Category: Ask Tim Grey

Today’s Question: Regarding the base ISO setting, someone told me that for Canon cameras it was 160. True?

Tim’s Quick Answer: I would say that in the case of Canon cameras the base ISO is generally 100, but you may see less noise at 160 ISO compared to 100 ISO. The same concept would generally apply for higher ISO settings as well.

More Detail: My understanding is that many (or most) digital cameras only use hardware amplification for certain ISO settings. These are often in one-stop increments, so that hardware amplification is employed for 100 ISO, 200 ISO, 400 ISO, and so on.

For “in between” ISO settings, the nearest hardware amplification value would be used, and then the signal is processed after the capture to increase or decrease the effective amplification with software.

What that means is that a capture at an ISO setting of 160 is really a capture at 200 ISO with the resulting image darkened by one-third of a stop. The result is that while there may have been more noise in the initial capture, that noise was masked by the image having been darkened. By contrast, at an ISO setting of 125, the lower setting of 100 ISO would be used for the actual capture, but then the signal is amplified by one-third of a stop after the capture by software.

The key here is that in general software amplification is inferior to hardware amplification. This is why you might see more noise at 125 ISO than you would at 160 ISO or potentially even 200 ISO.

The specific results will vary from one camera to the next, based on a wide variety of factors related to base sensor sensitivity, the nature of the various types of hardware and software amplification applied to the signal, noise reduction applied to the resulting data, and more.

To be sure, you will often see that noise levels do not increase in a linear manner as you raise the ISO setting. Furthermore, you may see less noise at a higher ISO setting in some cases, as noted above. This is part of the reason I strongly recommend doing some testing on your own to get a better sense of the overall noise behavior for your camera. This is especially important if you tend to use very high ISO settings on a regular basis in your photography.

Today’s Question: I tried to open my Lightroom catalog and it said, basically, it was corrupted but to try again later. My hard drive would not release from the computer, repeatedly saying it was busy. I shut down the computer, and the next day I tried repair again and it worked. What happened and why did it work a day later?

Tim’s Quick Answer: While it is possible that this was simply a case of random file corruption, the specific circumstances cause me to worry that the hard drive (or other hardware component) may be the source of the issue. I would therefore want to immediately make a backup of all of your data, and to perform at least some basic testing to try to confirm there are no ongoing issues.

More Detail: File corruption in general can be quite frustrating, in part because there isn’t generally any warning that something has gone wrong until it is too late. I’ve seen many photographers (myself included) who had original raw captures appear as corrupted, long after the source files had worked perfectly fine.

While it is certainly possible for a software issue to lead to such file corruption, in my experience it is more often a hardware issue. It can be challenging to test the full chain of hardware devices involved in reading and writing data on a computer, but I would attempt to perform some testing to gain confidence in the overall setup.

For example, I would try writing files to and reading them from an external hard drive, swapping out the data cable, and also testing the same drive on a different computer. The idea is to change each variable individually as you try to determine where a problem exists.

You can also have a computer repair shop perform some tests on the various hardware involved, in an effort to confirm whether there are problems with any of the hardware you’re using.

At the very least, however, I would immediately make a full backup of all data, ideally to more than one backup drive. As I’ve noted in previous Ask Tim Grey email newsletters, I also highly recommend using the built-in backup feature to backup the Lightroom catalog. In particular, this backup provides you with the option to test the integrity of the catalog files as well to perform optimization of the catalog. Both of these steps can help avoid problems and improve performance with Lightroom.

Today’s Question: In a recent email you suggested doing some testing in order to get a sense of the impact of ISO on noise levels for a given camera. How do you recommend doing that testing?

Tim’s Quick Answer: I recommend capturing a series of test exposures that enable you to see the impact of various camera settings on the noise levels in your photos. The key is to create a series of simple captures, focusing on changes to on variable at a time (to the extent possible).

More Detail: There are a number of variables that affect noise levels in digital captures, but one of the most significant is generally the ISO setting. This will therefore typically be the key variable to focus on, but you’ll want to consider other factors as well.

To begin with, I would generally use a subject with a solid color and minimal texture, such as a gray card. A blank backdrop or other simple surface can be used as well. Then, with the camera on a tripod, configure the camera for a normal exposure. I would typically use Aperture Priority mode with the lens aperture wide open, to ensure the fastest possible shutter speeds. This will help ensure that the impact of a long exposure is not affecting your test results.

Then capture a series of images at varying ISO settings, starting at the base ISO for your camera and increasing in perhaps one-stop increments. So you might capture an image at 100 ISO, then 200, then 400, then 800, and so on, until you reach the maximum ISO setting (or the maximum setting that you actually want to test).

As you raise the ISO setting, you may find that the wide-open aperture causes you to be unable to achieve a proper exposure with the available range of shutter speeds, so you may need to stop down the lens as part of the capture sequence.

You might also want to capture longer exposures in a similar manner, both with in-camera long exposure noise reduction turned on and turned off.

When it comes time to review the results of this testing, keep in mind that in most cases the software used to generate previews from raw captures will apply some noise reduction by default. You therefore may want to process all of the captures in a batch with default adjustment settings but with noise reduction disabled.

By reviewing the series of captures (and the metadata for each of them) with no noise reduction applied, you’ll get a clear sense of how much noise you can expect at different camera settings. Again, in particular this would mean evaluating results at various ISO settings, but you’ll also want to see how your camera performs with long exposures of varying durations.

After reviewing your results, you’ll have a much better sense of the noise behavior of your camera, as well as what sort of limits you might want to employ to help ensure minimal noise whenever possible.

Today’s Question: How do I determine the optimal ISO for my camera? I don’t remember anything like that in the manual or specifications when I bought my camera.

Tim’s Quick Answer: As a general rule the “base” ISO for a camera will be the lowest ISO setting available using the normal control for the camera. The special “low” ISO options available on some camera models would not generally be the base ISO.

More Detail: As noted in a recent Ask Tim Grey eNewsletter, in most cases you can expect the least noise and best overall image quality by using the “base” or “native” ISO setting for your camera. In most cases, that base ISO will involve the least amount of amplification to the signal being gathered by the image sensor, which translates into less noise and greater dynamic range.

There are, of course, some exceptions in terms of how specific cameras function or the results you can achieve at various settings. And, of course, as many photographers have found, it isn’t always easy to find out which ISO setting is the “base” setting.

For most digital cameras you will find that an ISO setting of 100 (or sometimes 200) represents that base ISO. As noted above, in most cases the lowest setting you can set with the normal ISO adjustment control on the camera will typically be the base ISO that will provide the best image quality. The “extra” settings with a lower value that are typically found on a separate menu control for cameras with such an option are generally not the base ISO setting, and won’t necessarily provide improved image quality.

Again, there are many variables involved among the different camera manufacturers and models. That is why I always recommend performing some testing of your own to get a sense of the impact various ISO settings have on noise levels for your camera. In particular, this type of testing can help you get a better sense of how high you can raise the ISO setting before you start to see problematic noise in your images.

Today’s Question: With a high-resolution camera do you recommend making use of the embedded preview option in Lightroom Classic CC rather than generating Standard previews on import?

Tim’s Quick Answer: On balance, I still recommend using the Standard (or 1:1) preview option in Lightroom rather than making use of the embedded previews that are included in proprietary raw captures.

More Detail: Choosing the option during import to use the embedded previews rather than generating Standard (or 1:1) previews could potentially speed up your workflow a little bit, since the embedded previews are already available and Lightroom would therefore not need to perform any additional work to generate replacement previews.

However, the embedded previews won’t necessarily match Lightroom’s interpretation of the photos, since the embedded previews are generated by the camera rather than Lightroom. Also, those embedded previews would not reflect Lightroom adjustments, such as if you had applied a Develop module preset during the import process. I apply profile-based lens corrections at import, for example, so all photos will have that correction by default. The embedded preview would not reflect those changes.

So, on balance I still prefer to have Lightroom generate the Standard previews during import. It takes a little extra time as part of the overall import process, but I feel that is time well spent.

Today’s Question: When preparing a copy of an image in Photoshop for online sharing, after I save my JPEG and try to close the image, Photoshop asks if I want to save my changes. But I just saved the image! Why is Photoshop asking me about saving changes when I just saved my image?

Tim’s Quick Answer: The description makes it clear that the image in its current state is not supported by the JPEG image format. Therefore, Photoshop is asking you to save the image in order to preserve all features you have taken advantage of. If you don’t want to preserve those features, you could simply save the JPEG and then opt not to save the “second” time.

More Detail: There are a variety of features you can leverage in Photoshop that are not supported by a JPEG image file. For example, you can’t save a 16-bit per channel image as a JPEG. JPEG images also can’t include layers, saved selections, alpha channels, among certain other limitations.

If you have an image open that includes features not supported by the JPEG image format, you can generally still save the image as a JPGE. For example, let’s assume you are working with an image in the 16-bit per channel mode. You can still choose File > Save As from the menu and save the image as a JPEG, and that JPEG file will automatically be created in the 8-bit per channel mode.

But after saving that JPEG file, the image in Photoshop will still be the 16-bit per channel image you had been working with. Therefore, after saving a JPEG copy and closing the image in Photoshop, you’ll be prompted to save the image because at that point the full image (or the changes you’ve applied if the image had been previously saved) will not have been saved.

So, just because you’ve saved a JPEG copy of the image doesn’t mean you’ve saved all features of the image you’re working with. When that situation exists, Photoshop tries to make sure you’re not losing any unsaved changes based on the lack of support for certain features with JPEG images.

Today’s Question: How much should I stop down my lens aperture if I want to achieve optimal depth of field when photographing with a long lens from a long distance from a landscape?

Tim’s Quick Answer: When photographing a scene from a considerable distance, you might be surprised at how much depth of field you can achieve even if you don’t stop the lens aperture down much (or at all). When focusing at a distance of about one-quarter of a mile with a 200mm lens, for example, stopping down to f/8 will provide a depth of field that covers the full scene all the way to infinity.

More Detail: This was a question asked by a workshop participant while we were atop Steptoe Butte in the Palouse region of eastern Washington State. That means we were about one thousand feet above the surrounding terrain. Even assuming you are focusing on a portion of the scene relatively close to the base of the butte, your focus point would still be about one-quarter of a mile or so. If you were using a 200mm focal length, at f/8 you could have everything from about 500 yards to infinity in focus.

I think many photographers who have experience with landscape photography tend to think it is always necessary to stop down to f/16 or f/22 to achieve any significant depth of field for a scene. When using a lens with a longer focal length, of course depth of field becomes a more significant concern. But when you are focusing at a considerable distance, you will have greater depth of field. I often find photographers are surprised at just how much depth of field they will achieve when focusing from far away, even with a long lens.

When you combine a distant focus point with a longer lens that will be capturing a relatively narrow field of view, there’s a good chance that even with a relatively shallow depth of field you will still be able to have the full scene in focus. For example, even a 500mm lens focusing at a distance of about one-quarter mile will provide a depth of field that is about 500 feet deep. That may very well provide adequate depth of field for the full scene, considering the narrow field of view with a 500mm lens.

When focusing close, such as with macro photography, getting enough depth of field can be a challenge. But when focusing from a considerable distance, you may be surprised at just how much depth of field you can achieve, even without stopping down the lens significantly.

Today’s Question: Another photographer wrote that using 100 ISO, if possible, is better than 200 ISO as a standard choice. Do you agree?

Tim’s Quick Answer: In many (perhaps most) cases, it is better to use 100 ISO rather than 200 ISO. However, it is important to note that the lowest ISO setting is not always the best option for every camera, in part because the lowest ISO is not necessarily the same as the base ISO.

More Detail: The image sensor in a given camera has a native sensitivity to light. You can think of this in very general terms as the result you would achieve with no amplification applied to the signal recorded by the sensor. When you raise the ISO setting, you are under-exposing the image and then amplification is applied to effectively brighten the resulting image. The result of this amplification will be some degree of noise. A greater increase in ISO setting will generally yield a greater amount of noise.

It seems logical that the lowest ISO setting should, in theory, provide the least amount of noise, since the lowest ISO setting presumably involves less amplification. However, the lowest ISO setting is not necessarily the base ISO setting. Reducing below the base ISO setting can reduce dynamic range, which can also affect overall image quality.

For optimal image quality, it is generally best to use the base ISO for your camera. In many cases this will be 100 or 200 ISO, depending on the specific camera you’re using. So, if your camera’s native ISO is 100, then you can expect better overall image quality at 100 rather than 200 ISO. If the native ISO for your camera is 200, then you may see reduced noise at 100 ISO, but you could also expect reduced dynamic range.

So, as a general rule, using the native ISO will produce the least noise with the maximum dynamic range, all other things being equal. It is important to note, however, that it can often be preferred to have a little more noise caused by an increased ISO setting, rather than having motion blur in the image caused by a shutter speed that is too slow.

Today’s Question: I saw in a recent Lightroom [Classic CC] update that you can add a color to a folder. Do you recommend using this feature, and if so how?

Tim’s Quick Answer: I do think the new ability to add a color label to individual folders can be a great help in a workflow for organizing photos in Lightroom Classic CC. You can see this new feature in action on my Tim Grey TV channel on YouTube here: https://youtu.be/FE6q1MASRhQ

More Detail: It has long been possible to add star ratings and color labels to your photos, such as to identify favorite photos. With a couple of recent updates to Lightroom Classic CC, you now have similar options for folders.

The “Favorite” feature for folders is essentially a star rating for a folder, but without the ability to assign a set number of stars. A folder is either marked as a favorite (with a star), or not marked as a favorite. Color labels are similar, except that you have the full range of color label options available for folders.

I have been using the “Favorite” feature to literally identify folders that contain images I’m most likely to use in the near term. I can then filter the folder list to see only the favorites, in order to more quickly find the specific folder I’m looking for.

The color label adds some new possibilities in the context of organizing your folders. For example, I’ve started assigning a red color label to folders that I have not yet completed a full review of my photos. For example, while leading a photo workshop in the Palouse region of eastern Washington State, I simply didn’t have enough time to properly sort through my photos each night. So instead I marked the folder for that trip with a red color label to clearly identify it as a folder I need to go back and review.

As with the “Favorite” feature, you can filter folders to only show those that have a color label assigned to them. At least for the current version of Lightroom Classic CC you aren’t able to filter by a specific color label for the folder list, but even being able to filter the list to only those that contain a color label (versus no color label) is very helpful in my view.

You can get a better sense of how the color label and “Favorite” features work for folders in Lightroom Classic CC in a sample lesson from my “Lightroom Quick Tips” course from GreyLearning, which we have published to my YouTube channel here:

https://youtu.be/FE6q1MASRhQ

Today’s Question: What happens when I delete a synchronized photo [in Lightroom]? Is it deleted everywhere? Generally I want to keep my photos on my home computer, where I do my own backups. I don’t want to store them in the cloud. If I delete them on my phone, what happens on my PC?

Tim’s Quick Answer: If you are using the cloud-based Lightroom CC, deleting a photo from any device will cause that photo to be permanently deleted from every device, including your computer at home. If you are using Lightroom Classic CC (as is the case here), deleting a photo from a synchronized location (rather than the original) will only remove the synchronized copies, and will not delete your original photo.

More Detail: Lightroom Classic CC and Lightroom CC are very similar (and somewhat interactive) when it comes to synchronizing photos. That said, there is a fundamental difference between the two in terms of how synchronization happens.

With Lightroom CC, all of your original photos are synchronized to the cloud, and available on all devices via the Lightroom CC application on a computer, app on a mobile device, or web browser through the Lightroom site (https://lightroom.adobe.com/).

Because Lightroom CC is synchronizing all of your original photos, the idea is that the cloud-based storage becomes your primary storage. Therefore, when you delete a photo that is synchronized via Lightroom CC from any platform that enables you to access those photos, all copies of that photo will be deleted. In other words, the photo will no longer be available anywhere unless you have a separate backup copy.

With Lightroom Classic CC, synchronization involves proxies of your photos rather than the original source images. Therefore, deleting from a mobile device, web browser, or copy in a collection will not cause the original source capture to be deleted. Keep in mind, of course, that with the Lightroom Classic CC desktop application it is indeed possible to delete the original source image file, which would cause that photo to be removed from all locations, such as a synchronized collection.

It is important for photographers to understand the fundamental differences between Lightroom Classic CC and Lightroom CC, so they can both make a decision about which option is better suited to their workflow, and also be sure they are using an appropriate workflow for managing their photos.