Category: Ask Tim Grey

Today’s Question: I created a selection in Photoshop for a JPEG capture, and saved that selection so I could put it to use again in the future. When I choose the Save command from the File menu, however, Photoshop prompts me to save the image as a Photoshop PSD file. I just want to save the updates to the JPEG image. Is that not possible?

Tim’s Quick Answer: No, it isn’t possible to save a JPEG image with a saved selection. Saved selections (among a variety of other features in Photoshop) can only be included with images saved as either a Photoshop PSD file or a TIFF image.

More Detail: When you open any supported image type (such as a JPEG image) in Photoshop, you can make full use of all of the available features within Photoshop for that image. So, for example, after opening a JPEG image you can save selections, add adjustment layers, and much more.

However, in order to save some of the advanced features of Photoshop as part of an image file, you need to use a supported image file format. A JPEG image, for example, doesn’t support layers, layer masks, saved selections, and other advanced features of Photoshop.

While you can use these various features with a JPEG image (or other supported image formats), that doesn’t automatically mean you can save the image in the same file format with all of the advanced features included.

JPEG images don’t support alpha channels, which are required to support the option to save selections as part of an image in Photoshop. The reason Photoshop is prompting you to save the JPEG as a PSD image is that you have made use of features that the JPEG file format doesn’t support.

So, if you want to retain your saved selections or other advanced features, you’ll need to save the image as a Photoshop PSD file or as a TIFF image.

Today’s Question: Does the Lightroom backup for the catalog also backup your photos? If not is there a way to accomplish this?

Tim’s Quick Answer: No, the Lightroom catalog backup feature does not backup your photos. While it would be possible to backup both your photos and the catalog using the “Export as Catalog” command, I recommend using a different solution for backing up your photos.

More Detail: When you use the backup feature in Lightroom, you are only backing up the Lightroom catalog, not your photos. In other words, you’re backing up the information about the photos and not the photos themselves.

As noted in yesterday’s Ask Tim Grey eNewsletter, there are some benefits to using the Lightroom catalog backup feature for backing up your catalog, including the option to check the integrity of the catalog and optimize the catalog. Therefore, it is a good idea to use the Lightroom catalog backup feature even if you have another backup solution that is also backing up your catalog.

For your photos you’ll need a different backup solution. I personally prefer a “synchronization” approach to backing up my photos and other data, which is covered in the “Backing Up with GoodSync” video training course in the GreyLearning library. If you’re not a GreyLearning subscriber you can purchase this individual course at a discounted rate using this link:

http://timgrey.me/greysync14

In theory you could also use the “Export as Catalog” command to backup both your Lightroom catalog and your photos in a single process. However, to make this approach useful you would need to export (and therefore copy) your entire catalog of photos. That could obviously require considerable time. Therefore, I only recommend using the “Export as Catalog” feature as a backup option when you need a one-time solution for copying your Lightroom catalog and photos to a different location, or for backing up everything in one overall process. For an ongoing backup solution I recommend something a bit more streamlined, such as the synchronization approach referenced above.

Today’s Question: If I’m backing up the drive with all my images and Lightroom each night to a cloud site and multiple external hard drives, is there an advantage to backing up the Lightroom Catalog in Lightroom? It can be time consuming and if my daily back up is providing the same level of “protection,” what’s the value?

Tim’s Quick Answer: The key advantage to using Lightroom to backup your catalog in addition to any other backups you may be performing is that Lightroom enables you to check the integrity of your catalog and optimize the catalog as part of the backup process.

More Detail: Obviously if you have an excellent backup workflow that provides you with redundant copies of your Lightroom catalog, then the option within Lightroom to backup the catalog may seem redundant. At least in concept there is no need to have a Lightroom version of your catalog backup if you have another perfectly good backup to restore from in the event of a problem.

However, Lightroom also includes the option to check the integrity of your catalog and to optimize the catalog as part of the catalog backup process. Both options are available as checkboxes within the “Back Up Catalog” dialog in Lightroom.

The “Test integrity before backing up” option will cause the catalog to be checked for any problems that could ultimately lead to a corrupted catalog file. I highly recommend employing this option whenever you backup your catalog from Lightroom, to help minimize the risk of a corrupt catalog that could cause data loss.

The “Optimize catalog after backing up” option will cause Lightroom to perform some housekeeping chores for your catalog. You can also find this option on the File menu if you want to optimize the catalog outside the context of backing up your catalog. Optimizing the catalog with this process can help improve overall performance. Therefore I recommend performing this task every time you backup your Lightroom catalog (or about once a month if you aren’t using the Lightroom catalog backup feature), or anytime you notice degraded performance in Lightroom.

It is also worth noting that it is a good idea to backup your Lightroom catalog to a location that is on a separate storage device from your original catalog. For example, if you store your Lightroom catalog on the internal hard drive on your computer, you can store the backup copies on an external hard drive.

Today’s Question: What is the difference/advantage of changing a file to sRGB via “assign profile” and “convert to profile” [in Photoshop]?

Tim’s Quick Answer: If you want the colors in the photo to remain unchanged (to the extent possible), you should use the “Convert to Profile” command. If you want to change the appearance of colors in the photo based on a profile, you would use the “Assign Profile” command. In general I would say that photographers today are therefore more likely to want the “Convert to Profile” command, and not the “Assign Profile” command.

More Detail: There are two basic reasons you might want to change the color space associated with a photo. The first (and most common for photographers these days) is to change a photo to a different color space based on a specific output scenario. For example, when preparing a photo to present online, it can be a good idea to convert to the sRGB color space to help ensure more accurate color for the photo being shared. In this type of scenario you want to maintain the same appearance of colors in the photo.

The other scenario is one where you actually want to change the appearance of colors based on a profile. For example, if you scan a slide or negative, you could use an ICC profile for the scanner to apply an automatic correction to the scanned image. The scanner profile would then be used as the basis of a change in color appearance for the photo to make the resulting colors more accurate.

These days I find that many photographers have a need to convert a photo to a different profile for reasons related to how that photo is being shared. In this type of situation you want to maintain the color appearance of the photo, so the “Convert to Profile” command would be appropriate.

Only when you actually want to change the appearance of a photo based on an ICC profile should you use the “Assign Profile” command. These days I would say that most photographers are therefore probably not using the “Assign Profile” command much, if at all.

Today’s Question: Please help me understand the difference in field of view (really image size) between an ASP-C lens on a crop frame body and a full frame lens on a full frame body.

For example, would a 11-16mm APS-C lens set to 16mm mounted on my camera body with a 1.6X crop factor have the same angle of view as a Canon 16-35mm full frame lens set to 16mm mounted on a full frame body? Would both images be the same size?

I understand about multiplying the focal length times the crop factor when switching a lens between bodies. I don’t understand the difference, if any, in image size between a full frame lens and a crop frame lens when each is mounted on its respective body and set to the same focal length.

Tim’s Quick Answer: A 16mm lens on a “cropped” sensor will not provide the same field of view as a 16mm lens mounted on a “full frame” sensor. The field of view of the actual lens remains the same in both cases. However, because the smaller sensor is capturing only a portion of the image circle projected by the lens, in this case the cropped sensor camera will produce a field of view equivalent to a 25.6mm lens (16mm X 1.6) on a full-frame camera, assuming a 16mm focal length lens in both cases.

More Detail: I think most photographers understand the basic concept of a “cropped” sensor. Because the 35mm film capture format became such a popular format, it is used as the basis for a great deal of photographic equipment. So we have “full frame” digital cameras that have an image sensor that is essentially the same size as a single frame of 35mm film. As such, with a “full frame” camera your lenses will provide the same field of view you may have come to expect when using a given focal length lens with a 35mm film camera in the past.

A camera with a “cropped” sensor is simply capturing a smaller area of the image circle projected by the lens. So while you aren’t actually getting any extra “zoom” factor from your lens, you are getting a smaller field of view that matches what a longer focal length lens would achieve with a full frame camera. So you’re getting a zoom effect without an actual optical zoom.

For example, on a camera with a 1.6X “cropping factor”, a 100mm lens would produce the same field of view as a 160mm lens on a full frame camera. You aren’t truly zooming, at least from an optical standpoint, but you are achieving a smaller field of view equivalent to that of a longer focal length lens.

An additional point of confusion can result from lenses that are specifically designed for “cropped” sensors. However, the only real difference here relates to the size of the image circle being projected by the lens. A lens designed for a cropped sensor camera generally can’t be used on a camera with a full-frame sensor, because the image circle projected by such a lens will not cover the full area of the image sensor on a full-frame camera.

The bottom line is that there is a relationship between focal length and field of view. However, the specific field of view achieved with a lens of a given focal length depends upon the size of the image sensor being used to capture the scene. Ultimately the real challenge here is in describing the behavior of a lens while talking about the focal length of the lens.

A great solution in my opinion would be for lenses to be described not on focal length but instead based on field of view. But again, that field of view depends upon the size of the image sensor used to capture an image, and many lenses can be used with cameras of varying sensor sizes. In other words, there isn’t really a simple way to describe the field of view of a lens unless you also refer to a specific sensor size.

It is worth noting, by the way, that whatever field of view you’re ending up with for a given sensor and lens focal length combination, in general you are making use of the full image sensor to capture that scene. Thus, while a smaller sensor doesn’t truly provide additional zoom for a given lens, it can still provide excellent image quality for that image with a smaller field of view. In other words, we are largely talking about semantics here. Once you’re using a given camera, you can simply focus on the field of view you want to obtain when making a decision about which lens to use.

Today’s Question: Why is it that when I import my photos into Lightroom they don’t always follow the sequence that they were shot? For instance, I might shoot 7 frames of someone kicking a ball, however in the filmstrip at the bottom they aren’t in order?

Tim’s Quick Answer: The underlying reason here is that the sort order isn’t set to Capture Time. More than likely you’re seeing the “Added Order” sort order in this scenario, so switching to the Capture Time sort order will give you what you’re looking for.

More Detail: The “Previous Import” collection that is created when you import photos into Lightroom will default to the “Added Order” sort option every time you import. Because of the way files are written to and read from digital media, it is quite likely that this sort order will not match the capture time sort order for the photos.

There are a few things you can do here. First, of course, you can change the sort order using the “Sort” popup on the toolbar below the Grid view display for the images that have been imported. If the toolbar isn’t visible you can choose View > Show Toolbar from the menu.

You could also switch to the folder that you have imported the photos into, rather than browsing the “Previous Import” collection. Simply go to the Folders section of the left panel in the Library module and select the applicable folder. Assuming the sort order had been previously set to “Capture Time” for that folder, switching to the folder will result in the same capture time sort. But, of course, you can change the sort order for the folder if needed.

If you prefer not to see your images with the “Added Time” sort order, you can also disable the option to view the “Previous Import” collection after each import operation. To disable that feature, start by choosing Preferences from the Lightroom menu on the Macintosh version of Lightroom or from the Edit menu on the Windows version. Then go to the General tab, where you can turn off the “Select the ‘Current/Previous Import’ collection during import” checkbox before closing the Preferences dialog.

Disabling this option will cause you to remain in the folder that was selected prior to the import operation. In other words, if you are browsing the destination folder with the Capture Time sort order enabled, with this checkbox disabled in Preferences you will still be browsing the same folder with the capture time sort order after importing new photos.

I haven’t a clue why Adobe seems to think that the “Added Order” sort option is useful, or why it should be the default for the “Previous Import” collection. I would love to be able to set the default sort order under all conditions to “Capture Time”, but this isn’t currently an option in Lightroom.

Today’s Question: Your recent advice about setting Lightroom to automatically write changes into XMP got me thinking. This is the way my computers are set up [with the “Automatically write changes into XMP” option turned on]. However, many years ago with my travel laptop I got in the habit of selecting all files after a trip and then choosing File > Save metadata to file [from the menu]. As I recall I included this step to make sure that any editing, captioning, and keywording would be retained when I exported the files as a catalog.

Is this an unnecessary step if I automatically write changes into XMP?

Tim’s Quick Answer: Correct. It is not necessary to use the “Save metadata to file” command if you have already enabled the “Automatically write changes into XMP” option in the Catalog Settings dialog for your catalog(s). Furthermore, if you’ll be using the “Export as Catalog” option, neither approach is needed because all of the information about your photos will be included in the exported catalog.

More Detail: The “Save metadata to file” command and the “Automatically write changes into XMP” option are performing the same task in terms of saving most metadata to your actual image files (or to an XMP sidecar file in the case of RAW captures). The only difference is that the former option is a manual approach and the latter option is an automated approach.

Therefore, if you have enabled the “Automatically write changes into XMP” option there is no need to use the “Save metadata to file” command. This is true even if you have only recently enabled the “Automatically write changes into XMP” option for a catalog that has been in use for an extended period of time.

When you turn on the “Automatically write changes into XMP” checkbox on the Metadata tab of the Catalog Settings dialog in Lightroom, Lightroom will immediately get to work updating the metadata for all of the photos managed by the current catalog. The only issue here is that you don’t actually see an indication of progress for this task. Therefore, you may prefer to issue the “Save metadata to file” option one time after enabling the “Automatically write changes into XMP” option and selecting all images in your catalog. Doing so will provide the peace of mind of seeing an indication of the progress of this task on the top panel, so that you’ll know when it is actually finished.

Regardless of whether you prefer the “automatic” versus “manual” approach here, it is important to keep in mind that not all updates you apply in Lightroom will be reflected with these changes. Features that are specific to Lightroom, such as pick and reject flags, collections, and virtual copies, will not be included in these updates. However, as noted above, if you use the “Export as Catalog” command when it is time to merge your “traveling” catalog with your “master” catalog, all information within the Lightroom catalog will be included with the copy of the catalog created through the “Export as Catalog” command.

Today’s Question: I just wanted to point out a tip.  The easiest way to adjust the diopter is to just focus on the LED read out in the viewfinder.  When the numbers look sharp the diopter is in focus!

Tim’s Quick Answer: This is, of course, a great tip regarding the diopter adjustment. Thank you to Lewis Kemper (among other photographers) for pointing this out.

More Detail: My approach of setting focus with the camera and then adjusting the diopter based on that is mostly an old habit based on my preference to make sure that I am always making a diopter adjustment based on a view of the image, rather than the text that also appears in the viewfinder.

This habit is mostly owing to the fact that I’m a bit of a “control freak”. While setting the diopter based on the text in the viewfinder works perfectly well, personally I feel more comfortable setting the diopter based on the focus within the image I’ll be reviewing when adjusting focus. Of course, if the viewfinder image appears in focus, so too will the text that appears within the viewfinder.

While I do adjust the diopter in the camera based on my vision, in some respects this is more about the convenience of having an accurate view through the viewfinder and at least for me not especially critical for my photography. In actual practice I will either trust the autofocus in the camera to achieve a good result, or I will focus manually. When focusing manually, I will almost always employ the Live View display rather than the viewfinder display, because this approach makes it much easier to ensure critical focus for the scene.

So, while I still use a test subject that I know I have set good focus for to make a diopter adjustment, there is really no reason you should not use the text within the viewfinder for this purpose instead. And of course using that text can be much faster and easier than the approach I use when making a diopter adjustment.

Today’s Question: Can you explain why you recommend increasing the value for Vibrance but then reduce the value for Saturation [in Adobe Camera Raw or Lightroom]? It seems to me that a negative value for Saturation would just negate the use of Vibrance.

Tim’s Quick Answer: The key here is that the Vibrance and Saturation sliders operate in different ways. Increasing the value for Vibrance helps balance the overall saturation levels in the photo. A negative value for the Saturation slider helps tone down the overall intensity of colors. The result is more balanced saturation levels without colors that are too intense.

More Detail: I think it can be helpful to consider a theoretical example to better understand the relationship between the Vibrance and Saturation sliders available in Lightroom and Adobe Camera Raw.

Let’s assume a hypothetical situation where we have three areas of a photo that represent saturation levels of 20%, 50%, and 80%, respectively. If we then increase the value for the Vibrance slider, the colors with lower saturation levels will receive a stronger boost in intensity than the colors that have relatively high saturation levels to begin with.

So, let’s assume that after a given increase in the value for the Vibrance slider that the saturation levels noted above have increased to 50%, 70%, and 85%. In other words, the color that wasn’t very saturated received the strongest boost, the middle value received a more moderate boost, and the highest value received a relatively minor boost. The way I think about the net effect here is that the overall saturation levels have been “equalized” to some extent.

Another way to think of the Vibrance adjustment is that it applies a stronger effect to colors that “need” the most adjustment, while minimizing the effect on colors that don’t need much of a boost because they are already highly saturated.

Of course, while the Vibrance adjustment provides a “balanced” approach to adjusting the intensity of colors in a photo, once you’ve gotten the saturation levels balanced adequately the overall saturation may be too high. If so, a small reduction in the value for the Saturation slider can provide the solution.

Because the Saturation slider operates in a more “linear” way (compared to the Vibrance slider), it won’t completely negate the effect of increasing the value for Vibrance. So, you can apply a relatively strong increase in the value for Vibrance to equalize colors so they are more balanced relative to each other, and then use a negative value for the Saturation slider to help tone down the result so the colors in the image don’t appear too intense.

Today’s Question: I recently had eye surgery and now I have to wear glasses for the first time. I need to adjust my diopter to compensate for my changes in vision. Is there a prescribed way to accurately adjust the diopter?

Tim’s Quick Answer: There are two basic steps involved in adjusting the diopter on your camera. First, you need to make sure that critical focus has been achieved on a test scene. Then adjust the diopter so that the scene through the viewfinder is also in focus, based on the way you intend to actually use the viewfinder later.

More Detail: The diopter adjustment available on many camera models enables you to essentially adjust the focus within the viewfinder to compensate for your own vision. For example, many photographers who wear corrective eyeglasses prefer not to wear their eyeglasses when using the viewfinder. The diopter makes it possible to apply compensation so that (in this example) you can see a sharp image through the viewfinder when you aren’t wearing your eyeglasses.

When establishing focus before adjusting the diopter setting, I strongly recommend using a scene that will make it as easy as possible to evaluate the focus. For example, I often use the focusing target of the X-Rite ColorChecker Passport Video (http://timgrey.me/checkerpassportvideo) to make it easier to achieve accurate focus initially as well as to evaluate the diopter adjustment setting. You could also use something like a page with crisp printed text. The key is to have something to focus on that makes it easy to evaluate that focus.

You can certainly use autofocus to establish focus on the subject you’re using for this purpose. Personally, however, I prefer to use the Live View display (with the camera mounted on a tripod) to help ensure the best accuracy. Zooming in with the Live View display (not with the lens) enables you to get a close look to evaluate focus, and then to adjust the manual focus setting on the lens as needed.

Once you have the scene focused accurately, you can look through the viewfinder and evaluate the scene. Be sure to use the same approach you intend to use for your actual photography, in terms of whether or not you’ll be wearing eyeglasses, for example. Then adjust the diopter until the viewfinder display is in sharp focus.

Be sure to rotate the diopter dial in both directions to an out of focus position, so you’ll be better able to determine the diopter adjustment setting that will produce the sharpest view possible. In other words, don’t just turn the diopter adjustment until you think the image is in sharp focus through the viewfinder. Instead, continue past the point you believe represents optimal focus to confirm that doing so results in an image that is less sharp. You can then turn the adjustment back to the point of optimal sharpness.

Once you’ve adjusted the diopter setting it is a good idea to make a note of what setting you have used. That way you can periodically check to confirm that the diopter setting hasn’t changed. And, of course, it is worth noting that our vision does tend to change over time, so it is a good idea to periodically perform this adjustment process again to confirm you are getting the sharpest view possible through the viewfinder.