HMC40 - First Look
- Thread starter Barry_Green
- Start date
In auto mode everything is auto. Or you can switch to manual, set shutter speed explicitly but keep aperture/gain on auto, this is "shutter priority" mode for you. Just the same like consumer cams work.
studio1972
Well-known member
Coming from Canon to the HMC151, I was surprised that there were no cheap solutions for this, I must admit.
I ended up buying the manfrotto focus/iris controller as I was only really concerned with using it for focus pulls. It's a really nice accessory and is much better made than the cheapo lanc controller I had for my canon, but it was a lot more expensive.
Sorry for straying off topic. Looking forward to the gain/noise test results, this will be the make or break factor for me.
BobDiaz
The Professor
I'm beginning to wonder if the Manual F-Stop setting doesn't just go up to an F-Stop like F5.6 (and no higher) and use the ND filter to make it appear as if the F-Stops were going higher.
Assume F5.6 is the highest F-Stop on the camera before diffraction limits the resolution. IF F5.6 was the highest F-Stop the camera went to and any number higher, like F8, F11, ... is really just the ND filter being added in, the display could say it's higher F-Stops and it would act like it, but we wouldn't have to ever deal with resolution loss due to diffraction.
That would be a cool feature.
Bob Diaz
Assume F5.6 is the highest F-Stop on the camera before diffraction limits the resolution. IF F5.6 was the highest F-Stop the camera went to and any number higher, like F8, F11, ... is really just the ND filter being added in, the display could say it's higher F-Stops and it would act like it, but we wouldn't have to ever deal with resolution loss due to diffraction.
That would be a cool feature.
Bob Diaz
That is what I meant by "virtual f-numbers".
This is a very lame approach for a professional camcorder.Barry_Green
Moderator
In "auto" mode you don't know what the gain is. It applies whatever gain it thinks it needs, and the display just says "AGC".
Barry_Green
Moderator
I'm pretty sure it doesn't work that way, because that would be completely un-professional. If it says f/8, it should be f/8.That is what I meant by "virtual f-numbers".
I think it's much more likely that the iris controls the iris exactly as it says it does, and the camera just adds ND if it thinks it needs it. If that's the case, then I can imagine a circumstance where you could be stopping the iris down, but the image doesn't actually get any darker, because the camera would be removing ND to compensate. Which might be a little weird, but I'd prefer that over having it not actually change the iris when I specifically tell it to.
BobDiaz
The Professor
That is what I meant by "virtual f-numbers".
ASSUMING that's the way it works, this will be a case of difference of opinion. IF Panasonic came out and said that anything higher than F x.x is just F x.x plus ND filter, I'd be VERY happy with that feature. As long as F x.x was just before the point where diffraction limits the resolution.
I have 3 guidelines for video cameras:
(1) The perfect video camera does not exist. There's always going to be some give and take (compromise) between cameras.
(2) The higher priced cameras offer something more than the lower priced cameras. IF there was NO difference, why would anyone purchase the higher priced camera? So try to view the camera in the context of what it costs.
(3) There's a lot of subjective judgment in deciding which camera is best for you. Different people have different needs and standards, so what may be right for one user, may not be right for another.
Bob Diaz
Right. But if you are saying that it has 6 steps per stop, and the Canons and the Sonys have 3-4 stops to cover, this is 6x4 = 24 clicks of the IRIS wheel with f-number not moving. Panasonic might have thought that a customer may freak out and consider that the camera is not working, so it came up with this lame scheme. What it should have done is freeze the f-number BUT add ND info either in f-numbers or in decibels. 6dB == 1 stop, so each ND-related click would add 1dB of ND, similar to gain.
It would show something like:
OPEN - Gain 34dB
...
OPEN - Gain 1dB
OPEN
...
F4
F4 - ND 1dB
F4 - ND 2dB
...
F4 - ND 24dB
F4.4 - ND 24 db
...
F8 - ND 24 dB
This would be totally counter-intuitive. On consumer cams the equivalent of IRIS wheel controls overall exposure, meaning shutter speed, aperture, ND and gain combined. On better cams there is a dedicated shutter speed selector. With shutter speed locked the exposure dial controls aperture, ND and gain. After all, a consumer cares more about brightness/darkness than about aperture by itself, the latter is simply a means to control brightness/darkness (DOF comes secondary).
So when I flick the IRIS wheel I expect image to get darker/lighter with EACH click of the wheel. Whether this is achieved with changing aperture size, adding/removing ND filter or adding/removing gain is up to the camcorder. This approach works well on the Canons and the Sonys, it is easy to understand and it delivers exactly the result a consumer expects.
If the IRIS dial works as you say, then it uses one scheme for aperture/ND and another scheme for aperture/gain; no sane engineer would devise such a weird control. Again: the primary task of IRIS wheel is to brighten/darken the image. Aperture, ND and gain are only the means of achieving that, and DOF effect comes secondary after brightness.
If IRIS worked as you are saying I would be able to set precise aperture for DOF, but what about brightness? How I can control it? How I can remove hotspots? How I can pull blacks up? There are no other buttons but the IRIS.
Could you reach a knowledgeable Panasonic person (preferably an engineer) who could explain what EXACTLY is happening in the camera?
This is the least I expect from Panasonic. They should have put it in the user's manual.
Barry_Green
Moderator
On consumer cameras, yes. This is a professional camera. If I want to set my iris to something, I darn well want my iris set to that position.
Most certainly it is not. The task of the IRIS wheel is to control the iris.
If it was labeled "exposure" then I'd agree with you. But it is not. It's labeled "iris" and it is supposed to control the iris.
I'll figure it out, hopefully today.
If there were separate dials to control gain and ND filter then I would agree with you. But there are none. The manual clearly says that ND is automatically controlled by IRIS. And we know that gain is controlled by IRIS as well.
Also, it says IRIS, not APERTURE. This is Panasonic's way out. It uses the same labeling on the consumer cams, the control that is used to change aperture/gain is called IRIS. It works exactly the same, only the consumer Panasonics do not have ND filter.
Could you explain how do you change brightness if the IRIS dial worked as you are imagining?
Barry_Green
Moderator
Less worried about imagining, more concerned with actually finding out. So I took it outside, in the broadest brightest sunniest north carolina daylight.
The iris wheel does exactly what I would expect -- every click of it decreases the brightness very slightly. It's an iris wheel. That's what it does. The iris updates every tick to show the new f-stop, and the brightness of the image decreases proportionately and predictably with every click. Like a professional camera should.
So -- ND filter... that's a question. I don't know that there even is one in there. I've asked for the engineers to please give me their take on it. I've stared into the lens looking for the actuation of an ND filter, such as was easy to see on the HV20, and I didn't notice any such actuation.
Is an ND filter truly necessary? Maybe not. Again, this camera is 3 stops slower than the HMC150 -- it's like it has an ND filter all the time!
But even in the brightest sunniest conditions, I could get an f6.8 on a face, at 1/50 shutter. Pointing at the clouds and pure blue sky, I could still get pure blue although the clouds looked burnt out, at f/10.5. A little tweaking with the shutter would have brought them back.
And that's without DRS. DRS will probably reign in the highlights rather aggressively too.
The iris wheel does exactly what I would expect -- every click of it decreases the brightness very slightly. It's an iris wheel. That's what it does. The iris updates every tick to show the new f-stop, and the brightness of the image decreases proportionately and predictably with every click. Like a professional camera should.
So -- ND filter... that's a question. I don't know that there even is one in there. I've asked for the engineers to please give me their take on it. I've stared into the lens looking for the actuation of an ND filter, such as was easy to see on the HV20, and I didn't notice any such actuation.
Is an ND filter truly necessary? Maybe not. Again, this camera is 3 stops slower than the HMC150 -- it's like it has an ND filter all the time!
But even in the brightest sunniest conditions, I could get an f6.8 on a face, at 1/50 shutter. Pointing at the clouds and pure blue sky, I could still get pure blue although the clouds looked burnt out, at f/10.5. A little tweaking with the shutter would have brought them back.And that's without DRS. DRS will probably reign in the highlights rather aggressively too.
studio1972
Well-known member
Is an ND filter truly necessary? Maybe not. Again, this camera is 3 stops slower than the HMC150 -- it's like it has an ND filter all the time!
Even here in the UK, I sometimes have to change the shutter speed to enable the iris to be open with the 1/64 ND applied on my HMC. I guess it is quite possible that with a much less sensitive sensor they decided they didn't need a ND filter like you say.
This is a problem if you want to keep the iris open on the HMC40 though, all you can do is change the shutter speed. Where did the idea of an auto ND filter come from anyway, was this actually mentioned anywhere by panasonic?
1) I believe that these f-numbers are virtual.
2) If there is no mechanical ND filter inside, maybe this is just negative gain. If it works as well as a real ND filter then why not?
Would be really nice if you could find first-hand information from Panasonic engineers. Thanks for taking time for replying.
2) If there is no mechanical ND filter inside, maybe this is just negative gain. If it works as well as a real ND filter then why not?
Would be really nice if you could find first-hand information from Panasonic engineers. Thanks for taking time for replying.
studio1972
Well-known member
Why do you believe that? It's not like they are unusual compared to other cameras. Why would they add an ND filter if the iris can do the job?
Because they say that the cam has a built-in ND filter.
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ATL Media Group
Veteran
Excellent. Years of using a fully manual lens makes you appreciate true iris control. I want a real iris like the one you describe. Actually, an iris ring on the lens would be better, or a smooth non-clicking fully variable wheel... But this'll do.
I wish you could turn off auto ND and add one to the front of the cam when needed.