Author Topic: Capture priority vs Exposure priority  (Read 5803 times)

Audionut

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 3657
  • Blunt and to the point
Capture priority vs Exposure priority
« on: September 15, 2013, 08:40:13 PM »
Topic split from http://www.magiclantern.fm/forum/index.php?topic=8309.0



I honestly don't understand why you would need to check for overexposure well after a shot has been taken.

My brother in law and I were doing some shots of fireworks at the local show last night.
I was trying to explain to him that we would take some test exposures first to ensure that we had our focus and exposure nailed.  He had the mentality of just setting the camera up with basic adjustments for fear of missing a single firework.

After convincing him to check the first exposure, he soon realised that missing the first few fireworks was far more preferable then capturing all fireworks with borked settings.

And the same applies here.  Why are you not checking your exposure decisions on the first captures.  What's the point of being able to capture a scene quickly when important highlight detail is being pushed to white?

chris_overseas

  • Moderators
  • Member
  • *****
  • Posts: 234
Re: Shutter vs exposure - which has priority
« Reply #1 on: September 16, 2013, 01:11:54 AM »
I honestly don't understand why you would need to check for overexposure well after a shot has been taken.

When shooting wildlife and action it's often not possible to check the exposure carefully before, during, or immediately after shooting - doing so might mean missing "the" shot. I'll often shoot a lot of images over the course of a two week trip, without a laptop, and in the evenings I want to whittle down my images to save processing time later and/or free up some CF card space. Having the RAW histogram available at that point would be invaluable to me. Currently I often find myself keeping two similar photos with slightly different exposures because I can't be sure if I've blown highlights or not.
EOS R5 1.1.0 | Canon 16-35mm f4.0L | Tamron SP 24-70mm f/2.8 Di VC USD G2 | Canon 70-200mm f2.8L IS II | Canon 100-400mm f4.5-5.6L II | Canon 800mm f5.6L | Canon 100mm f2.8L macro | Sigma 14mm f/1.8 DG HSM Art | Yongnuo YN600EX-RT II

Audionut

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 3657
  • Blunt and to the point
Re: Shutter vs exposure - which has priority
« Reply #2 on: September 16, 2013, 07:14:14 AM »
When shooting wildlife and action it's often not possible to check the exposure carefully before...............shooting

I realise I am dumping everyone into 2 groups here, but in my experience there are 2 kinds of photographers.

Those who shoot auto/semi auto modes and perhaps do not place enough thought into exposure, and those who place exposure towards the top of their priority list.
To often I see people who explain the need for fast captures, and in my opinion, probably actually use it as an excuse.  "I couldn't check my exposure because I was to busy killing the shutter"!

I haven't yet met some who materializes into a scene with their finger on the shutter button ready for that split second moment.  In other words, when walking to the scene, unpacking equipment at the scene, setting up tripods or whatever, these are perfect opportunities to observe the scene and make exposure decisions.

I am well within the second group of photographers.  And I take that a step further by placing far to much thought into exposure, at the expense of action/composition.
The life of a photographer will be much easier when we have cameras with 24bit or more precision and 20+ stops of dynamic range.

Currently I often find myself keeping two similar photos with slightly different exposures because I can't be sure if I've blown highlights or not.

Try the faithful picture style with the contrast dropped 2 or 3 steps.
If you're interested, I have created a picture style with the brightness mapped from an x-rite color checker.
I trust it enough that if the JPG preview shows white, the data has been clipped.

chris_overseas

  • Moderators
  • Member
  • *****
  • Posts: 234
Re: Shutter vs exposure - which has priority
« Reply #3 on: September 16, 2013, 09:26:59 AM »
I realise I am dumping everyone into 2 groups here, but in my experience there are 2 kinds of photographers.

Those who shoot auto/semi auto modes and perhaps do not place enough thought into exposure, and those who place exposure towards the top of their priority list.
To often I see people who explain the need for fast captures, and in my opinion, probably actually use it as an excuse.  "I couldn't check my exposure because I was to busy killing the shutter"!

To give you an idea of where I sit between the two extremes you described - on a three week trip to Antarctica I came back with 1,200 photos (that's a lot for me on a trip of that duration). Compare that to one person I met on that trip who finished up with over 50,000(!). Generally speaking I'm pretty closely aligned with your approach and I prioritise exposure pretty highly over "spray and pray" when I can. I'm just saying that it's not always possible to do so.

I haven't yet met some who materializes into a scene with their finger on the shutter button ready for that split second moment.  In other words, when walking to the scene, unpacking equipment at the scene, setting up tripods or whatever, these are perfect opportunities to observe the scene and make exposure decisions.

In the past 12 months I've spent roughly 16 weeks on safaris. It's a a constant battle to anticipate what might happen next. Perhaps a large bird might swoop past - is it likely to be white or dark? What will the backdrop be like, bright sky or dark trees? What if there's a fleeting glimpse of a leopard? A zebra bursts out of the bushes with a lion in hot pursuit? Even an animal walking slowly through mottled light against a changing background is extremely hard to expose correctly for in advance. To make things worse, sometimes two or more of the above can happen at the same time!

My current way of dealing with these situations is to have the C1,C2,C3 custom modes preconfigured for various combinations of fast shutter speeds, AF tracking options and exposure compensation. I'll quickly switch to whichever custom mode I think is most suitable for the given event, often adjusting the exposure comp based on experience/intuition as I'm lining up the shot(s). Not ideal but being a bit out on the exposure is far better than missing the shot completely. If you know a better way I would genuinely love to hear it, I know my approach isn't perfect.

Regarding wanting the histogram while reviewing later. Take the mottled light example above - I might well end up with 2-3 shots that are similar in terms of composition and aesthetic appeal, but because of the changing light between shots the quality of the exposure might become a deciding factor on which I choose to keep. I don't think anyone mentioned retaking shots. For me at least it's generally just to help decide which to keep. Having said that, I do make mistakes at times and I'd rather find out I'd screwed up an exposure during review on camera than once I finally get it back to my PC, I might have time to try again if I catch it early.

Anyway, I think we're going on a bit of a tangent here. There's no doubt in my mind that a RAW histogram in the picture viewer would be incredibly useful - even just for those cases when I accidentally half-press the shutter again before I've had time to review the histogram properly :) It doesn't seem like I'm the only one who feels this way, and as Marsu42 pointed out Canon included the histogram during review for a reason. Having a RAW one would be better.
EOS R5 1.1.0 | Canon 16-35mm f4.0L | Tamron SP 24-70mm f/2.8 Di VC USD G2 | Canon 70-200mm f2.8L IS II | Canon 100-400mm f4.5-5.6L II | Canon 800mm f5.6L | Canon 100mm f2.8L macro | Sigma 14mm f/1.8 DG HSM Art | Yongnuo YN600EX-RT II

Audionut

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 3657
  • Blunt and to the point
Re: Shutter vs exposure - which has priority
« Reply #4 on: September 17, 2013, 05:58:14 AM »
I shoot full time manual.  For me, I find this extremely easier then constantly trying to compensate for Canons own metering decisions.  As a last resort, I still have the meter in the viewfinder if I need a base exposure.

For me, changing lighting conditions involves a sunny day with cloud movement, from full sun to full shade etc etc.  Where there are no clouds on a sunny day, the light does not change.  The light falling on the subject will change (depending on orientation etc), and the exposure adjustments I make based on this are purely from an artist standpoint.  Am I happy for the subject to remain in the shadows (to convey the actual lighting conditions), or will I overexpose the scene because I am placing my exposure priority on the subject.

Generally (especially in full sun), this exposure decision can be satisfied solely with shutter (ability to adjust exposure quickly).  Where I need to place priority on shutter speed, I would shoot at a higher ISO to ensure I have that same exposure latitude with shutter.

If I am placing exposure priority on the subject (most often), I would find my exposures for subject in light, and subject in shadows in advance.  If I need to place priority on capture speed, I will (also) place priority on underexposed (not 13 stops under, but 1/2-1 stop under is fine in raw and allows extra highlight detail) settings.  In other words, if I need to move the dial 4 steps to the right for wanted exposure, I don't casually move the dial 4 steps to ensure it only moved 4 steps.  If it moves 5 steps then so be it.  1/2 stop exposure settings help here as I am placing priority on capture speed not fine exposure adjustment, and the helps to reduce adjustment steps needed.

If there is enough fill light from the environment then it actually becomes easier.  I can place more priority on highlights (which don't change under full sun), as there is enough fill in the shadows.

Dual ISO is making these (exposure) decisions much easier for me.  100/400 results in no highlight problems in all but the extreme cases (no different to missing the exposure and blowing highlights under normal shooting), provides 2 stops of DR increase (less worry about shadows), and also provides 2 stops of (extra) exposure latitude.  ie:  I can miss the exposure of the base exposure (ISO 100) on the under side by 2 full stops, the ISO 400 sample of the sensor in dual ISO picks up my slack.
Don't get me wrong, in controlled conditions where capture speed is non essential, I will take the time to ensure perfect exposure, but where capture speed is of greater priority, dual ISO allows much greater freedom in exposure misses.

chris_overseas

  • Moderators
  • Member
  • *****
  • Posts: 234
Re: Capture priority vs Exposure priority
« Reply #5 on: September 17, 2013, 05:36:27 PM »
I get the full time manual thing. I'll do that too fairly often - generally when I have plenty of time such as landscapes, when I know I can't rely on Canon's metering, or sometimes when I don't want the exposure to change (situations like the cloudless days you point out). However I'm not exclusively M, I often prefer Av + EC depending on what makes the most sense (or simply feels right...) to me at the time.

You clearly go to a lot of trouble to avoid being under any pressure in the first place, by determining your exposures in advance as much as possible. That makes sense. I'll do that when I can but for me at least it often doesn't feel practical. In fact I think if I was to do that as standard, I'd spend more time preparing my camera (for shots that often wouldn't even materialise) than I would trying to spot my subjects or simply enjoying the nature I'm in. Even if I was prepared for both sun and shade I am certain I'd miss shots because it simply isn't possible to be ready for everything in advance. Think white birds vs grey vs black birds on bright vs dark backgrounds, shooting into or out of the sun. Any combination of the above or more could and does happen at any time. That's where I think trying to reconfigure full manual on the fly is going to be a curse (for me at least). Here's a concrete example:

http://redyeti.net/extra/IMG_4816.jpg

It's a photo from a few years back but is probably the first time I really became aware of the issue and it gave me a lot to think about afterwards, so I think it's a good case study. When I took this I was lining up for a landscape shot with the sun behind me. The landscape was fairly bright. I was on aperture priority f/16 or so, ISO 100, fairly slow shutter, possibly a small amount of EC. I happened to spot the monkey in my peripheral vision, in deep shade at the time but scampering quickly towards the thin beam of light you see in the photo (it was the sun streaming through a gap in a wall). From that moment I had probably something like 2 or 3 seconds to:

a) turn around
b) change my zoom and frame the monkey
c) increase my ISO
d) open the aperture wide
e) dial in some EC (I should have dialed it down a bit but in fact I overlooked it for this shot, my brain wasn't quick enough to think it through properly. The histogram ended up quite a way right but fortunately didn't blow the highlights - kinda a best case scenario but certainly a bit lucky)
f) change to high-speed continuous shooting and AI servo
g) fire off a burst of 3 shots

Of the 3 shots, only this one caught him with the full backlighting, and it was the first shot in the sequence, the other two were too late. If I was in full manual I'd also have to have changed my shutter speed too which alone would probably have meant I'd have just missed the shot. There would also be a high chance I'd have screwed up the exposure calculation in my head badly enough that it would have ruined the shot anyway. If you can reliably predict and prepare for a situation like this then reconfigure your camera in time my hat is off to you. For me, that's too busy, I'd rather stick with the devil I know which is Canon's metering and override it as needed based on my experience of how it behaves.

Of course the above steps don't apply to me anymore anyway, it is now much quicker and simpler. These days I only ever use AI servo combined with back button focus since it works well in all situations. Then I have preset custom modes to reduce the steps above to the following:

a) & b) stay the same
c) turn the dial to the appropriate custom mode. I have them all set a bit different (eg Av, Tv, M + auto ISO) and constantly fine-tune them but generally they set high-speed continuous shooting, higher (or auto) ISO, high shutter speed, some EC, custom AF tracking options etc
d) potentially override the ISO/shutter/EC somewhat if I think the scene warrants it (generally not required but perhaps one or two clicks of a wheel)
e) start shooting

That reduces my response time to unexpected action to somewhere in the region of a second or so. It has earned me many shots that I don't see how I could have taken any other way. How can full M possibly compete with that in terms of speed in getting set up? There's simply no way. I know I'm at the "mercy" of Canon's metering, but I understand it's behaviour well enough that it rarely causes me serious issue these days.

Note also that I'm only talking about wildlife/action photography. When I'm purely shooting landscape etc, I often take an approach similar to the one you've described. I'm not quite as hardcore though since it can be a tossup for me on whether I go full manual or just Av+EC. For wildlife I'm still going to stick with my current setup, I still can't see the upside to using M sorry.

As for dual ISO... I fully agree with what you're saying about dual ISO making exposure decisions easier due to the increased leeway it gives and I certainly intend to try and use it the same way as you've described. The limitation I have with it currently is that ML settings do not get swapped out with the custom modes. That means I'd still need to enable dual ISO through the menus when needed, which makes it impossible to use for time-limited scenarios like the above. If ML settings were tied to the custom modes I'd be incredibly happy but that doesn't sound very easy to implement just yet. A couple of other concerns I have with dual ISO is the extra step it adds to the workflow (no big deal really) along with the small loss in vertical resolution. With wildlife I often have to crop because it's not always possible to get close enough to the subject - resolution can really start to matter.

I'm going to continue to experiment and adjust my workflow based on what you've said and what dual ISO offers. Thanks for splitting off the thread, this is a good discussion.
EOS R5 1.1.0 | Canon 16-35mm f4.0L | Tamron SP 24-70mm f/2.8 Di VC USD G2 | Canon 70-200mm f2.8L IS II | Canon 100-400mm f4.5-5.6L II | Canon 800mm f5.6L | Canon 100mm f2.8L macro | Sigma 14mm f/1.8 DG HSM Art | Yongnuo YN600EX-RT II

RenatoPhoto

  • Moderators
  • Hero Member
  • *****
  • Posts: 1509
  • 5DM3 / 7D
Re: Capture priority vs Exposure priority
« Reply #6 on: September 17, 2013, 10:11:00 PM »
If ML settings were tied to the custom modes I'd be incredibly happy but that doesn't sound very easy to implement just yet. A couple of other concerns I have with dual ISO is the extra step it adds to the workflow (no big deal really) along with the small loss in vertical resolution. With wildlife I often have to crop because it's not always possible to get close enough to the subject - resolution can really start to matter.

+1
I shoot birds.  Mostly been using c1,c2, and c3.  I am now experimenting with M for use with ETTR and it is very useful to get the best exposure.  C1, C2, and C3 are my fast shooting methods and usually will quickly take a few shots in AI Servo plus continuous shooting for sure "killing the shutter" as Audionut puts it.  Since I shoot in AI each photo has the chance of adjusting the focus and also my exposure may change a little.  Some people make consider this improper, but who cares, it gives excellent results because you increase your probability of getting perfect shot.  Excellent Bird photography is 90% being at that magic moment and the rest is having good equipment and knowing how to use it.

Once i get a couple of shots I will switch to M mode and fire a few slower shots (AIServo) with AETTR (which I have to enable via ML menu).  After I get a couple of shots with the lighting just right, I switch to video mode and do some RAW video of my bird at cropped mode.  Works really good and produce amazing stuff with cropped video.

I hope that the next step is to get ETTR to work properly in the Tv and Av modes.  It kind of works now, so the idea is to get some quick shots like in C1, stop shooting, to let AETTR adjust the exposure to optimum ETTR and then, after ETTR settles, fire away for a few more shots. 

When using ETTR use the option to link to Canon shutter, it allows you to quickly change the Slowest shutter speed.  This is very useful when things change rapidly and you do not have time to go into ML menu and adjust Slowest shutter speed: Bird on the ground 1/100, bird in flight 1/2000, etc  ;)

Also playing with SNR settings.  I typically use C2 with a +2 EC and use it for back-lit bird-on-a-tree shots.  If you set SNR at 6-2 or 7-2, ETTR will compensate for the backlit situation, I am still paying with this to optimize results.

I need to go outside now and shoot some more..
http://www.pululahuahostal.com  |  EF 300 f/4, EF 100-400 L, EF 180 L, EF-S 10-22, Samyang 14mm, Sigma 28mm EX DG, Sigma 8mm 1:3.5 EX DG, EF 50mm 1:1.8 II, EF 1.4X II, Kenko C-AF 2X

chris_overseas

  • Moderators
  • Member
  • *****
  • Posts: 234
Re: Capture priority vs Exposure priority
« Reply #7 on: September 18, 2013, 01:09:23 AM »
+1
I shoot birds.  Mostly been using c1,c2, and c3.  I am now experimenting with M for use with ETTR and it is very useful to get the best exposure.  C1, C2, and C3 are my fast shooting methods and usually will quickly take a few shots in AI Servo plus continuous shooting for sure "killing the shutter" as Audionut puts it.  Since I shoot in AI each photo has the chance of adjusting the focus and also my exposure may change a little.  Some people make consider this improper, but who cares, it gives excellent results because you increase your probability of getting perfect shot.  Excellent Bird photography is 90% being at that magic moment and the rest is having good equipment and knowing how to use it.

Totally agree with all that. I only really apply the above to birds in flight though. If they're on a branch I'll take more time from the outset, then switch to C1/2/3 once I think/hope it is about to fly away.

Once i get a couple of shots I will switch to M mode and fire a few slower shots (AIServo) with AETTR (which I have to enable via ML menu).

Me too - AETTR is great once you've got a shot or two under your belt already and there's time to spend a bit more time to try and get a better shot. Not that it matters but I don't really think of M+AETTR as true "manual". I tend to think of it as a very smart Av/Tv hybrid instead. Manual to me means the camera has no say in the exposure whatsoever, rather than the dial being set to M. Semantics.

When using ETTR use the option to link to Canon shutter, it allows you to quickly change the Slowest shutter speed.  This is very useful when things change rapidly and you do not have time to go into ML menu and adjust Slowest shutter speed: Bird on the ground 1/100, bird in flight 1/2000, etc  ;)

Yep I do already, love it! One thing I was wondering though, is there any particular downside to linking to the Canon shutter? For me at least I couldn't come up with a reason to ever want to turn it off.

Also playing with SNR settings.  I typically use C2 with a +2 EC and use it for back-lit bird-on-a-tree shots.  If you set SNR at 6-2 or 7-2, ETTR will compensate for the backlit situation, I am still paying with this to optimize results.

I haven't had a chance to experiment with that yet so that's good to know, thanks for the tip.

I need to go outside now and shoot some more..

+1 :)
EOS R5 1.1.0 | Canon 16-35mm f4.0L | Tamron SP 24-70mm f/2.8 Di VC USD G2 | Canon 70-200mm f2.8L IS II | Canon 100-400mm f4.5-5.6L II | Canon 800mm f5.6L | Canon 100mm f2.8L macro | Sigma 14mm f/1.8 DG HSM Art | Yongnuo YN600EX-RT II

Audionut

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 3657
  • Blunt and to the point
Re: Capture priority vs Exposure priority
« Reply #8 on: September 18, 2013, 06:07:17 AM »
I like having constants.  Portraits/weddings are my target market, so having scenes in the same light exposed with the same settings makes life much easier in PP.  When I am processing 300+ photos for the client, the more I can limit post exposure adjustments, the less chance I have of becoming bored and limiting (my own) creative potential.
Plus my complete and utter dislike for digital ISOs swayed me away from Av/Tv/auto ISO modes.

The AutoEXPO module has great potential.  It allows fine adjustment of aperture/shutter/ISO curves in it's exposure decisions.  Currently it works simply as a P mode, with no quick Av/Tv priority or EC adjustment.  Hopefully this is just a matter of being able to control/link adjustment wheels.  If the white point can be found via means other then LV (for automatic ETTR in Av/Tv priority), this would the holy grail for me.
I could use AutoEXPO in Av priority with settings decisions controlled via curves, all with auto ETTR where needed.  Add dual ISO (for tone mapping) and post deflicker (for automatic post exposure adjustments) and what more could a photographer want!

a1ex is toying with the idea of linking AutoETTR with AutoEXPO for automatic EC adjustment.

I've tried playing with custom modes previously, but just couldn't find a way to exploit the benefits.  I guess I find it easier to set everything as needed prior to capturing, also my shooting needs probably don't vary so much where I need different presets.
With the 5D3, I BBF with AI Servo/One Shot control on the DOF preview button.  I can adjust the shooting mode via the top LCD depending on needs and automatically have the other mode available via the DOF button, so I can work in AI Servo priority or One Shot priority.  With separate shutter/aperture controls and ISO controlled via set+dial, for me this allows quick adjustment of everything I need on a day to day basis.  In M mode I have Av/Tv priority at my finger tips, and I guess I find that easier then switching to a predefined set of parameters where I have to switch my mindset.

I've been toying with the idea of leaving AutoETTR in set/double half shutter trigger mode.  Where exposure change is large, hit the button and you're good to go.  Currently it's a little slow (in that I can beat it), but it's accuracy is perfect.  Auto Snap trigger mode is quicker (where the scene isn't extremely difficult when using SNR/dual ISO), it has the advantage of capturing stills in it's processing, so you don't necessarily miss shots (subject to exposure flaws (your own initial exposure settings)), but (of course) it always wants to auto snap.  I need to find a good fall back solution after auto snap has completed and then bug a1ex about his thoughts.

Quote
One thing I was wondering though, is there any particular downside to linking to the Canon shutter? For me at least I couldn't come up with a reason to ever want to turn it off.

The only one I can think of is that you can have the minimum shutter locked (so you can't accidentally change it).


Nice capture on the monkey too :)  I've run out of time to explain in detail, but would have opened the aperture and bumped the ISO (shutter adjustment dependent on what was set for the landscape), and held the DOF preview button (I would have been in One Shot mode).  Before dual ISO, I can confidently say that I probably would have been around a stop over and blown all of that lovely highlight detail in the fur.  With dual ISO, I have a tendency to preference under exposure (in quick exposure adjustments) because I have dual ISO picking up the slack.

I need to go outside now and shoot some more..

+2

I'm in a rush to go and do that now :)