Struggling with highlight exposure in bright sunlight

GrahamH

GrahamH

Well-known member
My normal filming preference is to shoot 720P60 with shutter locked at 1/60s, manual iris, and zebras set for 100%.

I've only had the HMC40 a couple of months, and for the first time this week I've been shooting in full sun rather than semi-overcast. And I keep finding that I can't reduce exposure sufficiently to stop zebras appearing in bright areas. (By 'bright' I'm meaning a white wooden fence, a white t-shirt, or white areas on a billboard - I'm not meaning specular reflections from glass or chrome).

At 0dB gain and "F11" I still have zebras showing ... if I turn the iris dial any further the iris closes completely.

I've shot using equivalent manual settings with several cameras (Sony HC1, FX7 and Canon HF10) in bright places (like Colorado skifields) and have never encountered this problem - it's as though the internal ND filters of the HMC40 don't provide enough range. But surely that can't be right - so am I missing a n00b setting somewhere?

(I do realize I can fix this by accepting a faster shutter - but I don't want to change the motion signature). Any advice appreciated!
 
Well, first thing I would do is to use an polarizing filter. I rarely shoot outside anymore without one, even with a mild overcast. It tends to solve or at least mitigate a number of problems. Even though you aren't getting spectacular reflections, you will be getting glare, even from otherwise "flat" surfaces. The polarizing filter will really cut down the glare as well as add a slight bit of ND effect. It will also give a nicer dynamic range to the colors.

Quite frankly, I think you should rethink accepting a faster shutter, too.
 
The polarizing filter will help reduce the exposure by around 1 and 1/3 stops; it's a big help.

I wish the Built-In ND Filter on the HMC40 was a bit stronger, but it is what it is....

A 0.9 ND filter will help by reducing the light by 3 F-Stops.


Bob Diaz
 
Adding a filter is going to be problematic with a wide-angle adapter onboard already. Hmmmm .... starting to wonder if I've made a mistake not getting the HMC150.

Edit: I checked the manuals....

HMC40 minimum aperture (f2.8) + max. ND filter = f11

HMC150 minimum aperture (f3.0) + max. ND filter (1/64) = f22 i.e. two extra stops!
 
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I use a 62mm Tiffen polarizing filter with my wide angle adapter (you have to put it over the last field element, of course) and the 43mm for regular angle use. It works quite well on the wide angle, though I have to zoom about 5 increments in for vignetting, but since this is a 0.5x wide angle, I don't feel like I am losing that much.

Whether you use a 150, 40, or any camera, a polarizing filter should be in your standard set up for outdoors sunlit shooting, whether you are shooting wide angle or normal.
 
While I don't disagree with you Bic, when I mentioned on another forum that I was sad that my Panasonic 0.7X had no front filter thread I got this reply...

"...For very good reason .... they don't want you fitting filters (two extra air-to-glass surfaces) when you're working at focal lengths in the 2.5 mm region. It's hard enough keeping both surfaces of the aspheric absolutely spotless; adding a filter doubles your problems."
 
GrahamH said:
While I don't disagree with you Bic, when I mentioned on another forum that I was sad that my Panasonic 0.7X had no front filter thread I got this reply...

"...For very good reason .... they don't want you fitting filters (two extra air-to-glass surfaces) when you're working at focal lengths in the 2.5 mm region. It's hard enough keeping both surfaces of the aspheric absolutely spotless; adding a filter doubles your problems."
Click to expand...

WOW! Not a good reason at all, IMHO. I didn't realize the Panny lens had no front filter threads, though. That just doesn't make any sense. You have to put the filter on the field lens side or else you will introduce all sorts of focus, coma, and vignetting problems to the optical train. Even my discussions with Panasonic folks confirmed this (they didn't tell me about their wide angle lens not having a thread, however).

Cleaning the optics isn't really that big of a deal. You do have to keep your optics clean and dust motes will show up grandly in reflected light, but it is just something you do, regardless of the focal length.

Actually, I keep my polarizing filter on my wide angle lens most of the time since my most frequent use of the wide angle shots are outside. So cleaning the inner two surfaces between the filter and lens is typically a one time thing.

The wide angle lens, because of its larger aperture (going from 43mm to ~62mm), will gather more light, btw, and will certainly impact your exposure situation noticeably. It certainly argues even more strongly for additional filtering capabilities, especially with a polarizing filter.

Don't know what to tell you with respect to filters, though, given that situation. Unfortunately, you are left with a lot less flexibility.
 
The 40 has a built-in automatic ND filter. It's not quite like the HMC150 or HVX200, where you manually switch it in; instead it's an automatically integrated part of the process of setting the iris. It's always present at any f-stop from 2.8+.
 
Polarizing filter changes the color, and color in this camera is fantastic, don't do that.
Just go cine gamma D, and use DRS 1 AND 2 as long as you have good light, because this gamma adds noise,
in low light scenes use cine gamma V.
Keep your finger on the manual gain control,AND CHANGE SPEED AS NECESSARY.
http://video.felipehenao.com
 
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Here in Arizona, the sun is relentless. I've had good results setting Scene File "A.IRIS LEVEL" to -2, letting the shutter go to 1/120 to 1/250, and experimenting with DRS.

"A.IRIS LEVEL" -2 minimizes me having to contantly adjust iris. The faster shutter, beyond the obvious exposure control, will rarely be noticeable. And DRS used sparingly can improve detail. When possible, I duplicate a shot with DRS off, then on.

An additional ND filter or polarizer is a great solution if you like the look. Near water or other reflective surfaces a polarizer is almost a must.

For additional information on Scene File settings, Barry Green's HMC Book is a great help.

Good luck
 
dan.carter said:
letting the shutter go to 1/120 to 1/250 .... will rarely be noticeable.

Maybe I'm just over-sensitive to this particular issue, but I have to completely disagree -- I find shutter speeds above 1/60 really jarring and not at all nice to watch on a big screen!
Click to expand...
 
I've noticed that the shutter speed sensitivity is related to frame rate. At 60p, even a shutter speed of 1/500 of a second does not seem to matter much, but drop to 24p and that fast of a shutter speed does matter and will generate a strobe like effect.

With 30p, I find that most of the stuff looks OK at 1/120 speed, but I'm not shooting fast action sports and maybe fast movement would make a difference.


Bob Diaz
 
I think it's all subjective - I've shot some stuff with the 40 in bright daylight - 1080 24p, probably 1/250 shutter speed. I don't think the footage strobes at all, and there was a decent of movement (it was a fashion show).
 
Ogrus said:
There is...

When iris is fully open... then you manually control gain
Click to expand...

OK, fair enough. I meant that there is no dial labelled "gain" on an HMC40, and the "Iris" dial only affects gain once the lens is wide open, which is not going to be the case in bright sunlight.

Anyway, with a bit of experimentation I've solved my problem. It turns out the inner diameter of a 77mm ND filter fits quite snugly over the outer rim of my threadless Panasonic wideangle adapter. I've added several small drops of contact adhesive to make that outer rim slightly tacky, and the ND filter now attaches securely while still being easy to remove. This makes me happy because the Pany adapter is full zoom through and nicely sharp - I leave it on the camera for 95% of my shots.

HMC40-ND.jpg
 
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