HMC-40, no ND filter?

B

bradywurtz

Active member
Ok, so i've owned the HMC-40 for a year or so now and got it and realized there is no ND filter on it. big upset.

then when i recently looked on BHPhoto, in the description for the camera, it says it has an auto on/off nd filter built in. and then doesn't describe it at all really

then i talked to someone on live chat for BHPhoto and they said they're not positive about it, but apparently when you lower the iris, it activates the nd filter and adjusts accordingly as you lower it

i found that this is completely false. as you lower the iris, it starts slowing down your F stops, and it displays so on the screen.

this is NOT the same as using an nd filter. if i want a real shallow depth of field, i need the fstop to be real low like 1.8 or something. but if i need it to be darker cause i'm outside, i throw an ND filter on it so that i can cut down on the light, but not lose my depth of field.

but on this camera, the only option i have if it's to light outside, is to keep dropping my f-stops down lower and lower, and i can actually see my depth of field becoming bigger and bigger.

i focused on a window frame in my house and had a tree unfocused in the background from across the street. as i start dropping my f-stops down to 10 and further, i can see that the tree on the other side of the street becomes more and more in focus.

bottom line and question:
is there something i'm missing on how to activate this 'Auto on/off ND Filter'? or is Panasonic just flat out lying to us. In which case, I feel like if I call them up, i should be able to get a full refund from them for lying.
 
I don't understand why people can't ask simple questions without having to resort to assuming that the company is "just flat out lying to us." Whatever happened to simple civility?

I documented the filter issue thoroughly in The HMC Book, and also on this forum. There is a neutral density filter that is integrated into the exposure system. It engages automatically, and invisibly to the user. It is not like other cameras where to toggle ND on or off. On the HMC40 and HMC80, as you stop down the iris ring, it will close the iris up to a certain point. Once it hits f/2.8, further stopping down the iris wheel does not, in fact, change the camera's physical aperture, it instead causes more and more neutral density filter to be applied. Once you've stopped down to the point where the ND filter is fully engaged and there's no more ND filter it can apply, then the iris starts closing down again.

They did this for some very good reasons, primarily that the tiny chips (1/4" chips) are subject to diffraction quite early. The engineering decision was made to keep the iris as open as possible as long as possible, to keep the video quality as high as possible.

I wish they would have included a stronger ND filter, because I find that outdoors the built-in filter is borderline adequate, it still results in some pretty deep f-stops outdoors.
 
Yea cause i've played with my camera messing with dropping the iris down and it shows the f stops getting slower and slower. and it never mentions anything about ND being applied, nor does it visually look like it is. it must be such a small amount, that it doens't actually amount to anything that is useful.

and as i slowed down my f stops on the iris dial, i could see, with each step down, the trees at my neighbors house across the street, gradually became more and more in focus. it wasn't like there was a huge gap where it stayed the same. so when it says it's at a certain f stop, i has to be telling the truth. and if not, i can't understand for the life of me why the company would say 'hey, let's make it say it's gradually slowing down the f-stops, but our consumers will OBVIOUSLY understand that it really means that once they get to 2.8, anything after that is just a lie and that there is actually just a little bit of nd filter being added after that. but it makes more sense to just keep saying the f stop is at 3, 3.4, and so on.'

where is the thread where you talked about it on this forum, i'd like to take a look at it.
 
Again, I described the process quite thoroughly in The HMC Book, which you should have gotten free in the box if you bought a new HMC40 in the last 9 months or so.

Shine a flashlight in the lens and stop down the iris and watch what happens, you'll see that the brightness changes with every tick of the lens, but the iris changes only down to about f/2.8, then any further darkening happens by an ND filter being brougth into the optical path more and more, and when the ND filter is fully engaged and you try stopping down more, then the iris starts changing again.

They did this to prevent the video from becoming way too soft, as it would if they'd just let the iris change for every increment.
 
In bright outdoor light, you will be wanting external ND filtration. I leave a CP on the cam most of the time which is worth about .75 stops and makes up for what the cam really needs. In extreme circumstances, you may want more.

It is a bit unconventional, but it does work ok, It would have been nice to have a couple more stops of ND.

Grant
 
bradywurtz said:
i focused on a window frame in my house and had a tree unfocused in the background from across the street. as i start dropping my f-stops down to 10 and further, i can see that the tree on the other side of the street becomes more and more in focus.
Click to expand...

Funny. My VX1000 and FX7 did the exact same thing when I stopped down. Conspiracy?
 
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