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Post by BuckSkin on Nov 16, 2018 21:56:12 GMT
I often switch back and forth between Shutter Priority and Aperture Priority, depending on the immediate subject and whether I have time and remember to switch. On Shutter Priority, I have a high enough shutter speed set so as to hopefully freeze the action and prevent blurry photos. On Aperture Priority, I mostly keep the aperture at F-8, so as to have a bit of focus range while hopefully not being too dark. These two images are screen-shots of the unadulterated, straight out of the camera, RAW pictures as displayed in FastStone. When these two shots were taken, I had the camera on Aperture Priority, Evaluative metering. They were taken exactly eight seconds apart, with the darker picture being the first. I was standing in almost the same set of tracks. As you can see, I got two entirely different exposures.     These are only two examples of several that I run across when looking over a days shooting. Had I been using Manual mode, with set exposure, I may not have got it right, but I would have gotten it uniform. |
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Post by Bailey on Nov 16, 2018 23:51:14 GMT
It seems you have ISO set to Auto because you have ISO 100 in one image and ISO 200 in the other. That is a 1 stop difference in exposure. In this case to keep the same exposure value in the 2 images the same (assuming constant aperture F8) one shutter speed should be either double or half the other, depending on which image you choose as the correct exposure.
If your camera can't set the exact shutter speed it has calculated, then it will use the nearest one available. Another possible contributor to the difference in exposures is the metering mode you used. If it was spot metering then the element of the scene metered in each shot could be significantly different. I normally shoot in manual mode, but even when using aperture or shutter priority I set the ISO manually to suit what I am shooting to help avoid any nasty surprises in post processing. The reason I never use Auto ISO is because the camera could set a lower ISO than I would ideally like resulting in too slow a shutter speed or it could set a higher ISO than I need and so introduce unnecessary noise.
Hopefully this scenario shows what I mean. To correctly expose a scene in aperture priority, let's assume I need F10, ISO 200 and the camera calculates a shutter speed of 1/200s. If for some reason I need to change ISO to 400 (1 stop difference) then the camera should calculate a shutter speed of 1/400s to maintain the same exposure value. If my camera doesn't have a 1/400s shutter speed setting available then it will use the nearest available and so result in a slight different exposure and look in each image. Hope this makes sense 
On a side note, I am not sure why you going from ISO 100 and 1/99s to ISO 200 resulted in a shutter speed of 1/32s (difference of 2.56 stops/EV).
Maybe one of the clouds partially blocked the sun? |
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Post by BuckSkin on Nov 17, 2018 1:45:36 GMT
On that particular day, I had ISO set on Auto with a maximum allowable of 400.
As I look at the photos here, one atop the other, since the Focal Length remains constant, it appears that I obviously backed a step away for the brighter shot, as it has the wheels showing.
My main objective in posting these two consecutive shots was to demonstrate what can happen when one or more exposure variables change slightly.
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Post by Bailey on Nov 17, 2018 2:01:37 GMT
... My main objective in posting these two consecutive shots was to demonstrate what can happen when one or more exposure variables change slightly. oh ok.....I thought your main objective was to try to prove your thread title "A Good Case for Manual Mode" which it hasn't to me. In any case your exposure values haven't changed just slightly. Your ISO has changed by 1 stop and your shutter speed has changed by ~1.5 stops for a total of ~2.5 stops. There is clearly something else going on between the 2 shots with a huge change in EV like this.
The obvious question is why did your camera calculate such a huge difference in exposure in the space of 8 seconds if there was no change in lighting conditions?
What metering mode did you use?
Let's take a look at your posted exposure settings - Photo 1 (Darker image) - F8 1/99s ISO 100 Photo 2 (8 seconds later) - F8 1/32s ISO 200 To maintain the same exposure value of Photo 1 in Photo 2, the shutter speed for photo 2 should have been 1/200s to compensate for the ISO being increased by 1 stop to 200. Your actual shutter speed is 1/32s for some reason. That is a huge difference from what it should be at 1/200s. If I had your camera I would want to know why the shutter speed for photo 2 is a long, long way from what it should be. |
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Post by BuckSkin on Nov 17, 2018 2:54:03 GMT
.....I thought your main objective was to try to prove your thread title "A Good Case for Manual Mode" which it hasn't to me. I didn't expect that it would. |
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Post by Bailey on Nov 17, 2018 2:56:34 GMT
.....I thought your main objective was to try to prove your thread title "A Good Case for Manual Mode" which it hasn't to me. I didn't expect that it would.
No problem.....as my previous posts show why
If you can post anything that shows anything I posted earlier is not correct I am all ears and eyes.
btw, what metering mode did you use?
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pontiac1940
CE Members
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Post by pontiac1940 on Nov 17, 2018 3:13:09 GMT
Not going to comment on the paired photos shown by BuckSkin.
However, BuckSkin has raised a good topic: shooting in M. A and S priority have their uses, but in changing light (shooting flying birds) or simply shooting a subject with huge dynamic range such as a bald eagle or even a bride and groom, M mode works well. Depending on metering zone employed, movement and other things, exposure can be way off if the metering zone hits a particularly bright or dark area in the scene. But in M mode (unless light has instantly changed) the subject/scene should be exposed correctly no matter in what part of the scent the camera is aimed: light spot, dark spot. No matter.
Depending on camera, I use M for 99% of the photos I take. Yes, it fails on occasion...say, light on a fast-moving subject varies...or subject X is in bright sun and then subject Z suddenly appears in shade. But I used to get more exposure wrecks in A or S. (Been playing with a new minimum SS and auto ISO with a crazy high upper limit and it works well in low light conditions.)
Kind of weird that we have such fancy cameras and choose to use the decades-old manual exposure method.
Good subject.
Clive
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Post by Bailey on Nov 17, 2018 4:04:26 GMT
... But in M mode (unless light has instantly changed) the subject/scene should be exposed correctly no matter in what part of the scent the camera is aimed: light spot, dark spot. ... Yes that is true "in theory" if using Evaluative or perhaps even Centre Weighted metering modes and depending on the lighting in the scene, but regardless of whether you are in M,A or S mode. But all metering modes will struggle with a scene containing predominantly a single colour in even light, for example a scene in the snow, because all digital cameras will try to convert what they "see" to 18% grey. In a scene containing predominantly snow you will need to add some positive exposure to make whites be captured as white. In a scene containing predominantly black you will need to shorten the exposure to capture blacks as black.
It more than likely won't be true if spot metering is set unless you spot meter an 18% grey or equivalent in the scene.
The metering systems in modern cameras nowadays are normally very intelligent and good (That's why I am questioning the OP's exposure settings and how they came about ). The best way I know to check if the exposure is correct, or at least very close, is by reviewing the in camera histogram and checking for blinkies on the camera's lcd screen when reviewing the image. But if you set Spot Metering (doesn't matter if M,A or S mode) then only the small (~5%) of the scene the metering point is aimed at will be used to meter the scene, doesn't matter if you are in M, A or S mode. An example of where spot metering could appropriately be used and the other two modes probably struggle (and again doesn't matter if in M,A or S mode) is inside a poorly lit building with stained glass windows lit directly by the sun outside. If it is extremely important to properly expose the stained glass window then I would use spot metering. You could also use HDR techniques but that's another story. Also, as I posted earlier, I normally shoot in manual mode, especially landscapes and panoramas where the exposure settings for each shot must be the same. At an event or anywhere else where I am pointing and shooting to capture action I would normally use aperture or shutter priority depending on whether freezing action or DOF are more important.
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Post by Bailey on Nov 17, 2018 10:54:44 GMT
Well....given we don't know the metering mode that was used it is very reasonable for anyone to assume that spot metering was used resulting in the ~2.5 stops difference in exposure in the OP's 2 images and also assuming nothing else had changed significantly that hasn't been posted.
I don't believe the huge difference in the op's exposures has anything to do with them being shot in aperture priority mode. The only difference between M and the A, S modes is that in M mode you need to tell the camera the settings you want for aperture, shutter speed and ISO. In A, S modes you tell the camera 2 settings and it calculates the 3rd for you. The metering system is obviously the same in all 3 modes.
Even if spot metering was not used by the op, you should not see a 2.5 stop exposure difference assuming nothing changed significantly in the 8s between shots.
Perhaps consider this for example:
1. Say you set your camera in evaluative metering mode with aperture priority and set F5.6, ISO 100 and the camera tells you the shutter speed needs to be 1/300s.
2. You take the shot and it looks great and properly exposed.
3. You then immediately set your camera to M mode and set the aperture to F5.6, ISO 100 and shutter speed to 1/300
4. Assuming in the 5-10 seconds it takes to do step 3 nothing changes in the scene or lighting. You then take another shot.
Your 2 images should be just about identical. No way should you see 1 stop, let alone 2.5 stops, difference in the images.
If your camera's metering system is functioning properly and everything remains equal between shots then it doesn't matter, in terms of exposure, which of the 3 modes M, A or S you are shooting in. You choose M, A, S modes to suit the type of shooting you are doing at the time (as Clive and I posted earlier) and not because of some misconception that one mode will produce more accurate exposures than another.
Another way of thinking about it is this........if the cause of the 2.5 stops exposure difference in the two images is solely due to them having been shot in aperture priority and nothing else, then this could be a huge problem when shooting in burst mode!!.......I would be extremely disappointed if my camera produced a 2.5 stop exposure difference in a group of burst photos.
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Post by tonyw on Nov 18, 2018 1:34:35 GMT
Interesting discussion and I rarely ever use manual. 99% of the time I use Aperture Priority and Auto ISO as I like to get the DOF the way I want it. Most of the time I’m using my mirrorless Fuji which has the big advantage of the viewfinder showing you the end result as well as the histogram and if its not right a tweak of the exposure compensation dial will fix it. I’ve become a big fan of mirrorless what you see is what you get.
Tony
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Post by BuckSkin on Nov 18, 2018 2:12:09 GMT
the viewfinder showing you the end result as well as the histogram You can see in the viewfinder what a DSLR user sees on the LCD screen ? That would be different. |
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Post by Bailey on Nov 18, 2018 2:36:45 GMT
Interesting discussion and I rarely ever use manual. 99% of the time I use Aperture Priority and Auto ISO as I like to get the DOF the way I want it. Most of the time I’m using my mirrorless Fuji which has the big advantage of the viewfinder showing you the end result as well as the histogram and if its not right a tweak of the exposure compensation dial will fix it. I’ve become a big fan of mirrorless what you see is what you get. Tony
Hi Tony,
out of curiosity, why do you prefer to use Auto ISO?
When I am in Aperture Priority mode I lock in the aperture to get the DOF I want (like you do) but then I look at the lighting and set an appropriate ISO to ensure I get sufficient shutter speed for hand holding. On a bright sunny day ISO 100 will normally always give me more than enough shutter speed. If for some reason I need to use a very small aperture then I might have to up the ISO a stop or two to ensure a fast enough shutter speed. I normally take a couple of test shots first anyway to make sure my exposure settings suit the situation.
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Post by Bailey on Nov 19, 2018 2:58:24 GMT
the viewfinder showing you the end result as well as the histogram You can see in the viewfinder what a DSLR user sees on the LCD screen ? That would be different.
Mirrorless cameras have been around for quite a while now. They have an electronic viewfinder.
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Post by tonyw on Nov 22, 2018 1:28:56 GMT
Interesting discussion and I rarely ever use manual. 99% of the time I use Aperture Priority and Auto ISO as I like to get the DOF the way I want it. Most of the time I’m using my mirrorless Fuji which has the big advantage of the viewfinder showing you the end result as well as the histogram and if its not right a tweak of the exposure compensation dial will fix it. I’ve become a big fan of mirrorless what you see is what you get. Tony
Hi Tony,
out of curiosity, why do you prefer to use Auto ISO?
When I am in Aperture Priority mode I lock in the aperture to get the DOF I want (like you do) but then I look at the lighting and set an appropriate ISO to ensure I get sufficient shutter speed for hand holding. On a bright sunny day ISO 100 will normally always give me more than enough shutter speed. If for some reason I need to use a very small aperture then I might have to up the ISO a stop or two to ensure a fast enough shutter speed. I normally take a couple of test shots first anyway to make sure my exposure settings suit the situation.
On my particular camera Auto ISO is very convenient and works well. I set the minimum shutter speed and maximum ISO and the camera does a very good job of picking the optimum ISO. I can see in the viewfinder what the settings are for the particular scene and if I need to change them I can always do that but I like having the camera ready to go for a quick shot. Tony |
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pontiac1940
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Post by pontiac1940 on Nov 22, 2018 3:07:37 GMT
Got my first DSLR camera (actually a translucent mirror) with EVF in 2013 and loved it. I never wanted to use an optical VF again. My new camera is mirrorless so has EVF. Handy. Give you immediate feedback on exposure. Tony said, " Auto ISO is very convenient and works well. I set the minimum shutter speed and maximum ISO and the camera does a very good job of picking the optimum ISO." As noted I normally use M mode, but tried the AUTO ISO and min shutter speed a few weeks ago and it is brilliant. It is most worthwhile in low and variable lighting. Although the new cam is exceptionally noiseless at high ISOs, I still prefer to use a low-ish ISO for birds and want to use M mode. But in poor conditions when you are forced to high ISO anyway then what Tony described is a very cool feature. Two months ago I attended a 50th reunion from university. I shot candids of the alum when they got up for 2 minutes to tell us what they had done for the past 50 years! I shot in M mode and high ISO but lighting as variable: some stood near back lights and others not. Did not know what Tony described at the time. My pix were okay but needed some help in ACR. Using the auto ISO/min speed would have been a charm. Next time. (Well not the 100th reunion!) Clive |
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