Category: Ask Tim Grey

Today’s Question: [When attempting to move photos to a new hard drive in Lightroom, as addressed in a prior edition of the Ask Tim Grey eNewsletter,] What if some of the photos in the folders being moved are not in the Lightroom catalog?

Tim’s Quick Answer: When you move photos from one hard drive to another in Lightroom, only the photos actually included in the Lightroom catalog will be moved to the new hard drive. Any photos on the drive that are not being managed in Lightroom will be left behind on the existing hard drive.

More Detail: It obviously makes sense that moving photos within Lightroom would only affect photos that are actually being managed in your Lightroom catalog. This also underscores one of the reasons I highly recommend that if you are using Lightroom to manage your photos, you should use Lightroom to manage all of your photos. In other words, from my perspective it is best not to have photos included in your photo storage structure without also having those photos included in your Lightroom catalog.

If there is any chance that some of the photos stored on the existing hard drive are not included in your Lightroom catalog, it is important to review the existing hard drive after moving photos to your new drive, in order to make sure there aren’t any photos or folders “left behind”.

If there are photos left behind on the existing hard drive after you’ve moved photos to a new hard drive within Lightroom, you’ll need to determine what to do with those photos. If the photos aren’t in your Lightroom catalog because they are “rejects”, you could certainly delete those remaining photos if that is your preference. You could also import those photos into Lightroom, moving them to the new storage location in the process by using the “Move” option in the Import dialog.

I should add that this overall topic is also (I think) a reminder of an issue that some photographers have been confused about. The Folders section of the left panel in the Library module in Lightroom is a reflection of your existing storage structure for your photos. Thus, moving photos within Lightroom will cause photos to be moved on your hard drive. And, as noted above, photos that aren’t in Lightroom won’t be affected by what you do within Lightroom.

Today’s Question: I have my photos stored on my computer’s hard drive, My computer is giving me nasty warning signs that I am running out of space. I need to move the photos from the computer to an external hard drive, and I need to do it from within Lightroom, as you impressed upon us. You told us to create a new folder for the external hard drive and drag the photos into it, but I’m having difficulty setting that up. The external hard drive is not showing up in Lightroom. Could you review the process for me? I would appreciate your help with this.

Tim’s Quick Answer: The “trick” here is to create a new folder on the new hard drive from within Lightroom. Doing so will cause that new folder (and thus the new hard drive) to appear in the Folders list in the Library module in Lightroom, even though Lightroom is not yet managing any photos on that new hard drive.

More Detail: To create the new folder, first make sure the new hard drive is connected to your computer and otherwise ready for you to copy photos too. Then, in the Library module in Lightroom, click the “plus” symbol to the right of the Folders list on the left panel. From the popup menu that appears choose “Add Folder”.

In the dialog that appears, navigate to the new hard drive, and click the “New Folder” button. Type a name for that folder (such as “PHOTOS”), and press Enter/Return on the keyboard to create the actual folder. Then click the “Choose” button to confirm the new folder and close the dialog.

At this point the new folder (and thus the new hard drive) will appear on the list under Folders on the left panel in the Library module. You can then drag-and-drop folders from the original location to the new location. You can even select multiple folders from the list by clicking the first folder you want to select and then holding the Shift key while clicking the last folder you want to select.

I should hasten to add that it is important to make sure you have a good backup copy of all of your photos before performing this task, just in case anything goes wrong in the process.

More details about this process (and more tasks for cleaning up your Lightroom catalog) can be found in my video training course “Cleaning Up Your Mess in Lightroom”, which is available in the GreyLearning video training library (http://www.greylearning.com).

Today’s Question: This may be a bit of a stretch, but… The subject of blend modes reminded me of a technique that I think involved a blend mode [in Photoshop] to determine whether the frames of a panorama are aligned well. I know there are automatic options for assembling composite panoramas, but I like to put them together myself. Can you remind me of the blend mode option, if I’m even remembering these few details correctly?

Tim’s Quick Answer: It is indeed a blend mode that provides the feature you’re looking for in Photoshop, where you’re able to see the degree to which the pixels in two overlapping layers actually match. That blend mode is the Difference blend mode.

More Detail: To use the Difference blend mode for evaluating the alignment of two image layers, simply change the blend mode for the upper image layer on the Layers panel. So, you can click the thumbnail for the upper of the two layers you want to compare, to make sure that layer is active. Then click the popup at the top left of the Layers panel (the popup has the default value of “Normal”) and choose Difference.

With the Difference blend mode, any pixels that are an exact match on the upper and lower layer will appear as black. Any pixels that aren’t an exact match will appear as a color that differs from black to the degree there is a “mismatch” between the pixels.

In other words, when using the Difference blend mode for this purpose, your goal is to have as much black in the image as possible. You can move the image layers, resize the image layers, transform the image layers, and more, in order to achieve the best alignment possible.

While I do find that various software tools (including Photoshop) do a great job of automatically assembling and aligning the individual frames for a composite panorama, I also find the Difference blend mode to be tremendously valuable when I choose to take a “manual” approach for any reason.

Today’s Question: How do I know when I should be capturing several images for an HDR (high dynamic range) instead of just a single exposure?

Tim’s Quick Answer: Conceptually, whenever the histogram display for a single exposure shows clipping at both the black and white ends of the histogram (or significant clipping at one of the two ends), you might want to capture bracketed exposures to possibly assemble into a high dynamic range (HDR) image.

More Detail: With practice, of course, you can learn to anticipate when the overall contrast (or dynamic range) of the scene you are photographing is significant enough that a single exposure won’t be able to contain the full range of tonal values in the scene. The limitations in terms of dynamic range vary from one camera to the next, but over time you will develop a sense of when you’re near (or past) the limitations of your camera.

Of course, just because the dynamic range of the scene is beyond the capabilities of your camera to record in a single capture doesn’t mean you should create an HDR image. A photo with clipping of detail in the darkest shadows could simply be a dramatic photo, and a photo with clipping of highlights could simply be a very nice “high key” photo.

That said, my approach is to capture a sequence of bracketed exposures whenever I know (or my camera’s histogram display tells me) that the full dynamic range of the scene can’t be captured with a single photograph. This provides the flexibility of deciding later whether I want to create an HDR image or simply work with the best of my various exposures.

So, there is an element of experience in terms of being able to anticipate when the dynamic range of a scene exceeds the capabilities of your camera. There is also an artistic decision to be made here in terms of how you will interpret the scene. But in general I prefer to have bracketed exposures whenever the scene has a high dynamic range, so I have more flexibility when processing my photos later.

Today’s Question: Is there a difference between the Overlay and Soft Light blend modes in Photoshop? I see some people using one versus the other with the same basic techniques.

Tim’s Quick Answer: The Overlay and Soft Light blend modes are both “contrast” blend modes that enable you to achieve both a brightening and darkening effect with an underlying image at the same time. The effect of both is essentially the same, with the difference being that the Overlay blend mode creates a somewhat stronger effect than the Soft Light blend mode.

More Detail: The first three categories of blend modes in Photoshop enable you to apply a darkening effect (with Multiply being the first of these blend modes), a lightening effect (with Screen being the first of these blend modes), or both (with Overlay being the first of these blend modes).

I refer to the blend modes that can both lighten and darken as the “Contrast” blend modes. There are a variety of situations where you might use a contrast blend mode, such as dodging and burning by painting onto a separate layer or reducing haze and enhancing detail with the “High Pass” sharpening technique.

With a contrast blend mode, any pixels on the layer to which you have applied the blend mode that are lighter than middle gray will have a lightening effect on the underlying image. Any pixels that are darker than middle gray will have a darkening effect on the underlying image. So if you have both light and dark areas in the layer you’ve applied the contrast blend mode to, you’ll brighten some areas and darken others, leading to (generally speaking) increased contrast.

The Overlay blend mode simply applies a stronger effect than the Soft Light blend mode. Thus, some photographers prefer one over the other. I, for example, prefer the Overlay blend mode because it provides a stronger effect.

It is important to keep in mind, however, that with many of the techniques where you might employ a contrast blend mode, you’re going to reduce the Opacity setting for the layer to which the blend mode is applied. Therefore, the final effect can be the same with either Overlay or Soft Light, with the only difference being the specific Opacity setting you use to achieve the final effect.

In general you can think of the Overlay and Soft Light blend modes as being interchangeable. Just keep in mind that the Overlay blend mode provides a stronger contrast effect than the Soft Light blend mode.

Today’s Question: I’m new to Facebook, and was wondering when you post images from Ligthroom directly to Facebook, can you have multiple pictures in one timeline event? I see you can post to photo albums, etc. But each image is a separate timeline event. With some posts I would like to group more than one picture to a single timeline event.

Tim’s Quick Answer: Yes, you can publish multiple photos from Lightroom to Facebook as a single event on your timeline. You just need to create a new collection for that task, and then publish all of the photos in that collection at the same time. Facebook will then include all of the photos published as part of that process in a single timeline event.

More Detail: You first, of course, need to authorize Lightroom to access your Facebook account, which you can do by clicking the “Set Up” link to the right of Facebook in the Publish Services section of the left panel in the Library module in Lightroom.

Once you’ve configured Lightroom to be able to access your Facebook account, the next step is to create a collection for publishing a group of photos to Facebook. You can start by selecting the photos you want to include on that collection. For example, you might filter your photos so you can only see those you’re interested in sharing on the Filmstrip. Then select the specific photos you want to share to Facebook.

With those images selected, right-click on the Facebook item in the Publish Services section of the left panel and choose “Create Collection” from the popup menu that appears. In the Create Collection dialog, configure the settings for this collection, including the details in the “Facebook Album” section, such as the “Album Name”. When you’re finished configuring these settings, click the Create button to actually create the collection.

Finally, viewing the new collection under Facebook in Publish Services, and with the Grid view enabled (which you can do by pressing “G” on the keyboard if you were in the Loupe view), click the “Publish” button toward the top-right of the images in the Grid view display. This will cause all of the photos to be published to the Facebook album you specified, and once the process is complete the publication of those photos will appear as a single timeline event.

Note that as the several photos are published, you will initially see an event for a single photo, but that will update as each photo is published so that you still only have a single timeline event for all of the photos you just published.

Today’s Question: [Using a separate layer for image cleanup work in Photoshop, as covered in the September 7th edition of the Ask Tim Grey eNewsletter] would all be great except for the final critical step, sharpening. I don’t see any way around making a second file, or double BG layer, and still get to a suitably sharp image.

Tim’s Quick Answer: This is exactly why I perform sharpening as part of a specific “output workflow”, where I create a copy of my master image, flatten that copy, resize for the intended output size, and sharpen the image. Thus, the sharpening is being applied to a flattened (and resized) copy of the master image. In most cases I don’t even need to save this duplicate output file, because any future output will be created based in the “master” image file that still contains layers.

More Detail: Today’s question is a follow-up to the question I addressed in the September 7th edition of the Ask Tim Grey eNewsletter, which related to the use of an empty layer for image cleanup work. One of the key benefits to this approach is that the file size is not significantly increased the way it would be if you instead created a copy of the full Background image layer.

By taking this approach, I am able to retain all of the layers I used to produce the final image as part of my “master” image file, without unnecessarily increasing the file size. My approach is to never flatten this master image, always preserving the layers for maximum flexibility should I decide to make any changes to the image.

Of course, while I never flatten my master image, that doesn’t mean I won’t flatten a copy of that image for purposes of my output workflow. As noted above, this workflow involves making a copy of my master image (via the Image > Duplicate command on the menu). I can flatten the copy in the process of creating this duplicate by turning on the “Duplicate Merged Layers Only” checkbox in the Duplicate Image dialog. I will then resize based on the intended output for the image, and apply sharpening (generally using the Smart Sharpen filter). This results in an image that has been optimized for the specific output size and output conditions, based on (for example) the print I plan to produce.

If I think I’ll likely want to print the same image at the same size in the future, I could save this derivative image with a reference to the output size in the filename. But personally I don’t tend to need to re-print the same image at the same size very often, so I generally don’t save the derivative image. Instead, I simply return to my original master image whenever I need to produce additional output for that photo.

Today’s Question: You mentioned capturing video with your digital SLR at 30 frames per second with a 1/30th of a second shutter speed. But that means the camera is constantly capturing frames. How is it that the buffer never gets full the way it does with still captures?

Tim’s Quick Answer: The short answer is that video is captured at a much lower resolution than the camera is capable of for still images, and so it is possible to capture video at a high frame rate for an extended period of time without filling the memory buffer in the camera.

More Detail: Let’s assume a somewhat typical (or at least popular) camera that is capturing images with a 22-megapixel sensor. That would involve maximum pixel dimensions for a still image of (for example) 5,760 pixels by 3,840 pixels. At a frame rate of six frames per second, the camera is capable of capturing 17 images before the buffer is full and capture speed will slow.

However, that full buffer represents 17 RAW captures of 22 megapixels. By contrast, full 1080p high definition (HD) video is “only” 1,920 pixels by 1,080 pixels, which is the equivalent of about 2 megapixels. In other words, there is a lot less information being captured when recording video rather than full-resolution still captures, and so you can capture many more frames without filling the buffer.

In general you will find that a digital camera that offers full HD video recording will be able to capture video continuously without filling the buffer. Of course, there are other factors to consider when it comes to recording video for and extended period of time, including overall file size, heat buildup, and other considerations. But you generally won’t need to worry at all about the buffer limitation of your digital SLR when you’re capturing video rather than still captures.

Today’s Question: What is the difference between Opacity and Flow? I think I halfway understand this, but would sure like to hear your explanation.

Tim’s Quick Answer: Opacity is the degree to which a color you paint with will be opaque versus transparent, while Flow relates to whether there will be a fade-in and fade-out effect relative to opacity for each brush stroke. These options are available in various contexts (though all related to painting) within Photoshop, Lightroom, and other applications.

More Detail: I think it can be helpful to use airbrush painting as an analogy for understanding Opacity and Flow. With an airbrush you are spraying paint onto a surface. Think of Opacity as the degree to which the paint is “watered down”, which determines whether the paint will completely cover the surface you’re painting to or allow that surface to “show through” a relatively light coating of paint.

The Flow setting relates to how fast the paint is being sprayed out of the airbrush. If the paint is flowing quickly (a high setting for Flow), even if you move the airbrush extremely fast across the surface the paint will have a high effective opacity. If the paint is flowing slowly (a low setting for Flow), you are better able to vary the effective opacity along a paint stroke by varying the speed at which you move the airbrush across the surface.

So, Opacity is your primary control for determining whether your brush strokes will completely cover up underlying pixels or blend somewhat so the underlying pixels still show through. Flow is related, in that it affects the rate at which the color will be applied as you’re painting.

In other words, with Flow set below 100%, when you paint with the brush the effective opacity will initially be lower than what the Opacity is actually set to, transitioning to the full Opacity setting. Similarly, when you stop a brush stroke there will be a transition from the set Opacity to a lower value.

This explanation, of course, probably doesn’t leave the impression that the Flow setting is especially helpful. But that’s because there are two additional considerations you’ll want to take into account when making use of (or evaluating the value of) the Flow setting.

To me the real value of the Flow setting isn’t the Flow setting all by itself, but rather the Flow setting in the context of painting with a pressure-sensitive device such as a tablet and stylus. When using a pressure-sensitive device (with the Fade Jitter setting set to “Pen Pressure” on the Brushes panel in Photoshop, for example), the amount of pressure you apply with the stylus while painting determines the behavior of the brush strokes based on the Flow setting. In other words, you can use the pressure you apply when painting with the stylus to control the Flow behavior. That means instead of a fixed transition from a reduced opacity to the value based on the current Opacity setting, you can vary the transition so your stroke Opacity (and the transition between opacity effects) varies.

Another option in Photoshop is the Airbrush feature. This allows the opacity of your brush stroke to build up, based on the Flow setting. So, with a low Flow setting and a relatively low Opacity setting you can paint a quick brush stroke to paint with a low effective opacity. If you slow down (or stop) the movement of the brush the paint will “build up”, creating greater effective opacity for that portion of the brush stroke.

If you think about the Opacity and Flow settings in the context of a real-world airbrush (or can of spray paint), I think it will be easier to understand these settings in software such as Photoshop and Lightroom.

Today’s Question: Which brand of Neutral Density Filter do you use? Is it the B+W 77mm 3.0 ND MRC and the equivalent 6-stop neutral density filter?

Tim’s Quick Answer: For my photography I generally carry a 10-stop (for dramatic photographic possibilities) and a 6-stop (for slightly faster shutter speeds) neutral density filter. I typically use filters from B+W, as I have found them to provide excellent quality at a competitive price.

More Detail: A ten-stop neutral density filter (with a density value of 3.0) provides excellent creative possibilities in your photography. With a filter this strong you can achieve 30-second exposures even during full daylight, and you can achieve longer exposures during darker (or night) conditions. With a ten-stop neutral density filter I find I can produce images that would otherwise be impossible, and I have a great deal of fun in the process.

For situations where I don’t need quite as long an exposure time (and I don’t want to increase the ISO setting just to get a faster shutter speed while using a 10-stop neutral density filter) I also carry a 6-stop filter. If I only carried the 10-stop filter, I would need to raise the ISO setting to 1600 to achieve the same shutter speed as the 6-stop filter while using the 10-stop filter. So I find it helpful to have an “extra” filter in my bag to help avoid the need to raise the ISO setting too much.

Because I also shoot a lot of video, I carry a 2-stop neutral density filter in addition to my 6-stop and 10-stop filters. This is primarily for situations where I need just a little bit of help to achieve a 1/30th of a second exposure based on video captured at 30 frames per second. Sometimes I only need 2-stops of density to get to the target shutter speed for video, and with video in particular I try to avoid raising the ISO setting. So, I carry a 2-stop neutral density filter in addition to the other two filters when I anticipate capturing video along with stills during a photo outing.

You can find all three of the neutral density filters I reference here using the following links:

10-Stop Neutral Density Filter: http://timgrey.me/nden10

6-Stop Neutral Density Filter: http://timgrey.me/nden6s

2-Stop Neutral Density Filter: http://timgrey.me/nden2stop