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Forums Lobby GET TO KNOW YOUR CAMERA & MASTER IT Nikon D60/D50/D40 (Public) topic #18302
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Subject: "D40 Exposure compensation" Previous topic | Next topic
hotmog Registered since 27th May 2007Thu 31-May-07 10:25 AM
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"D40 Exposure compensation"


Worcester Park, London, UK
          

Further to my earlier post (http://www.nikonians.org/dcforum/DCForumID201/17400.html), I have been playing around and taken more test shots just to get a feel for how the metering on my camera behaves in different situations.

The problem I had was that some shots which looked great when viewed on the D40's LCD appeared badly under-exposed with excessive colour saturation (even when the colour mode was set to 1a) when downloaded and viewed on my PC. These shots were all taken in P mode using Matrix metering without any exposure compensation.

My concern was compounded because the general consensus of opinion seems to suggest that the D40 tends if anything to over-expose using Matrix metering. In Ken Rockwell's D40 User Guide, he quotes: "I set my exposure compensation to -0.7 because my D40's metering firmware is defective, just like the D80's meter. It usually overexposes." He also states: "Seeing how poor the matrix meter has become in the D40 (it requires constantly varying levels of compensation) I intend to try center weighted metering."

He then alluded to the nub of the problem I had: "If anything, the brilliant LCD makes even underexposed images look great! Be sure to check the color histogram if you're shooting in a dark environment." That was exactly it - I couldn't tell just by looking at the image in the LCD whether it was correctly exposed or not!

I had noticed the histograms (both the simple and colour ones) before in the playback display, but didn't really understand what they were telling me. Then I found this article http://www.luminous-landscape.com/tutorials/understanding-series/understanding-histograms.shtml, which really opened my eyes to the usefulness of this tool.

Using the histogram to judge the exposure of subsequent outdoor shots I have taken seems to confirm that most of them were indeed under-exposed if no compensation was applied (the vertical lines tending to bunch at the left-hand margin). On average I found I needed to adjust the exposure by +0.7, occasionally +1.0, to achieve optimum results.

Ken Rockwell does say that the firmware installed on his D40 as of 02 January 2007, reads A 1.00 and B 1.00. But he also says, elsewhere "I've never bothered installing the new D40 firmware that came out in January 2007; I'm too busy shooting." I presume that must refer to version 1.10, which is the version on my D40, so I'm wondering if the over-exposure fault that Ken attributes to version 1.00 of the firmware has now been over-corrected in version 1.10? The firmware upgrade notes on the Nikon website don't make any mention of this. Does anyone know?

But the main thing I wanted to draw your attention to was what a useful tool the histogram display can be in achieving accurate exposures. Do take notice of it if you don't already!

  

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Replies to this topic
Subject Author Message Date ID
Reply message RE: D40 Exposure compensation
blw Moderator Awarded for his high level of expertise in various areas
31st May 2007
1
Reply message RE: D40 Exposure compensation
hotmog
31st May 2007
2
     Reply message RE: D40 Exposure compensation
blw Moderator Awarded for his high level of expertise in various areas
31st May 2007
5
Reply message RE: D40 Exposure compensation
Ginseng
31st May 2007
3
Reply message RE: D40 Exposure compensation
hotmog
31st May 2007
4
     Reply message RE: D40 Exposure compensation
blw Moderator Awarded for his high level of expertise in various areas
31st May 2007
6
          Reply message RE: D40 Exposure compensation
hotmog
31st May 2007
7
               Reply message RE: D40 Exposure compensation
Schnauzermom
01st Jun 2007
8
               Reply message RE: D40 Exposure compensation
blw Moderator Awarded for his high level of expertise in various areas
01st Jun 2007
9
                    Reply message RE: D40 Exposure compensation
hotmog
01st Jun 2007
10
                         Reply message RE: D40 Exposure compensation
blw Moderator Awarded for his high level of expertise in various areas
01st Jun 2007
11
                              Reply message RE: D40 Exposure compensation
hotmog
01st Jun 2007
12
                                   Reply message RE: D40 Exposure compensation
blw Moderator Awarded for his high level of expertise in various areas
01st Jun 2007
13
                                        Reply message RE: D40 Exposure compensation
hotmog
01st Jun 2007
14
                                             Reply message RE: D40 Exposure compensation
blw Moderator Awarded for his high level of expertise in various areas
01st Jun 2007
15

blw Moderator Awarded for his high level of expertise in various areas Nikonian since 18th Jun 2004Thu 31-May-07 01:01 PM
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#1. "RE: D40 Exposure compensation"
In response to Reply # 0


Richmond, US
          

First, and probably most important, is the monitor on your PC calibrated? If not you really don't know what you're looking at. The LCD on your camera is also not calibrated, and frankly they tend to be pretty far off reality from both a brightness and also a color perspective. Moreover, for various practical reasons (like trying to stand up to daylight), the LCD is usually quite a distorted representation. If you're comparing the uncalibrated LCD to an uncalibrated PC, you really are comparing what amount to random numbers! (It's not quite that bad, but that's the idea.)

The histogram is indeed a very useful tool.

Once you've got a calibrated monitor, try putting your camera on a tripod, then use the bracket function to shoot sequences of exposures from -1.3 to +1.3 EV. Once you do that, I have a suspicion that you'll find that you'll pick the +0 exposure most often. I used to think that the matrix meter was not to be trusted, until I noticed that the +0 version of bracket sequences was usually the best single frame.

This won't a real popular comment, but I'd completely ignore what Ken Rockwell has to say. I don't read his site - until someone posts a quote here, and then I drop my teeth and have to go respond to it. In this particular case I have no personal experience with the D40, so I won't comment. But I now keep count - the previous five times I've read a Ken Rockwell quote, it was at best controversial personal opinion presented as fact.

_____
Brian... a bicoastal Nikonian and Team Member

My gallery is online. Comments and critique welcomed any time!

  

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hotmog Registered since 27th May 2007Thu 31-May-07 01:25 PM
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#2. "RE: D40 Exposure compensation"
In response to Reply # 1


Worcester Park, London, UK
          

Thanks for those interesting comments, Brian. So - how do I calibrate my PC monitor? I've adjusted the brightness, contrast and colour temperature so that it looks right to my eyes subjectively, but what objective method can I use?

I'd would test it out with bracketed exposures, unfortunately it is a feature that the D40 does not have.

  

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blw Moderator Awarded for his high level of expertise in various areas Nikonian since 18th Jun 2004Thu 31-May-07 09:30 PM
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#5. "RE: D40 Exposure compensation"
In response to Reply # 2


Richmond, US
          

Calibration: unfortunately, this again requires an outlay of $, unless of course you can borrow one. There are things that look like a hockey puck on a string that have light sensors in them. You sit it on your screen while a program puts different colors on the screen; the device measures the difference between what it requested and what it senses, then applies a color correction profile to make the colors come out correctly.

These things used to be terribly expensive ($500) but now they're down to $100 and possibly lower. I have a Pantone ColorVision Spyder - it cost $95 something like two years ago. I assume that they are somewhat less expensive now. You do need to recalibrate periodically, but that might mean every few months. You can easily share this with a friend or two.

Bracketed exposures: oops, sorry. Instead, you can manually do it. Put the camera on a tripod, then shoot pictures at -1, -.7, -.3, 0, +.3, +.7, etc. Do it for several different scenes. Then look at the batch of them on a calibrated monitor.

_____
Brian... a bicoastal Nikonian and Team Member

My gallery is online. Comments and critique welcomed any time!

  

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Ginseng Registered since 02nd Apr 2007Thu 31-May-07 03:24 PM
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#3. "RE: D40 Exposure compensation"
In response to Reply # 0


US
          

I've found that when I'm outside in bright or partial sun, I have to set expo comp to -0.3 to -0.7 to obtain a reasonable histogram and exposure without blowouts. When I'm inside and shooting with bounce flash, I need to set +0.3 to +0.7 to prevent underexposure. I've found that color Ia gives noticeably less saturated images than color IIIa or vivid mode.

I am using the latest version of firmware, 1.10

Wilkey

  

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hotmog Registered since 27th May 2007Thu 31-May-07 03:43 PM
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#4. "RE: D40 Exposure compensation"
In response to Reply # 3


Worcester Park, London, UK
          

That's interesting, because with mine I've found that it's often in bright sunlight that it tends to under-expose more - as can be seen in this shot that can be viewed at
http://www.dadween.plus.com/images/DSC_0008s.JPG
and which was taken with default settings:
Lens: 18-55mm F/3.5-5.6 G
Focal Length: 55mm
Exposure Mode: Programmed Auto
Metering Mode: Multi-Pattern
1/200 sec - F/7.1
Exposure Comp.: 0 EV
Sensitivity: ISO 200
Optimize Image: Normal
White Balance: Auto
AF Mode: AF-A

Maybe it's just my camera, then?

  

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blw Moderator Awarded for his high level of expertise in various areas Nikonian since 18th Jun 2004Thu 31-May-07 09:32 PM
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#6. "RE: D40 Exposure compensation"
In response to Reply # 4


Richmond, US
          

That shot looks pretty good to me - and my monitor was recalibrated last night. (But it's a bit blurry.)

Before deciding if it's a lens, camera, user, whatever - calibrate.

_____
Brian... a bicoastal Nikonian and Team Member

My gallery is online. Comments and critique welcomed any time!

  

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hotmog Registered since 27th May 2007Thu 31-May-07 10:55 PM
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#7. "RE: D40 Exposure compensation"
In response to Reply # 6


Worcester Park, London, UK
          

Brian - from your description of the Pantone ColorVision Spyder you have, it seems like it only adjusts the colour balance which I don't find to be the particular issue. You say that the shot of Roly (our ginger tom cat) looked pretty good to you on your newly calibrated monitor - could you make out any of the detail of the foliage in the background? (I cannot).

Here's the original again:
http://www.dadween.plus.com/images/DSC_0008s.JPG

I've used the auto-adjust feature in PictureProject, that came with the camera, to enhance the D-lighting and brightness in this image:
http://www.dadween.plus.com/images/DSC_0008sp.JPG

What I was going to do next was to upload those two images back on to my D40 so I could compare their respective histograms - I know this did confirm that the first one was under-exposed when I looked at it originally. However something strange has now happened - I connected the camera to my PC via the USB lead as usual, selected the two files and copied them back to folder on the SD card -G:/DCIM/100NCD40. When I disconnect the USB lead and press the replay button on the camera I get ! FOLDER CONTAINS NO IMAGES. If I reconnect the USB lead and click on the same directory path on my PC the photos are clearly shown to be present there.

I know this used to work as I've done it before on several occasions. I've tried reformatting the SD card, recreating the sub-directory and copying the files back, then taking another photo - which is the only one that shows up on replay - yet all 3 show up when viewed on the PC. I've also turned off and reset the file sequence numbering in case that was causing the problem, but to no avail.

Woss goin' on?


  

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Schnauzermom Registered since 19th Feb 2007Fri 01-Jun-07 12:20 AM
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#8. "RE: D40 Exposure compensation"
In response to Reply # 7


US
          

If I recall correctly, firmware 1.10 changed things with regard to viewing files after they'd been moved/edited:

When attempting to edit images, which had already been edited using a computer, with options in the D40's retouch menu, the camera sometimes froze. Therefore, images that have been edited using a computer can no longer be edited using the camera.

  

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blw Moderator Awarded for his high level of expertise in various areas Nikonian since 18th Jun 2004Fri 01-Jun-07 02:32 AM
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#9. "RE: D40 Exposure compensation"
In response to Reply # 7


Richmond, US
          

> from your description of the Pantone ColorVision Spyder you have, it seems like it only adjusts the colour balance which I don't find to be the particular issue.

It also affects brightness (but you're right, I didn't really say that).

So you're aiming to get shadow detail? Roly seems equivalently exposed in the two, which is why I think that it was exposed properly.

You're not really having an exposure compensation problem, but more that you want different lighting than you have. You can postprocess what you want (that's what you did with PictureProject), but you risk getting a lot of noise in the areas that you boost. If I were faced with this scene and wanted background detail and not so much shadow, I'd do a bounce flash off the ceiling - almost straight up.

_____
Brian... a bicoastal Nikonian and Team Member

My gallery is online. Comments and critique welcomed any time!

  

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hotmog Registered since 27th May 2007Fri 01-Jun-07 08:45 AM
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#10. "RE: D40 Exposure compensation"
In response to Reply # 9


Worcester Park, London, UK
          

Thanks for the input, guys.

The camera having "rested" overnight, I've just tried uploading the files again - and now it's worked! No idea what was going on last night, but today it happily lets me copy files back that have been post-edited, as well as ones that have not. I can also perform in-camera editing on those shots, including ones that have already been edited in PictureProject. The only restriction I've found is that the "Filter Effects" option is greyed out on CSC_xxx files where that option has already been used on them before.

The following two shots show the D40 back display replay of the original and the brightness/D-lighting enhanced versions of the Roly shots in my previous post. Apologies for the dreadful quality, but they are simply to show the histograms in each case.

http://www.dadween.plus.com/images/P6010001.JPG
http://www.dadween.plus.com/images/P6010002.JPG

I think this proves objectively and beyond doubt that the original is under-exposed, clearly demonstrated by the fact that the vertical lines are all bunched up at the left-hand margin with nothing at all on the right.

The second (enhanced) shot still shows nowhere near an ideal exposure balance across the range, but is somewhat of an improvement.

I agree with you Brian about the background detail. It was shot in bright sunlight with strong contrasting shadows, so I should have used fill-in flash to bring that out. I don't have an external flash so couldn't use the bounce option, and being outdoors, the "ceiling" in that instance was a little too high!

  

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blw Moderator Awarded for his high level of expertise in various areas Nikonian since 18th Jun 2004Fri 01-Jun-07 11:29 AM
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#11. "RE: D40 Exposure compensation"
In response to Reply # 10


Richmond, US
          

> I think this proves objectively and beyond doubt that the original is under-exposed, clearly demonstrated by the fact that the vertical lines are all bunched up at the left-hand margin with nothing at all on the right.

The reason there is nothing to the right of the histogram is that there is nothing in the original scene that is much lighter than mid-tone. If you take a picture of a pile of coal, that histogram will be strongly bunched to the left, or at least you hope it is. If it isn't, what you'll have is a grey pile of coal, and that's obviously not what you want.

I still think the meter is doing what it's designed to do. In this case, I think it is seeing a subject in the middle and exposing for that. The camera doesn't have the option - like you do - of exposing the cat one way and the background a different way. (Although I won't be surprised if someone makes a camera with something like that!) It can either expose the background properly, or it can expose the subject properly. If it exposes for the background, Roly will be blown out. (And that would be terrible! ) If it exposes for Roly, the background ends up in deep shadow.

_____
Brian... a bicoastal Nikonian and Team Member

My gallery is online. Comments and critique welcomed any time!

  

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hotmog Registered since 27th May 2007Fri 01-Jun-07 12:32 PM
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#12. "RE: D40 Exposure compensation"
In response to Reply # 11


Worcester Park, London, UK
          

I think I understand what you're getting at, Brian, but if it is the mid-tones (Roly in this instance) that are the brightest part of the picture, then should not the vertical peaks that represent them be more towards the centre of the histogram if they have been properly exposed? There are two peaks, one right up against the left-hand margin in the very dark quadrant, the second on the line between "very dark" and "dark", with a low hump in the middle. In the enhanced version, both peaks have moved to the right somewhat, although are still in the dark half.

I know the last thing Roly would want is to get blown out - except when he's on the ear'ole for food (which is most of the time) But neither is he a sack of coal, and I would have expected his admittedly modest mid-tones, by definition, to feature somewhere more in the middle if correctly exposed, unless there is more to this histogram-guided exposure malarky than I have bargained for

  

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blw Moderator Awarded for his high level of expertise in various areas Nikonian since 18th Jun 2004Fri 01-Jun-07 01:44 PM
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#13. "RE: D40 Exposure compensation"
In response to Reply # 12


Richmond, US
          

You get it, but I don't think your eye is calibrated to which things are which yet. In the original image, the peak on the left is probably the area with the shadows. The second peak is probably the large dark-to-medium blue around Roly. Roly is right in the middle - he's the third, much more modest bump in the center of the histogram. He doesn't show up as clearly because his ginger color is spread out across a fairly wide range of gingers, from fairly orange to approaching cream. That causes the peaks to be lower in magnitude.

_____
Brian... a bicoastal Nikonian and Team Member

My gallery is online. Comments and critique welcomed any time!

  

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hotmog Registered since 27th May 2007Fri 01-Jun-07 03:03 PM
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#14. "RE: D40 Exposure compensation"
In response to Reply # 13


Worcester Park, London, UK
          

Thanks for that explanation Brian. I think I've got the hang of it now. This is obviously where the RGB colour histogram can prove a useful supplement to the basic monochrome one in identifying which areas are which exposure-wise.

Looking at the colour histogram of the Roly shot, the low hump in the middle is found only in the red sector, with a slight tailing-off in the green and nothing in the blue, which appears to confirm that it is does indeed represent the digitalised feline himself. The peak at the extreme left-hand margin is found in red, green and blue, while the second peak to its right is only present in the green and blue sectors. This again ties in with your hypothesis concerning the shaded areas.

Holy histogramology - great thinking, Batman!

  

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blw Moderator Awarded for his high level of expertise in various areas Nikonian since 18th Jun 2004Fri 01-Jun-07 09:52 PM
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#15. "RE: D40 Exposure compensation"
In response to Reply # 14


Richmond, US
          

(To the sound of the musical...)

By George, I think he's got it!


_____
Brian... a bicoastal Nikonian and Team Member

My gallery is online. Comments and critique welcomed any time!

  

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