Category: Ask Tim Grey

Today’s Question: What is the best configuration to use the same Lightroom Classic catalog on two computers? Do I need to move the catalog to an external hard drive?

Tim’s Quick Answer: Yes, if you want to be able to access the same Lightroom Classic catalog on more than one computer, my recommendation is to keep the catalog on an external hard drive. For convenience, I suggest keeping the catalog on the same external hard drive where your photos are stored.

More Detail: The core architecture of Lightroom Classic does not support storing the catalog on a network volume, which limits your options when it comes to accessing your catalog from more than one computer. While it is feasible to store the catalog on a cloud-based storage platform such as Dropbox or OneDrive, I don’t recommend doing so because of the risk of corruption or a lack complete synchronization.

Therefore, if you want to be able to access a single catalog on more than one computer, the approach I recommend is to store the catalog on an external hard drive along with your photos. You can then connect that external hard drive to any computer with Lightroom Classic and open the catalog from the external hard drive.

If you want to take this approach, first quit Lightroom Classic so the catalog won’t be in use. Then copy the folder that contains your catalog and related files to the external hard drive. Once the folder is copied, rename the original to indicate it is now just a backup copy, such as by adding “Backup” to the beginning of the folder name.

You can then double-click the catalog file (with the .lrcat filename extension) from the folder on your external hard drive to open that catalog in Lightroom Classic. Windows users should note that they’ll need to be sure the external hard drive retains the same drive letter on each computer, so Lightroom Classic can find them where they are expected.

Today’s Question: One thing I’ve never understood is all the stacking for HDR. I’ve done that and it’s cool and all but in normal conditions I simple take two exposures one for the darks and one for the light and then blend them. What is the purpose of taking more than two shots when you can capture all the darks and lights with two?

Tim’s Quick Answer: For high dynamic range (HDR) images you only need enough exposures to cover the full range of light from the darkest shadows to the brightest highlights. If two exposures are enough, there’s no need to capture more.

More Detail: You can most certainly assemble two exposures into an HDR image, or even just blend the two images with a layer mask in Photoshop. However, more often than not I find that in situations where a single exposure won’t cover the full range of contrast in a scene, two exposures isn’t quite enough either.

To start with, I recommend separating exposures for HDR by two stops. If you separate by more than two stops, you may not have enough overlap in the tonal range for the exposures, causing problems for the final HDR image. You can separate exposures by less than two stops, but there’s no benefit to doing so.

Another consideration is that it is often easiest to use automatic exposure bracketing (AEB) to capture the exposures for an HDR image, in part to enable you to have those exposures captured in a short a time period as possible to avoid changes between exposures in the scene you’re photographing. Most cameras default to three exposures for bracketing, though many cameras offer additional options such as to bracket five, seven, or nine exposures.

I often capture bracketed exposures in sets of five images, just to provide some insurance with the bracketing, and to avoid needing to frequently change the camera settings to capture a different number of bracketed exposures. But if you end up with more bracketed exposures than you really need, you can exclude the unnecessary exposures when assembling an HDR image or even delete the exposures you don’t need.

Today’s Question: Using Android Open Camera, which image mode provides better image quality, PNG or JPEG?

Tim’s Quick Answer: The PNG option will provide better image quality than the JPEG option. That also means, however, that the PNG files will generally take up considerably more storage space than the equivalent JPEG images would.

More Detail: The PNG (Portable Network Graphics) file was introduced in many respects as a higher-quality option to the JPEG (Joint Photographic Experts Group) file format. However, the PNG file format has not seen anywhere near the wide adoption of JPEG files. Therefore, not many cameras offer PNG capture, while nearly all offer JPEG as a capture format.

If image quality is your primary concern, PNG is a better option than JPEG. Just be aware that the PNG files will be considerably larger than JPEG images, so will consume more space. That translates into not being able to capture as many PNG files as JPEG images on a given storage device.

For example, a JPEG that is around 13MB in size would translate to a PNG file of about 32MB in size. That’s a pretty significant increase in file size. In fact, in many cases a raw capture will be smaller than a PNG file, and so raw (or DNG) can be a better solution when image quality is your primary concern. A raw capture contains more bit depth, for example, with a file that will generally be smaller than an equivalent PNG file because the image data for a raw capture generally only contains one of the three RGB color values for each pixel.

Today’s Question: When you see a large amount of out-of-gamut color on an image (like most of the reds on a male vermillion flycatcher), should you just let the software figure out how to bring them into gamut and is that what the proof setup shows, or should one adjust something (and, if so what) to bring the colors into gamut?

Tim’s Quick Answer: In general, the software you’re using for printing will do a good job of converting the colors based on the output limitations. However, you may want to consider a different print configuration, or to apply some adjustments to compensate.

More Detail: Today’s question is a follow-up to a recent question about previewing what a print will look like on your monitor display via the soft proofing feature that is available in Photoshop and Lightroom Classic. In particular, it relates to the Gamut Warning feature that is available in Photoshop but not Lightroom Classic. This is an overlay that indicates which areas of an image contain colors that cannot be produced accurately with the intended printer, ink, and paper combination.

When you print a photo that has out-of-gamut colors, the colors that are out of gamut will automatically be shifted to a color value that can be printed. With the Relative Colorimetric setting for the rendering intent, any out-of-gamut colors will be shifted to the closest printable value. With the Perceptual setting, all colors in the image will have their saturation reduced to the point that out-of-gamut colors can be printed. I generally prefer to use Relative Colorimetric because it maintains the accuracy of most colors in the print.

Many printers use a single set of inks, and so the real variable (other than using a different printer) is to consider different papers. For example, a glossy paper will generally have a color gamut that is quite a bit wider than with an uncoated matte paper. So, if you find significant areas of the photo are out of gamut with a particular matte paper, you might consider a semi-gloss or glossy option instead.

You can also apply adjustments to the image to try to compensate for color that are out of gamut. However, this can often lead to unintended consequences. For example, you could shift the hue of the reds so they are perhaps a bit more orange, bringing them back into gamut. However, that can also lead to a situation where the color fidelity is obviously wrong, and worse than would have been achieved by simply letting the software manage the colors as part of the printing process.

Today’s Question: What would be the best way to determine at what point the higher ISO settings start to degrade image quality? I am guessing take the same exact shot at the lowest ISO setting and then work your way up to a high ISO setting. Then compare at 200% or 300% magnification. What exactly should I be looking for in the magnified image?

Tim’s Quick Answer: Yes, I recommend capturing test photos at different ISO settings, and then evaluating the results. It is a subjective decision, but you’re both learning how your camera behaves in terms of noise at different ISO settings, and also getting a sense of at what setting the noise tends to be beyond your comfort level.

More Detail: With most cameras you’ll see increased levels of noise as you increase to higher ISO settings, and with many cameras the noise can really start to be a problem as you get up above around 1600 ISO or so.

There is also variation in terms of the light levels in the scene, as well as other factors such as increased noise with long exposures. I therefore recommend capturing test photos of a scene that includes a relatively wide range of tonal values, from dark shadows to relatively bright highlights. I also recommend avoiding long exposures for the baseline testing, such as by using a relatively wide-open lens aperture so that even at a low ISO setting the shutter speed will be reasonably fast. You can separate the exposures by one stop, which means doubling (or halving) the ISO setting for each photo. For example, you could set the ISO to 100, then 200, then 400, and so on.

I then recommend zooming in to evaluate the images at about 100% as well as at about 400%. It can be helpful to cycle through the images multiple times to get a better sense of the noise behavior. I also suggest making sure you have captured a sample photo at the highest ISO setting your camera offers. There’s a good chance that when you look at that image up close, you’ll immediately conclude there is too much noise. This can help provide some context when evaluating the other photos.

There’s a very good chance (depending on your camera) that you’ll start to see that the noise is more obvious especially as you get up to the image at around 800 or 1600 ISO. Some cameras will have relatively problematic noise at lower ISO settings, and some provide relatively low noise at high settings.

Noise can be exhibited as both significant tonal variations and color variations at the pixel level. Noise will also be more prevalent in the shadow areas of the image rather than highlight areas. It can be helpful to brighten the images you’re evaluating so you can better see the noise that may be present in the shadow areas.

Again, this is a somewhat subjective evaluation, but the aim is to get a sense of what ISO setting start to be problematic in terms of noise from your perspective. Based on that, you can do your best to try to stay below the threshold you’ve decided on, to the extent that the circumstances will allow you to keep the ISO value below that level.

Today’s Question: Can you clarify what you meant when you said that you “think about exposure based on compensation”, in the context of preferring aperture priority mode?

Tim’s Quick Answer: I tend to think about setting exposure on my camera based on how the meter is likely to be “fooled” by the scene in front of the lens. Based on this mindset, I find it more intuitive to set an exposure compensation setting in conjunction with a semi-automatic exposure mode, rather than potentially needing to constantly evaluate and refine the exposure settings in manual exposure mode.

More Detail: My overall view about establishing exposure settings on your camera is that it doesn’t matter what approach you use as long as you can arrive at appropriate settings confidently and relatively quickly. My view is that whatever approach resonates with you is probably the best approach to use unless there are other reasons to choose a different approach.

When I evaluate a scene in front of my lens, I’m often considering how the meter is going to be “fooled” by the scene. Based on this, I find it easiest to refine exposure based on applying exposure compensation. Furthermore, depth of field tends to be a priority for me in many cases, and so I tend to favor aperture priority mode. Therefore, I find it most comfortable to use aperture priority, dial in the lens aperture I want to use, and then apply an exposure compensation adjustment as I deem appropriate.

I could certainly use manual mode, adjusting the shutter speed after establishing my preferred lens aperture, to the point that the meter shows the applicable level of exposure compensation. However, for situations where I’m photographing various areas of a scene and therefore needing to adjust exposure based on framing, I find it much faster and easier to use exposure compensation combined with aperture priority mode, for example, rather than having to more frequently adjust exposure settings in manual mode to manually compensate for exposure changes.

I should hasten to add that in many cases manual mode can offer advantages that are more important than the factors that cause me to usually favor aperture priority mode. For example, if I’m photographing a moving subject such as a bird in flight with a fixed lighting condition but variable background as the bird moves across the scene, locking specific exposure settings in manual mode can be far and away the best approach.

Ultimately, whatever approach you’re most comfortable with and that will enable you to establish accurate exposure settings as quickly as possible is probably the best approach. I pretty much never use fully automatic exposure modes, but if they work for you then I think it is perfectly fine to use them. But I also don’t think it makes sense for photographers to try to “force” themselves to use manual exposure mode if they’re not comfortable with it in certain situations.

Use the camera settings and options that best help you achieve good exposures consistently, and whatever that consists of I would say represents a good approach for you.

Today’s Question: I used to be able to open and merge photos to HDR [high dynamic range] in Camera Raw, but either I’ve forgotten how or something has changed. Can you advise me?

Tim’s Quick Answer: You can assemble high dynamic range (HDR) images in Camera Raw by opening multiple photos, selecting them on the filmstrip, and then right-clicking and choosing “Merge to HDR” from the popup menu.

More Detail: I’ve found that many photographers have overlooked the fact that you can assemble HDR images in Camera Raw (as well as Lightroom and Lightroom Classic). This can be an important detail, because in my experience you can expect better HDR results using Camera Raw as compared to the related feature within Photoshop.

I recommend initiating the process of assembling an HDR image from Adobe Bridge, to make it easier to select the multiple bracketed exposures and open them in Camera Raw. After selecting the images, you can simply double-click one of the selected thumbnails to open them all in Camera Raw.

If the filmstrip isn’t displayed automatically in Camera Raw, you can toggle its visibility by clicking on the filmstrip button to the right of the zoom setting popup ate the bottom-left of the Camera Raw interface. Select all the photos on the filmstrip (such as by pressing Ctrl+A on Windows or Command+A on Macintosh), then right-click on one of the thumbnails and choose “Merge to HDR” from the popup menu.

This will bring up the HDR Merge Preview dialog, where you can adjust the settings for the image processing. Then click the Merge button, and the HDR image will be created. You’ll be prompted to save the image, and the result will open in Camera Raw so you can refine the adjustment settings before opening the final result.

Today’s Question: On your advice I use Time Machine to back up the internal hard drive on my computer (I also follow your other workflow for my external drives). When a Time Machine backup finishes, it shows me that the backup covers a date range from several months ago to today. I don’t understand what this date range means, and why does it only go back so far? Is this not a complete backup?

Tim’s Quick Answer: If Time Machine finished backing up successfully, you do have a complete backup. The date range you refer to indicates how far back you can go to access older versions of documents and files that have been backed up. This is one of the key advantages of a Time Machine backup.

More Detail: You can think of Time Machine as providing two key backup options, which combined cause it to be a great solution especially for backing up the primary internal hard drive on an Apple computer.

One of the core features of a Time Machine backup is that it provides a complete backup of all user files (not system files such as the operating system), and a Time Machine backup can be used to restore a computer. For example, whenever I buy a replacement computer, I perform a Time Machine backup for the existing computer, then use that backup to setup the new computer, and all my files are on the new computer just like the old computer.

The other feature of Time Machine relates to where the name “Time Machine” comes from. You can effectively go back in time to find files that had been lost, damaged, or unintentionally modified. For example, if I accidentally delete a file today and empty the trash so the file is truly lost, I can use Time Machine to go “back in time” to yesterday, where I can find the file in the location it had been saved.

Even if a file hadn’t been lost, you can use Time Machine to access older versions of files. For example, if I modified a document yesterday, but today realized that in the process I had deleted important information from the document, I could use Time Machine to recover an older version of the document to access the information I had deleted in error.

The dates shown for a Time Machine backup in System Settings indicate the farthest back you can go to find older versions of files, as well as the most recent date that a backup was completed. The available date range is dependent on how large the hard drive is and how much data you’re backing up. As the hard drive fills up, older files are discarded from the backup.

So, if you want to be able to go back further in time to find older versions of files that had been modified or deleted, you can simply use a larger hard drive for your Time Machine backup. Doing so will provide more storage space for the backup, which means more files going further into the past can be retained before the hard drive gets low on space and older backups need to be discarded.

Today’s Question: I’ve noticed that when you share details of a photo, it is very common that your camera was set to 400 ISO. Is there a reason you seem to favor ISO 400 for many photos, assuming my observation is accurate?

Tim’s Quick Answer: I do use 400 ISO as my default setting, based on it offering good noise performance combined with often being a good choice based on preferred shutter speed and aperture settings.

More Detail: I recommend that photographers develop default settings that will work for them most of the time (or that are likely to be good for their next anticipated photo opportunity), and to set those as the default settings for their camera. For example, many cameras offer custom user setting options, so you can quickly establish preferred default settings.

My most common starting point for camera settings is to be in aperture priority mode (because of the way I think about exposure based on compensation) with the lens aperture set to f/8 (which is around the sharpest lens aperture for the lenses I most often use) and the ISO set to 400.

Based on the conditions I tend to shoot in and my preferences in terms of overall camera settings, I find that 400 ISO is a good default setting. My primary camera doesn’t generate much more noise at 400 ISO than I can expect at 100 ISO, so I don’t feel that I’m losing any significant image quality with this setting. Using 400 ISO also helps me achieve a little bit faster shutter speed, which is often advantageous.

Obviously, in many cases I will need to change settings. I might want to adjust the lens aperture to change the amount of depth of field in an image, for example. I often target a faster or slower shutter speed to change how motion is (or is not) rendered in the photo. And when I change either of those settings, I’ll often need to change the ISO setting as well. However, even though I often change the settings, those outlined above generally represent a great starting point for me.

Since those are my default settings, and they work well for me a good percentage of the time, it is quite likely that photos I capture will have an ISO setting of 400. In fact, after getting this question, I checked my stats in Lightroom Classic and found that with my current primary camera, 43% of my photos were captured at an ISO setting of 400. Another 34% were captured at 100 ISO, for situations where I was either trying to get a longer exposure or minimize noise.

So, clearly I am a bit of a creature of habit when it comes to camera settings (among other things). But the point is that I recommend having default settings that are most likely to meet your needs, adjusting them as needed based on the circumstances of your photography.

Today’s Question: I realize my printer can’t necessarily print all colors that might appear in a photo or be seen on my monitor display. But is there a way in Photoshop to find out which colors in a photo my printer won’t be able to print, if applicable?

Tim’s Quick Answer: Yes, you can see an indication of which areas of a photo contain colors that can’t be reproduced by your printer configuration by using the gamut warning feature for soft proofing.

More Detail: The soft proofing feature in Photoshop enables you to see a preview on your monitor of what a print will look like based on a profile for the printer, ink, and paper combination you’ll use.

One of the features associated with soft proofing is the gamut warning display, which indicates areas of an image that can’t be reproduced with the intended printer configuration. Note that this requires you to have a profile for the output conditions, which generally means an ICC profile for the paper you’ll be printing with and the printer you’ll be using. These profiles can often be obtained from the paper manufacturer.

The first step is to enable soft proofing for the image. So, with the image open in Photoshop go to the menu and choose View > Proof Setup > Custom from the menu. In the Customize Proof Condition dialog select the applicable ICC profile from the Device to Simulate popup. I recommend setting the Rendering Intent popup to “Relative Colorimetric” unless you have a reason to use a different option when printing, and I recommend turning on the “Use Black Point Compensation” checkbox so that black in the image will be mapped to black in the profile.

I also suggest turning on both the “Simulate Paper Color” and “Simulate Black Ink” checkboxes if they are available for the selected profile. When you have configured the settings, click the OK button. The image will now appear different, providing a simulation of what the final print will look like. Keep in mind that there are inherent limitations involved with previewing a print that depends on reflected light on a display that uses emitted light.

Once you’ve enabled soft proofing, go back to the View menu and choose Gamut Warning. This will cause an overlay to appear on all areas of the image that have colors that are beyond the capability of the printer configuration based on the selected profile. This overlay is gray by default, but you can change the setting on the Transparency & Gamut tab of the Preferences dialog.

Based on this preview you can either choose to print on a medium that will have a wider color gamut, such as a glossy rather than matte paper, for example. You can also attempt to apply adjustments to optimize the photo based on the output limitations. Or, of course, you can simply use this as an informative or evaluative tool, so you have a better sense of what to expect from the print before committing ink to paper.