Underexposure in camera using light meter Sekonic L-308S

[george013]

Denis,

Are you surprised that the histogram doesn't go to the right despite having whites in the picture? Is that what you're wondering?
In your first post it was the different result using a different way of measuring.

George

[DennisS]

Denis,

Are you surprised that the histogram doesn't go to the right..

George

Nope - do not care about the histogram - just that the subject is exposed correctly. I understand that the histogram can look different based on the complete frame and not just the exposure on the subject. I did not change the way I measured - pointed to each light separately (with the other off) to get the reading. I did find that using the lumidisc got me a better result though but still a bit under.

[DennisS]

1. How far from your subject is your key light located? To be shooting wide open with studio lights and to have an aperture that large strikes me as a bit strange. You are not pushing a lot of light out for this to be happening.

Distance is about 3 feet. The selection of aperture was just for the test and I assumed if the meter gives me f/2.8 then it was within the limits of the camera for the same ISO/Shutter.

2. What light modifier(s) are you using and how large are they? Are you using grids on them?

Two softboxes - one about 30*20 and the other slightly smaller maybe 24*20 and no grids. They both have the inner diffuser.

3. Are you metering all of the shots with your flash meter at exactly the same distance from the light source? I assume your meter is reading exactly f/2.8 at 1/200th at ISO 100? Or is the reading showing a decimal stop as well?

Yes - metered all at same distance - held the meter in front of the card/color checker, etc and pointed at source. I set the meter at thirds, and modified the flash power to show f/2.8 for ISO 100 and 1/200th.

[DennisS]

Could you post the screen captures somewhere around 1500x1000px?

Yep - will do when I get home later tonight. Thank you for reviewing and your feedback.

[chauncey]

I do some studio stuff and don't use a light meter...shooting tethered using a displayed histogram
in real time works quite well. Only rarely is exposure adjustment needed. What am I missing?

[Mike Buckley]

I do some studio stuff and don't use a light meter

I would be willing to bet that you do.

[xpatUSA]

Are you surprised that the histogram doesn't go to the right..

Nope - [I] do not care about the histogram - just that the subject is exposed correctly.

[Manfred M]

Okay - Dennis, based on the information in your previous posts, I tried to replicate what I think you were doing in your shots. You'll recognize some of the gear. I am posting SOOC camera shots with no manipulation other than taking the default AdobeRGB colour space I have set my camera to and converting it to sRGB so that the images display correctly on everyone's screens.

I find that I need to drop my shutter speed to 1/150th when shooting studio lights. You can see that 1/200th was too fast right along the bottom edges of the frames where I am catching a bit of the first curtain. I knew this would happen from previous experience, but decided to keep the settings to remain consistent with your camera settings.

First shot - this is a shot of my flash meter after I set up a single light with an ungridded 24" x 36" softbox. I shot at ISO 100, 1/200th sec and f/2.8. The only other reading that is of interest is the 100%, which indicates that 100% of the light in the image comes from the flash (i.e. an ambient light sources were overpowered by the flash. Positioning of the light was the classical 45º / 45º positioning that you used. I did not use either a fill light or reflector for the original shots (single light source).

My softbox was about 3ft from the subject, but sitting at the camera right position (you were camera left, I believe). I also set the meter to show decimal stops, so a reading of f/2.80 shows the exposure is as close as I can get it within the accuracy of the meter. Your setting to 1/3 stops is not as accurate and could explain some minor differences.




Second Shot - this is a screen capture of a the Lastolite Exylite 18% gray target. I aimed my softbox at the centre of the target and added sample points near the edge of the target and at the centre of the target to show the reading as the effect of lightfall-off is seen. The centre (point 2) shows a value of 109, 111, 110. I had the Lumisphere located at this centre spot and pointed at the the flash. The colour balance is quite close, but not perfect and I seem to be closer the the 119, 119, 119 theoretical number that Ted and I were discussing. This could be a result of using 1/3 stop reading increments on your meter (or it could be due to something else).

Regardless. I see some light drop off as well.

When I look at the my histogram (I virtually always shoot to the histogram). my black point is about 2 and my white point is about 240. Both values are close and suggest that the white in the image is not pure white, but close to pure white with perhaps a tiny bit of underexposure. I prefer this as I have good light distribution and no shadow or highlight clipping.



Third shot - Here I've included the ColorChecker Passport just to see what values I get from each of the gray tiles. I am wearing a middle gray shirt and black pants, and I see a slight increase in the white point (up to 247). I guess I was acting as a large reflector, even with the colour choice in clothing.



Fourth shot - single flash. When I look at the histogram, I show values from 0 through 255, but the amount of whilte in the shot is quite marginal and I would pull the white point back a bit.




Fifth shot - I removed the gray card and replaced it with a piece of white foam core, and move the c-stand and support arm camera left. The card is close to the subject and I would normally crop this out in post. This is my preferred solution to this type of shot; one active light and one passive one. I get a full range of colors from 0 to 255. Again, I might pull the white and black points in a touch.




Sixth shot - You can see the setup I used for the last shot here. The softbox can be seen in the top left hand corner, the reflector, camera and model.





I suspect that your results are probably not as underexposed as you think it is and I think you are probably within 1/3 stop of having a correct exposure, which is a lot better than we could often hit in the film days when apertures could only be changed in full stop increments.

[DennisS]

I find that I need to drop my shutter speed to 1/150th when shooting studio lights. You can see that 1/200th was too fast right along the bottom edges of the frames where I am catching a bit of the first curtain. .

You know - I did see that light drop off on the bottom of my gray card shot too..!!! I put it off to the light being higher than the card position but now all this makes sense.

Thank you so much for this effort. I will change the settings from 1/3 on the meter, try a lower shutter and test again tonight. For a moment I thought this was a bad investment but thanks to your knowledge and effort I feel much better now. Great stuff - glad to belong to this helpful group.

BTW: I was wearing a grey long sleeved sweater too...!!!

[Mike Buckley]

OFF TOPIC

in the film days when apertures could only be changed in full stop increments.

Are you sure that's accurate? I have a bad memory and don't have a lens from those days handy, but I'm reasonably confident half-stop increments were available throughout the entire range of settings except perhaps the extreme ends of the range where the very last increment might have been closer to 1/3 stop.

[Manfred M]

OFF TOPIC



Are you sure that's accurate? I have a bad memory and don't have a lens from those days handy, but I'm reasonably confident half-stop increments were available throughout the entire range of settings except perhaps the extreme ends of the range where the very last increment might have been closer to 1/3 stop.

Depends on the lens. I have some that are single full stops and some that are 1/2 stops (except at the extremes)

[Manfred M]

Dennis - in my experience, the best way to learn lighting (or for that matter, just about anything) is to use a systematic and incremental approach. Start with one light (you'll be surprised how much you can do with a single light) and work that until you are comfortable with it before moving on to adding a second light, etc.

The same thing goes for light modifiers and other tools (gels, scrims, flags), etc. None of these devices are particularly difficult to master, but unfortunately, unless you do things incrementally, you'll never figure out how each change in your lighting setup affects other ones, so I do one at a time and when each setup is complete, I turn them all on to see how the total lighting solution works.

Finally, don't get too into a formula to try to figure out the right exposure. I suspect that what you are trying to do by getting a middle gray reading is more likely to lead you astray than give you a good exposure. I trust my light meter and depending on what I see on my histogram, I might tweak the exposure a bit, but usually I find that I get a decent exposure by using the meter readings. So far as the histogram goes, I don't want to see blocked shadow details or blown highlights in studio shots. While I know there is a bit of headroom on either side (because the histogram is based on the jpeg), I tend to be a bit conservative in pushing the limits, as in a studio situation, I control the lighting and can afford to do so.

[DennisS]

Manfred - you are the greatest...!!! You were on the money about setting the meter to read in 1/10. The moment I did that I had to up the flash power on both units - of course this time I measured at 1/125 sec - and voila...!!! All the shots were bang on...!!! I would never have thought to do this...!! I cannot thank you enough.

[jcuknz]

In my lengthy carear of messing with cameras and things I quickly learnt that a meter is a guide not a rule and adjusted according to results ... LOL

[Mike Buckley]

Manfred - you are the greatest...!!!

He certainly does have that reputation. I'll never forget that he explained while I was on a vacation in Iceland how to get my camera working fully operational after being so dead that it wouldn't even turn on.

[Mike Buckley]

OFF TOPIC

I have some that are single full stops and some that are 1/2 stops (except at the extremes)

Despite that I raised the subject, now that I have reviewed my old lenses I realize that all of them have only full-stop increments. However, I had forgotten that the camera body has Aperture Priority mode and Exposure Compensation in half-stop increments.

[jcuknz]

I too checked a number of my lens and while all have click-stops it largely depends on the design as to if positions between stops are posssible .... mostly they are too close together except for a Polaroid Tominon f/4.5 135mm which permits inbetween positions f/4.5 to f/11 but the the markings and clicks are too close above that.
A final check of my Russian Lubital II, bought 35 years ago and never used, doesn't have click stops and plenty of room between the stop markings to make precise adjustments