Understanding your camera’s built-in metering system

Logan7 wrote in post #3390570
Two thoughts:

1. This particular shot is a great example of why I'd love to own a nice GND filter sytem.

2. Who out there actually uses exposure compensation? I've found it to be a pretty useless feature. If I want the exposure brighter or darker straight out of the camera, I adjust my shutter speed to be higher or lower of the meter's center point. If that fails to produce the image I want, it's usually not to the point where the highlights or shadows are irrecoverably lost and I straighten it out in PP.

Obviously, adjusting shutter speed has implications other than exposure levels if shooting fast-moving subjects, but isn't exposure compensation a factor independent from the data captured by the sensor? In other words, isn't it always adjustable in PP with the same results as adjusting it on the camera?

TMR Design wrote in post #3392377
Just about every photographer out there, from point and shoot to DSLR user.

Hi Logan,

Based on the above statements it would seem that you don't understand exactly what EC is and what it means to apply EC and perhaps don't completely understand exposure. Don't you realize that if you're adjusting your shutter speed from the camera's 'suggested' exposure (meter needle centered) that you ARE applying EC? Why do you only adjust shutter speed? Do you also realize that you can adjust your aperture to accomplish the same thing? Whether your compensating with shutter speed or aperture, if you're deviating from what the camera suggests then you're adding EC. If you went out shooting a variety of scenes and centered the needle for every one of them I can guarantee that your keeper rate will be low, and a good portion of your photos will have to be post-processed. So what do we do? Apply EC.

Post processing should be a last resort. Doesn't it make sense to you that it's simpler and better to nail the shot in-camera knowing you got the shot because of your knowledge rather than having to do post processing to recover highlights or shadows? Why go through that when 95% of the time you have the tools to get the shot right in the first place?

If you've read this thread carefully and looked at the images then you should understand that no matter what mode you're shooting in you need to understand how to apply EC to achieve correct exposures and compensate for the camera's inability to meter a complex scene.

Your comment about having shadows and highlights that can't be recovered is not correct either. If you blow out a sky you can't recover from that. There's noy way to turn a blown out white sky back to a blue one with white clouds. If you have shadows that have gone into black you can't recover fom that, and sometimes these conditons present themselves even when over or underexposed by 2/3 of a stop. It's not uncommon at all to have blown out skies and black areas in a shot where you've centered your needle. Once you leave that center position, again, you're applying EC.

So what you are classifying as a ueless feature is the exact feature that every single photographer uses on a daily basis to achieve correct exposures.

Not too long ago I participated and showed examples in another thread called Exposure Compensation. It might help you better understand EC and a little more about metering.

Logan - if you're using any of the program modes and adjust your shutter speed, you're not changing the exposure one bit. If you change the shutter speed, the camera will change the aperture in the opposite direction to keep a consistent exposure. EC is for those times when you don't want to keep a consistent exposure in a programmed mode. For instance, if you're out shooting a winter scene. Your meter will tell you (dumb meter - but that's all it knows about) what exposure will make the overall scene a nice middle grey. This means dull, grey snow, which isn't what you have (unless it's 5 days after the storm and you're in New York City). So the photographer using program modes will dial in +1 or +2 EC, adding light. The photographer using M will open up 1-2 stops or slow the shutter 1-2 steps to achieve the same thing. But EC only really works in the auto modes (and on every shot while it's set); in M, you do the same thing each and every shot as you meter the scene. But EC in the camera directly affects the captured exposure. Dial in +2 while watching your exposure settings and you'll see shutter speed and/or aperture change as you do.

To your first point, regarding grads, if you're referring to number six's second shot, ND grads may help some, but you'll have a problem with the trees being darkened too much since grads have a straight linear transition from dark to light - and you'd need a shaped one to match the flow of the sky. This is one of those cases where multiple exposures and merging of the lyers would work best.

Pictures are worth a thousand words.

Karman

Thanks to Rich and Jon for excellent contributions to this thread.

MaDProFF wrote in post #3390988
Newbie Alert!!!!
I fully understand the concept, I can just never remember what metering modes symbols are for what metering really bugs me

Hi there MaDProFF,

I don't know what camera you use but I think the symbols are consistent in Canon cameras. I have a 30D and these are the metering modes.

Print it out or go to your manual (30D manual, page 81), print it out, laminate it and keep it in your bag so when you forget you don't just scratch your head and wonder.

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Jon_Doh wrote in post #3391076
Robert, Rich and all thanks so much for your comments. They are helpful for newbies as well as seasoned photogs.

Rich, I hope your sister is doing well.

My pleasure Jon,

I know what it's like to have frustration over exposures and understanding metering. I'm glad this thread has proven to be useful to you.

Sparky98 wrote in post #3391589
I really appreciate the information. One of the things that makes POTN such a great site is that there are so many people willing to share their knowledge.

You are so right Sparky. There are so many talented and knowledgeable people here so willing to help and give of themselves. Even though the forums are so packed with "help me spend my money" threads there are great questions being asked and some amazing answers. Sometimes not..lolol

madferrit wrote in post #3392433
Hi Robert,

This is an excellent thread and i've added it to my favourites. I think this will develop as more people ask questions they feel haven't been answered. Well done!

Also, i'd definately agree with your statement about Understanding Exposure.

This is the one thing that has constantly thrown me off about the book
and i've tried at least 3 times to understand Bryan, but it hasn't helped.

Many thanks once again for making things much clearer than Bryan has ever done (for me at least)

Hi madferrit,

Sometimes even the best books are not what a novice needs. I'm not saying that we need to take everyone by the hand and teach them how to use their camera but for some it doesn't come as easy as it does to others and what seems so logical to me may not make any sense to you.

I got Understanding Exposure just after realizing thay my point and shoot in manual mode was an amazing camera. It made sense but a lot of it didn't sink in and as previously stated, it never tied things in with my camera's metering system, which obviously plays an important part in all of this. If it were as simple as centering the needle and getting a perfect shot every time, well... that would be awesome, wouldn't it? But this is not how things work.

Don't get me wrong either. I think Understanding Exposure is a great book. I just completed the book for the 5th time the other night and I can honestly say that I not only understand and aprreciate it more now but I enjoyed it more. Things make a heck of a lot more sense now that I have more knowledge and experience.

Robert,

Great post...I have one question...are you saying to generally use evaluative metering and then dial up EC adjustments to if the area of interest appears darker or lighter than the overall scene? I really liked the adjustment of the 2nd picture in your 2nd post. Does this approach give you better balance for exposure than spot metering?

Thanks,

Hi Jim,

I'm not saying to use Evaluative Metering all the time. You still need to determine what is happening in the scene and can use any metering mode that seems appropriate for the shot. I used Evaluative Metering as my example because it is what more people use or fall back on as a default.

I could take the same shots and use other metering modes and results will vary. For instance, I had posted the images below to the Exposure Compensation thread mentioned earlier and they are very good examples of how the meter responds to the variances and location of shadow and highlight differently in evaluative and spot metering.

What I've done is to place 2 sheets of foam board next to each other. One is white, the other black. I used a gray card for my custom white balance and took each set of shots twice, once using evaluative metering and then using spot metering. I added the viewfinder markings so you can see how I was panning to the left of center and then to the right of center.

Again, it becomes obvious how the camera wants to adjust for middle (18%) gray and with such extreme contrast you see how it makes white into dark gray and how it makes black into light gray.

This should help people understand what it means when everyone keeps saying that "the camera is adjusting for 18% gray" or that "it's trying to make everything gray". We hear and see that all the time but I suspect there are many that don't fully understand what it means. Until I saw this type of demonstration it didn't really make sense. Hopefully this will help others to grasp the concept.

Take a look.

TMR Design wrote in post #3392783
Hi there MaDProFF,

I don't know what camera you use but I think the symbols are consistent in Canon cameras. I have a 30D and these are the metering modes.

Print it out or go to your manual (30D manual, page 81), print it out, laminate it and keep it in your bag so when you forget you don't just scratch your head and wonder.

LOL, more like stick it to my damm forehead, I actually did print it out from the canon site once, as it was annoying me so much, it is the same as the white balance icons, i can never remember whats ones are what, (ofc some are obvious) though I think those icons could be a bit bigger

I have a 30D to, and I will make a point of printing them out again and keep looking at them to learn.

I just wanted to take a second and thank you for this post. It is very helpfull to have a set of images that shows how using EC to adjust from how the camrea "views" the proper exposure effects the final image. I have also read Understanding Exposure, (5 times ) and seeing a set of images rather than just a "correct" one is much more helpfull. Thank you again.

Hi Dustin,

Glad I could help.

Robert, thank you for posting this. It is really a great help to be able to see different examples. I do not have PS and I do minimal PP on my photos. The program I do have does not adjust EC (plus I prefer to have my photos be as close to 'as is' as possible. Probably seems weird to some) so learning how to correctly expose is an important tool for me. I would be very interested in an *assignment * of sorts (that someone mentioned) to learn more.
Cheers!

ETA: Is using exposure lock and recomposing as effective as EC in cases where there's a definitive difference in areas of brightness and darkness? In what instances would you use exposure lock as opposed to EC?
Thanks!

TMR Design wrote in post #3393256
Hi Jim,

I'm not saying to use Evaluative Metering all the time. You still need to determine what is happening in the scene and can use any metering mode that seems appropriate for the shot. I used Evaluative Metering as my example because it is what more people use or fall back on as a default.

I could take the same shots and use other metering modes and results will vary. For instance, I had posted the images below to the Exposure Compensation thread mentioned earlier and they are very good examples of how the meter responds to the variances and location of shadow and highlight differently in evaluative and spot metering.

What I've done is to place 2 sheets of foam board next to each other. One is white, the other black. I used a gray card for my custom white balance and took each set of shots twice, once using evaluative metering and then using spot metering. I added the viewfinder markings so you can see how I was panning to the left of center and then to the right of center.

Again, it becomes obvious how the camera wants to adjust for middle (18%) gray and with such extreme contrast you see how it makes white into dark gray and how it makes black into light gray.

This should help people understand what it means when everyone keeps saying that "the camera is adjusting for 18% gray" or that "it's trying to make everything gray". We hear and see that all the time but I suspect there are many that don't fully understand what it means. Until I saw this type of demonstration it didn't really make sense. Hopefully this will help others to grasp the concept.

Take a look.

IMG NOTICE: [NOT AN IMAGE URL, NOT RENDERED INLINE]

IMG NOTICE: [NOT AN IMAGE URL, NOT RENDERED INLINE]

If you don't mind, in the evaluative shot, were you using all AF points, the center one, or none? Reason I ask is that my experience leads me to believe that evaluative metering acts something like center-weighted averaging except that it gives weight to the active focus point. I have not done direct experiments like yours to prove this, but that's how it seems to work in real-world shooting.

Hi Tom,

I'm using the center AF point for both sets of images. I would tend to agree with you and at times certer weighted and evaluative will give me the exact same expsoures. In many cases I'll choose center weighted averaging and find it to be a bit better than evaluative but honestly, if I'm in either one of those modes I've got my finger on the jog wheel and I'm all set to dial in some EC.

I use a method that I mentioned in passing much eariler in the thread but I find it's great way to get an idea of where things are and what effect a change of 1/3 or 2/3 (or any value) stop will have.

If you meter the scene and center the needle in Manual or meter in Av or Tv with no EC, that gives you your standard exposure. If you see you've got sky or water or dark trees then remember the aperture/shutter speed (depending on the mode you're shooting in) and then meter off the bright or dark area. See what the difference in exposure is and choose an expousre in between. You can make the creative decision to lean one way or the other but you now have a range and you know where each of the areas of the scene will be properly exposed. So you're sort of doing your own averaging but you make the call, not the camera.