Should my ISO have to be this high?Dodgy histogram?

F

Foggy

I am currently playing around with my new(to me) GH2 and I am finding I need a much higher ISO setting than I would have thought.

I am completely new to this and intend to spend the next few weeks experimenting and learning but this has thrown me.

I am currently shooting in the movie mode with the Driftwood v7 hack and a panny 14-45 lens. The room I am messing around in is only small at maybe 10 feet by 10 feet and even though no natural light can come in it has a tall 5x 40 watt bulb lamp in the corner which makes the room easily light enough to read and walk around comfortably,it certainly isn't a low light condition.

Now I have the camera set to f3.5 and a shutter speed of 1/50 (double ish the frame rate of 24fps which I have read is the best settings for a natural look?) and I am at the 14mm end of the lens.The histogram reads yellow all the way upto 2000 ISO which I am lead to believe means it isn't even close to being properly exposed until that point,at which the histogram turns white and the majority of the bars are nicely in the middle, however ISO 2000 seems very high to me?

I could be wrong or It could be I am overlooking something simple, but at the moment it is throwing me off whilst I am trying to learn the relationship between ISO,focal length,shutter speed,exposure etc.

Any advice hugely appreciated.

Cheers
 
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Foggy said:
The room I am messing around in is only small at maybe 10 feet by 10 feet and even though no natural light can come in it has a tall 5x 40 watt bulb lamp in the corner which makes the room easily light enough to read and walk around comfortably,it certainly isn't a low light condition.

Now I have the camera set to f3.5 and a shutter speed of 1/50 (double ish the frame rate of 24fps which I have read is the best settings for a natural look?) and I am at the 14mm end of the lens.The histogram reads yellow all the way upto 2000 ISO ......
Click to expand...

Even Tho a room may be bright enough for you to read and walk around in doesn't mean it would be good for a properly exposed picture. My best guess of what to try at least would be to turn up the SS and the ISO, and try and get properly exposed picture, then adjust to see what they can be changed to. Also if that doesn't work try and make the room too bright. My father was a professional photographer for around 30-40 years, so I learned a bit, it's like when you get your photo taken there is that very bright light they adjust so they can have their ASA(ISO) as low as possible while having the settings they want. Tell me what all happens to see if I can help anymore.

Cheers,
Krught
 
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That lamp is only a 200w fixture (if you do some straight multiplication to come to that determination -- which is probably inaccurate, it's probably lower)...

It is a low light situation. I've got my windows open as the sun is hitting golden hour outside with a few shears over the windows (no direct sunlight, all diffused) and a few practical lamps at 60w a piece. Easily brighter than your setup. My light meter tells me 1/50 @ f/3.5 ~~ ISO 1600 - 2000. My typical key light on set is never lower than a 500w @ 10 feet from the subject. 200w lights are used to illuminate shadows to gain enough exposure to see a little detail in them. This allows me to shoot under ISO 800 (usually around 400 as a goal).

Cameras are hungry, feed them :)

Here's a good way to contextualize how much light your camera wants (I learned about this form Jim Jannard, although not personally - that would be too cool - just a blog post during the early days of RED ONE testing):
http://www.bhphotovideo.com/indepth/photography/tips-solutions/sunny-16-rule
http://en.wikipedia.org/wiki/Sunny_16_rule
 
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"correct" exposure puts caucasian skin in the main light at ~85% brightness, Darker skin at ~65%.

Be mindful of the 100% brightness bits, and know that the bottom end clips as well, so you may end up needing to add light to the shadows to provide that little bit of detail that the camera can fit into its exposure range (dynamic range). lighting is a balancing act. I like to expose or the key light (whatever that may be), then add fill on a dimmer and backlight a bit brighter to make a subtle outline on the shoulder to provide some definition (3-point lighting). I like to backlight opposite the Key side (personal preference - although that depends on the scene and the set). Then set the background illumination on a dimmer if possible to be able to control the subject/background ratio.

Dimmers are cheap: harborfreighttools.com has "router speed controls" that work like a champ and are really affordable (~$20ish).
 
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Foggy said:
I could be wrong or It could be I am overlooking something simple, but at the moment it is throwing me off whilst I am trying to learn the relationship between ISO,focal length,shutter speed,exposure etc.

Any advice hugely appreciated.

Cheers
Click to expand...

A couple of points that might help you out.

The lens you are using is probably not staying at 3.5 when you zoom it out to 14mm.

http://www.bhphotovideo.com/bnh/controller/home?O=&sku=657970&Q=&is=REG&A=details

Note how it is described as a 3.5-5.6 lens. This means that the aperture changes depending on what focal length you are at. I only mention this because you did not note it in your op, but at the widest and longest ends of the lens it is likely to be 4-5.6 and is only 3.5 (which is probably a T4 anyway, more on that below) in the middle of the lens's range.

You can test this by observing the f-stop number in the display info at different zoom lengths. It sounds like you were not compensating for this on your 14mm shot. If you were, I apologize. I also am not totally familiar with this lens, so it is possible that it is one that can go wide open at its widest range, but usually zooms like this end up stopping down slightly at each of the far ends.

Second - the histogram and the GH2 is less than stellar during live view. The best I have been able to get out of mine is to take a still of the scene, then during playback toggle through the display types to get one that shows a thumbnail of the image and a separate histogram for the R, G, and B channels. Barring using an external monitor with either false color or a proper waveform, the 3 channel histogram is your best bet for seeing a closer representation of what is really happening.

About F-stop vs. T-stop. F-stop is a physical measurement of the aperture diameter to the focal length of the lens. A T-stop is the actual transmission loss as measured through the glass. Often, lenses will rate slightly slower T-stop than their F-stop. This is likely true of your lens as well. We're talking fractional stops here. For example, f1.9 cinema lenses are often described as T2 (like old s16 zooms for example).

And remember. 100 iso @ f2.8 = 100 foot candles. Every change is either a 2x or 1/2 increment in those numbers. So if you are at 200 iso @f2.8 you want 50 foot candles. If you are 100 iso at f4 you want 200 foot candles. Etc. Starting from that point makes determining the math for where you are at easier. I haven't had too much trouble with my GH2 just metering it at the ISO I set it at. Perhaps a little underexposed, but since one wants to protect the highlights anyway that is a nice safety buffer. I should probably be much more empirical about this, but I usually am only working with a borrowed or rented meter and more relying on false color or waveform from an external display. Bad habit. :lol:

Reading through your scenario again (and Knightly's metering) it all pretty much makes sense. Your eye is much more light sensitive with much much more dynamic range than your GH2. The trick has always been knowing how the camera sees the scene compared to your eye - rarely are they seeing things the same way.
 
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That's pretty typical when the lens has a variable f-stop - the wide end is faster and the far end is slowest.

f/3.5 isn't particularly fast in any case, so based on his description of the room I think there's just not enough light.
 
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More light when wider with variable aperture lenses... the f/3.5 would be at the 14 end, with the f/5.6 at the 45. I have quite a few lenses that do this (fixed aperture zooms are generally much more expensive).

Find your self a nice f/1.8 lens. I got my 50mm for around $25 or so (nikon nikkor lens + adaptor). Here's an example of the amount of light that will let through (concentrate on exposure, not the zoominess of it in this video -- this is a 75mm):

https://www.youtube.com/watch?v=BT0EwHCPMb4
 
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Thank you folks,a lot of good reading and a lot to take in. I have read that an F1.8 20mm and an F1.8 50mm will be good additions to my setup and allow me to shoot at lower ISO settings in low light situations (exactly as you just demonstrated Knightly).I need to be buying lenses on the cheap as I have been stretching myself just to get the camera. I will have a look for the nikkor lens and adapter as that sounds a bargain,just need to find a 20mm cheap too after that.

In the meantime I continue to learn.
 
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When considering which lenses to buy, avoid anything that would take an adapter containing its own lens. The added glass is often not as high in quality as the lens you're attaching with it. Lookup the adaptor before pulling the trigger on buying the lens.
 
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