help..pictures washed out. (WITH NEW PICTURES)

[Bluelens]

I brought this up in the "Canon digital EOS cameras" area, but now that I have some pics for examples, I wanted to bring it up here. Hopefully this is the right place to post it. If not then hopefully it will get moved to where it should be.

Anyway. I am using the Canon Digital Rebel with a Sigma 28-300 lens. I started out the pictures with the camera in fully manual mode and through combinations of shutter speed, f stops and going to Av, Tv, P and A-DEP on the camera, these are the results. I am suprised that the lower the f stop the less blow-out the images were, uderdeveloped yes, but I would have thought the opposite would have happened. In all the images the ISO was at 100.

The final settings (I places f stop, shutter speed and ISO ratings on the images) are the result of the camera meter giving me a mark in the "0" indicating a properly exposed image.

Do you think this has more to do with the Sigma lens or the camera itself? Is there some calibration that I have yet to do?

There are 9 pictures, so I will just post the links to save everyone browser time.

http://www.bluelens.net/300d/10.jpg

http://www.bluelens.net/300d/13.jpg

http://www.bluelens.net/300d/5.jpg

http://www.bluelens.net/300d/12.jpg

http://www.bluelens.net/300d/7.jpg

http://www.bluelens.net/300d/9.jpg

http://www.bluelens.net/300d/6.jpg

http://www.bluelens.net/300d/8.jpg

http://www.bluelens.net/300d/11.jpg

Thanks for your help.

[timmyquest]

This is going to be a very hard shot no matter what gear you have. your taking a picture of the backs of objects as the light is from the front and the sky is bright.

Go get a circular polarizer now and thank me later.

[G3]

The dynamic range in this photo is so wide that it would be difficult to get the sky and the foreground exposure correct at the same time. Here, I would suggest using a graduated Neutral Density filter to bring the exposure for the sky down a couple of stops to try to get it back to within a stop or two of the foreground exposure.

[Tom W]

Out of curiosity, where was the sun in relation to these pictures? Did you use a lens hood? Did you have a poorly-coated or uncoated UV filter on the lens?

It looks like some loss of contrast is making a photographically difficult situation even more difficult. This may (or may not be) be a result of some lens flair, even though there aren't the tell-tale "circles of light" that often accompany it.

[Tom W]

The final settings (I places f stop, shutter speed and ISO ratings on the images) are the result of the camera meter giving me a mark in the "0" indicating a properly exposed image.

Do you think this has more to do with the Sigma lens or the camera itself? Is there some calibration that I have yet to do?

Thanks for your help.

Woah - this part caught my eye the second time I read it. Are you saying that all of these pictures gave metered indication that the exposure was correct?

Now that's odd. I would recommend testing again with a different lens, and with this lens (but find a subject that doesn't have quite as wide a dynamic range).

What metering mode were you using? (I apologize that I'm not sure what modes the Digital Rebel offers)

[Tom W]

As I went through the shots, it is becoming evident that the aperture isn't closing down as indicated. The change of image exposure from f/4.5 & 1/2500 to an exposure of f/7.1 and 1/1000 ought to give similar results given that the EV number is about the same, but they obviously don't in these pictures.

Try cleaning the contacts on the lens and camera - it seems that they aren't communicating for some reason.

Is this a relatively new Sigma lens or an older one?

[CyberDyneSystems]

Nice detective work Tom!

Looks like there is definately a hard ware issue.

[PacAce]

I brought this up in the "Canon digital EOS cameras" area, but now that I have some pics for examples, I wanted to bring it up here. Hopefully this is the right place to post it. If not then hopefully it will get moved to where it should be.

Anyway. I am using the Canon Digital Rebel with a Sigma 28-300 lens. I started out the pictures with the camera in fully manual mode and through combinations of shutter speed, f stops and going to Av, Tv, P and A-DEP on the camera, these are the results. I am suprised that the lower the f stop the less blow-out the images were, uderdeveloped yes, but I would have thought the opposite would have happened. In all the images the ISO was at 100.

The final settings (I places f stop, shutter speed and ISO ratings on the images) are the result of the camera meter giving me a mark in the "0" indicating a properly exposed image.

Do you think this has more to do with the Sigma lens or the camera itself? Is there some calibration that I have yet to do?

There are 9 pictures, so I will just post the links to save everyone browser time.

http://www.bluelens.net/300d/10.jpg

http://www.bluelens.net/300d/13.jpg

http://www.bluelens.net/300d/5.jpg

http://www.bluelens.net/300d/12.jpg

http://www.bluelens.net/300d/7.jpg

http://www.bluelens.net/300d/9.jpg

http://www.bluelens.net/300d/6.jpg

http://www.bluelens.net/300d/8.jpg

http://www.bluelens.net/300d/11.jpg

Thanks for your help.

Sounds like a simple case of not knowing how to use the "meter" of the camera.

I've had this discussion before but I'd like to re-iterate. That thing that you think is a "meter" does NOT function as a meter except when the camera is in "M"anual mode. In any other modes, the meter is an exposure compensation indicator. If you haven't set the EC, the meter will ALWAYS be in the middle and, hence, does NOT indicate that the exposure is correct.

In the "M" mode, you have to set the aperture and the shutter combination so that the meter reading is in the middle at 0. You may want to go a little left or right of center to compensate fo the lighting such as backlighting (go +2/3 or more) or when the background is very dark (go -2/3 or more).

In the Av, Tv, you have to set the aperture (Av) or the shutter (Tv). The camera will automatically set the other setting. BUT you have to make sure that there are no blinking numbers in the viewfinder. If there is, then that mean that you have selected a setting that is outside the proper exposure range of the camera. In that case,you have to adjust the aperture (Av) or shutter speed (Tv) so that the setting selected by the camera does not blink.

Once you have this figured out, then you'll be ready to move to exposure compensation so that the bright sky does not cause your foreground subjects to be too dark, etc.

[Bluelens]

Out of curiosity, where was the sun in relation to these pictures? Did you use a lens hood? Did you have a poorly-coated or uncoated UV filter on the lens?

It looks like some loss of contrast is making a photographically difficult situation even more difficult. This may (or may not be) be a result of some lens flair, even though there aren't the tell-tale "circles of light" that often accompany it.

I have a Hoya UV filter on and the lens hood was in place. Unfortunately the only other lens I have is a Canon 38-50, so the testing cannot be totally comparison-able (?) Yeah new words all the time ;)

I will give it a shot though and see what difference there is by setting at the same focal length and settings.

The Sigma lens I have had for about a year now. Perhaps it is time to scrape up for a better one.

Thanks for the input.

[Bluelens]

Sounds like a simple case of not knowing how to use the "meter" of the camera.

I've had this discussion before but I'd like to re-iterate. That thing that you think is a "meter" does NOT function as a meter except when the camera is in "M"anual mode. In any other modes, the meter is an exposure compensation indicator. If you haven't set the EC, the meter will ALWAYS be in the middle and, hence, does NOT indicate that the exposure is correct.

In the "M" mode, you have to set the aperture and the shutter combination so that the meter reading is in the middle at 0. You may want to go a little left or right of center to compensate fo the lighting such as backlighting (go +2/3 or more) or when the background is very dark (go -2/3 or more).

In the Av, Tv, you have to set the aperture (Av) or the shutter (Tv). The camera will automatically set the other setting. BUT you have to make sure that there are no blinking numbers in the viewfinder. If there is, then that mean that you have selected a setting that is outside the proper exposure range of the camera. In that case,you have to adjust the aperture (Av) or shutter speed (Tv) so that the setting selected by the camera does not blink.

Once you have this figured out, then you'll be ready to move to exposure compensation so that the bright sky does not cause your foreground subjects to be too dark, etc.

I started out in "M"anual Mode and was workign off the 0 on the indicator. This is what produced some of the blown out shots. When I snapped the shutter there were no flashing numbers and everything was stable. Like Tom had mentioned, and CDS reiterated, perhaps it is a conflict with the lens I have. A cleaning of the contacts will be done before the next outing I take.

Thanks for the info though.

[PacAce]

Are you saying that each one of the pictures you posted links for were all taken with the camera set to "M"? And that in each one, the meter was a '0' (in the center of the scale)?

From what I've seen from those images, the only one that seems to have been shot the way the camera wanted it (assuming you were using center focusing) is the first one (10.jpg). But due to the bright sky, the foreground is really underexposed. The 2nd one (13.jpg) is better but still a tad underexposed. Probably another 1/3 stop would have done it.

Then 3rd one (5.jpg) starts leaning towards overexposure of the foreground.

But if you're saying the each one of these were taking in Manual mode with the meter at mid-point, then there's something definitely wrong somewhere. Would it be possible for you to post the original EXIF of each of these pictures?

[Tom W]

But if you're saying the each one of these were taking in Manual mode with the meter at mid-point, then there's something definitely wrong somewhere. Would it be possible for you to post the original EXIF of each of these pictures?

That's what I was thinking, Leo. Look at the aperture/shutter speed settings that he printed. On most of the images, they are exposed for a similar Exposure Value (EV), but yet, as he stops down and uses a slower shutter, the pictures become brighter and brighter, almost as if the aperture was not physically closing down, despite reporting that it is doing so.

The true EXIF would be helpful.

Does the digital Rebel have DOF preview?

[PacAce]

But if you're saying the each one of these were taking in Manual mode with the meter at mid-point, then there's something definitely wrong somewhere. Would it be possible for you to post the original EXIF of each of these pictures?

That's what I was thinking, Leo. Look at the aperture/shutter speed settings that he printed. On most of the images, they are exposed for a similar Exposure Value (EV), but yet, as he stops down and uses a slower shutter, the pictures become brighter and brighter, almost as if the aperture was not physically closing down, despite reporting that it is doing so.

The true EXIF would be helpful.

Does the digital Rebel have DOF preview?

Actually, Tom, the EV were NOT consistent. Looking at the shutter values and the aperture values (I listed each one down) the aperture and shutter values are NOT going up or down in equal increments. The Aperture seems to be going down in 1 stop increments but the shutter speeds are changing by more than one stop most of the time.

Then there a series of pictures (the last three) where the aperture is at f/29 but the shutter speed is set to 1/200, 1/80 and 1/2. I can't see how each one of these settings could have resulted in the meter being at 0 in Manual mode when the aperture is constantly at f/29. That's why I'd like to see the original EXIF. Either the camera is really busted or the settings were not set in Manual mode.

BTW, here are the settings of each of those shots:

10.jpg - f/4.5 1/4000
13.jpg - f/4.5 1/2500
5.jpg - f/7.1 1/1000
12.jpg - f/11 1/320
7.jpg - f/16 1/500
9.jpg - f/22 1/80
6.jpg - f/29 1/200
8.jpg - f/29 1/80
11.jpg - f/29 1/2

[PacAce]

I am suprised that the lower the f stop the less blow-out the images were, uderdeveloped yes, but I would have thought the opposite would have happened.

BTW, Bluelens, the f stop values going lower in your case had no direct relationship to each other since the shutter speeds did not stay the same. However, if they had all been the same, then your impression about making the f stop number lower and lower (aperture open wider and wider) would cause the images to get more amd more blown out would be correct.

[Tom W]

Actually, Tom, the EV were NOT consistent. Looking at the shutter values and the aperture values (I listed each one down) the aperture and shutter values are NOT going up or down in equal increments. The Aperture seems to be going down in 1 stop increments but the shutter speeds are changing by more than one stop most of the time.

Then there a series of pictures (the last three) where the aperture is at f/29 but the shutter speed is set to 1/200, 1/80 and 1/2. I can't see how each one of these settings could have resulted in the meter being at 0 in Manual mode when the aperture is constantly at f/29. That's why I'd like to see the original EXIF. Either the camera is really busted or the settings were not set in Manual mode.

BTW, here are the settings of each of those shots:

10.jpg - f/4.5 1/4000
13.jpg - f/4.5 1/2500
5.jpg - f/7.1 1/1000
12.jpg - f/11 1/320
7.jpg - f/16 1/500
9.jpg - f/22 1/80
6.jpg - f/29 1/200
8.jpg - f/29 1/80
11.jpg - f/29 1/2

Well, you're right - I only looked at a couple of them, f/4.5 @ 1/2500 (EV-15.6), f/7.1 @ 1/1000 (EV-15.6), and f/11 @ 320 (EV-15.2). The fact that these three showed a considerably different exposure was what caught my attention.

But you're right, there are some exposure inconsistencies beyond that.

EXIF might show something other than what is reported.

[PacAce]

You're right, Tom. For those pictures with the same EV value, they do seem to be off by close to a stop in exposure. I didn't realize the EVs were so close to each other until I wrote a little VB program to calculate the exact EV for me. I was initially "roughing it" by eye-balling the aperture and shutter values. You probably hit the nail on the head with your "lens doesn't want to stop down" diagnosis.

We'll have to start calling you Sherlock TomW from now on. Or would you prefer TomW, Magnum, PI? :D

[Tom W]

You're right, Tom. For those pictures with the same EV value, they do seem to be off by close to a stop in exposure. I didn't realize the EVs were so close to each other until I wrote a little VB program to calculate the exact EV for me. I was initially "roughing it" by eye-balling the aperture and shutter values. You probably hit the nail on the head with your "lens doesn't want to stop down" diagnosis.

We'll have to start calling you Sherlock TomW from now on. Or would you prefer TomW, Magnum, PI? :D

Gosh - you can tell the programmers from the end users. You wrote a VB program to calculate EV and all I did was set up an excel spreadsheet. :)

Well, troubleshooting without seeing is part of my job. But I don't think I've earned that nickname yet. But if there has to be a nick, I prefer Magnum PI. :)

[PacAce]

You're right, Tom. For those pictures with the same EV value, they do seem to be off by close to a stop in exposure. I didn't realize the EVs were so close to each other until I wrote a little VB program to calculate the exact EV for me. I was initially "roughing it" by eye-balling the aperture and shutter values. You probably hit the nail on the head with your "lens doesn't want to stop down" diagnosis.

We'll have to start calling you Sherlock TomW from now on. Or would you prefer TomW, Magnum, PI? :D

Gosh - you can tell the programmers from the end users. You wrote a VB program to calculate EV and all I did was set up an excel spreadsheet. :)

Well, troubleshooting without seeing is part of my job. But I don't think I've earned that nickname yet. But if there has to be a nick, I prefer Magnum PI. :)

Problem with the spreadsheet is that I have to find the value by looking across the top and down the side of the table and seeing where they meet up. Not good for my old cross-eyed visual orbs.

With a program, all I do is enter the Av and Tv values to get Ev. And beside, the programming was a lot quicker for me than me creating the spreadsheet would have been. Just took me all of 3 lines of code. :D


At any rate, you will henceforth also be known as Magnum PI, our Photo-sleuth Impresario (sorry, couldn't come up with better word for the 'I' in PI). :)

[Tom W]

Problem with the spreadsheet is that I have to find the value by looking across the top and down the side of the table and seeing where they meet up. Not good for my old cross-eyed visual orbs.

I know what you mean. I have to dress things up with multi-colored rows and columns and all that to keep things straight.

With a program, all I do is enter the Av and Tv values to get Ev. And beside, the programming was a lot quicker for me than me creating the spreadsheet would have been. Just took me all of 3 lines of code. :D

It takes me more than 3 lines to log into the computers at work every day.

At any rate, you will henceforth also be known as Magnum PI, our Photo-sleuth Impresario (sorry, couldn't come up with better word for the 'I' in PI). :)

Awww shucks!! :oops:

[Bluelens]

That's why I'd like to see the original EXIF.

I will post the EXIF data tonight.

Not all the pictures were taken in "M" mode. I don't know if the EXIF data will show the camera mode or not. Unfortunately I don't remember which shots were "M" and which were not. And unless it shows on the EXIF data, the diagnosis would probably come to a halt. If so, then I will just have to go otu and try to re-create.

Thanks for all the help so far. You guys have educated me a lot so far.

I am hoping that the issue lies with the lens and not the camera.

[PacAce]

That's why I'd like to see the original EXIF.

I will post the EXIF data tonight.

Not all the pictures were taken in "M" mode. I don't know if the EXIF data will show the camera mode or not. Unfortunately I don't remember which shots were "M" and which were not. And unless it shows on the EXIF data, the diagnosis would probably come to a halt. If so, then I will just have to go otu and try to re-create.

Thanks for all the help so far. You guys have educated me a lot so far.

I am hoping that the issue lies with the lens and not the camera.

If you get the EXIF info out of FVU or EVU or even zoombrowser, you'll get the info I'm looking for because it will tell you if you shot in M, P, Av, etc. And that's what I wanted to see.

[stopbath]

Looks like you have a faulty aperture or aperture mechanism.

Suggest setting the camera on a 1 second or longer exposure, closed down fully.

While looking into the lens, trip the shutter. Does the aperture not close down, or close down very slowly?

If it closes down slowly, look for dark marks on the aperture blades. That would denote an oil leak. Likely caused by heat.

If the lens does not close down, try another lens. If that closes down, then the lens is faulty, if both do not close down, then the camera or both lenses are faulty.

EXIF data will likely be wrong, as it is likely created by what the camera is attempting to set, not what actually got set. (That is the lens was wide open, even though the EXIF data said f16...)

[Bluelens]

Here are some test shots I did tonight. It looks like the issue might be with the lens. What do you think?

I took 3 set f pictures. Each set is with both of my lenses set to 80mm on the Canon and 81mm on the Sigma (that shouldn't taint the testing too much I wouldn't think). The other settings stayed the same (f/stop, shutter speed, ISO) The camera was in "M"anual mode the entire time and no flash was fired.

The first batch is at f/32
http://www.bluelens.net/300d/test/canon1.jpg
http://www.bluelens.net/300d/test/sigma1.jpg

The second batch is at f/29
http://www.bluelens.net/300d/test/canon2.jpg
http://www.bluelens.net/300d/test/sigma2.jpg

The last batch I went the total opposite direction and opened up to f/5.6
http://www.bluelens.net/300d/test/canon3.jpg
http://www.bluelens.net/300d/test/sigma3.jpg

What do you guys think? The Sigma lens is the problem, either not properly communicating with the camera or just not working at the lower f/stops?

[PacAce]

Yup, there's definitely something wrong with the aperture mechanism of the Sigma lens as Tom had suspected. I'm surprised this is happening to a lens that's only about a year old unless you both it used. At any rate, you'll either have to have it repaired or replace it with another or use it only with the aperture wide open. :)

Well, at least I'm glad you figured out what the hecks going on with your pictures taken with that lens.

[pjamedia]

I was just trawling the net searching for this exact issue when I found this post. I bought the same lens second hand for my Canon 20d and have the same issue. I figured this out as the DOF preview button, beside the lens mount on the 20d, doesn't close down the aperture at all. Not sure if it's an incompatibility issue on the new digitals (as this is a 35mm EF lens), but it obviously should work fine as the digitals accept either EF or EF-S lenses, and I have a Canon EF lens that works a treat.
I'll get someone with a 35mm Canon to give it a go.

Cheers, Paul