Aperture Blades

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Today’s Question: What are “aperture blades?’  You talked about those in the context of sunburst shots [in the webinar on wide-angle photography].

Tim’s Quick Answer: The aperture blades are the individual components that are used to form a roughly circular shape for the lens aperture that allows light to pass through the lens to the image sensor (or film).

More Detail: An aperture is in theory a perfect circle through which the light passes from the lens to the image sensor. With many lenses, when the aperture is wide open the aperture blades are retracted to the point that the aperture is a true circle, with no impact from the aperture blades.

The issue is that the circle for the lens aperture needs to be at different sizes, based on the f-stop you’ve selected. So the circle would be small for f/22 and large for f/2.8, for example. But making a perfect circle that can be resized isn’t all that easy. So instead, the aperture is comprised of a series of “blades”.

These blades generally have an arc on the side that will form the outer edge of the circle for the aperture. A series of these blades are assembled in something of a circle, so the inner edge of each blade helps to form a portion of the circle. These blades can all be brought closer in to the center of the circle to form a small aperture, and further away to form a large aperture.

Of course, with multiple blades forming the circle, that circle won’t in fact be a perfect circle. There will be little “notches” where one blade overlaps with another. Those notches are what cause the sunburst effect to occur when the aperture is stopped down to a small size (such as at f/22).

For those who may have missed my webinar presentation on wide-angle photography, which included a discussion of how many blades are used to create the aperture for a given lens, you can view the recording on the Tim Grey TV channel on YouTube here:

https://youtu.be/Q8As06fppwI

Missing Tools on Menu

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Today’s Question: In a previous answer you said that on the Tools menu [in Adobe Bridge] I will have a Photoshop option. I had that in older versions but don’t have that option now and I don’t know why, or how to get it. Can you help?

Tim’s Quick Answer: This issue will most likely be resolved by simply enabling the startup script for Photoshop from within the Preferences dialog in Adobe Bridge. If that option is not available, re-installing Photoshop should provide a solution.

More Detail: There are a variety of startup scripts for Adobe Bridge that enable various features from other applications. In order for those features to be available, the applicable startup script must be enabled in Bridge.

To get started, you can choose Adobe Bridge > Preferences from the menu on Macintosh, or Edit > Preferences on Windows, in order to bring up the Preferences dialog in Bridge. Then select the Startup Scripts page from the list at the left side of the dialog. At this point you should see various Adobe applications listed within the preferences dialog, including Adobe Photoshop CC 2018.

If you’re not seeing the Photoshop commands on the Tools menu in Adobe Bridge, that most likely means that the checkbox for Adobe Photoshop CC 2018 is turned off here. Simply turn the checkbox on (including for other applications if you’d like) and click the OK button to close the Preferences dialog. Then quit and restart Bridge, and the menu commands for Photoshop should then be available on the Tools menu.

If there is not a startup script available for Photoshop, that most likely means something went wrong with the installation of Photoshop. In that case you would likely need to reinstall Photoshop in order to resolve this issue.

Black and White Scans

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Today’s Question: When scanning a black and white negative what advantage (if any) is there to scanning as an RGB image? I have been creating 48-bit scans as if I were scanning a regular color transparency, inverting the image to get a positive, and then trying to optimize the effects across the three channels (accounting for the film stock tint). I’m not sure I’m getting anything more than scanning as a black and white negative directly to a greyscale image.

Tim’s Quick Answer: The potential advantages of scanning a black and white negative as a color image are extremely minimal in terms of image quality in most cases. Except for scenarios where the black and white film has a clear color cast, I would tend to simply scan to grayscale, unless you intend to add color to the image later.

More Detail: There’s no question that scanning a negative in color mode yields more information than scanning in grayscale mode. However, that doesn’t necessarily translate into information that benefits the quality of your final image. With a truly neutral black and white negative, you would end up with three channels (red, green, and blue) if you scan in color, but the real difference between those channels would be minimal in terms of detail in the photo.

It is more important to scan at a high bit depth, and at the maximum optical resolution of your scanner, in terms of getting maximum information from the negative. Scanning in color will produce a file that is three times larger (because you would have three channels in the image instead of one), with very little difference in the final result.

If the film has a strong color cast to it, then scanning in color could be slightly beneficial. And if you intend to add color to the final image, it might make sense to start with a color (RGB) image, since that’s where you would be ending up anyway. But in general the benefit of scanning a black and white negative in color are minimal, in addition to the larger file size and additional workflow steps required for converting the color scan to a true black and white image.

So, I typically scan black and white negatives in grayscale mode, since the potential advantages of scanning in color are quite minimal.

In-Camera Flash

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Today’s Question: All other things being equal (which I realize isn’t actually the case), would you recommend opting for a camera with a built-in flash? Or do you think it is always better to use a separate flash?

Tim’s Quick Answer: Recognizing that “all other things being equal” is not so easy in the real world, I do think it is nice to have a built-in flash to use for supplemental light on occasion.

More Detail: To be sure, whenever using artificial light, it is generally best to get that light at least some distance from the lens. This will help prevent red eye when you are photographing people, and it can also help prevent the odd “dark halo” effect that can occur when the flash is close to the lens and you are photographing subjects relatively close to the lens.

In a studio environment, of course, you would likely have multiple strobes or other lights that would be positioned strategically around your subject. In other environment you might use one or more external flash units. Even if a flash is mounted on the hot shoe of the camera, that would still get the flash further away from the lens than a built-in flash would be. Even that small difference can make a big difference for your photos.

That said, I certainly find myself in situations where I don’t have a flash unit with me, and in those cases I appreciate having a built-in flash on the camera. To help compensate for the issues of having a flash that is so close to the lens, I will more often than not reduce the strength of that flash so it is contributing light that supplements (rather than overpowers) the ambient light.

So, given the choice, I certainly prefer to opt for a camera that has a built-in flash, just so it is available when other flash units are not available. I wouldn’t consider a built-in flash to be a “must have” feature, but it is certainly a “nice to have” feature I would prefer to have, as long as all of the other specifications were comparable for the camera models I was considering.

Anti-Fog with Hand Warmers

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Today’s Question: When doing time lapse of shooting stars my lens will often fog up as the temp changes. I solved the fogging by using those disposable hand warmers that you open and expose to the air. I use a rubber band to hold it wrapped around the front lens area. Works great.

Tim’s Quick Answer: This is a great tip! I heard variations on this recommendation from several readers who use hand or toe warmers on their lenses or in their camera bag in order to warm up their lenses and prevent fogging up in humid environments.

More Detail: Today’s “question” is obviously not actually a question, but rather a tip submitted by a reader (and echoed by several other readers). I thought this tip was worthwhile sharing here, even without the usual “question and answer” format.

As noted in the Ask Tim Grey eNewsletter from May 9th (http://asktimgrey.com/2018/05/09/anti-fog-wipes/), in my experience anti-fog wipes don’t actually provide any benefit in terms of preventing your lenses from fogging up when you take them from a cold environment to a relatively warm and humid environment. Instead, I suggested either waiting for the lens to warm up to the ambient temperature, or to use a hair dryer to warm up the lens before heading out (as recommended by a reader).

Using a hand or toe warmer for this purpose obviously provides a number of advantages. To begin with, you could simply put a warmer into your camera bag before you head out, so that your lenses will have a chance to warm up before you start using them.

In addition, attaching a warmer directly to the lens can help ensure the lens remains warm over an extended period, to help prevent fogging. In short, anything you can do to safely warm up the lens to match (or exceed) the ambient temperature will help prevent condensation fogging on that lens.

Value of Tilt-Shift

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Today’s Question: What is your opinion on the use of Tilt-Shift wide-angle lens to reduce (eliminate) perspective distortion?

Tim’s Quick Answer: I think a tilt-shift lens can be incredibly helpful for correcting (and often eliminating) perspective distortion. The key question is whether it makes sense for an individual photographer to add a tilt-shift lens to their camera bag.

More Detail: A tilt-shift lens enables you to move lens elements relative to each other, which makes it possible to correct for perspective distortion as well as to alter the alignment of the depth of field. While a tilt-shift lens is especially valuable for correcting perspective in architectural photography, there are a wide variety of other situations where such a lens can be helpful.

If you were photographing a building from ground level at a relatively close distance, there will always be a degree of perspective distortion, where the building seems to be leaning away from you. In that situation, I would absolutely recommend using a tilt-shift lens if you had one in your bag.

As a result, the real question to me isn’t whether a tilt-shift lens could be helpful, but whether it might be worthwhile to add a tilt-shift lens to your camera bag.

If you frequently photograph subjects (such as architecture) where your photos would benefit from perspective correction, a tilt-shift lens might absolutely be a worthwhile addition to your collection of gear. But if you only need this type of perspective correction (or to apply other creative possibilities) on a somewhat infrequent basis, it might not be worth spending extra money for a tilt-shift lens (or to carry the extra weight of that lens).

Keep in mind that some of the effects you can achieve with a tilt-shift lens can also be accomplished in processing after the capture, although the quality might not be equivalent. This is why in general I consider a tilt-shift lens to only be a worthwhile investment for photographers who will take advantage of its unique benefits on a somewhat frequent basis.

Enhanced Split Toning

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Today’s Question: I like applying a split toning effect to some of my black and white photos. I generally use the Camera Raw Filter to apply the effect, but that only enables two colors to be chosen. Is it possible to create a similar effect with more than just two colors?

Tim’s Quick Answer: You can create an effect similar to split toning but with multiple colors by using a Gradient Map adjustment layer in Photoshop.

More Detail: The Gradient Map adjustment layer in Photoshop enables you to define a gradient that can then be used to map color values in the gradient based on tonal values in the photo.

The first step is to add a Gradient Map adjustment layer to the image. So, select the top layer on the Layers panel, and then click the Add Adjustment Layer button (the half-black/half-white circle icon) and choose Gradient Map from the popup. On the Properties panel select the black-to-white gradient as a starting point.

Next, click within the gradient shown on the popup in the Properties panel to bring up the Gradient Editor dialog. To add a color as a gradient stop, click directly below the preview gradient. Then select a color for that gradient stop, and drag the stop left or right as needed to refine the gradient.

You can continue adding multiple colors, which will be based on tonal ranges within the image. So, the darkest values will be on the left of the gradient, and the brightest values on the right. Be sure to select a color with the desired tonal value, in addition to the overall hue and saturation.

Once you have finalized the gradient, you may want to save it as a preset for future use. To do so, simply click the “New” button in the Gradient Editor dialog. The preset will then be available to use as the starting point for other images. When you’re finished working on the gradient map, you can click the OK button to close the Gradient Editor dialog, and continue working on your image.

Precise Cleanup

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Today’s Question: Is there a way to precisely align my cleanup work in Photoshop? For example, when I need to clean on a horizon line, it is important that my cleanup work be aligned with that horizon.

Tim’s Quick Answer: For precise cleanup work in Photoshop, I recommend turning on the “Show Overlay” checkbox in the Clone Source panel. This will cause the source pixels to appear within your brush cursor, so you can easily align those source pixels in the destination area you are painting the cleanup into.

More Detail: The Clone Source panel in Photoshop includes a variety of options related to the source of pixels being used for cleanup tools where you can select a source manually. That includes the Clone Stamp and Healing Brush tools, for example. When you need to be precise with these tools, I recommend turning on the “Show Overlay” option.

If the Clone Source panel isn’t currently visible, you can choose Window > Clone Source from the menu to bring it up. In addition, the applicable tools include a button on the Options bar that will bring up this panel.

I don’t consider most of the options in the Clone Source panel to be especially helpful in my typical workflow. But the Show Overlay option can be tremendously useful. Admittedly, I do find that having this option enabled can be a bit distracting, so I only turn it on when I actually need it for precision painting with a cleanup tool.

To view the overlay showing source pixels you need to have the Show Overlay checkbox turned on, and you need to have sampled a source area by holding the Alt/Option key on the keyboard while clicking in the area of the image you want to use as the source of pixels for your cleanup work. At this point, your mouse pointer that shows the brush shape will display the source pixels within that shape. This enables you to very precisely align the brush before actually painting into the image.

Anti-Fog Wipes

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Today’s Question: I’ve seen lens wipes advertised as preventing lenses from fogging up. Do you have any experience with these to know if they actually work?

Tim’s Quick Answer: No, in my experience the wipes that are promoted as being “anti-fog” do not prevent lenses from getting fogged up. Instead I recommend getting the lens to match the ambient temperature to minimize the risk of fogging.

More Detail: In most cases lens fogging is the result of the lens being cold in a humid environment. In my experience the most typical scenario is coming out of an air-conditioned building into a warm and humid environment. The cold lens (and other gear) causes condensation in conjunction with the humidity in the air.

I generally find that in this type of situation, I’m not really able to plan ahead. For example, if it was possible to leave my camera outdoors safely, that would have ensured the camera was not colder than the ambient air, and thus condensation would be less likely to form.

If you’re able to plan ahead, warming up your camera either by taking it outdoors before you plan to start photographing, or using a hair dryer to warm up your camera gear, can help minimize the risk of fogging.

Otherwise, I will simply wait for my camera gear to warm up, which generally takes about five minutes. In extreme cases it may be necessary to use a lens cloth to wipe excess moisture from the lens elements. But very often simply waiting will resolve the issue.

If anyone knows of lens wipes that actually provide an anti-fog capability, please let me know. All of the wipes I’ve tested were not able to prevent fogging at all.

Previews Disappeared

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Today’s Question: The other day I launched Lightroom only to see a message that there was a problem with my catalog and it needed to be checked. When the check was complete, Lightroom indicated that the catalog was damaged and needed to be repaired. Thankfully that was successful, but in the process all of the previews for my images changed to gray rectangles. As I browse folders the previews are being rebuilt, but is there a way to build previews for all images at one time?

Tim’s Quick Answer: You can indeed build previews for all images in your Lightroom catalog. Simply navigate to the All Photographs collection in the Catalog section of the left panel in the Library module, select all images, and then go to the menu and choose Library > Previews > Build Standard-Sized Previews.

More Detail: While I’ve certainly known photographers who have ended up with a Lightroom catalog that was corrupted to the point of not being able to be recovered, in many cases Lightroom will be able to repair whatever problems occurred with the catalog so you can get back to work without losing any information. Of course, this underscores the importance of backing up your Lightroom catalog on a somewhat regular basis.

When a catalog is repaired, I have found that the previews file becomes problematic. Fortunately, it is very easy to generate new previews for all images in your Lightroom catalog.

As noted above, the “All Photographs” collection found in the Catalog section of the left panel in the Library module enables you to view all images in your entire Lightroom catalog. You can then select all of the images by choosing Edit > Select All from the menu.

It is important to note that in order to note that in order for Lightroom to build previews for your photos, the source image files must be available. For example, if your photos are stored on external hard drives, those drives must be connected to the computer in order to build previews.

To build previews for the selected photos, you can then choose the appropriate option from the Library menu. When you navigate to the Library > Previews submenu, you’ll see that you can build Standard previews or full resolution 1:1 previews. Select the option that makes the most sense to you, and Lightroom will get to work.

The process of building previews for an entire catalog can take considerable time. Obviously, the specific time will depend upon how many images are in your catalog. However, you can expect the process to require several hours, and possibly a full day or more. Fortunately, photos that already have previews will be skipped, meaning that Lightroom won’t waste time building previews unnecessarily. That also means you can cancel the task and restart it at a later date if needed.