Posted by Jack Garrett on July 1, 2009 at 12:19 PM
I've been using 3 exposure, 1 stop bracketing for my HDR images for a while now and for the most part it works well. In the past week I've read 2 articles where they recommend 3 exposure, 2 stop bracketing. I'm interested to hear what some of you think on this. Also, if you resort to 2 stop brackets, would you then eliminate using GND's and let photomatix take care of the tone mapping, etc? I'm not crazy about getting into 7 exposure, 1 stop stuff unless someone can convince me there is a real need for it.
I'm not knowledgeable enough to answer your question, Jack, as it's something I've wondered about, too. (3 exposures, or 5? Or 6? Half-stops or two-thirds? Or full?) I just wanted to mention that when I glanced at the title of your post, I thought it was asking about HDR backpacking! I need a nap.
I haven't read it yet, but the new issue of Photoshop User mag (NAPP members receive this, not sure if it's sold at B&N, etc.) is all about HDR imaging.
I've played with the number of exposures quite a bit. Initially I was doing three 2-stop exposures, but found that in some instances there still wasn't enough dynamic range. I've done as many as seven 1-stop exposures, but found the processing time to be too much - and the results weren't that different from three 2-stop exposures. My current approach is to find the aperture/shutter-speed combination that assures nothing in the image is blown out (I turn on the clipping indicator on the LCD display). From that point I drop the shutter speed 2 stops and take my second shot. Then I drop the shutter speed 2 more stops and take the last shot - maybe. I try to get the last shot to have around 50% of the image blown out (clipped). If the third shot doesn't get me there I'll drop 2 more stops and take a fourth shot. When I'm doing HDR exposures I most often don't use GND's - but it really depends upon what I'm shooting. Hope this helps.
Jack, while still learning HDR, it seems like the formulas help one get started and then you need to use your judgement based on the situation. Another article is in Outdoor Photography by George Lepp.
I select the depth of field and then the exposure I want to use (as the midpoint) then use bracketing and set it to 9 shots at 1 stop (no 2 stop option on my Nikon) apart, then I take them as quickly as possible, usually in highest speed mode. Then I select the 3 or more images I want to use, often 3 shots at 2 stops apart is just fine.
If I could bracket at 2 stops then I'd likely use that and shoot 5 shots.
With a rapidly changing sunrise or sunset you have to be pretty quick to get stable clouds and leaves.
Even with the traditional grad ND filter there are problems with movements and then you can get filter misting as was recently mentioned.
In my opinion a range of three full stops should cover most any situation. Since most cameras are designed to easily do four stops (two under and two over the metered exposure) you will want to determine which direction to weight the exposures.
In theory, the more individual captures you use, the smoother/better/more realistic the blended result will be. 3 is good, 6 is better, but really, 9 is overkill.
So it's hard to define a fixed formula. But the principle remains the same - just make sure each shot contains what you want in it, for that part of the tone range being represented.
The way I shoot (and the final result I'm looking for), I usually end up using 4 at the very most... more often, though, three is plenty. That said, those three might be separated by 1/2 stop, or a full stop. It just depends on the scene.
I'm certainly no expert but both books I read on the topic of HDRI echo the information provided by Nat. In theory, more exposures = more information for the HDR software to work with = smoother tonal gradations, less noise, etc. In practice, I've never found a situation that required more than 4 exposures. Usually, 3 exposures provides plenty of information.
I've actually stopped using HDRI software. I'm much happier w/ the results I get from manual blends though it certainly takes a lot more time. So, take my advice for whatever it's worth!
Posted by Jack Garrett on July 1, 2009 at 10:44 PM
This months OP has something on manual blends that I'm thinking of trying....I'm still learning most of this Photoshop stuff beyond the basic levels and curves. Here is my question regarding what most of you are saying though. My camera can do a 3 shot bracket at up to 2 stops. Once that is done, do I then use negative and positive exposure compensation to get the remainder of the exposures or do I turn of bracketing and do the final negative and positive exposure manually...geez this gets confusing!
I recently took an HDR class through Nikkonians and both Bill and Nat are very close to what they taught in the class. I also shoot on CH and take 5 or 7 exposures depending on the difference in stops from metering the shadows and highlights. Then it is a matter of how your camera works to determine the proper settings in camera and how you are going to shoot, Aperture Priority or Manual. I find AP easier once I find the proper exposure (midpoint) first then setup the number of bracket shots that I need. To me, that is the most critical part. If that is not setup correctly, you will have to do a lot more in Photoshop. The more contrast a scene is, the more bracketing (5-7 exposures) you need to do, the less contrasty the scene, will allow you to get away with 3 exposures. How many stops, that depends on how many stops apart your highlights are from your shadows. Not always the case but a good starting point.
If you are just learning and you shoot in RAW, you may want to shoot one shot either metering for shadows or highlights. Process that image and save as highlights or shadows. Then take the original image and process for the other and save. Then you can blend them together in PS.
To quickly get a 5 stop (6 exposure) range, which is the max that the Canon 5DII and 50D (and similar) can do from a single exposure reading, do the following (assumes standard control assignments):
1. Choose the custom function that specifies that bracketed exposures are taken in the sequence -, 0, +. This is a one time change. I prefer this setting so my exposures line up in sequence from darkest to lightest. Makes it easy to review the set to see if you captured the dynamic range that you want.
2. Set the AEB setting to +- 1 stop through the menu
3. Use a TRIPOD and cable release!
4. Compose and get the exposure - don't shoot
5. Adjust the exposure compensation to -1
6. Shoot three quick exposures - These will be -2, -1, 0 compensation
7. QUICKLY dial the back dial six clicks clockwise to adjust the exposure compensation to +1. If you do this immediately after the last exposure you won't have to get another exposure reading for the compensation dial to work. Plus you want to minimize time between exposures. This assumes your exposure increment is 1/3. It'd be 4 clicks for 1/2 stop increments.
8. Shoot three more exposures - These will be 0, +1, +2 (you will have a dup of the 0 exposure)
I agree with Nat that the more information the better. I do come across situations where 5 stops of dynamic range are needed or not enough. Of course you could argue that maybe that is a shot to skip.
I also agree with Bret, I tend to get the results I want from manual blends. I usually mask for the blend but I'm looking forward to trying George Lepps blend-if technique in this months OP.
It's been awhile since I've played with Photomatix, might be time to give it another chance. I always had a hard time getting it just right with the tone mapping controls. One technique that I've had success with, that Rod Hanna reintroduced me to, is to bring your HDR tone mapped image from photomatix (or PS) into an image with the original images as layers, then use masks (probably luminosity masks) to bring elements of the original exposures into the HDR image where things might be funky. This is time consuming and a little advanced, but effective.
Have fun with HDR!
2.
Posted by Brent Murphy on July 2, 2009 at 10:59 AM
I broke my favorite GND about a year ago, and since then have decided to try HDR instead of shelling out the money for a new grad. I know I need to replace my GND, but just haven't found the need yet.
Generally, I set my D300 to auto-exposure bracketing and CH shutter release. I shoot 5 exposures at 0, -2, -1, +1 and +2. Bring them into LR as a stack, so I can keep track of them. Then export to Photomatix. Sometimes I will use all 5 exposures, sometimes only 3. (The D300 can't auto-bracket more than 1 stop). Depending on the shot, I will play with all three blending methods in Photomatix, to see which gives me the best results (details enhancer, tone compressor, image blend). Once I'm happy, that image gets saved, and moved to the top of the stack in Lightroom.
After blending, you really need to do a close inspection of your image. One thing I've noticed is that HDR tends to emphasize things like sensor dust. This is more true in some modes than others. I think the Photomatix manual describes the pros and cons of each blending method pretty well.
There are some situations where a two-stop bracket might be okay, but for my Nikon I'd rather do 3, 5, 7, or 9 one-stop exposures, using Aperture Priority and a remote release. I'll use CH shooting unless a mirror lock-up delay is called for. By conforming to the camera's natural operating modes (1-stop max), I can use the remote release, guaranteeing a minimum of camera motion between shots. When I go to do my HDR work, I won't always take every shot, but will look at each for obvious problems and exposure of various parts of the image. I may take a -2, 0, and +1 shot from the stack, and I get more keepers because I can take a slightly sub-optimal exposure to compensate for a bad (e.g. blurry) shot and the HDR software will compensate.
I still use TUFuse, so I run the selected image stack through Photoshop's layer alignment, crop to the common layer boundary and save out, then run the aligned stack through TUFuse and bring the resulting HDR image back to Photoshop for final editing. I've been very pleased with the HDR output I've used so far.
He does a terrific job of explaining how to use HDR bracketing, specific circumstances under which to use it, and differentiates between HDR and single-image tone mapping.
Discussion
15 repliesThanks,
Jack
I haven't read it yet, but the new issue of Photoshop User mag (NAPP members receive this, not sure if it's sold at B&N, etc.) is all about HDR imaging.
Bill Brennan
If I could bracket at 2 stops then I'd likely use that and shoot 5 shots.
With a rapidly changing sunrise or sunset you have to be pretty quick to get stable clouds and leaves.
Even with the traditional grad ND filter there are problems with movements and then you can get filter misting as was recently mentioned.
In theory, the more individual captures you use, the smoother/better/more realistic the blended result will be. 3 is good, 6 is better, but really, 9 is overkill.
So it's hard to define a fixed formula. But the principle remains the same - just make sure each shot contains what you want in it, for that part of the tone range being represented.
The way I shoot (and the final result I'm looking for), I usually end up using 4 at the very most... more often, though, three is plenty. That said, those three might be separated by 1/2 stop, or a full stop. It just depends on the scene.
I've actually stopped using HDRI software. I'm much happier w/ the results I get from manual blends though it certainly takes a lot more time. So, take my advice for whatever it's worth!
If you are just learning and you shoot in RAW, you may want to shoot one shot either metering for shadows or highlights. Process that image and save as highlights or shadows. Then take the original image and process for the other and save. Then you can blend them together in PS.
1. Choose the custom function that specifies that bracketed exposures are taken in the sequence -, 0, +. This is a one time change. I prefer this setting so my exposures line up in sequence from darkest to lightest. Makes it easy to review the set to see if you captured the dynamic range that you want.
2. Set the AEB setting to +- 1 stop through the menu
3. Use a TRIPOD and cable release!
4. Compose and get the exposure - don't shoot
5. Adjust the exposure compensation to -1
6. Shoot three quick exposures - These will be -2, -1, 0 compensation
7. QUICKLY dial the back dial six clicks clockwise to adjust the exposure compensation to +1. If you do this immediately after the last exposure you won't have to get another exposure reading for the compensation dial to work. Plus you want to minimize time between exposures. This assumes your exposure increment is 1/3. It'd be 4 clicks for 1/2 stop increments.
8. Shoot three more exposures - These will be 0, +1, +2 (you will have a dup of the 0 exposure)
I agree with Nat that the more information the better. I do come across situations where 5 stops of dynamic range are needed or not enough. Of course you could argue that maybe that is a shot to skip.
I also agree with Bret, I tend to get the results I want from manual blends. I usually mask for the blend but I'm looking forward to trying George Lepps blend-if technique in this months OP.
It's been awhile since I've played with Photomatix, might be time to give it another chance. I always had a hard time getting it just right with the tone mapping controls. One technique that I've had success with, that Rod Hanna reintroduced me to, is to bring your HDR tone mapped image from photomatix (or PS) into an image with the original images as layers, then use masks (probably luminosity masks) to bring elements of the original exposures into the HDR image where things might be funky. This is time consuming and a little advanced, but effective.
Have fun with HDR!
2.
Generally, I set my D300 to auto-exposure bracketing and CH shutter release. I shoot 5 exposures at 0, -2, -1, +1 and +2. Bring them into LR as a stack, so I can keep track of them. Then export to Photomatix. Sometimes I will use all 5 exposures, sometimes only 3. (The D300 can't auto-bracket more than 1 stop). Depending on the shot, I will play with all three blending methods in Photomatix, to see which gives me the best results (details enhancer, tone compressor, image blend). Once I'm happy, that image gets saved, and moved to the top of the stack in Lightroom.
After blending, you really need to do a close inspection of your image. One thing I've noticed is that HDR tends to emphasize things like sensor dust. This is more true in some modes than others. I think the Photomatix manual describes the pros and cons of each blending method pretty well.
I still use TUFuse, so I run the selected image stack through Photoshop's layer alignment, crop to the common layer boundary and save out, then run the aligned stack through TUFuse and bring the resulting HDR image back to Photoshop for final editing. I've been very pleased with the HDR output I've used so far.
He does a terrific job of explaining how to use HDR bracketing, specific circumstances under which to use it, and differentiates between HDR and single-image tone mapping.
For what it's worth,