Night Photography HDR Question

[skydiver_8]

I've seen some spectacular night shots done in HDR but searching the forums and the tutorials I can't seem to find which point in the scene to meter from as a starting point for the bracketing. I've attached a night photo scene with the following specs.

Canon XSI
Evaluative Metering
Aperture 5.6
ISO 200
Lens EF S18-55 F3.5
Focal Length 29mm
Jpeg Fine
White Balance Mode Auto
Manual Focus
Self Timer 14 seconds

Since this single photo was close to the composition that I wanted prior to manipulation in PSP, do I bracket from this point or do I use the longer and shorter shutter speeds to achieve the required exposure bracketing? Any help is appreciated. Once I get a starting point I can work from there. Should I be spot metering a particular area in the photo or meter the entire scene?

386096

[joooowan]

dont shoot jpeg

[Scottes]

Get used to using your LCD's Histogram to get an idea of the correct exposure. It will take some experience, but you'll get used to it with a little testing and/or time spent analyzing shots and checking each shot's histogram.

The histogram will change with the number of lights in the scene, as well as the amount of black sky, so try different scenes.


It's best to bracket exposures until you get used to using your LCD screen and/or Histogram to judge exposure.

But with night HDR, skip AEB and go manual mode and just take more shots than you think you'll need. Make sure your darkest shot barely has any "blinkies" indicating over-exposure. You'll generally get some because of bright streetlights and such, but you certainly don't want large areas blinking. Make sure you take a couple extra bright shots to ensure that the darker - not darkest - shadows are exposed enough to show detail.

You don't always have to use all the shots you take in a series, but at least you'll have them. And having too many shots ensures that you will have a correct exposure.


Taking a lot of shots kinda requires a tripod, and just using manual mode. I can tell you that a remote timer, like the TC-80N3, is a great benefit to night HDR shooting. You can just use the remote to programs the times (from 1 second to a whole lotta seconds), and you don't have to touch the camera.

At times, you will find that you want shots shorter than 1 second, so you will have to touch the camera, and you might introduce some shake. Don't worry, since these shots will only be capturing the brightest lights, and a little movement won't affect the final shot very much. The shots at 1 sec or longer will be done from the remote, and those will capture the mid-tones and shadows - the majority of the image - and the stability will be easy since you won't be touching the camera for these shots.


If you are stuck, for some reason, with doing only 3 shots, you have to get used to the LCD to tell you which exposure is correct. And then bracket 1 darker and 1 brighter from that shot.


A very good trick for getting the right exposure at night is to set the ISO to the highest setting, and shoot wide open. This will allow the fastest shot possible, and will get you to the correct exposure. Then count the stops back to ISO 100 and f/8 or f/11 or whatever you wish.

For example, let's say that I shoot handheld and get a proper exposure at ISO 3200, f/4, and 1/60th second. But I want ISO 100 for the least noise, and f/16 for a large depth of field. So I set the camera to Manual mode and count off the stops:
Changing ISO from 3200 to 1600 to 800 to 400 to 200 to 100 is 5 stops.
And changing aperture from f/4 to f/5.6 to f/8 to f/11 to f/16 is 4 more stops.
So I'll need to change shutter speed by 9 stops.
So I'll go from 1/60 to 1/30, 1/15, 1/8, 1/4, 1/2, 1s, 2s, 4s, 8s - a 9-stop change.

ISO 3200, f/4, 1/60th will give the same exposure as ISO 100, f/16, 8 seconds.


For this shot, I think this is an excellent exposure. It looks great. Great shot, great exposure, great processing.

I think that the white balance may be off, though. I'm assuming that front boat is white, but has an orange cast to it. You might want that, and I wouldn't blame you - I love the different colors that a night shot gets from all the different temperatures of the lights involved.

[skydiver_8]

Get used to using your LCD's Histogram to get an idea of the correct exposure. It will take some experience, but you'll get used to it with a little testing and/or time spent analyzing shots and checking each shot's histogram.

The histogram will change with the number of lights in the scene, as well as the amount of black sky, so try different scenes.


It's best to bracket exposures until you get used to using your LCD screen and/or Histogram to judge exposure.

But with night HDR, skip AEB and go manual mode and just take more shots than you think you'll need. Make sure your darkest shot barely has any "blinkies" indicating over-exposure. You'll generally get some because of bright streetlights and such, but you certainly don't want large areas blinking. Make sure you take a couple extra bright shots to ensure that the darker - not darkest - shadows are exposed enough to show detail.

You don't always have to use all the shots you take in a series, but at least you'll have them. And having too many shots ensures that you will have a correct exposure.


Taking a lot of shots kinda requires a tripod, and just using manual mode. I can tell you that a remote timer, like the TC-80N3, is a great benefit to night HDR shooting. You can just use the remote to programs the times (from 1 second to a whole lotta seconds), and you don't have to touch the camera.

At times, you will find that you want shots shorter than 1 second, so you will have to touch the camera, and you might introduce some shake. Don't worry, since these shots will only be capturing the brightest lights, and a little movement won't affect the final shot very much. The shots at 1 sec or longer will be done from the remote, and those will capture the mid-tones and shadows - the majority of the image - and the stability will be easy since you won't be touching the camera for these shots.


If you are stuck, for some reason, with doing only 3 shots, you have to get used to the LCD to tell you which exposure is correct. And then bracket 1 darker and 1 brighter from that shot.


A very good trick for getting the right exposure at night is to set the ISO to the highest setting, and shoot wide open. This will allow the fastest shot possible, and will get you to the correct exposure. Then count the stops back to ISO 100 and f/8 or f/11 or whatever you wish.

For example, let's say that I shoot handheld and get a proper exposure at ISO 3200, f/4, and 1/60th second. But I want ISO 100 for the least noise, and f/16 for a large depth of field. So I set the camera to Manual mode and count off the stops:
Changing ISO from 3200 to 1600 to 800 to 400 to 200 to 100 is 5 stops.
And changing aperture from f/4 to f/5.6 to f/8 to f/11 to f/16 is 4 more stops.
So I'll need to change shutter speed by 9 stops.
So I'll go from 1/60 to 1/30, 1/15, 1/8, 1/4, 1/2, 1s, 2s, 4s, 8s - a 9-stop change.

ISO 3200, f/4, 1/60th will give the same exposure as ISO 100, f/16, 8 seconds.


For this shot, I think this is an excellent exposure. It looks great. Great shot, great exposure, great processing.

I think that the white balance may be off, though. I'm assuming that front boat is white, but has an orange cast to it. You might want that, and I wouldn't blame you - I love the different colors that a night shot gets from all the different temperatures of the lights involved.



Thank-you very kindly for the time that you took to publish this info...very, very helpful and answered many more questions than I asked but should have. Just as an added note to your comment at the end, yes, the boat is white but there are a number of huge lights in the area that cast the warm colour....good eye.

[skydiver_8]

dont shoot jpeg

Thanks....this is an older photo. I now shoot RAW exclusively.

[pknight]

A very good trick for getting the right exposure at night is to set the ISO to the highest setting, and shoot wide open. This will allow the fastest shot possible, and will get you to the correct exposure. Then count the stops back to ISO 100 and f/8 or f/11 or whatever you wish.

For example, let's say that I shoot handheld and get a proper exposure at ISO 3200, f/4, and 1/60th second. But I want ISO 100 for the least noise, and f/16 for a large depth of field. So I set the camera to Manual mode and count off the stops:
Changing ISO from 3200 to 1600 to 800 to 400 to 200 to 100 is 5 stops.
And changing aperture from f/4 to f/5.6 to f/8 to f/11 to f/16 is 4 more stops.
So I'll need to change shutter speed by 9 stops.
So I'll go from 1/60 to 1/30, 1/15, 1/8, 1/4, 1/2, 1s, 2s, 4s, 8s - a 9-stop change.

ISO 3200, f/4, 1/60th will give the same exposure as ISO 100, f/16, 8 seconds.


I am planning to take some nighttime HDR shots, and have been looking for some advice, which is why I ran across this old thread. The tip quoted above made sense to me at first, almost to the point of purchasing the cable release with the timer functions, but then I got to thinking.

What is the point, in the example above, of taking the ISO 3200, f/4. 1/60 exposure using the camera's meter, when if you set the camera to AV mode, ISO 100, f/16, it would just give you the 8 second exposure automatically? If we are relying on the meter to tell us what the right exposure is, just set the ISO and aperture the way you want them and use AEB. Much simpler than counting f-stops back and forth to adjust shutter speed.

Now, there may be other reasons to stay in Manual while taking nighttime HDR shots, but narrowing in on the approximate 0 EV exposure can be more straightforward than computing new shutter speeds for ISO 100 from a high-ISO exposure as described here. (That is, if I can take the ISO 100 shot in 8 seconds, that is going to be much faster than computing the new shutter speed and adjusting the camera accordingly.)

[kirkt]

Well, metering at night is not necessarily an intuitive way to get your exposure, as the field you are shooting is generally darkness, with some isolated areas of light. If you use your reflectance meter in your camera to meter the scene, it will meter the scene to mid gray, so the exposure you make will be overexposed and the sky will be washed out (the camera tries to give you a meter reading to make the dark sky mid gray).

Determining exposure at night is easier with digital cameras, because you can shoot and evaluate the appearance of your exposure settings in real time. So, as that older post suggested, use a high iso and shoot wide open so that your exposure shutter speeds are low and you aren't waiting around for 8 seconds each time to see if the changes you made to your settings gave you the image you want.

Using high iso and large aperture gives you short shutter speeds, so you can get results quickly and home in on your base exposure level in EVs quickly. Once you have established your base exposure, you can reconfigure your iso, aperture and shutter into any combination that preserves the EV that was determined previously. In the exploratory phase, you are not so interested in DoF or noise, but overall distribution and appearance of tone. Once you get that nailed you can reconfigure for the look you want, and use a remote release/MLU to minimize touching the camera. Also, on some cameras, long exposures may add auto noise reduction, which can effectively make the acquisition time of a single image twice the shutter speed at which that image was exposed. More wasted time when dialing in your exposure.

Kirk

[pknight]

Sure. I understand all of that, but I'm just saying that if you want a test photo there is not much to be gained by shooting one at a very high ISO and then computing the required shutter speed for the ISO and f-stop you want. Unless you are shooting at the bottom of a mine you aren't going to have exposures longer than 10-15 seconds at ISO 100 (and typically much shorter than that). With HDR you aren't trying to get shots of subjects that are going to be gone in 10 seconds. Just shoot your test at ISO 100 and dispense with fiddling with ISO settings and computing shutter speeds across ISO levels and f-stops. It will save you time and effort. You may need to adjust because the meter will be easily fooled by night settings, of course, but this high-ISO test shot (which will be fooled just as much as the ISO 100 shot) just seems to be introducing unnecessary extra steps. (And I can certainly resist turning on auto noise reduction!)

[kirkt]

Let's just say that i can take 2 or 3 test shots at high iso and wide open while I wait to see if my single test shot at 8 seconds is suffcient. If computing equivalent exposure is overly burdensome, then don't do it this way. Your original query asked what the point of the high iso, wide open approach was. If you understand the point but think it is not as useful as simply setting the camera to your final settings and letting the meter determine your exposure, go for it. Since you already agreed that metering at night presents problems that might require adjustments, would you rather wait 8 seconds to find this out, or simply use the fastest shutter speed to get the exposure you want and then make the inevitable necessary final adjustment?

After shooting a few night scenes, this will become moot anyway, as experience will probably get you 90% of the way there right off the bat.

Either way, you'll get the exposure you want, the way you want to, so no biggie. I was simply trying to answer your question.

Kirk

[Scottes]

Kirk explained it well. But if you're shooting 15-second exposures then it's not very useful. If there comes a time when you're shooting 15-minute exposures then this high-iso-wide-open technique will save quite a bit of time, allowing you to get the correct exposure in a couple minutes rather than an hour or more.

[J-Blake]

I've played with HDR's at night on several occaisions. If you are trying to pull detail out of the dark areas you will need exposures much longer than 30s. I've played with 5 minutes and higher and still wished I taken longer exposures when I got home. What I've done in the past is to play with shutter speeds so that I know I've got the range covered. If my 0 EV is metered at 15 or 20s then I'll usually take a number of shots beyond this. Something like 30, 45, 1m, 2m, etc. You can tell by using your histogram the impact of time on exposure to some degree.

For shots like the OP, you're going to find that there is movement in these water shots which may become difficult to merge even with antighosting software. I agree with Scotties take on it that it's best to go at it single exposure. Not to say it can't be done, but there will lots of hurdles and frustration.

If there's a rule of thumb when it comes to adjusting stops of light beyond 30s using shutter speed I'm not aware of it. Can anyone elaborate on this? If I'm understanding you guys right, the tricks you're talking about work up to the 30s rule. Then what?

[pknight]

I've played with HDR's at night on several occaisions. If you are trying to pull detail out of the dark areas you will need exposures much longer than 30s. I've played with 5 minutes and higher and still wished I taken longer exposures when I got home.

Thanks. This is what I was looking for. I didn't know just how long an exposure to expect. Clearly if we are talking minutes, then the high ISO test is very helpful.

One issue that I haven't seen addressed in this regard is the additional noise you get, even at the lowest ISO settings, with very long exposures. I have taken long ISO 100 night exposures that I wished I had used ISO 400 with, because the shorter exposure would have resulted in less noise than was caused by the higher ISO. I assume that NR prior to merging the images is absoultely necessary with night HDR.

[kirkt]

If you are shooing a static scene, you can try shooting several identical images at identical exposures and averaging them to reduce noise as well.

Kirk