« Posts tagged reference

What’s in Your Library?

December 2, 2010 / posted in Learning / No Comments

Yes, I read a lot. For me, learning is a continual process. I have a number of photography books in my library that I refer to often. I heard it said that the day you stop learning is the day you die! Well I don’t plan on dying anytime soon, so my library of photography books (as well as other subjects I’m interested in) will continue to grow. Here is a picture of some of the photography books I have. I did not include the how-to specifics on Photoshop and Lightroom that I have. (click the image for a larger view)

Photography Library

My four favorites are the ones in front, primarily because I love landscape photography and HDRi! The other book “Vision & Voice” by David Duchemin has got to be my all time favorite book. David takes you through his process of expressing his vision & voice through photography using Adobe Lightroom. It is a powerful book and has helped me to begin to understand the process of refining my vision. This vision is the one that caused me to take the image to begin with. The voice is how to express the story you want the image to project. Well worth the money I spent to get this book. If you are looking to add a book to your library this Christmas, this is the book I would recommend.

As for HDRi photography, I absolutely love Jack Howard’s approach in “Practical HDRi”. As the name suggests, it is a very practical approach to learning the art of HDRi photography. This would be my first recommendation of books on HDRi photography. Jack also gives a couple of bonuses in his book, but I’m not going to tell you what they are, you’ll have to get the book for that!

I like a wide variety in my library (as you can see in the image above) and I don’t think any library on photography would be complete without Brian Peterson. You just have to have at least one of his books. Me, I have three and I also subscribe to his emails from the Perfect Picture School of Photography (PPSOP). There are lots of video tutorials he does and sends them out to his subscribers.

Anyway, if you can’t tell, I think education and continual learning are important no matter what you are interested in, and the more you invest in your learning, the better off you’ll be! So do yourself a favor this holiday season and invest in your education, be it through books, classes, or workshops! :)

Exposure Fusion in Photomatix – A Reference

August 12, 2010 / posted in Photomatix, Tutorial / 4 Comments

If you are looking for a good way combine multiple exposures to achieve dynamic range in a natural or realistic maner, you should give the exposure fusion method a try. Although you can achieve realistic looking images using the tone mapping options, exposure fusion will give very good results with a lot less work on your part. The exception is that if you have moving objects in your scene, you might want to use the tone mapping option to take advantage of the deghosting feature. Additionally, for really high dynamic range images, tone mapping will be the better option as exposure fusion doesn’t handle really high dynamic range very well – i.e. it won’t look natural.

The first options you have within exposure fusion allows you to select how the exposure fusion should work or which method you want to use. There are five options.

Average will average the exposures together based on the available information in the exposures. You do not have any options available to you with this method and I find it rare that you would ever want to use it. After all, when would you want a straight average of anything?

Highlights & Shadows – Auto looks at the highlights and shadow information in each of the exposures and blends these exposures together to achieve a natural and realistic look. Again, there are no adjustments that you can make with this method. Although the results look pretty good, I would rather have some control over the outcome rather than letting the computer decide what the final image should look like. So again, it is rare that I would use this method.

Highlights & Shadows – 2 Images allows you to select which two images of your set to use then applies the “auto” method to blend these images together for the final result. There are no adjustments available other than selecting which two images to use. This method may get you the result you’re looking for, but if you want to tweak your image, this is not the method to use.

Highlights & Shadows – Intensive applies a rather aggressive blending or fusing method that often causes banding or an unnatural look in clouds. Luckily, this option gives us three sliders for some control of the final look. Of the three sliders, Radius has the most effect on the image because it sets the weighting amount to use when fusing the images together. The higher the number the less banding and haloing you will see, but it takes significantly longer to process the image. If you use this method, and you should try it, adjust the radius first to dail in the overall look of your image, then adjust the local contrast using the Strength slider. Negative numbers on the strength slider will flatten your image by removing contrast and positive numbers will punch up the contrast and increase depth. Lastly adjust Color Saturation to your desired amount. Just remember, too much of a good thing is not good – make small adjustments and maybe don’t adjust the color at all within photomatix. Save the color adjustments for photoshop, lightroom, or other photo editing software used in your post processing work flow.

Highlights & Shadows – Adjust applies the same blending or fusing of the auto method, but allows you to make a number of adjustments to the final image. This is the default method for exposure fusion and is the method you will end up using for more than 90% of your images for which you use exposure fusion.

At left you see the adjustment panel for the adjust method. I will go through each of these controls in the order in which you should use them (which is not the order – top to bottom – they are presented). Although I am suggesting a certain order for using these controls which I hope will make sense, you can use them in any order you choose. So let’s get started.

Blending Point – this controls the weighting given to the under exposed images versus the over exposed images. If you want the fusion to use more information from the underexposed images, move this slider to the left or into the negative numbers. Likewise, move the slider to the right or into the positive numbers if you want to include more information from the over exposed images. Another way to think of this control is to think of it as an exposure control – negative numbers will under expose where positive numbers will over expose your image.

Accentuation – this is the same as the Strength slider in the intensive method. It controls local contrast. Moving the slider to the left into negative numbers will remove contrast and flatten the look of your image. Moving the slider to the right into the positive numbers will punch up the contrast and increase depth.

Shadows – this controls the brightness of the shadow areas without affecting the highlights. If the shadow areas in your image are too dark, move this slider to the right to brighten up the shadows. Again, remember a little adjustment goes a long ways. Don’t over do it.

White Clip – Think of this as a fine tune adjustment for contrast in the highlight regions of your image. Increasing this slider – moving it to the right – will increase contrast in the image but does it at the expense of detail in the highlights. You will lose detail in the highlight regions when increasing the white clip slider.

Black Clip – works the same way as the white clip, just does it’s work in the shadow regions of your image. Increasing this slider – moving it to the right – will increase contrast in the image at the expense of detail in the shadow regions, i.e. you will lose detail in the shadows when increasing this slider.

Midtone – controls the overall brightness of the image but also affects contrast. Moving the slider to the left reduces brightness in the image and increases contrast. Moving the slider to the right will brighten the image but reduce overall contrast. To dial in just the right look may require multiple adjustments to Accentuation, White & Black Clip, and Midtone sliders. Just make small adjustments as you dial in the right look.

Color Saturation – does just what the name suggests, it adjusts the saturation of the color in the image. This is a global control and as such you may want to consider making color adjustments in photoshop, lightroom, or other photo editing software that is designed specifically to work with color. I have at times increased this slider to add just a little more color to my image, but I will always fine tune the color in other photo editing software.

360 degree image – removes the seam from a 360 degree panorama. This is another option that is probably better left to another application that is designed specifically for processing panoramas.

Presets – allows you to select and/or save presets for use. If you have dialed in a specific look that you like, save it as a preset. Then on the next image all you need to do is select your preset and your done!

Again, remember that when you click on the process button, you are not done. Your image is now at that RAW stage and additional post processing is needed to finish up and give the image it’s final look.

That’s all! Hope you find this reference of use.

Optimal Hyperfocal Distance

August 4, 2010 / posted in Tips, Tutorial / No Comments

What exactly does that mean? I thought that once I set the hyperfocal distance everything from half that distance to infinity would be in good focus, am I wrong? No, that would be correct. It would be in “good” focus. Now what if you need everything from point A (up close and personal) to point B (a good distance away) to be in “sharp” focus? This is where the optimal hyperfocal distance comes into play. By the way, it’s not really an optimal “hyperfocal distance” as much as it is an optimal “f/stop” for the determined mid distance. Huh?

Ok, I see I need to explain this a bit. I came across some information (on Ken Rockwell’s site) that provided a different formula to calculate an optimal distance for a given f/stop. By using this formula, you will basically obtain “sharp” focus from point A to point B (with a few disclaimers). The disclaimers are mine, not Ken’s. I used the formula to calculate a new “Optimal Hyperfocal Distance” chart, and have been testing this all day. The results were amazing!

Here’s how it works:
1. Set the focal length you want to use on your lens.
2. With your camera on auto-focus, focus on the nearest point you want to be in sharp focus. Now look at the focal distance on the lens.
3. With the camera still on auto-focus, focus on the farthest point you want to be in sharp focus. Now look at the focal distance on the lens.
4. Switch the camera to manual focus, and dial the focus ring on the lens to exactly half way between the near focal point (step 2) and the far focal point (step 3) and estimate what this distance is. For example, if my near point read 8 ft, and the far point read 20 ft, I would set the focus ring to approximately 12-14 ft.
5. Now I go to the chart and scan across the line of distances for the focal length I set in step 1. When I find the distance that closely matches that determined in step 4, I will look to the top of the column for the f/stop to use.
6. Dial in the f/stop, frame the shot, and take it.

Ok, time for the disclaimers. If for example your near point is 20 ft, and your far point is 120 ft, then the dialed in focal point would be roughly 70 ft on my lens. Well half of 70 ft is 35 ft which is greater than our near point of 20 ft. So some adjustments are needed and some sacrifice of focal quality either at the near or far point will be necessary.

I got the best results from this when using the widest angle focal length available on my lens, and being reasonable on the near focal point.

Here’s a new table to download which works as is for 35mm film or full frame digital cameras. For those of you with the DX (1.6 crop) sensors, you will need to set your focal length on your lens, then multiply that number by 1.6 to get the focal length to use in the chart. Since the formula is rather complex, I’m not going to present it here.

Download the chart:
Optimal Hyperfocal Distance (250)

This is one to play around with and see what kind of results you get. Just be sure to always use the auto-focus to determine the near and far focal distances or the results won’t be what you would like them to be. As a note of information, when I did this with my 28-300mm lens set at 28mm, the near distance was about 8 ft, and focusing in on an object that was more than 500 ft distant gave me a reading of about 21 ft. Pretty weird, but I went with it anyway and the result was amazing. When setting the lens to 50mm and using the same focal points the auto-focus read 22 ft for the near point and 120 ft for the far point. Camera position didn’t change, focal points didn’t change. Just the focal length of the lens changed and this caused the auto-focus to read differently. Using these numbers I had a distance of 71 ft which meant my near point would not be in sharp focus – which was definitely the case when I took the shot.

Play around with it and see what you get! I would be interested to know how this works for you. Enjoy.

———
UPDATE:

Here’s another way to determine the distance to get the same results. With your lens on manual focus, look at the markings on the focus ring. If you want everything from say three feet to infinity in sharp focus, put your thumbs at the edges of the marks and turn the focus ring until the alignment dot is exactly half way between your fingers (or between the 3ft and infinity marks). Estimate what this distance is in relation to the distance markings and use it in the chart to look up what f/stop to use. For example, on my 28-300mm lens, half way between 3ft and infinity is about 20ft on the focus ring markings. Using 20ft with the lens at 28mm the chart indicates an f/stop between f/8 and f/11 and based on the distances it looks like f/10 would be the best choice. Works really well and I think this is a whole lot easier (and I’m all about the easy way to do it)!

BTW, using this method and this chart (downloadable above) is far sharper than using the standard hyperfocal distance charts.

Hyperfocal Distance – revisited

August 2, 2010 / posted in Tips, Tutorial / No Comments

Ok, this is being revisited because it can be such a difficult thing to understand. I wrote a short article on this a few months ago as part of the depth of field series, but even so, another look might be of use.

So what is Hyperfocal distance and why would I care? Basically, hyperfocal distance is an optical property that is based on the sensor size, the focal length, and the aperture. This is defined as the distance at which when focused, everything from half this distance to infinity will be in acceptably sharp focus. There is a mathematical formula to calculate it which is basically H = FL^2 / (fs * CoC) + FL. Looks rather cryptic doesn’t it?

H = Hyperfocus Distance in milimeters
FL = Focal Length
FL^2 = Focal Length Squared
fs = Aperture
CoC = is based on the size of the sensor. This value will be 0.03 for film and full frame digital sensors, and will be 0.02 for DX (1.6) crop sensors (which is the vast majority of digital SLR’s).

The formula gives the results in milimeters. So to convert to meters, multiply by 0.001 or divide by 1000. To convert milimeters into feet, multiply by 0.00328125.

Based on this information, with my full frame digital camera set to a focal length of 28mm and an aperture of f/16, the hyperfocal distance would be 5.5 feet. So everything from 2.75 feet to infinity should be in focus when I take the shot.

Ok, so I understand what it is, but why do I care? There are several situations where having this knowledge comes in handy. The one that most people think of is when shooting landscapes, and yes, that is a very good application of using the hyperfocal distance. For example, if I come upon a scene that I want everything from two feet to infinity in good focus, I would set the aperture for f/22 (or maybe f/32) because this helps to give more sharpness throughout (depends on the lens and the sweet spot – more on this in the next article), set the lens to 28mm or less, manually focus my lens to four feet – which I got from the calculation (2.8 feet for f/32), mount the camera on the tripod and dial in the correct shutter speed for the exposure desired.

Another application is that of a journalist/photographer that needs to get the shot amidst a lot of action – i.e. other photographers trying to get the same shot. You could set the camera to f/8, 17mm, focus at four feet, dial in the correct shutter speed and fire away knowing that your resultant shots will be in focus. Ever hear the phrase “f8 and be there!” Setting your camera in this manner is what the phrase refers to.

There are many other possible applications where this technique allows you to get the shot when focusing on a subject would be difficult or otherwise impossible. The following shot of Sprague Lake in Rocky Mountain National Park was taken using the hyperfocal distance. Focusing through the view finder would have been very difficult with this shot as the camera was being held only inches off the water.

Sprague Lake - Rocky Mountain National Park

Sprague Lake - Rocky Mountain National Park

So, to make things a little easier for you (I’m all about easy), I’ve created a spreadsheet in Microsoft Excel that gives the hyperfocal distance for all the major f/stops, and the most common focal lengths. There is a version for full frame cameras, and another for DX crop cameras. Feel free to download them – they are free. If you change the CoC number, then entire table will recalculate with the new value. Likewise, if you change the aperture value or the focal length, the table will recalculate. This has been setup to print at the size of a credit card so you can have it laminated and carry it with you. Laminating it makes it durable and waterproof.

Here’s the downloads:

This first link is for the full frame sensors or 35mm film cameras
Hyperfocal Distance Chart CoC 0.03 (210)

This second link is for the DX crop sensors
Hyperfocal Distance Chart CoC 0.02 (259)

That’s all for this entry!

Tone Mapping in Photomatix – A Reference

July 24, 2010 / posted in Photomatix, Tutorial / 3 Comments

Tone mapping using the details enhancer in Photomatix Pro 3 can be a confusing prospect. How are you supposed to know what settings to use on each of the many controls? This was a question I asked many times when I started using Photomatix. Refering to the manual gave me some indication of what the controls did, but I was still left without any idea how or when I should use them.

After much experimentation and reviewing multiple sources of information on the subject, I have come up with what I believe will be a helpful reference. A reference that should be a big help to those just starting out in the world of HDRI photography, and a good refesher for everyone else.

Photomatix Tone Mapping

So lets get started. The image to the left shows the details enhancer controls in the tone mapping option of Photomatix. You will notice that the color settings section is not expanded. The reason for this is simple – making changes to the color of an image is better done in Photoshop, Lightroom, or other image editing software specifically designed for this purpose. Therefore, we will not cover the color settings here.

At the top of the details enhancer controls are five sliders that will control the overall look of your image. Let’s look at each of these controls in the order of impact (could also think of this as the order to apply these controls).

Smoothing – This controls the transitions between the edges in your image. So what does that mean? It means that the more you increase this setting (move the slider to the right) the sharper the definition of the edges in your image. Another way to think of this – the higher the number, the more photo realistic your image. The lower the number (moving the slider to the left), the more painterly or grungy your image will look.

Strength – This controls how strong the overall contrast enhancement effect will be. If you are familiar with Photoshop, think of this as opacity. The higher the number (slider to the right), the stronger the effect. You may end up adjusting this slider multiple times as you dial in the look you want for your image.

Luminosity – This controls how bright the shadow areas of your image will be. The higher the number the lighter the shadows, and the lower the number the darker the shadows. For a more photo realistic image move this slider to the left. This control along with Smoothing and Highlight Smoothing is what you will use to control “halos” in your image. Halos are areas of light around edges and are typically found in the transitions between buildings and the sky. Adjusting the strength may also be necessary if you wish to remove the halos compeletly.

Microcontrast – This controls how exagerated the fine details are in the image. The higher the number, the more exagerated the fine detail becomes, and the lower the number the less exagerated the fine details. For a photo realistic image, this slider should be kept towards the middle range and will depend on the image.

Color Saturation – This control does pretty much what the name suggests – it controls the intensity of the color and affects all colors in the image equally. Warning, it is very easy to over do it with this control. Make small adjustments only, or leave as is and do all color adjusting in Photoshop, Lightroom, or other editing software.

After adjusting these five controls you will have dialed in about 90% of the overall look of your image, and in some cases, no additional adjustment in Photomatix is needed. However, there will be some images that will need additional fine tunning. That is what the remainder of the controls are for. We go through these from top to bottom starting with the White Point adjustment in Tone Settings.

Note of Particular interest: if the control in Photomatix has “smoothing” in the name of the control, then the higher you adjust this control the more photo realistic your image will become. The lower the number the more illustrative the look. However, like with all things good, you can over do it so make small adjustments.

White Point – This controls how bright the brightest point in the image will be. As you adjust this, watch the effect on the histogram. You should see the histogram move to the right as you adjust this control to a higher number. Adjusting too far will cause clipping (a loss of detail) in the highlights.

Black Point – This controls how dark the darkest point in the image will be. Again, as you adjust this, watch the effect on the histogram. You should see the histogram move to the left as you adjust this control to a higher number. Adjusting too far will cause clipping (a loss of detail) in the shadows.

Gamma – This controls the overall brightness of the image. Moving the slider to the left (to a higher number) darkens the image, and moving the slider to the right (to a lower number) lightens the image. After making an adjustment to the Gamma, you might need to go back and adjust the Strength slider.

Now we move into the Miscellaneous Settings.

Micro-Smoothing – This control smoothes out local detail enhancements and tends to reduce noise giving your image a cleaner look. The higher the number the stronger this effect.

Highlights Smoothing – This control determines how much to reduce the contrast enhancements in the highlight areas of the image. The higher the number the larger the area of highlights are affected. This control also has the effect of preventing white areas from turning grey and for light blue areas from turning dark blue or grey. This control also helps to reduce the halo effect where bright areas come in contact with darker objects.

Shadows Smoothing – This control reduces contrast enhancements in the shadow areas and will help to reduce noise in the darker regions of your image.

Shadows Clipping – Can you guess what this control does? I’ll bet you can – it controls the amount of clipping in the shadow regions of your image. The higher the number, the more shadow detail is clipped. This can be useful in reducing noise in these areas, but it comes at the cost of detail – so use sparingly.

That’s it! At this point you have merged multiple images together and mapped them to the point of a RAW image straight out of the camera. What do I mean by this? Simple, once you have made all your adjustments in Photomatix, you are now at a starting point of post processing your image in the same manner as you would with a single image straight out of the camera. You should not make the mistake of thinking you are done when you save the image in Photomatix, because you are not. You are just beginning.

Hope you find this as useful as I do. I refer to my cheat sheet everytime I begin a tone mapping process. Oh, one other thing. Determine what type of look you want for your image, then select a preset that gets you close to that look. Then go through the controls and dial in the look you really want. This is the easiest and fastest way to tone map an image.

Have fun!