Auto vs other mods - different results?

[Alexander Rahlis]

Hi all, I hope u could help cause this issue driving me crazy!
I own G5 camera, and I was trying to take the same picture with 5 different modes:
Auto, P, Tv, Av, Manual.

for some reason I got different results on all the photos!
When in fact i expected G5 to choose the same numbers for all modes.

The numbers I got:
Auto: F2.0 - 1/60
P: F2.0 - 1/10
Tv: F2.0 - 1/60 (I set Exposure to 1/60 like in Auto)
Av: F2.0 - 1/10 (I set F to be 2 like in Auto)
Manual: F2.0 - 1/60 (I chose ISO=200, and Flash 1/3, all other combinations gave very bad results)

So my question is why when I shoot on "P Mode" for example th e camera chooses Automatically F2 and 1/10 Exposure,
When for the same picture but on Auto it choses F2 1/60? How can it be?

The Tv setting came somehow the same. but then again on the Av, i got difference although everything should be the same!

On Manual I finally set f2, 1/60 but again got picture which looks different from the Auto pic with the same settings!

All the settings where set to auto when possible. (ISO, WB, etc...)The shots where taken using tripod.

I am lost please explain.

The photos can be seen here (http://community.webshots.com/album/483271562YaSGed).

Thanks,
Alex.

[lefturn99]

I'm quite surprised the camera didn't use 1/60 in P mode with flash. That seems to be a common thread with many different cameras. Did you use an external flash?

You would think that as long as you had ISO on Auto, P and Auto should be the same. And if they are the same, you could set Av, Tv, and M like the other two and get exactly the same settings and results.

One thing that concerns me is that the Aperture is bumped up against the maximum size. When you took the shots, did you half-press to see if the exposure was correct? If any of the readings in the upper left of the LCD were in red, you were "out of spec".

Have you run the same tests without the flash?

[RafaPolit]

Hi Alex...

I assume that since in Auto mode the camera can change all the settings, it is quite possible that it changed the ISO to stay in the 1/60 range (which is the slowest shooter the camera aims for in order to get a steady shot). Only if the f stops can go any lower or the ISO can't go higher, it will go bellow 1/60.

In P mode you set the ISO, so probably the camera needed the 1/10 to achieve equal amount of light.

In TV it gave you F 2.0 because it can't go any lower, but probably the F value was in red (at least thats how it works on the Pro1, probably the same with G5). In AV again, the camera chooses the 1/10 wich is the correct shutter speed for the ISO you set and the F2.0 value. In Manual, you can aim for anything you want, the question is what did the Light Meter said about your settings? (again, in the Pro1 you will read a -1/3 or something like that in the upper left corner)

Just an idea..., hope it helps.

Rafael Polit Jr.
Quito, Ecuador.

[Alexander Rahlis]

Thanks for the answers!
I all the modes - P, Av, Tv - the ISO speed was on Auto!

So there is no reason for the camera to change the exposure espessially on P!

Also i did half press and checked, I was always ok with the settings - no REDs no +-,
except on Manual it gave me -1/3. (also why? it should be the same as auto, i used the same exposure and aperture!)

lefturn99, I use the built in flash.
I tryied without the flash like u asked:
Auto: F4 - 1/400
P: F5 - 1/250 (ISO-Auto, no bad readings)

Again, i don't understand how with all the parameters on auto, i don;t get the same results on all the modes?

Regards, Alex.

[Robert_Lay]

Dear Alex,

The over-riding issue here is that you are making very rash assumptions about what you think the camera should be doing in each mode.

I suggest several things that should be tried before you even think about enabling the flash, which when used is going to complicate the issue.

1) Shoot a scene in Auto using Auto ISO and note and record ISO, Shutter and Aperture.
2) Shoot the same scene in P and note and record ISO, Shutter and Aperture.
3) Shoot the same scene in Av by setting the aperture and ISO to those recorded in (2) and note and record ISO, Shutter and Aperture.
4) Shoot the same scene in Tv by setting the shutter and ISO to those recorded in (2) and note and record ISO, Shutter and Aperture.
5) Shoot the same scene in M by setting the shutter and the aperture and the ISO settings to that recorded in (2) and note and record ISO, Shutter and Aperture.

Compare the results of all 5 shots - they should be the same. Think about the results and the setups for each step. You should now begin to understand that in Av you set the aperture and the shutter should be controlled by the light meter. Conversely, in Tv mode you set the shutter and the aperture should be set by the light meter. In P mode both the aperture and shutter will be set by the light meter, and it is difficult to predict what they will be, but they "should" result in the same exposure. In Manual mode you set everything, and the settings that you make should be consistent with what the camera told you in P mode.

At any point where your results are not what they should be, come back and let's hash over that step again.

Before you start this series of experiments, you should carefully choose your exposure sensing mode to be "Evaluative", and you should be shooting the same scene for each of the 5 shots.

Once you have fully understood how the modes are supposed to work, you can venture into use of the flash, which is another thing altogether.

[Alexander Rahlis]

Bob, I did exactly what u said. if u look on the first post i wrote. the only differnce i used flash, but than on my second post i tryied without flash too.

I perfectly understand how the modes work and the meaning of Av and Tv. and thats why i choses the apperture or exposure to be the same as in auto mode. but lets simpify the discussion lets concentrait only on
Auto and P mode:


NO FLASH,
SAME SCENE
TRIPODE USED (to prevent shaking and shifting of points of evaluation. )
EVALUATIVE LIGHT METERING SET.
AWB SET.
THE ISO IS ON AUTO IN BOTH CASES! (I hope it will rule out the ISO questions once and for all.)the readings where different!
Auto: F4 - 1/400
P: F5 - 1/250
And the pictures of course looks different!

Please someone who has G-series camera (or any other canon camera) try to do the same and see for urself. If u tell me that u get the same results than something wrong with my camera or with some other settings (which i can't figure out now)

Again to remind:
THE ISO IS ON AUTO IN BOTH CASES!
TRIPODE USED!

Will be very greatfull for anyone to actually try it.
Thanks,
Alex.

[Robert_Lay]

Dear Alex,

Please check your Exposure Correction - I think it is set to something other than zero.
Turn the camera on and put it in Program (P) mode. You cannot make this check in Auto mode.
Press the omni control where it shows [+/-] to turn on Error Correction. I think you will find that it is not set to zero.

Another place to look is to look at the EXIF data for the pictures. There is a parameter called Exposure Bias. That should be zero if the Error Correction is set to zero.

Please try again - my G5 gives me the same settings when in P and Auto.
Thanks,

[RafaPolit]

Hi Alex,

I know how frustrating this things can be, and how anoying it is to read everyone asking what one has already checked or discarded or whatever the case may be, but these questions are necesary to clarify what comes to mind to the people trying to help, and to get deeper into the real problem.

That said, in your second example, 1/400 at f 4.0 is almost the same exposure reading as 1/250 at f5.0, almost... not trully the same but very near, and also, that is a much better scenario to analyze since the camera can choose both higher and lower shuter speeds and higher and lower f stop settings.

Just to go deeper into the "anoying" questions:

first: is your scene in a light controlled situation? That is, indoor with artificial lighting and consistent color temperature and etc. or is it a situation where a window or some kind of uncontrolled factor can be an issue? (an outdoor test will truly involve uncontrolled factors that can explain the differences)

second: In Auto Mode there is really absolutely no control over any setting but the size of the image, even the ISO cannot be really set to Auto, but it is in Auto nonetheless, whatever you do (I understand that the Auto ISO in P should therefore yield the same results, so I agree: the problem is not there! ;) ). But the camera will "remember" settings like the ones pointed by Bob: if you have chosen Exposure Compensation, it will change the final result... judging for your readings, the ND filter is probably not on, but its worth checking.

third (and the most important): Check the evaluation method used in the P mode... im not sure which is the one the Auto mode uses, but im guessing Evaluative Metering is the one used... the evaluation method will truly change the readings depending on the center subject and global lighting of the scene.

Can you post these two images to judge how different or similar they are? Im wondering: are 1/400 f4.0 and 1/250 f5.0 completely different or merely not exactly the same? (differences can reside in different WB if the situations are changing even in the smallest of measures, for instance something as simple as your place behind the camera can cast different shadows that can misslead the WB evaluation)

Rafa Polit (jr.)

[Alexander Rahlis]

Hi again!
RafaPolit, Robert_Lay,
Thanks for help i found the mistake (but only for outdoors). It was my fault sorry :(
I didn;t notice that the flash in PMode was not on AUTO, so it probably fired and i didn;t noticed.
So now WITHOUT using the flash i get same results!

But the problem remained when i go indoors and use the flash.
don;t confuse between AUTO_MODE and AUTO_FLASH in the discussion below:

I put the FLASH on AUTO_FLASH this time and i see the results different between the AUTO_MODE and P Mode.
But i found the source of the problem so we can narrow it pretty much to P mode only, it should be easy now.
The problem is that on P mode the camera gives me the SAME exposure reading whethere i set FLASH ON, or OFF, or AUTO_FLASH !
I always get 1/25 - F2 for my scene. Camera doesn;t compensate when using the flash in P mode
The pics can be seen here.
http://community.webshots.com/album/483271562YaSGed

Any ideas why the camera ignores the flash?

cause that is the cause of the problem, the camera ignores the flash in P mode, but DOES NOT ignore the flash in AUTO_MODE
So the camera DOES compensate when flash is ON in the AUTO_MODE.

The (+-) Flash is on Zero in the Func menu.

Thanks Again,
Alex.

P.S. Again if u can check it on ur camera and tell me that it works fine for u that the problem is me again (or my camera).

[Robert_Lay]

Dear Alex,

I now have the two pictures downloaded from your web site and am working on the problem. Please be patient. I will be back to you within the hour.

Thanks,

[Robert_Lay]

The problem is that on P mode the camera gives me the SAME exposure reading whethere i set FLASH ON, or OFF, or AUTO_FLASH !
I always get 1/25 - F2 for my scene. Camera doesn;t compensate when using the flash in P mode


Dear Alex,
I looked at your two pictures on the Web site. It would be better if you could save your pictures and post them using ordinary methods, because we need to see the EXIF data, and the EXIF data is not embedded in your pictures. We need to be able to independently verify what your camera is doing on each shot.

The picture WITH FLASH ON is slightly brighter (very little difference) than WITH FLASH OFF. It is also slightly warmer in tone. The differences between the two pictures is hardly significant enough to notice unless you have the two pictures side-by-side for comparison.

My guess is that you are expecting the flash to have more effect than it does. If you have a much DARKER scene to start with, then the flash will make a very noticeable difference. However, in your scene, the ambient light is enough that the camera CAN give proper exposure without flash. Therefore, when the flash does fire, the sensor cuts the flash off very quickly - so the flash contributes almost nothing.
So, in my opinion, you would have to start your indoor experiments with a much darker scene in order to realize any major contribution with the flash.



Any ideas why the camera ignores the flash?

cause that is the cause of the problem, the camera ignores the flash in P mode, but DOES NOT ignore the flash in AUTO_MODE


I don't think that the camera is ignoring the flash in either mode. I think that if you put the flash into ON mode, it will always fire, but its sensor shuts it off almost immediately when it sees that there is enough light. If the flash is in AUTO mode, it may not fire at all if the ambient light is adequate. Again, we must have the EXIF data in each image in order to verify the camera's actual behavior. If you are saving the pictures using Save for the Web, then that may be why you are losing the EXIF data. I don't know what program you are using to process your images before posting to the Web site.


P.S. Again if u can check it on ur camera and tell me that it works fine for u that the problem is me again (or my camera).

In my opinion, the problem is not with you and also not with the camera. The problem is that the scene is bright enough already that the flash is not making a significant contribution. There are ways in which you can demonstrate that the flash does exactly what it is supposed to do, but it is almost impossible to get the flash to contribute significantly when the scene is already bright enough that the camera can get a good exposure without the flash.

Remember that the internal rule that the camera uses to control the flash is that it shuts the flash down as soon as the integrated scene brightness is at the correct level.
I don't think you will ever see the flash completely dominate the picture unless you turn off the room lights.

Also, remember that you did not really complete the experiments. You should complete all the steps in the NO FLASH experiment to be sure that you are getting the correct behaviour for Av and Tv modes and that you understand them. Such tests are very helpful in gaining a better appreciation of the separate functions of the light meter and the aperture and shutter functions in each mode.

[Alexander Rahlis]

Hi Robert,
the website indeed removed all the exif info from the pictures,
any idea where else can i post the pics, so the exif info will remain?

Also I will try to answer all ur other questions ASAP.

Regards,
Alex.

[Robert_Lay]

Dear Alex,

The EXIF data was NOT removed by the Web Site - It was removed by "Save for Web" in Photoshop.

[Alexander Rahlis]

Hi Robert, sorry for delay with the answer, couldn;t do it earlier.
I tryied the test with a very dark scene, and it confirmed my worries, the P mode is behaving very strange.
I got again the same exposure readings for all the FLASH variants (AUTO, ON, OFF) and it was
1/1 - F2

The flash on AUTO didn't fire at all actually, although the scene is VERY dark and could not be seen without flash. so the camera doesn't read the scene correctly in P mode.

Unfortunately i can't post photos with EXIF data, I don';t use any program to post them to the web, i use a webshoots site script that uploads my photos to it, and it removes the EXIF data, as well as renames the file.
I found that i can post the photos here.
but only two of them.
That's not a problem as the AUTO_FLASH and FLASH_OFF photos are EXACTLY the same inlcuding EXIF data.

35383

35385

I just want to know is it only my camera that does this mistake with flash? After all it SHOULD fire flash in the dark room when the flash is on AUTO? Isn't it?

And IT IS doing it right in the AUTO_MODE, so why not in the P MODE???
So if there is a problem with my particular item, i will try to fix it.
And if not than it is very strange nobody knows about it...

Regards,
Alex.

[Robert_Lay]

Dear Alex,

I have saved your two pictures above and your message.

I will study your message and the pictures and reply as soon as possible.
Please be patient, I will post a reply as soon as possible.

[Robert_Lay]

Dear Alex,

I now have my conclusions.

First, I have been assuming that we are talking about the built-in flash unit that is integral to the G5 - we are NOT using an auxilliary, external flash!

Also, I was able to see your EXIF data in the two pictures that you posted.

In image FLASH ON.JPG the EXIF data says Fired, compulsory mode.

The EXIF data is telling me that in FLASH AUTO.JPG you have used the button in the top left hand corner of the camera and cycled the flash to be OFF. Either the EXIF data is incorrect, or you are not using the button correctly, or the camera is broken - I have no way to know unless I can see the lightning bolt in the LCD monitor when you make the shot.

It is interesting that BOTH shots show shutter speed = 1 second. When my G5 is in P mode, the ONLY WAY that I can get an exposure of f/2.0 at 1 second is if I turn the flash OFF using the button mentioned above.

Every indication is that you are setting that button to turn the flash OFF.

There is nothing else I can say.

[Alexander Rahlis]

Hi Robert,
I am using of course the Internal flash.
the picture was definately take on AUTO_FLASH.
I made the test 5-6 times before posting.
but the strange thing is that now i get the FLASH fired on AUTO,
although the scene is slightly different but the behaviour is very disturbing.
Another scene that i took now in P mode:
FLASH AUTO
35436

FLASH OFF
35437

The exposure again is the same in both photos.
and the pictures look very different.
The exposure in P mode should adjust it self to the situation, but it'snot what happens.

Maybe, the problems i have is because i once dropped my camera, although no external damage was seen, something could be wrong inside...
Thanks Alex.

[Robert_Lay]

In these last two shots there is consistency with respect to the two before that.

In each sequence of shots your EXIF data is telling me that the flash is turned off in one shot and is firing in the other shot.

The one with flash firing looks overexposed, but that is not unusual for a close-up flash shot.
Now to the issue of the FLASH OFF 202 picture. The only way that camera can give you 1 sec and f/2.0 in P mode is that you have turned the flash off, and the camera is giving you the largest exposure that it can order - namely 1 second and f/2.0. Under those conditions, my camera displays the aperture and shutter speed in RED in the monitor (telling you that it CANNOT meet the exposure required). In other words the camera is telling you that you cannot shoot this scene in P mode, because in P mode it cannot give a bigger opening than f/2.0 and it CHOOSES not to give you a shutter speed slower than 1 second. That is what its rules are saying. Unless you can satisfy me that my analysis is incorrect, then I say that the camera is working properly.

You have implied in your message that you are physically turning the flash to OFF mode in the shot named FLASH OFF 202. Why would you think that the picture should come out the same as with the flash on? The camera simply cannot meet that exposure requirement unless you put it in manual and give it a longer shutter duration.

I am becoming convinced that the problem is that you have not yet accepted the realities of P mode. It does NOT automatically adjust the camera to give the correct exposure - it only TRIES to - up to a point. Once the camera tells you that it CANNOT do it, then it's up to you to go to Av or Manual mode. Generall speaking Tv mode is already a loser if P mode can't do it.

[Alexander Rahlis]

Robert, it's not about hitting the bottom 1 sec! it happens always on every speed and shutter (1/1-F2 or 1/25-F2 or 1/60-F2 this is all the tests variants that i have done). even when i get no RED reading. we have been through this already, but u asked me specifically to do it in very dark conditions. Thats why i got the red reading.

The only thing i can't understand is why I get the same exposure with flash fired and not fired.
Even a beginner knows that when he enables/disables flash he should compensate with exposure or shutter. but this camera exposure stays always the same.
And it is AUTOMATICALLY choosen, not by me!!!

I think I understand the exposure/shutter issue pretty good, to know there is a problem here.

Example,
if i shoot a picture with FLASH ON and got 1/60-F2,
then when I put FLASH OFF i would expect some (maybe slight maybe big) change in the numbers, something like 1/40-F2.

So do u want to tell me that u when u turn flash off/on u don't need to compensate???

[Robert_Lay]

I cannot understand what you mean in your first paragraph.

In regard to getting the same exposure both with flash fired and not fired - As I said, my G5 camera also gives me the same 1 sec shutter speed setting and the same f/2.0 aperture setting in P mode, when the flash is turned off and the scene is too dark for P mode.

So your camera is working the same as mine.

Also, in that same scene, if I turn the flash on, the camera still calls for a 1 second exposure at f/2.0, but when the flash fires it gives me a good exposure, just like it did with your camera. Again, my camera is doing the same thing as your camera when the flash is turned on and the scene is dark.

You are insisting that the camera should do something different than what it does, and I am trying to explain that the camera is doing exactly what I would expect it to do. I think that you are expecting the commanded aperture and shutter speed to change when you turn the flash on. This I have to check again when I get home, but I am pretty sure that when I wrote my previous message and was doing the same thing with my camera, that the commanded settings did not change when I turned the flash on or off. When I get home on Sunday, I can double check that. Unfortunately, I am at my daughter's house and we are going camping through Sunday.

In your last paragraph, you ask when I turn my flash off/on do I need to compensate. Well, if I want to get a good exposure, then I certainly have to do something, because under the conditions of a dark scene, if I turn the flash off, I get a dark picture and if I turn the flash on, then I get a good picture - all in P mode - just exactly like the two pictures you got.

I think we will have to continue this on Sunday, because after tomorrow at 10 am EDST I will not have access to the internet until Sunday evening.

[Alexander Rahlis]

Robert, if u think that there is nothing strange with the fact that in P Mode the exposure settings don’t change when I play with FLASH on/off, than we have nothing to discuss here.
After all on the AUTO_MODE the exposure settings DO change when I play with FLASH on/off. And I would expect the behavior to be consistent.

But if u think that’s all like it should be. Than I don’t think we should continue the thread. I don’t need to convince u, and u will not be able to convince me that it is the right behavior.
I am here for understanding, and I think I got everything I could from this thread.
Thanks a lot for the help,
I really appreciate it!
Alex.

[Robert_Lay]

Well, I'm really sorry that you feel that way about it, because it means that I have failed in my efforts to help.

The time may come when you have a change of heart on this matter, in which case I hope you will bring us more information about your experiments. Knowledge is everything, and communication is often the biggest problem in exchanging information.

We will hope for a better day.

[RafaPolit]

Alex,

Im jumping in here one more time... the PRO1 and the G6 have both a setting in the menu called SLOW SYNCHRO, wich tells the camera to use whatever reading it would get without the falsh and then fire the flash (during the first or second curtain also selectable through menus)... this could expalin the differences, in Auto im almost sure this settings are overriden. Please try setting this menu feature to off and comment again on your results.

good luck,

Rafa Polit (jr.)
Quito, Ecuador

[Bryan Bedell]

Actually now that Rafa mentions the Slow Synchro, I'm reminded about that "Safety Shift" setting, too (in the G6 anyway) that overrides settings, that would affect the outcomes of the test, for sure.

Bb.

[Alexander Rahlis]

Thanks RafaPolit!!!
Slow Syncro was ON,
I turned it OFF and it worked!!!!!
Now everything works like it should be!

All the readings are consistent with what I would expect:
P mode consistent with AUTO, and FLASH ON/OFF gives different readings of exposure...
I actually understand now what is happening with my camera.

I am now gonna read about the Slow Syncro feature...

Thanks again
RafaPolit, Robert and everyone else who participated.

I will go shoot some photos now ;)
Alex.

[Robert_Lay]

Dear Rafa, BB and Alex,

Just got back from my camping trip.
I checked Slow Synchro on my G5 and it is set to OFF.
That would seem to indicate that there was a difference in the way my camera was set up in comparison to Alex's camera.

I want to thank both BB and Rafa for pointing out this possible difference.

According to the manual, page 61, if you set Slow Synchro to ON it makes it possible to use the flash with slow shutter speeds.

With my camera, with Slow Synchro turned ON, in P mode with Flash in Auto and in a dark room, the flash fires and the shutter speed will be 1 second.

Conversely, with Slow Synchro turned OFF, in P mode with Flash in Auto and in a dark room, the flash fires and the shutter speed will be 1/60 second. That's completely different behavior.

I'm still thinking about what all that means.

[RafaPolit]

Alex:

Great!!! It's a nice thing when this kind of "problems" come to a nice solution, and even better if one ends with a better understanding of one's camera, thats why this forums (this one in particular) are so great. Its nice to have been of some help.

To Alex and Bob, some more info on the Slow Synchro,

Normaly, one would use the Slow Synchro OFF to have 1/60 to 1/250 exposures to have sharp unblured subjects on the image, but, for example, on a night shot of a portrait against city lights for instance, or against a very very late sunset, the face of your subject will be perfectly lit, but the background would be completely dark, as 1/60 doesnt quite make it for this situation.

In this case, setting Slow Synchro to ON would force the camera to measure light as if shot without the flash, giving exposures up to 1". In those cases, the face would be exposed in an instant with the flash, but the background would have also a correct exposure. This would seem as a perfect solution for all shooting conditions, not only specific circumstances, but if your subject moves while "the other half" of the image is being exposed, your subject will have the flashes sharp definition, and a ghost of blur all around added because of this movement, which ruins the picture.

On the other hand, if everything in frame is within the range of the flash, setting it to ON will probably acomplish very little, and will introduce problems with hand shake, forcing the use of a trypod, with very little difference between the pictures. So this feature truly shows its value when several planes at large distances one from each other are in frame, or for special shots of fireplaces, candles, moving vehicles, and several other conditions.

So Alex, now that you will "go shoot some photos now" im sure you will share them with us!! Happy shooting

Rafa Polit (jr.)
Quito, Ecuador.

[Alexander Rahlis]

Thanks Rafa Polit,
it was indeed a very good explanation!

[Robert_Lay]

I agree with Alex and want to thank you again Rafa for the additional insight into how it is used. I saw what the manual says, but it was not at all obvious how you make use of the feature. You cleared that up quite well.

By the way, I have a friend who works as a transmitter engineer at the big short wave station near Quito - you may know some of those people - right? His name is Tim Zook.