Ask Tim Grey

Today’s Question: In an email you said, “Most cameras do not capture full color for each pixel in a photo”. Which cameras do capture full color for each pixel, how do they do that, and is it better than those that don’t?

Tim’s Quick Answer: The vast majority of cameras employ a sensor where only a single color value (typically red, green, or blue) is captured for each pixel. One notable exception is the Foveon X3 sensor, which was used in Sigma camera bodies, but which has not been used in a new camera in more than ten years.

More Detail: Many photographers are familiar with the basic process employed by color film, where several light-sensitive layers are stacked together. Each of those layers is sensitive to a different color of light, and so full color can be captured.

Digital cameras in general operate differently. For each photo site on the sensor, which will translate to a pixel in the final image, a colored filter results in only a single color value being captured. That generally means that for each pixel only red, green, or blue information is captured. The “other” values, such as the green and blue values for a red pixel, are calculated after the capture using software.

The Foveon X3 sensor operates in a manner similar to film, with layers of sensors recording three color values for every pixel. While this provides a potential advantage, there are also technical limitations that create challenges. In my experience the overall image quality and noise performance of the Foveon X3 sensor were inferior to all other sensors I tested at the time.

So, when I refer to the fact that “most” cameras do not capture full color for each pixel, for all intents and purposes you can take that to mean that all current cameras use the approach of capturing a single color value for each pixel, and calculating the full color value after the capture.

Today’s Question: Lightroom Classic [as well as Adobe Camera Raw] has a slider for Tint (green/magenta) which is one of the pairs of opposing colors on the color wheel. It also has Temperature which is for blue/yellow. But there is no slider for the third pair of opposing colors on the color wheel (red/cyan). Why is that? Wouldn’t it make more sense to have a slider for each primary pair of opposing colors on the color wheel?

Tim’s Quick Answer: There is no need to have three sliders in order to be able to achieve any desired shift in colors. If, however, you prefer to work with three sliders rather than two, you could make use of the Tone Curve adjustment in Lightroom Classic.

More Detail: While there are three primary colors (red, green, and blue) in the context of a digital image being optimized using software such as Lightroom Classic and Adobe Camera Raw, there is no need to actually have adjustment sliders for all three of those channels.

A color wheel is a common tool for displaying the full range of color hues that are available within the visible spectrum. The color wheel forms something of a rainbow going around in a circle.

When you are shifting the color balance in a photo, you are effectively moving all color values for a photo in a particular direction toward a specific color. For example, the Temp (or color temperature) slider causes pixel values to shift in appearance between more blue versus more yellow.

In this way you can think of a color balance adjustment as representing a shift in direction across the color wheel. If you could only shift color values along a single axis across a color wheel, you would be very limited in the type of color adjustment you could apply. This is why software does not employ a single slider for a color balance adjustment.

With two sliders you can adjust colors in any desired direction across the color wheel, with movement along two axes. Imagine that these two axes are aligned with one that allows movement up and down, and another that allows movement left and right. That would allow you to navigate to any destination on the color wheel, though not in a straight line. Instead of moving diagonally toward the top-right, for example, you would use one movement upward and another movement to the right.

Of course, some software applications make use of three sliders for color balance rather than only two. And there’s no reason software couldn’t employ more than three sliders as well. But Adobe opted for two sliders (Temp and Tint) as the primary controls for color balance in Lightroom Classic and Camera Raw. If you prefer to use three sliders, you can make use of the Red, Green, and Blue curves with the Tone Curve adjustment.

Today’s Question: As a follow-up to the question about media cards, do you recommend always choosing the fastest card available?

Tim’s Quick Answer: In my view there is no need to opt for the fastest media card available unless you actually have a need for that speed. For many photographers a “slow” card will still provide more than adequate performance.

More Detail: The speed rating for a media card indicates the maximum data transfer speed for the card. The speed rating indicated typically refers to the maximum speed at which data can be read from the card under specific conditions. The speed at which data can be written to the card is typically slower than the maximum read speed and can also be significantly impacted by the equipment being used.

If your camera does not support high-speed data transfer, then a faster card won’t necessarily provide you with any benefit. For example, if your camera can only write data at a rate of 30 megabytes per second a card that is capable of write speeds up to 300 megabytes per second won’t provide an advantage.

In addition, not all photographers capture photos (or video) at a rate that requires a high-speed media card. Cameras include a memory buffer where photos are stored temporarily at the time of capture, while waiting to be written to the media card. If you never fill up that buffer with continuous capture of photos, you won’t benefit from a faster media card even if it is supported by your camera.

If you fill up the buffer on your camera you will not be able to capture additional photos until that buffer clears by writing photos to the memory card. If you experience this situation with any regularity, I recommend looking up the specifications for your camera and buying a card that meets or exceeds that speed. If you don’t tend to capture continuous photos regularly, you can opt for a slower (and less expensive) media card.

Today’s Question: Could you please address best practices with SD media cards? After every shoot I download my images then re-format the card in camera. Does this somehow wear out or damage the card over time? How hardy are they? When should they be replaced?

Tim’s Quick Answer: Flash-based storage devices, such as SD cards, do wear out over time and can be damaged if not handled properly. I recommend using care when handling these cards and replacing them on a periodic basis.

More Detail: Flash-based media does wear out over time, so I don’t recommend trusting these media cards indefinitely. They can also be damaged, including with extremes of heat and moisture, so you’ll want to handle them with care.

In general, I recommend keeping media cards physically safe from damage, avoid letting them get wet, and keeping them in a moderate temperature range as much as possible. In other words, treat your media cards with the same type of care you would give to your other camera gear.

While media cards do wear out over time, they are also designed to last for extended periods of time. It is generally estimated that a media card could last for ten years. So, this doesn’t need to be a major source of concern for the photographer. However, I do recommend replacing your media cards every couple of years or so.

I find that most photographers don’t need to think too much about replacing their media cards periodically, because they replace them often enough in order to get a higher capacity card or a faster card (or both). But if it has been a more than a couple of years and you use your media cards regularly, you may want to consider replacing them.

Obviously, media cards can fail for a variety of reasons, including manufacturing defects. But in general, these cards are highly reliable and not something you need to worry about too much. Still, taking care to protect your media cards and replacing them periodically can help ensure greater overall reliability.

Today’s Question: Do you need to use any specific separation between words for keywords in Lightroom Classic, such as a comma or quotation marks? If not wouldn’t “New” and “Mexico” show up, rather than just “New Mexico”?

Tim’s Quick Answer: As long as you choose the option to separate keywords with commas rather than spaces in Lightroom Classic, you can indeed be able to search for “New Mexico” with the search results excluding images that only include “New” or “Mexico”, without the full “New Mexico” keyword.

More Detail: In Lightroom Classic you can choose whether you want to separate individual keywords with commas or spaces. I highly recommend using the option to separate keywords with commas, so you can include spaces in keywords.

First, you’ll want to make sure that you have enabled the option to separate keywords by commas rather than spaces. Start by going to the menu and choosing Edit > Preferences on Windows, or Lightroom Classic > Preferences on Macintosh. Go to the Interface tab and find the “Separate keywords using” popup in the Keyword Entry section. Select “Commas” (rather than “Spaces”) from that popup and close the Preferences dialog.

To perform a text search based on keywords that include spaces, you can use the “Contains Words” option for the search. On the Library Filter bar in the Library module, select the Text tab. Set the first popup to “Keywords”, and the second popup to “Contains Words”. You can then enter a keyword that includes a space in the search field, and only photos with that complete keyword will appear in the search results.

So, for example, if you had various photos with keywords of “New Mexico”, “New York”, and “Mexico”, when you search for “New Mexico” as outlined above, the images with “New Mexico” as a keyword would be included in the search results, but those with only “Mexico” or “New York” would not be included in those results.

Today’s Question: You mentioned that the Lightroom Classic catalog should be stored on “an internal or external hard drive”. But is there a reason you should make a choice between an internal drive versus an external drive for that catalog?

Tim’s Quick Answer: You should generally store your catalog on an internal hard drive if you want to maximize performance in Lightroom Classic, and you should store your catalog on an external hard drive if you want to be able to work with your catalog on more than one computer by moving the hard drive to the computer you currently want to work with.

More Detail: The most important thing to keep in mind in terms of where you store your Lightroom Classic catalog is that it should not be stored on a network storage location. That recommendation extends to cloud-based storage options, such as Dropbox. While it may be possible to have Lightroom Classic access the catalog with this type of connection, I highly recommend against this practice, due to the risk of corruption of the catalog.

Instead, you should store the catalog on a local hard drive. That leaves a decision between an internal versus external hard drive.

Generally speaking, storing the catalog on an internal hard drive will provide the best performance for Lightroom Classic, so this is the preferred approach. However, if you want to be able to work with your catalog on more than one computer, storing the catalog on an internal hard drive creates a challenge.

If the priority is to be able to work with your Lightroom Classic catalog on more than one computer, you can store the catalog on an external hard drive. In general that would mean storing the catalog on the same external hard drive you use to store your photos.

With the catalog on an external hard drive, you can easily switch between computers by connecting the drive to the computer you want to use. Assuming you have Lightroom Classic installed on that computer, you can then open the catalog from the external hard drive, enabling you to work normally with the same catalog across more than one computer.

Note that if your photos are also stored on that external hard drive, you’ll need to make sure that the path to the drive remains the same on each computer. That means assigning the same drive letter to the hard drive on each computer for Windows users, or making sure that the volume label remains the same for the hard drive for Macintosh users.

Today’s Question: I am a Lightroom user and have recently set up a Raid 1 Synology NAS [Network Attached Storage] system for my photographs. I want to work off of the NAS in Lightroom. How can I go about using Lightroom with a NAS?

Tim’s Quick Answer: You can use network attached storage (NAS) for storing your photos being managed by Lightroom Classic, but you should not store your Lightroom Classic catalog on that NAS storage device.

More Detail: As photographers we obviously need to store our digital photos. That generally takes the form of a storage device such as a hard drive, which might be a drive that is installed inside your computer or an external hard drive that you connect with a data cable such as a USB connection.

Another storage option is network attached storage (NAS), which you can think of as being an external hard drive where the data connection is via a network rather than via a direct data connection. In actual fact, a NAS device generally includes multiple hard drives that are strung together to create a high-capacity storage capability.

For all intents and purposes, you can think of a NAS device as being the same thing in general concept as an external hard drive. The key difference is that because the storage is connected via a network connection rather than via a direct data connection, multiple users on the same network can access the data on the NAS device at the same time.

Because NAS operates on a network environment, it is not supported for storage of your Lightroom Classic catalog. Among other things, having your Lightroom Classic catalog stored on a network means that there is the potential for more than one user to access the catalog at the same time, which would create a problem for that catalog.

So, you can store your photos on any storage device accessible from your computer. However, you should only store your catalog on a storage device directly connected to your computer, such as an internal or external hard drive.

Today’s Question: You mentioned [during the recent GreyLearning Virtual Photo Conference] that you had to upgrade your computer due to the failure of your previous MacBook Pro. I was wondering why you chose the Apple M1 chip versus a similar Mac with an Intel processor? I have been told that there are programs that will not work with the M1.

Tim’s Quick Answer: The primary reason I opted for a computer with the new Apple M1 chip was improved performance. I also wanted to test out the new chip so I could report back to my readers. Fortunately, compatibility issues have been virtually non-existent.

More Detail: When the new Apple computers featuring the Apple M1 chip were announced, I was intrigued but had no intention of buying a new computer. I figured I would just go to an Apple Store to do some testing of the new computers so I could report back on them and wait a while before I actually upgraded my computer.

Then my computer started failing, so I didn’t have much choice but to buy a new computer. There were options available with both the Apple M1 processor as well as the Intel processor. I was skeptical about making a change, in particular because of concerns about compatibility.

I did some side-by-side testing, however, and was impressed (perhaps even shocked) at how much better the performance was with the M1-based MacBook Pro compared to the Intel-based computer. I decided it was worth the risk of compatibility issues in order to get better performance and to be able to report back on my experience with the new processor.

I was a little surprised that I faced virtually no compatibility issues at all. Applications that do not support the new M1 chip natively can be run in a compatibility mode, and many applications (including most from Adobe) have been updated to natively support the M1 processor.

The only issue I’ve run into is that with the new M1-native version of Adobe applications the plug-ins that have not yet been updated to support the M1 processor will not work. If they are able to run standalone rather than only as a plug-in, that will provide a solution. Otherwise, you would need to keep an older version of the host application (such as Photoshop) installed in order to make use of plug-ins that have not yet been updated.

Overall I am extremely pleased with the performance of my MacBook Pro with the M1 processor, and am even a little grateful that my prior computer was starting to fail, since that forced me to upgrade a bit earlier than I otherwise would have.

Today’s Question: It seems that the standard color space is Adobe RGB. But if the vast majority of my photos are printed by a lab that will only accept images in the sRGB color space, it seems to me that I should synchronize the color spaces on my camera, monitor, and software to sRGB. But if I do, how much do I lose when viewing images on a monitor or projecting them to a plasma or LCD TV?

Tim’s Quick Answer: If most of your printed output is generated with a workflow that revolves around sRGB, it is perfectly reasonable to standardize your overall workflow on the sRGB color space, with very little risk of losing significant color or detail in your photos.

More Detail: The sRGB color space is often referred to as being a “small” color space, when in fact it is simply smaller than the other commonly used color spaces of Adobe RGB and ProPhoto RGB. The sRGB color space is still perfectly adequate for printing photos and is especially well-suited to images being displayed electronically, such as on a monitor or digital projector.

There’s no need to set your camera to the sRGB color space if you are shooting in raw (as I highly recommend doing). You can, however, set the in-camera color space to sRGB to get a bit of a more accurate preview of the image based on the sRGB color space.

In Lightroom Classic you don’t have control over the color space being used within Lightroom Classic, as a variation on ProPhoto RGB is always used in the background. When sending images to Photoshop you could certainly use the sRGB color space.

My personal preference in this type of workflow would be to use the ProPhoto RGB color space in Photoshop. Then use sRGB whenever you are exporting photos to be printed by the printer, or for digital sharing.

There’s no inherent benefit to using the sRGB color space through your full workflow, as color management in your workflow will ensure you are getting an accurate preview of the colors in your images. So, my recommendation in general is to use a larger color space for editing, and then the appropriate color space when preparing photos for specific output. That said, there’s certainly not any significant risk in converting photos to the sRGB color space when they will ultimately be printed or otherwise shared using that color space.

Today’s Question: Years ago, I thought it would be easy to give up the XMP sidecar [files associated with my proprietary raw captures] and started converting my raw files to DNG as part of my workflow. Am I losing something by doing this?

Tim’s Quick Answer: When converting to DNG you will retain your source capture data and the metadata you’ve added. You may, however, be giving up some proprietary metadata from your camera, and creating a minor issue with your backup efficiency.

More Detail: While you won’t lose any actual image data when converting a proprietary raw capture to the Adobe DNG (Digital Negative) file format, you may lose some proprietary metadata from the original capture. This would relate to special features of your camera that result in custom metadata being added, and that require software from your camera manufacturer to make use of.

For example, one of my cameras has a built-in dust removal feature. When I enable this option, the camera records data about dust on the sensor at the time of capture and embeds that information in the private metadata for the photo. Other software such as Photoshop and Lightroom are not able to make use of this information. Instead, you would need to use the software from the camera manufacturer to make use of that proprietary metadata, such as in this case to automatically remove dust spots from the image.

If you convert that proprietary raw capture to the Adobe DNG file format, you will likely lose any proprietary metadata. I say “likely” because there is an option to embed the original raw capture in the DNG file, but to me that would eliminate much of the benefit of converting to DNG, since the file size would be about double what it otherwise would be.

With metadata stored in the DNG file rather than an XMP “sidecar” file associated with a proprietary raw capture, your backup workflow may be affected as well. When you apply metadata updates, your backup software may need to copy the entire relatively large file for each DNG file you updated, rather than only needing to back up a small XMP file for each proprietary raw capture that you updated, since in the latter context the proprietary raw capture file would not have been updated.

So, overall, I would say that I still prefer to retain the original proprietary raw captures from my camera rather than converting to the Adobe DNG file format. That said, if you prefer to convert you aren’t risking the loss of too much information that would be of concern.