want it.

I also asked him if the 14-140 and other Lumix lenses were even capable of stepless aperture and he admitted that he did not know. So I tested, and even in manual iris control mode, no matter how slowly you turn the wheel, the exposure changes in STEPS. So even manually, none of the Panasonic lenses for this camera (including the so-called "video lens", the 14-140mm) are even capable of exposing between stops (although it's possible that a firmware update may be able to fix that in the future).

So, it appears for the moment that Panasonic made this great movie camera without having put any thought into producing any native micro 4/3 video lenses that actually work properly with it: Number of micro 4/3 lenses with stepless aperture control = ZERO (will someone please correct me if I'm wrong on this).

This means there is no way to automatically control the exposure on this camera! It just can't be done without stepless iris control or auto gain, (or auto shutter speed control) and this camera has doesn't have any of those things. :angry:

I would be thrilled if someone could prove me wrong on this because I need automatic exposure control in my particular application, which is shooting under changing lighting situations.
Help! Thanks.
 
Yes, this has been discussed elsewhere on this forum--it's definitely a drawback (though far outweighed by all the rest). The kind of shooting situations you describe might be better served by a AG-AC130 or other such camera. They only way I can think of to achieve a smooth exposure change within a shot is to have your (manual) lens's iris de-clicked and using it, not gain, to adjust exposure. Of course, you'd have to start with enough gain to give you the latitude to make the needed change.
 
I've had to ride the aperture on lenses but only manually on manual lenses (like talent crossing a threshold from bright outside to inside). I have an Oly 11-22 where the aperture is controlled by the camera and adjusts automatically when it zooms discreet steps, as you say, and it makes a muted clicking sound as a bonus! I use it as a variable prime. The AF100 is best suited to cinema style shooting in my experience. It's a lot different than the GH2 but offers more flexibility and control in some areas and less in others, especially auto lens function. Good luck.
 
Yes, I'm coming from the GH2, which offers auto gain control (auto ISO) and an aperture priority mode. Using these together with a manual lens makes auto exposure control seamless, and it keeps the ISO as low as conditions allow. I used the Panny 25mm f/1.4 that way in existing light and just left it wide open the whole time and got great results. I can't believe that Panasonic removed features from the $4500 AF100 that are in the $900 GH2. That's been a disappointment.

Although I've got most of the Panasonic lenses, I'm mostly intending on using a manual B4 zoom lens which has a stepless iris. I guess I will have to do as you suggest, start out with a pretty high ISO and ride the iris. It will be more work but ultimately will produce more accurate exposures. I don't want to move to the AG-AC130 or any other small sensor camcorder; the large sensor is the whole reason I'm into this and I would sooner just go back to shooting with the GH2, which I will still keep and use.

Thanks.
 
One thing I really like about the GH2 is pushing in that rear wheel and zooming in for focus manual lenses. That is SO handy. That's something I had to get on my monitor (TV Logic 5.6) for the AF100. I had the AF100 first so I'm just learning about the GH2 especially for video.
 
hscully said:
One thing I really like about the GH2 is pushing in that rear wheel and zooming in for focus manual lenses. That is SO handy. That's something I had to get on my monitor (TV Logic 5.6) for the AF100. I had the AF100 first so I'm just learning about the GH2 especially for video.
Click to expand...

Yes, the zoom in for manual focus on the GH2 is great, but only for still photography. Once the camera is rolling video, that feature is disabled. The AF100 has a much better focus assist feature for video. I wish the GH2 had focus assist DURING video shooting. It's sometimes difficult to nail focus perfectly on the GH2 while shooting video, particularly with wider angle lenses.
 
To the OP

This is one of the exact reasons I went with
the Sony FS-100. It does have step less iris
control and good auto iris and auto gain.
However, you do lose built in ND's and
HDSDI. I wish there was an AFS-100
combining the best of both of them.
 
alaskacameradude said:
To the OP

This is one of the exact reasons I went with
the Sony FS-100. It does have step less iris
control and good auto iris and auto gain.
However, you do lose built in ND's and
HDSDI. I wish there was an AFS-100
combining the best of both of them.
Click to expand...

apart from that ..and the fact you are lurking here, tell us you know you made a really big mistake going with the FS100

:nads:


:laugh:
 
alaskacameradude said:
To the OP

This is one of the exact reasons I went with
the Sony FS-100. It does have step less iris
control and good auto iris and auto gain.
However, you do lose built in ND's and
HDSDI. I wish there was an AFS-100
combining the best of both of them.
Click to expand...

In retrospect, that would have probably been more suitable to my needs. I'm shooting primarily low / existing light so the ND Filters are not a big deal for me, plus you can always buy ND filters if that's what you really need.

The reason I went with the AF100 is that I have a large investment in micro 4/3 lenses, B4 to micro 4/3 adapters, and B4 lenses with a fixed aperture that are good for existing light. Coming from the GH2 I wrongly assumed that I wouldn't be giving up auto gain--it never even crossed my mind.

Question: this 18-200mm lens that comes with the FS-100, what is the aperture? Is is parfocal? And are you useing / adapting other cine lenses on this rig?

Thanks
 
Shooter said:
apart from that ..and the fact you are lurking here, tell us you know you made a really big mistake going with the FS100
Click to expand...

Sorry Shooter, at first I thought you were addressing me.:Drogar-BlackEye(DBG
I don't mind that alaskacameradude brought up the FS100. Actually I might say I made a big mistake going with the AF100, except that I am primarily a buyer and seller on eBay and I picked up the AF100 for a low price, with the intention of giving it a tryout and then either keeping it or selling it back on eBay for a profit.

I may just go back to the GH2 after I've fully evaluated the appropriateness of the AF100 for my needs. To me picking up equipment at a deal gives me the chance to try it out basically for free, it's like renting for free. That way I can evaluate it objectively, without being locked into "ownership bias".

Re: the Sony FS100. I'm unfamiliar with it but I see that it has a super 35mm sensor. Other than that I don't know the drawbacks.

Why do you think owning that camera is such a big mistake?
 
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Shooter said:
apart from that ..and the fact you are lurking here, tell us you know you made a really big mistake going with the FS100:nads::laugh:
Click to expand...
Nope I LOVE my FS 100. I think the AF 100 is nice as well...just has different strengths and weaknesses than the FS 100. Why does one of them have to 'lose'? I think both are good in their own way. I keep up with the AF 100 and other cameras as I run a consulting business as well.. recommending gear to other businesses.
 
Turbodog said:
In retrospect, that would have probably been more suitable to my needs. I'm shooting primarily low / existing light so the ND Filters are not a big deal for me, plus you can always buy ND filters if that's what you really need.The reason I went with the AF100 is that I have a large investment in micro 4/3 lenses, B4 to micro 4/3 adapters, and B4 lenses with a fixed aperture that are good for existing light. Coming from the GH2 I wrongly assumed that I wouldn't be giving up auto gain--it never even crossed my mind.Question: this 18-200mm lens that comes with the FS-100, what is the aperture? Is is parfocal? And are you useing / adapting other cine lenses on this rig?Thanks
Click to expand...
Yes the kit 18-200 is the one with nice auto functions and really nice OIS. It holds focus like a video lens throughout the zoom. On the downside it is variable aperture (3.5 wide to 6.3 tight). It also has funky focus ring. A good 'event' lens though. I also have bought 3 Canon FD lenses off eBay which cost $20-70. I had no existing investment in lenses so chose a cheap route for now. A 28-90 F2.8, a 28 F2.5, and a 50 F1.4.I've posted several examples on Vimeo. They are both nice cameras you just need to figure out which one is right for YOU.
 
I was just messin with the guy for fun.

I dont have any experience of the FS 100 so havent got a valid opinion to offer.
 
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