Aperture Priority (AV) Mode Settings

[William W]

I still don't get your point.

If you do want to understand the point I am making, then I think that it think that it would help greatly if you would answer my question, which I will break down into three parts soliciting yes / no answers to each part:

1. When you are using A Mode, do you ever use Exposure Compensation?" If "yes" to this question then please proceed to answer questions 2 and 3.

3. Do you agree that if you use EC in A Mode then the Shutter Speed will change as a result of your action to use EC?

3. When you use EC in A Mode, do you use your knowledge to make a consideration of whether that change in Shutter Speed will affect the resultant image?

On the other hand, if you don't want to pursue this line of conversation, then that's fine too.

WW

[Saorsa]

1 YES

2 No, it is equally possible for the camera to adjust ISO if you have set auto ISO. My Nikon 1 cameras usually allow this to be something like A800 and I sometimes get odd ISOs in my EXIF. In program mode, I believe the camera only deals in Aperture and shutter speed.

3 Sometimes.

[William W]

OK

Thanks for answering.

*

Regarding answer 2, yes I understand that ISO might be affected if Auto ISO is set: I believe I mentioned that as fact, in an earlier post.

*

Maybe this will explain my point better -

Regarding your answer to question 3.

So, it seems to me we can now correctly assume that sometimes this is how you think about things before you release the shutter.



Let's say you are in A Mode and NOT using Auto ISO.

You have already chosen the Aperture to suit (as you mentioned) usually either optimum for the lens or your required DoF.

Considering your knowledge and experience, there would be some reason for your choice of ISO - (like as I mentioned, maybe you'd choose ISO800 on a cloudy day and ISO200 on a sunny day)

Also, it seems logical that when you choose your ISO you would be considering the typical Shutter Speed that the camera will set for you. For example on a very cloudy day I think it safe to assume that you would NOT choose ISO100 if you have set A mode to F/11 and you were shooting moving animals; further I think that it is safe to assume the REASON for you not choosing ISO100 in those conditions would be because your knowledge and experience would tell you that you would likely get SUBJECT MOVEMENT BLUR.

So if we can agree that you at the outset, have chosen all three exposure parameters to suit your required outcomes in the particular shooting conditions.

Now you start shooting - and something changes with the light - and you choose to use EC. It would be logical to assume that you make that choice to use EC because you think at the time it is the best choice for you to make, to keep getting good photos.

You answered that "sometimes" when you activate EC you make a consideration of the resultant shutter speed that the camera will choose.

OK - then when those "sometimes" occur my point is simply, that when you make that consideration of the Shutter Speed, it is a very similar way of thinking to the thinking that any experienced photographer would make if he were using M Mode and there were a change in the lighting conditions.

In both cases the photographer is choosing NOT TO USE the exposure that the TTL meter is indicating AND is also considering and also MANUALLY CONTROLLING the exposure parameters which he thinks that he should use to get the best outcome.

I do hope I have explained the point more clearly, thank you for continuing the conversation.

WW

NB
CAPS are for emphasis of key words or phrases - I am not shouting.
Personal pronoun 'he' is to be parsed as COMMON gender.

[mrinmoyvk]

Hi Adrian,

There is no straight forward answer to your question. Apperture defines the DOF but not sole aperture does that. Focal length aslo plays a great role in it. What you can achieve with f1.8 at 50mm can also be achieved with f5.6 at 200mm (just for example, dont stick to these numbers). Also aperture plays a great role in managing the amount of light enterring the camera, so you have to change it depending upon the lighting in the scene regardless of what DOF you want. As many above have suggested to go through the basics of Aperture, Shutter speed and ISO. It would be easy for you to get to know the details.

What I would suggest is to put the camera on Auto mode and click multiple pictures of objects in different lightning conditions and different distances from camera. Check the EXIF data for Aperture, Shutter speed and ISO values. You will get a brief idea of what camera does.

[Dave Humphries]

My personal development of exposure techniques proceeded thus:

I started using Auto (exposure) mode
When some photos were sub-optimal for recognisable reasons, I moved to P mode to have improved control, while still 'guaranteeing' a correct exposure (or close to)

When my knowledge improved to the point where I could see that the offered combinations of shutter speed (ss) and aperture could be improved if I chose a different ISO, I did that.

Then I moved to A (Aperture priority) mode, since in common use, this resulted in more correctly exposed photos because the range of apertures available is often more limited than shutter speeds.

In using A mode: with a set Aperture, determined by my working knowledge of required DoF and what's best for lens performance, plus a set ISO; chosen as William suggests above (I didn't have Auto-ISO back then), I began to experiment with EC to achieve even more (qty) correctly exposed shots. However, as has been stated, sometimes the shutter speed was too low (e.g. for subject movement), so I learned to recognise when to also change ISO.

By now, as William suggests, I am making all the decisions necessary to know when I can safely 'go manual' (use M mode) with exposure - but note that I don't always - in fact I still use Aperture Priority (and EC when necessary, adjusted shot-by-shot) 85% of the time - which is good for what I shoot; while for other's typical subjects, this may not be necessary or sensible.

You'll note that I adopted a strategy of dealing with one issue at a time, not trying to learn it all in one go.
Note also that during these phases, I practised a lot and I tended to stick to one or two subject types, further reducing the number of variables in the shooting equation, which allowed me to learn more quickly, so the fundamental principles became second nature.


So, to Adrian (the OP), I recommend the same course of action;
limit your choice of subjects and 'increment' yourself through the exposure control options for one subject type.
By the time you get to the third subject type, you'll probably find you'll start to know what to use intuitively.
Learning 'the fundamentals' by personal experience is going to be more successful than trying remember how to do it 'by numbers', as seems to be your intent.

If you must shoot all those diverse subjects, use the most appropriate Scene mode, study the images and the EXIF data and see what would have helped and how that could have been achieved.

You don't need to buy anything, your camera's meter will suffice, but your success will be limited without learning when you need to take control, there's no short cut I'm afraid, you've got to put in the practice and learn from your mistakes - no shame in that either btw.

So my advice; don't ask (such a vague, wide ranged question), go out and try for yourself.

Good luck, Dave

[davidedric]

I follow a route similar to Dave, though not quite as rigorously. Maybe it's my scientific training, but I learned to only change one variable at a time until you know what's going on. Isn't that the beauty of digital and EXIF: no more little notebooks and waiting for the film to come back

When I read on threads in other forums something like "I'm a beginner, I've just got my first dslr, and now I'm going out to shoot on manual" I groan a little. I groan a lot more at the encouragement they get. Rant over.

Dave

[MrB]

For a beginner (or anyone interested), learning can be fun and free on the computer with the camera simulator:

http://camerasim.com/apps/camera-simulator/

Cheers.
Philip

[DanK]

Dave (davidrc), isolating variables is indeed the core of experimentation, but Av and Tv don't do this any more than manual. Changing camera settings while maintaining a given exposure requires changing two variables. When you change aperture, you have to change either ISO or shutter speed to maintain exposure. In manual mode, you make the change and know what it is. In Av or Tv, the camera changes the second variable, and you look after the fact to see what it was.

IMHO, the starting point for teaching anything has to be deciding what specifically you want the student to have at the end. If the goal is for a newbie to become more comfortable with the camera and to gradually learn to control it, the process Dave Humphries suggests seems reasonable to me, although it's not what I would do myself. However, the OP suggested two specific goals to me: primarily, learning to use aperture settings, and secondarily, learning how to compensate for changes in aperture to maintain exposure. Dave H's process would be very inefficient for this goal because it would not create a lot of A/B comparisons (or it would create them scattered about).

So, if the goal is just to learn the effects of aperture, and not to learn about compensating changes, I would try to isolate the effects of aperture changes, consistent with Dave's (davidrc) suggestion of the scientific method. I would have the student take a given shot with the aperture either wide open or closed down and then repeat the same capture repeatedly while changing the aperture. It would make no difference whether the mode was Av or M, and it wouldn't be much harder to do it in M.

If the secondary goal is at play also, and the student wants to learn how to compensate for aperture changes, then the student has to compensate for aperture changes. I would do the same exercise, but this time only in manual mode, and I would have the student take note of the aperture changes and the compensating changes in shutter speed that move the needle back to the same point in the viewfinder.

Neither of these is hard, even for a beginner.

This reminds me of the difference between the American and Dutch ways of training kids to ride bikes. The American method is to put on 'training wheels' that keep the bike upright, so the kid doesn't have to balance. The Dutch method, as I understand it, is to have kids practice with bikes that have neither training wheels or pedals, using them as scooters, so that they learn to balance. The problem with the American method is that when you remove the training wheels, the kids fall down, and they have a hard time practicing balancing because they have to pedal. So, you find parents running along beside them, alternately holding onto the bike and letting go. If local groups are any indication, the Dutch method is beginning to pop up here in the US because it is so much more effective. One adult in my family who never learned to bike as a kid is now taking lessons using the Dutch method. She had one session without pedals, and the second time she was up and about with a bike that had pedals, pedaling along unassisted.

[rpcrowe]

Hi Adrian,

There is no straight forward answer to your question. Apperture defines the DOF but not sole aperture does that. Focal length aslo plays a great role in it. What you can achieve with f1.8 at 50mm can also be achieved with f5.6 at 200mm (just for example, dont stick to these numbers). Also aperture plays a great role in managing the amount of light enterring the camera, so you have to change it depending upon the lighting in the scene regardless of what DOF you want. As many above have suggested to go through the basics of Aperture, Shutter speed and ISO. It would be easy for you to get to know the details.

What I would suggest is to put the camera on Auto mode and click multiple pictures of objects in different lightning conditions and different distances from camera. Check the EXIF data for Aperture, Shutter speed and ISO values. You will get a brief idea of what camera does.

I agree with Mrinmoy... Another facet controlling the impact of DOF is the distance focused on and subject to background distance. I am stressing that the important facet is the "impact" of the DOF on your image, not necessarily, the amount of DOF itself. The distance between your subject and the background has absolutely nothing to do with DOF itself, rather it controls the impact of the DOF. A blurred background will separate your subject from the background and will also diminish the impact of a busy background. That is why the "BOKEH" produced is important. If the bokeh or "quality or the OOF areas is ragged and choppy, it will not diminish, but rather add to the distraction of a busy background. If it is smooth or "creamy" (as with my 70-200mm f/4L IS lens) it can eliminate the BG distraction totally...

Here is an example of a shot utilizing very shallow DOF that was done at 165mm @ f/5.6 (on a 1.6x crop camera 264mm equivalent) with my Goldendoodle quite close to the camera with the background quite a bit father away.



The background is totally blurred. I did not shoot this as an experiment so I didn't shoot with different focal lengths, different f/stops or different lens to subject distances.

Here is a shot of another doodle done at 189mm @ f/13. I wanted the dog's face in total focus with the background OOF. I achieved this by shooting at a long focal length (302mm equivalent) fairly close to the subject but using a relatively small aperture at f/13...



As far as Mrinmoy's suggestion to put the camera on auto and, "click multiple pictures of objects in different lightning conditions and different distances from camera." I would piggy back on that suggestion by also recommending the use of "P" or Programmed exposure mode and "AEB" auto exposure bracketing to experience the differences in imagery when shooting with different f/stops and shutter speeds. Using "P" rather than "A" will remove the variable or changing ISO levels from your testing. Shooting at "P" without AEB will also allow you to shoot at many different aperture/shutter speed combinations which will produce the same exposure...

The default sequence of AEB exposures with Canon DSLR cameras is: #1. correct - #2. as meter reads - #3. over. I would suggest setting the camera up to shoot AEB with the exposures in the sequence of Under, As the meter reads, and Over. You can accomplish this with Canon DSLR cameras by going into the menu, I am not familiar with other brands.

I think that this would be a good way to 1. gain experience in adjusting the exposure and 2. viewing (when the images are shown in a group - like in Adobe Bridge) the differences in imagery due to shutter speed and f/stop. You would see the exposures in a sequence of increasing exposure.

We of the digital age have a wonderful learning tool in utilizing the EXIF data of our images. In the days of film, it was not only expensive (film and processing costs) but tedious (writing down the exposures) to get this type of experience.

Another way to gain experience in the impact that aperture and shutter speed has on imagery, is to set your camera in Aperture Priority and then shoot a series of images while changing the aperture, Do this at various focal lengths and at various lens to subject distances to experience the gamut of aperture change results.

BTW: using DOF charts is all fine and good except that many times in fast moving photography, you simply have to "wing-it". I knew that I wanted the fastest shutter speed and the most narrow DOF (to blur a very busy background) in my series at this polo match, so I opted to shoot wide open at f/4 with my 300mm f/4L IS lens (480mm equivalent on my 1.6x factor Canon 7D). This image happened to be a keeper. Was it luck? No, I knew the effect that I was aiming for!



Was catching the ball and polo mallet in those positions luck? I'd like to say this was photographic skill but, actually it was a mixture of luck and the high speed burst capability of my Canon 7D -possibly in equal quantities.

Again, since this was not an experiment, I did not shoot at different apertures.

[DanK]

Apperture defines the DOF but not sole aperture does that. Focal length aslo plays a great role in it. What you can achieve with f1.8 at 50mm can also be achieved with f5.6 at 200mm (just for example, dont stick to these numbers)

I believe this is incorrect. this is from the tutorial on focal length on this site:

Note that focal length has not been listed as influencing depth of field, contrary to popular belief. Even though telephoto lenses appear to create a much shallower depth of field, this is mainly because they are often used to magnify the subject when one is unable to get closer. If the subject occupies the same fraction of the image (constant magnification) for both a telephoto and a wide angle lens, the total depth of field is virtually* constant with focal length! This would of course require you to either get much closer with a wide angle lens or much further with a telephoto lens

What does change with focal length is background blur, which is not the same as DOF. One of the best explanations I have found of the difference between the two is this post. Page down to the section on background blur, with the two photos of the gromit.

[dasmith232]

I'm new here... Kind of. I actually joined a long time ago, but wasn't very active and now hoping to become more engaged. This is the first thread that I've come upon.

I'm confused. According to the laws of physics, DOF is determined by magnification (aka, focal length), distance and aperture. Oh yeah, and the other factor is COC. This is explained quite clearly in the very same link from the post above, or from this link on optics and photography, or from any of several textbooks on optics or physics.

Yes, using a telephoto lens is effective when you can't get closer, but it's also effective as an artistic degree of freedom even when you can get closer.

If you fix the distance between the camera and a subject, and if using the same aperture, the DOF will change as you zoom in-and-out. Yes, you will pick up more or less surrounding background, but looking at the subject and the immediate objects behind (or in front of) the subject will definitely show a difference in DOF. This is an easy experiment to replicate.

If you change your position when changing the focal length to keep the subject size constant, then you're changing the distance which is back to one of the three things that changes DOF. Sometimes, people will confuse the DOF factors to include sensor size but that's also incorrect. What happens is that when someone changes their position to compensate for the different cropping, they're affecting DOF because of their position (not the sensor size).

[DanK]

If you fix the distance between the camera and a subject, and if using the same aperture, the DOF will change as you zoom in-and-out

Yes. The quoted text refers specifically to the case where you don't stay in the same place, where you change distance to maintain the same framing. If you want a given image, with a given framing, focal length isn't relevant for DOF, but it has a very large impact on background blur. The reason for the latter is simply angle of view. The angle of view decreases with focal length. Therefore, given a constant distance to the background, a longer focal length will capture a smaller area of the background and spread it over the same area in the image, creating more blur.

[dasmith232]

Ah, yes - very good. I encounter this discussion quite a bit and find a lot of misinformation out there. For me, the trigger wasn't your text (Dan), but rather the quoted text from the referenced article:

Note that focal length has not been listed as influencing depth of field, contrary to popular belief.

In fact, keeping other factors constant, the focal length has a greater impact than aperture alone.

Even with the additional text above, there isn't enough context to make that a correct statement. Perhaps the full article addresses this. But thanks for your reply; I appreciate it.

[Dave Humphries]

If you want a given image, with a given framing, focal length isn't relevant for DOF, but it has a very large impact on background blur. The reason for the latter is simply angle of view. The angle of view decreases with focal length. Therefore, given a constant distance to the background, a longer focal length will capture a smaller area of the background and spread it over the same area in the image, creating more blur.

That's the best (most concise) I've seen this described Dan - thanks.

The Grommit pictures in the other link show this when you look at the rear of that car in the background, the 'resolution' of the blur (term used loosely to describe the amount of detail visible in it) is the same, just you see it much larger in the telephoto shot, due to the reduced angle of view, so it looks more blurry.

[Dave Humphries]

For a beginner (or anyone interested), learning can be fun and free on the computer with the camera simulator:

http://camerasim.com/apps/camera-simulator/

Cheers.
Philip

Adrian,

This is quite a good tool to explore the options, although you could spend hours playing with it

[george013]

Adrian,

This is quite a good tool to explore the options, although you could spend hours playing with it

It shows but doesn't explain. Since a while I'm busy to make an animation in Javascript that shows what happens when you change the focus distance, change the aperture, magnification and all that stuff in a goniometric way. Until now I didn't find that. When it's "ready" I'll show it. In early days I did programming but I've no experience with Javascript.
George

[jcuknz]

I think Adrian that you need to think about what you want of the subject ... when you are not particularly bothered then it is quite useful to use an aperture in the mid range of that available where the lens is probably working best, so they tell me
That is the aperture I mostly use because my approach to photography is to have a subject and to 'hell' with the rest as I get the subject sharp and ignore the rest, often deliberately blurring the rest in editing and even part of the subject.


EXIF tells me I shot at f/11 here, probably the result of using 400 ISO as 'standard' with MFT as opposed to 100 ISO with my bridge cameras. edit .. I should have mentioned that the blurr in this shot was done in editing using Paint dot Net.

I can envisage using large, medium and small apertures in each of the cases you suggest depending on the composition of the shot ... that is the essence of photography as a creative process.

However if you want as much Depth of Field as possible then you may be able to use a small aperture with the reverse true of the large aperture ... though in choosing any aperture it is highly desirable to take note of the shutter speed is not too long to avoid camera shake or subject blur.

It really is as simple as that for all the extensive quibbling this thread has drawn

[William W]

Comment re Focal Length of Lens and DoF & Background Blur:

I was poised to respond to Post #24 in regard to the Focal Length affecting the DoF.
I chose to not respond, because I was unclear about the exact meaning of Post #24 and I did not have time, at that time, to expend
If I had responded, I would have written similar as Dan Kortez wrote in Post #30.

*

1. The Mathematics (i.e. how we calculate DoF for 'normal' Photography)

We have a formula for DoF (one can research that formula) and we plonk in the following arithmetic variables:

> The Focal Length of the Lens
> The Distance from the Film Plane to the Plane of Sharp Focus (simply - the ‘Distance to the Subject’)
> The Aperture of the Lens
> The Circle of Confusion

*

2. The Axiom of DoF:

If the following three variables all remain constant:
> the FRAMING of The Shot
> the APERTURE of the lens
> the CAMERA FORMAT*(1)

then for most practical shooting at typical distances (*2), the DoF will remain constant irrespective of the Focal Length Lens which is used.

Notes:

*(1) If the Camera format remains the same, that implies the CoC will remain the same.
*(2) Axiom begins to fail (but not that much) for Extremely Wide Angle Lenses and at very Short Subject Distances and at Subject Distances approaching the Hyperfocal Distance.
*(2) Axiom fails for MACRO PHOTOGRAPHY

***

Why does the Axiom work?

Grab an on line DoF Calculator
Pump in the numbers keeping the numbers for the CoC and Aperture the same
Change the numbers for the Distance and the Focal Length to always make the same FRAMING . . .

Bingo - the answer for the DoF stays the same

If one likes Mathematics - get the formula for DoF for 'normal shooting distances' - and it is quite apparent.

*

One really good Practical Use for all this theory and Axiom stuff:

I have found the axiom very useful when shooting Weddings and Portraiture, which constituted a vast portion of my professional life.

I didn't have mobile applications and on-line calculators - we did have dial calculators, but they were cumbersome and way too time consuming to use, when shooting on the hop - and I wouldn't even consider use a DoF mobile Application at a Wedding today anyway, for the same reason - way too time consuming.

However it was simple for me to learn three basic framing sets for three key apertures and from there memorize the DoF.

Here is an example of two of my cheat sheets, for a 135Format Camera:





After using the cheat sheets for a couple of weeks - the DoF for various Framing at various Apertures became embedded in my brain-box forever.

***

Re Background Blur (& Foreground Blur):

Bob Atkins has a downloadable Background Blur Calculator - I find it interesting.

It's worth a look, especially if you want to relate what you see in "Bokeh" into a numerical format.

Here: http://www.bobatkins.com/photography...ound_blur.html


WW

[jcuknz]

I worked out WW's position using scale drawings long ago and was quite gratified to find a Kodak booklet agreeing with me

I always set my lens to ten feet for vertical format full length people photos and fifteen feet for full length in landscape mode when using my usual 50mm lens on what we often call today 'full frame' but was simply 35mm then ... rarely used the rangefinder until I replaced my Leica with a Japanese fixed lens camera [ Topcon 35S ] with a wonderful 1:1 optical viewfinder instead of the tiny Leica tunnel [ IIIc et al. ] and used to deliberately put the lens out of focus to use the rangefinder to bring it back to sharp

[William W]

Aside comment:

. . . This reminds me of the difference between the American and Dutch ways of training kids to ride bikes. . .

There are lots of reasons for the variety of my activities, but one is I am qualified as a "Learn to Swim Teacher" (i.e. teaching people, mainly kids, but not necessarily kids, how to swim) - we do NOT use "floaties".

Apropos teaching my own children how to ride a bike - I did not use training wheels and I did not use that Dutch method either: but I did run along side with a light grip on the top of one shoulder for balance. They were about 3~4 years when we began to learn how to ride a bike. They got balance very quickly riding on flat ground.

Our daughters were in an outdoor pool at 4~6 months old and both could swim about 8 meters in still water unassisted 'dog paddle' at about 20~24 months old - I think that teaching such physical skills at a young age is very beneficial.

I think that Dan's thoughts on these things have some relevance to learning Photography.

WW