HDR Photography Tips: How Many Exposures Do I Need?

© Dave Wilson
This is a guest post from fellow photographer Dave Wilson.

I’m often asked how many exposures I use for my HDR images and tend to make myself unpopular by answering “As many as it takes.” This sounds glib but it is, in fact, the truth. Some people appear to be under the impression that you can get by with always shooting, for example, 3 images spaced 2 stops apart. This may work most of the time but that will likely be by luck rather than design. An outdoor scene will probably be captured fine using exposures from -2EV to +2EV but inside a cathedral with bright, stained glass windows, for example, it can take 11 shots (or more) spaced 1 stop apart (-5EV to +5EV) to capture the full dynamic range.

The point of bracketing for HDR is to ensure that you capture the entire dynamic range of the scene – as much shadow detail as you can get and all the highlights. To do this, you really have to check your histogram after taking a basic set of bracketed exposures and add to this set if needed.

These days, I typically start with either 5 or 7 images bracketed by 1 stop. The initial choice will depend upon the scene I’m shooting and my assessment of the dynamic range but it doesn’t really matter as long as you follow the next step. Once the initial bracket is done, make sure you don’t move the camera but review the brackets on your LCD with the histograms visible. The darkest image should have no blown out highlights (if you have the ability to turn on “blinkies” to warn of this, that’s really helpful) and you should see no significant bunching of data on the right of the histogram. The lightest image should have no solid shadows (data touching the left edge of the histogram). To be extra safe and to reduce noise in the shadow areas, I always try to ensure that my lightest exposure has no data at all in the bottom quarter of the histogram.

If you find that your outer exposures don’t meet the criteria given above, carefully turn off auto-bracketing (if you were using it) and dial in exposure compensation to allow you to shoot exposures on either end of your original bracket. If I shot a 5 image bracket (-2EV, -1EV, 0EV, +1EV, +2EV) , for example, and see that my darkest image still has blown out highlights, I will dial in -3EV and take another shot before checking and repeating as necessary. Most of the time, I shoot in manual mode with my camera set to change shutter in half stop steps since it makes this process a lot easier. I can turn off auto-bracketing then click my front thumbwheel the correct number of times to change the exposure as required for the other shots I need to take.

This brings up another comment I hear frequently from many photographers who state that their camera can only shoot 3 frames in auto-bracketing and, hence, they can’t bracket any wider than that. Remember that auto-bracketing is merely a tool that makes things a bit easier. Even if you camera can only take 3 shots in a sequence, you can still turn the automatic mode off and dial in the required exposures by hand as I do to widen your bracketed exposure range. Another option, if you have money to spare and a compatible DSLR, may be to purchase a Promote Control which will allow you to dial in the larger number of exposures without touching the camera at all but, even without this, a bit of control tweaking is all it takes to capture the full dynamic range of any scene you are shooting.

By making sure you capture the full dynamic range of the scene, you are certain to notice better final results – lower noise in the shadows, fewer blown-out highlights and generally cleaner images. Next time you are asked how many exposures it takes to produce an HDR, remember to answer “As many as it takes” and be ready for a longer discussion!

Photo by Dave Wilson. View more photos on Dave’s website. Dave can also be found on Twitter @dawilson

Thanks for reading and happy shooting

This Post Has 32 Comments

  1. Before anyone asks about the weird way I control my camera, I should point out that the “front thumbwheel” isn’t really a “thumbwheel” at all unless you have your camera upside down :-) Perhaps “rotary dial” would be better? Remind me to find a copy editor in future.

  2. Great stuff, Dave! I would love me some Promote Control! :D

  3. “Most of the time, I shoot in manual mode with my camera set to change aperture in half stop steps since it makes this process a lot easier.”

    Do you mean aperture? Or shutter speed? Surely you want to keep a constant aperture on all the shots so that the depth of field stays the same…?

    1. Dead right – yet another problem due to my lack of a decent copy editor! Actually, my camera is set up so that I can change both shutter speed and aperture in half stop increments but, as you note, I would only ever change the shutter speed while bracketing.

      If only Scott would give me edit privileges on this post! :-)

      1. Changed aperture to shutter :-) Sorry!

        1. Thanks, Scott! I don’t know why you are apologising though since this was one of my many errors and typos, I’m sure.

  4. What’s a histogram? And could you provide an image on what a blown out highlights look like on them? And underexposed shadows? ;)

    1. Miles Bintz, you’ve been to my HDR workshop and know fine what a histogram is and how they should look. Please go and troll somewhere else.

  5. Great tips Dave! My camera is actually limited on the EV range (+/- 2EV) which handicaps me from getting those shadow details and highlights. This is most noticeable in collaborative work when someone shares 7 or 9 brackets – the tone mapped images are much cleaner with less noise!

    1. That’s what manual mode is for, Jim. Most of my early work was shot on the D70 or D90 which only offered up to 3 shots, 2 stops apart as the widest auto bracketing option. In manual, though, the sky is the limit as long as you don’t mind clicking the shutter speed wheel a couple of times between each exposure.

  6. Your points are spot on. Wish I’d read your article before I photographed a dimly lit chapel this past weekend. I thought I could capture enough of the dynamic range with 3 exposures, but the clerestory windows and some intense lighting on the barrel vault were blown out. Well, live and learn. Try again this weekend.

    1. Dark churches are the places I’ve had to bracket widest. I think my worst was 13 shots (1 stop apart).

  7. Good advice Dave. Nothing worse than getting home and finding out you’re one bracket short in the shadows and now you’re shot is ruined. The Promote Control is a brilliant, if finicky device, but doing what you said and just carefully changing the exposure works fine if you don’t bang against your camera.

  8. Thanks so much Dave… very useful post, definitely, I need my Promote Control, since in one camera I just can make 3 brakets and other 9 brakets… :)

    1. You don’t NEED a Promote Control but you would LIKE one. Manual and a few clicks of the wheel work for me (because I’m too cheap to spend $300 or so right now :-) )

      1. Oh so very true. Sometimes I go out shooting with any cable releases just to go completely manual – including self timer!

        1. Bonus Tip: Did you know you can use the D700’s built in intervalometer to shoot a whole bracket in one operation? I’ve used this a few times when I’ve forgotten the cable release and it works very nicely.

  9. Great post Dave. Valid points and ones that are crucial to achieving a well exposed HDR.

  10. Dave, obviously you’ve dealt with the camera movement issue when adjusting the aperture for additional exposures. How do you lock the camera down that tight, that it doesn’t move when you make the adjustments?

    1. Use a light touch and buy an expensive tripod :-)

    2. Hmmm, adjusting the aperture may give you unwanted (or maybe wanted) effects. Changing +/- EV/EC would typically play with shutter speed.

      1. Aha – you noticed Ken’s deliberate mistake! Thankfully, Scott already edited out my typo in the main article.

  11. This is just a matter of personal preference regarding how you want your final image to look but I (usually) don’t like to get all the details in the shadows — I prefer some blacks to remain. I often still bracket the shots to get the details in case I want them but I often leave the lightest exposures out of the processing. Alternatively I may (1) tonemap with all of them and selectively mask out some detail or (2) simply bump up the blacks slider in Lightroom near the end of processing. Just depends on the image.

    Of course you know I love your stuff, Dave :-)

    1. Mike,

      How you process the final image is entirely up to you, of course, but I strongly believe in starting with the best data you can have then cutting information out later if you want. Regarding loss of shadow detail, I try to capture it to give me the option of doing something with it later. If I want to block it out in post, that’s easy. If it’s not there in the original brackets, however, I am left with no choice.

  12. Hey Dave, great post. I like your 1/4 of the way past the shadows on the brightest bracket tip. I’ve been able to grab 9 exposures using a 3AEB system at 1EV. If you click the wheel 12 times in either direction you can grab 12 brackets, discarding what you don’t need.

    Let me know what you think.

    1. Good tip, Scott. I used to do exactly this on the D90 which limited me to 3 exposures in auto-bracketing. On the D700, I typically start at 5 then add to the ends of the sequence one at a time in manual mode until the histograms show me I’m done.

      1. Nice, I only had to pull my hair out to figure it out. And to think this whole time you’ve been holding out on me. Shame on you! haha :)

        1. I have a few more tricks that I keep up my sleeve for workshop use. I’ve got to have something that the paying folks can’t get by just reading the web site :-)

          1. Secrets can be fun

  13. WOAH! That image of trinity church above made me do a double take, as I recently HDR’ed the exact same scene.

    Small world…

    1. It’s a very popular place :-)

  14. I am getting blue lense flare coming in through windows in my lightest expsoures, which translates into my photomatrix HDR image. Anybody delt with taking this out in Lightroom 4 prior to exporting to photomatrix? Also, I am not shooting with a hood, or wide angle lense.

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