Let's talk exposure

[dumbo_buddy]

hi all!

dh surprised me and told me that he ordered a canon xsi with kit lens along with the 55-250mm lens and carrying case for me! i've been researching dSLR cameras for a long time and i'm really excited to get started. i am looking to get the xsi for dummies book and am thinking about that understanding exposure book. looked it up and there's a new edition coming out in august.

is it worth waiting til august for the new edition or do i (a total beginner) need to understand exposure right away to begin using my camera properly?

thanks! this is a big investment and i want to use this to the fullest. i know it will take some time.

 

[VVFF]

Exposure really hasn't changed . I'm sure the new edition may be "prettier" in a lot of ways but if you feel you need some help no reason to wait.

 

[ukcatfan]

thanks! this is a big investment and i want to use this to the fullest. i know it will take some time.

Yes, but the book is only like $20 or so. I say get it now and then see if the new one is worth upgrading to. I doubt it will be.

 

[ThurlFan]

As much (and as quickly) as I learned from the current edition, I can't imagine advising someone to wait. You might as well wait the extra 5 months to open your camera also (only slightly exaggerating).

 

[TheGoofster]

I know how to get a long exposure in the dark, but I was wondering if it is possible to also get a long exposure during the day (or with plenty of light) without over-exposing, or washing out the shot? By long exposure I'm talking about 30 seconds or more.
For example, we are just now starting our rainy season here in Mexico City, and often we get some really nice lightning strikes during the day time. I would love to catch some of these in the same way that I would at night, by putting my camera in the bulb mode. I haven't actually tried it yet, but I imagine that a long exposure during the day would simply wash out the shot. Is there a way of doing this?

 

[ukcatfan]

You need a ND filter. It reduces the amount of light allowing longer shutter speeds.

 

[RBennett]

Like he said, you need a neutral density filter to help so that the extra light doesn't overexpose the shot. I believe zackiedawg has some really great shots that he posted in the Magic Kingdom in the middle of the day where he did this. He might chime in later or someone with a better memory than me might, but I want to say that his filter was a Hoya ND and it was a 8 stop filter. The problem with it is that the filter is so dark you can't really look through your viewfinder and see where your camera is pointed. You basically need to set it up where you want, then add the filter, and start shooting blind. The good thing about what you're wanting to shoot (I would think) is that with it being a midday rain the light won't be as bad as it is when the sun is out so you either don't need as many stops on a filter or you can keep the shutter open longer than he did during the day.


ETA: I REALLY hope he doesn't mind me adding a link to his photo site, but here is one of the shots I knew of to give you an example. I believe he said he used the Hoya ND 400 filter to get it. That's the next filter I want as well!

 

[MarkBarbieri]

I agree with what has been said. You need a neutral density (ND) filter. It's like putting dark sunglasses on your lens.

How powerful of an ND filter do you need? Test and find out. Take your setup out in the conditions you want to shoot and see what the lowest shutter speed you can achieve is. To do this, set your ISO at the lowest possible setting. Put your camera in AV mode and set your aperture at the highest possible setting. Check your shutter speed. That's the slowest you can go without a filter. Now, count how many times you have to double the shutter speed to get the duration that you want.

For example, let's say that at ISO 100 and an aperture of f/22, you are getting a shutter speed of 1/30 of a second and you want a 4 second shot. You would double 1/30 to 1/15, then to 1/8 (in photographer math, 1/15 times two is 1/8), then to 1/4, to 1/2, to 1, to 2, and to 4. In that case you doubled 7 times, so you would need an ND filter good for at least 7 stops. They Hoya ND400, the most popular filter for this sort of thing, is good for 9 stops, so you could actually go as long as 16 seconds (4 doubled two more times).

Most ND filters are only good for about 3 stops. They're useful for slowing moving water, but not for long exposures in daylight. You could stack them, but you may have problems with vignetting (darkening of the edges because the camera "sees" the edges of the filter). Also be careful not to get a graduated ND filter. Those are designed to make part of the scene darker than others. They are usually used to darken the sky so that you can get a good exposure of both the sky and things on the ground.

When you use an ND filter, be careful about light leakage. The biggest problem is light coming in from your viewfinder. That doesn't affect your shot, but it does affect your metering. Because you are usually shooting these with on a tripod with a remote shutter release (to minimize vibrations), you often take the shot with your eye away from the viewfinder. If you aren't shooting in manual exposure mode and you don't cover the viewfinder, the meter will pick up light coming in from the viewfinder and mess up your exposure level.

If you don't want to go the ND filter route, there is another option. You could take a long series of shots at the slowest shutter speed you can. You can then go into Photoshop (or whatever) and blend the pictures together. The results is very similar to a single long exposure. There are some serious downsides to this approach - far fewer "pictures" will fit on your memory card if you need to capture lots of files for a picture, it's a pain to work with all those files, and you'll be putting a lot of extra clicks on your shutter (which won't last forever).

 

[ssanders79]

Here is a DIY method using Welding Glass.

Here is a better post about the welding glass with some examples.

 

[mill4023]

I have a Nikon D80 with the 18-135 kit lens, a 50/1.8, and a 70-300VR.

Recently, I've been getting a lot of overexposed images, even after resetting all the settings and putting it on Auto mode.
So far, I've only noticed the problem when shooting with the 18-135, but I haven't shot enough with my other lenses to be 100% sure that it's a problem with the lens and not the camera itself.

Here are some examples:
http://www.facebook.com/photo.php?pid=1329249&l=2ec5450eb7&id=1592996690
http://www.facebook.com/photo.php?pid=1329258&l=b487d029d9&id=1592996690
http://www.facebook.com/photo.php?pid=1329263&l=1535c3144f&id=1592996690

And some of those have already been auto-corrected in PS, so the issue is worse than what you see there.

I also had a couple of pics where the top left corner of the picture was really dark. I'll try to post that one later.

Any ideas on what I should be looking at here?
Does this sound like a problem with the lens or the camera itself?

 

[zackiedawg]

Unfortunately, you're going to need to share a little more information for us to help you. The main and most important thing needed is to know your 'EXIF' information, which is the shot data for those photos. It will confirm what ISO, shutter, aperture, white balance, metering mode, focus mode, etc you were in when those shots were taken. There are tons of reasons why shots can get blown out like that, and overexpose - and they could range from simply the wrong metering mode, wrong ISO setting, or could be more serious up to and including sensor failure. Some cameras will tend to overexpose with some lenses all the time - if the overexposure is consistent in every shot, a simple adjustment to the camera's EV setting will offset the problem and allow you perfect exposures every time. If something was changed in your settings and the camera was moved into spot metering mode, for example, or the ISO is set to a high setting, this could also create such an issue.

 

[mill4023]

All I have access to at the moment is the pics I put on facebook, so I'll have to get that info later.
This issue just started a few weeks ago.
I did a reset of the settings (holding down both green buttons on the D80) and I'm still having the issue, so I figured it wasn't a problem with the settings.

I don't expect anyone to be able to diagnose the problem just by looking at the pics. I just wanted to see if anyone had some ideas of what kind of things could cause this problem.

Oh, one other possibly important thing I forgot to mention. When I extend the 18-135 all the way to 135, it seems to stick a little bit. That's one reason I suspected it could be a physical problem with the lens.

 

[SrisonS]

I can't get the pics to load on my phone. But a couple of things to look for anyway....

1) if the subject is dark or shaded, and the background is bright, you might see oveexposure.

2) like mentioned before, maybe play around with the EV setting.

3) Checo your manual about how to lock exposure (i.e. Point the camera elsewhere, lock that exposure, recompose the shot, snap away).

4). For a quick test to see if there's something wrong with your camera; go outside on a sunny day and take a picture of something that's nicely lit by the sun. If the pic is still overexposed (even in Auto mode), there might be something else going on with your camera.


Good luck!!!!

 

[Code]

Another thing to check is if the aperture of the lens is working properly (no stuck blades, no delay in closing, etc). Put the camera in A mode, set it to f/22 or whatever minimum aperture is for that lens, then look into the lens and press the depth of field preview button on the camera (below the lens on the right) and be sure the aperture is closing up as it should.

 

[Evad]

I was having the same issue with my D80 a while back. I tried many different things and nothing seemed to work. I sort of gave up on finding the problem and just fought through it. I would then fix things in pp. Then as suddenly as it it started it went away, go figure. Still don't know what caused it. I thought it was metering issue but to this day I'm still unsure. Hopefully yours well correct itself as well. Good luck!

 

[GrillMouster]

You may have switched the metering mode to spot or center-weighted. I noticed that a couple of the images you posted appeared to have been taken at bright times of day with the subjects in shadow and in the center of the frame. If the camera were metering for the subjects in shadow, then the rest of the scene, which was already bright, would be even brighter and overexposed.

 

[photo_chick]

Something is definately wonky.... post a couple of SOOC image when you can with the EXIF data.

 

[My2Girls66]

I did that with my D80 and 18-135mm lens once, well, probably more than once I didn't realize that the dial had gotten switched from Aperture to Manual(set to a too slow shutter speed on a sunny day) until I looked at the shots a few minutes later. I did it with my D50 once when the metering mode got switched to 'spot' from 'matrix' somehow. The light colors in my shots were all very over exposed. Hopefully its something simple like settings. I find the dial gets bumped to different settings occasionally.

 

[cpbjgc]

Looking through the pictures, I have to say I don't think its the camera, rather you are taking photos in very tough conditions for your auto-exposure to handle. All the pics look like they were taken on bright days with the sun pretty hich in the sky. Essentially, you have too much of a range in the light in your pictures from the brightest point to the darkest point.

In the second and third pics your subjects are backlit and the main features (ie their faces) are essentially in shadows. It looks like the camera was exposing for their faces which would result in the brighter areas in the frame to overexpose and blow out.

In short, the over-exposing is more likely photographer error as opposed to something wrong with your camera. I should know, as I have had (and still have) the same problems shooting in similar conditions.

What you need to do is take away the wide range of light in the pictures so that your camera can record both the bright and the dark without blowing out.

The first picture is a tough one, though a cirular polarizer or a graduated filter might help.

In the second and third photos what could help is using fill flash. By using your flash to brighten the darker areas of the photo, you should be able to capture both the foreground and background areas without blowing out the bright areas.

To help understand this issue, you might want to check out some books (such as Understanding Exposure which many here on the DIS recommend), or these articles from the Luminous Landcape website on understanding exposure and understanding histograms.

The one other thing I found helpful in dealing with this is to keep shooting and check out you histogram as you go along. Its only through experience that you start to recognize when light will be difficult and what steps you can take to deal with it (e.g. changing your shooting position or using fill flash).

Hopefully this is helpful for you.

 

[mill4023]

I totally forgot to get the original pics with EXIF over the weekend, so I'll have to try to remember to do that tonight.
It is NOT a settings issue because I had already reset everything to default settings.

I'm sure I've had plenty of bad pictures due to photographer error, but this time, I'm not taking the blame. I've done a lot of shooting in all kinds of lighting with the camera in Auto mode and although things aren't always perfect, I've never seen the kind of extreme overexposure I'm seeing now.

The photos I posted have been "auto-fixed" in PS. Those are the one's that ended up decent enough for me to put on facebook, just so my family could see some pics of the kids. The originals are much worse and I had a lot of shots that I didn't post at all because they were so bad.

I will try to remember to put up some unaltered pics with the EXIF data tonight.