That’s a Sweet Brick Wall

075 Photography Tip of the Week (audio)

There are many things in life that have a sweet spot and photography is no exception.  For this tip I’m interested in the sweet spot of your lens, specifically which aperture is the sharpest all around. It’s a very simple test and only requires a few minutes with each lens you want to test.  I call this the brick wall test.  You don’t have to use a brick wall, as long as you use something that has lots of detail.  Some people will put a newspaper on the wall, but I prefer to do this outside and newspaper blows around very easily.  So here’s my setup:

1. Use a tripod about 10 feet or 3 meters away from the wall, because you want all of your images to be almost exactly the same.
2. Set ISO to 100 or 200 and shoot during a sunny day.
3. Aperture priority mode.  Shutter speed doesn’t affect your sweet spot.  You will start with either your largest or smallest aperture and photograph the exact same image on each aperture setting.
4. Autofocus.  It shouldn’t matter how the focus is set since you aren’t moving the camera, but if you must set it, just center focus will be fine.
5. Using a cable release would be nice, but not overly necessary.

Once you’ve made all your images, load them up in a program where you can look at the centers of each image at 100%.  This becomes a value judgment on your part.  Cycle through the images until you determine which one is the sharpest.  Since you have locked down most all the variables and the only variation is the aperture you should be able to determine which f-stop is the sweet spot.

Here’s the images of various apertures side by side from my test.  As you can see they could all be the same image.  There is very little difference in coloring and overall look.  You can be fairly certain that the only measurable difference now is just the aperture.

Now let’s look at a section of the images at 100%.  You can see that f8.0 is noticeably sharper than either f4.5 or f22.  I’ve scrutinized over all my aperture settings for this lens and know that f8.0 is the sharpest or the sweet spot.

With this knowledge you now know that if you want to get sharper images, you will want to get that aperture as close to your sweet spot as possible and adjust your other settings to match.

After looking into what lens correction added (or didn’t add) to my portraits, I wondered if the lens correction being applied to each individual image before stitching the panorama would help.  One would think that the lens correction would straighten out the individual images and then the final panorama won’t have that bent bowtie effect.  So I decided to do a test with the following panorama.

Panorama Without Lens Correction

After applying the lens correction and restitching I came out with the following panorama.

Panorama With Lens Correction

It’s kind of hard to tell, but it appears that the center horizontal of the panorama is a bit straighter.  But the sky appears to have even more bend to it.  So I decided to overlay the images to see how different they were.

The difference

There’s a pretty big difference and I think that applying the lens correction to the individual images before stitching does help the final image.  What do you think?  Is it a positive difference?

This feature was one of my most anticipated of the Lightroom 3 and Adobe CS5 before they came out. I don’t have any fisheye lenses and generally don’t have anything that looks distorted but that little perfectionist in me wanted my images to be correct. Now that I’ve used it for several months, I find I often forget to turn it on and I don’t miss not using it. Am I missing something or is the lens distortion not a big deal unless you have an extremely distorted lens? There is more correction as your focal goes down.

Here’s one image taken with a Canon 28-135mm at a 28mm focal length. Looking at them side-by-side so to speak, you can’t really see what’s been corrected.

Once I put one image in a difference blend mode, you can start to see that the distortion wasn’t anywhere near my subject. Black is areas with no correction.  The colored section is where there’s been a correction to the distortion and it’s in an area I would probably crop out anyway. So I don’t see a need for it in this case. Do you enable lens correction for your portraits?

Keep it firm

074 Photography Tip of the Week (audio)

It’s time to check your camera, even though it’s working just fine.  Your lenses are clean, there is no dust on the body and your strap is secure.  But there is another thing you may need to check… the firmware.  Firmware is the software that runs inside your digital camera.  From time to time the camera manufacturer will post updated software (or firmware) for your camera.  These updates often include speed enhancements, new features and sometimes fixes to the way the images are processed.  In short there is generally no reason to not upgrade the firmware.

No image with this tip

So take a moment to go to your camera manufacturer’s website and see if there’s a firmware update for your camera model.  If you don’t know where to go just search on “firmware update cameramodel” where the cameramodel is the model of your camera.  They will have detailed instructions on how to check what version you have so you can see if your camera needs updating or not as well as how to perform the update.  In most cases the update is as simple as putting a file on a newly formatted memory card.  You put it in your camera with a fully charged battery and it does it’s magic.  Having a fully charged battery is very important.  You don’t want the camera to lose power part way through the update cycle.  In some cases you can just connect the camera to your computer and update directly without transferring to a memory card.  It really is that simple.

One thing you may have to do after the update is to change the date and time and any other user specified information like your copyright info or special settings. So don’t update your firmware right as you are heading out the door for your next photo session.  Pick a nice afternoon when you have plenty of time.  It shouldn’t take you more than a few minutes to perform the update, but I find that I like to use the time afterwards to look through the menus and see what new functions and abilities are buried within.

If you don’t know if HDR is for you and want to try your hand (or photography) at it, you have the option of of your choice of various 30 day trials for plugins and software.  But if you are like me, sometimes you get distracted and those trials run out or you may not have the time to really vest yourself into a new technology.  So a free program for HDR photography like HDRtist by Ohanaware may be what you are looking for.  It’s simple… really simple.  Drop the photos on the app and you have a single strength slider to control the look.  It appears that it’s more than just exposure blending, so you can make your HDR anywhere from bland to really punchy.  But if you want something funky, you’ll have to blend images from different scenes.

Here’s where you come in: Give HDRtist a try and tell me what you think.  I’m not affiliated with them in any way, just curious if you think a single slider bar is enough, even for freeware.