Author: Tim Grey

Today’s Question: I just saw an article that said raising the ISO setting does not actually increase noise in a photo, but instead shorter exposure durations cause noise. This doesn’t match what I’ve always read. What are your thoughts?

Tim’s Quick Answer: It is mostly true that raising the ISO setting isn’t the true cause of noise in a digital camera. However, it is important to keep in mind that the article in question specifically related to astrophotography. For more terrestrial forms of photography, it is still generally safe to assume that a lower ISO setting will translate to reduced noise levels.

More Detail: As I’ve said many times, noise is the opposite of information, and in the context of photography light is the information we’re dealing with. Thus, less light will translate into more noise. This is the foundation of the “expose to the right” principle, which calls for capturing photos that are as bright as possible without losing highlight detail in order to maximize detail and minimize noise.

However, this does not mean that you should use a high ISO setting to minimize noise. Quite the contrary for most photographic scenarios.

Raising the ISO setting will require that you either use a faster shutter speed or a smaller lens aperture opening in order to reduce the amount of light reaching the sensor. The amplification triggered by the increased ISO setting will then compensate for the exposure.

However, raising the ISO setting really translates into (potentially dramatically) underexposing the image, and then amplifying the capture information in the camera. The underexposure is indeed the key cause of noise, but that underexposure was caused by a higher ISO setting. So the two are related.

Furthermore, this issue is more nuanced than the article suggested, because there is a big difference between underexposing with versus without an increase in ISO. If you use the exact same shutter speed and aperture settings at a low versus high ISO setting, you will see more noise (and less detail) in the capture with the low ISO setting. This is an indication that the camera is able to do a better job of brightening the image (through amplification of the signal) than our computers are able to do by simply brightening pixel values.

But again, more light will help ensure the lowest noise levels. Thus, you generally want as much light to reach the sensor in the camera as possible. That, in turn, means keeping the ISO setting at the minimum setting, so that you will use a larger lens aperture and/or a longer exposure duration to compensate. That results in more light, and therefore less noise.

So for most photographic scenarios, it still holds true with most cameras that you want to use the lowest ISO setting.

The reason a different approach to ISO makes sense with astrophotography is that you generally don’t have any flexibility when it comes to shutter speed and lens aperture. You may be shooting with the lens aperture wide open, and the shutter speed at the longest exposure duration possible without introducing star trails. If you need more signal, your only option is to increase the ISO setting. As noted above, a higher ISO setting is generally preferable to a low setting when all other factors (shutter speed and lens aperture) are fixed.

Today’s Question: In a recent presentation you referred to having your camera automatically capture a bracketed sequence of exposures multiple times in an interval basis. How do you set that up to happen automatically?

Tim’s Quick Answer: This technique requires configuring your camera for automatic exposure bracketing and then using either an intervalometer or a built-in feature to capture multiple bracketed exposures over a period of time.

More Detail: A bracketed set of exposures enables you to later merge those exposures into a high dynamic range (HDR) image. If you also enable interval capture, you can create multiple sets of bracketed exposures over a period of time. This could be used to create an HDR time-lapse video, for example. Or it can be used to automate the process of capturing variations on a bracketed capture, such as when sky conditions are changing.

In my case I was using this approach to automate capturing photos while I was helping other photographers setup their shots, which is what led to my very lucky capture of lightning at sunset over New York City, which you can see on my Instagram feed here (don’t forget to follow me!):

https://www.instagram.com/p/Bi1q_b_n05l/?taken-by=timgreyphoto

The first step is to configure exposure bracketing on your camera. Note that in many cases you may need to use a timer mode to have the camera automatically capture all exposures in the bracketed sequence rather than requiring you to press the shutter release multiple times.

The second step is to configure interval capture. I happen to use a camera that has a built-in interval capture feature, and that also allows me to use bracketed exposures in conjunction with interval capture. If your camera is not so equipped, you can use a cable release with an interval capture feature to make this possible.

For example, photographers using a Nikon camera with a DC2 connection could use this cable release for interval captures:

https://amzn.to/2wwYzQX

Photographers using a Canon camera with a 3-pin connector could use this version of the same cable release model:

https://amzn.to/2woLI30

So, for example, you could configure your camera to capture bracketed exposures suitable for assembling into an HDR image in post-processing. You could then make use of an interval feature to perhaps capture a bracketed exposure sequence every minute, or however often makes sense based on the rate at which conditions are changing. And if the conditions include a bit of luck, you might also end up with a photo that includes lightning, as I did with the image linked above.

Today’s Question: Do you get better results with HDR (high-dynamic range) software or manual blending?

Tim’s Quick Answer: The results will vary based on the photographic conditions and the software you’re using. However, in general I find that using HDR software to assemble images provides a better result than attempting to combine images manually using software such as Photoshop. In addition, HDR software enables you to have that work automated for you, so you don’t need to manually combine the images into a composite.

More Detail: There’s no question that I have had situations where the contrast range of the scene, subject movement within the scene, or other factors make it difficult to successfully employ HDR software to create a good final image. However, in most cases I have been able to create better images more quickly using HDR software compared to using more manual methods such as layer masking to create a composite image.

Part of the benefit of HDR software is that it isn’t simply combining images via masking, but is rather more intelligently calculating appropriate pixel values throughout the image based on the full range of information available in the bracketed set of exposures. Furthermore, with tone-mapping you can choose how the final image is interpreted.

When you manually assembling a composite for a given area you will generally only be able to see a single image. It is possible to further blend images with opacity and blend mode options, but typically a composite would involve using a single image layer for each area of a photo. This provides less flexibility in terms of how pixel values are ultimately determined.

Therefore, my recommendation is to start with HDR software, and to use HDR software in most cases to create the initial image based on the bracketed exposures. Only if the HDR approach doesn’t provide a good result would I consider creating a composite based on multiple exposures, at least in the most typical types of scenarios when exposure bracketing might be used with the intent of creating an HDR result.

Today’s Question: You said: “Note that on the Windows platform you are able to adjust the scaling of Photoshop to help improve the experience on high resolution displays.”  How do you do that?

Tim’s Quick Answer: Windows users can adjust the overall interface scaling in the Display section of Settings for the operating system, provided you are using Windows 10 Creators Update or later. Photoshop will make use of that setting, with a few additional options available for fine-tuning the scaling of the Photoshop interface.

More Detail: This is a follow-up to yesterday’s answer about using a high-resolution display on a Macintosh computer. I mentioned that Macintosh users don’t have the ability to adjust the interface scaling in Photoshop, while Windows users do. That said, similar to Macintosh, you may find that simply adjusting your operating system settings provides an adequate solution.

In the Settings for Windows you can go to Display in the System category. There you’ll find a scaling control, which enables you to enlarge the overall interface independently for each monitor display you have connected to your computer. Most applications (including Photoshop) will be affected by changes you make to these settings.

There is also a separate UI Scaling control that can be changed in Photoshop on the Interface tab of the Preferences dialog. In addition, on both Windows and Macintosh you can adjust the UI Font Size control to adjust the size of text within Photoshop. Increasing the font size can obviously make that text easier to read on a high-resolution display.

On the Workspace tab of the Preferences dialog you can also choose a couple of options to reduce the amount of space consumed by some of the controls after scaling your overall display. You can turn off the Large Tabs checkbox if you’d like to reduce the size of the tabs for each image you have open in Photoshop. You can also turn on the “Enable Narrow Options Bar” checkbox if you would like to reduce the overall size of the Options bar below the menu bar.

Note that some of the changes you make in the Preferences dialog in Photoshop will require you to restart Photoshop before the changes take effect.

Today’s Question: My new computer has a higher definition “Retina” display. On the new display, images viewed in the Photoshop window look much smaller than usual, even though they look normal-sized when displayed on Flickr. In Photoshop the photos are too small to sharpen properly. I’m puzzled that they behave that way on Photoshop but look the way they always have on Flickr. Any ideas that might be helpful to me?

Tim’s Quick Answer: The issue here is that the display is set to a very high resolution, thus causing the image to appear smaller. You can scale the display resolution in the Display options in the Preferences dialog for the operating system, or simply zoom in on the image.

More Detail: When you set an image to the 100% zoom setting in Photoshop, one pixel on the display is used for each pixel in the image. This is preferred for evaluating sharpening, for example. But on a very high-resolution display such as the Retina displays from Apple, this can cause the image to be smaller than is comfortable for you.

You could change the resolution of the display in your operating system, or simply zoom in on the image within Photoshop. In either case, however, you will be scaling the image on the display. That is less than ideal in terms of evaluating sharpening, but doing so won’t cause a major issue in this context. Keep in mind, for example, that the image is likely being scaled within the web browser based on the hardware configuration for each person browsing your photos.

Note that on the Windows platform you are able to adjust the scaling of Photoshop to help improve the experience on high resolution displays. Thus far this feature has not been made available on the Macintosh version of Photoshop.

Today’s Question: Is there any advantage to actually making a borderless print, as opposed to making a normal print and then trimming off the edges to make a borderless result?

Tim’s Quick Answer: In my view the only real advantage to making a borderless print is convenience. If you’re using an inkjet printer to create the print, I actually recommend not printing with the borderless option, and instead trimming the print to create a borderless effect.

More Detail: There’s no question that if you want a borderless print, it is convenient to have the print come out of the printer borderless. In other words, with an image that goes right up to the edge of the paper, with no white border.

If you’re using a dye-sublimation printer to create borderless prints, then as far as I’m concerned the borderless capability is a great feature. That said, most photographers are using photo inkjet printers to create their own prints. When it comes to inkjet printers, I actually recommend against borderless printing.

As you can probably appreciate, it isn’t really possible to spray droplets of ink with such precision that they will go right up to the edge of the paper without spraying past the edge of the paper. For this reason there are components within the printer (typically employing a sponge) to catch the ink overspray.

With many photo inkjet printers, the components for capturing the ink overspray are not something that the user can replace themselves. In other words, you’ll need to take the printer to a service facility to have those sponges replaced when they get fully saturated.

This is why I prefer not to create borderless prints with photo inkjet printers. Instead I will print with empty space around the photo (such as printing an 8″x10″ image on an 8.5″x11″ sheet of paper). I will then trim the paper to create a borderless print.

By the way, I highly recommend the RotaTrim line of rotary paper trimmers. I have noticed that the 20-inch model is currently being offered at a significant discount from the list price on Amazon, and you can find that version of the RotaTrim trimmer here:

https://amzn.to/2o245pT

Today’s Question: When I print a borderless photo using Lightroom Classic CC, the long side of the photo is cropped. I can move the photo from side to side (in the portrait orientation) to select where I want to crop but I don’t want it cropped at all. How do I prevent this from happening?

Tim’s Quick Answer: Put simply, when you are making a borderless print you will always need to crop the image unless you are printing to a paper size that matches the aspect ratio of the photo.

More Detail: Most digital cameras have a sensor with an aspect ratio of 3:2 or 4:3. However, most common paper sizes for creating photo prints do not match this aspect ratio. Many photo printers that support borderless printing are able to print borderless only at specific sizes. A commonly supported borderless print size is 8.5″x11″, or “US Letter” size.

However, for a digital SLR capture with a 3:2 aspect ratio, an image enlarged to 8.5 inches on the short side would be 12.75 inches on the long side. Therefore, the image would need to be cropped to remove 1.75 inches from the longer side in order to fit the borderless print size.

The only option other than cropping in this type of scenario would be to reduce the image size to fit within the confines of the paper size being used for printing. However, that would result in white space on two sides of the print, creating a “letterbox” type of effect. In other words, the image would no longer be a truly borderless print that fills the page.

So, if you want to make a borderless print, you’re really going to need to crop the image to match the aspect ratio of the paper you’re printing to. This can be done when processing the image, or when sending the photo to the printer. But you can’t create a borderless print with an image that has a different aspect ratio than the paper you’re printing to.

Keep in mind that printers capable of borderless output can only print borderless for certain output sizes. For example, the printer I generally use to print photos supports borderless printing for only 8.5″x11″, 11″x17″, and 13″x19″ paper sizes.

Today’s Question: I made a selection in Photoshop CC and then added an adjustment layer. Everything looks fine, and the layer mask shows what I expected. I made a selection again and then used Quick Mask mode to modify the selection. When I added an adjustment layer, this time there is no layer mask. What am I doing wrong?

Tim’s Quick Answer: This is a matter of selections being treated differently in Photoshop depending on whether you are in Quick Mask mode or the “normal” selection mode. After using Quick mask mode to refine your selection, you can switch back to “normal” selection mode before adding the adjustment layer and the layer mask will reflect your selection.

More Detail: A common approach to applying a targeted adjustment to a photo in Photoshop is to first create a selection of the area you want to adjust, and then add an adjustment layer. The layer mask associated with the new adjustment layer will automatically reflect the selection that was active, so that the adjustment only affects the area that had been selected.

When you are in Quick Mask mode making changes to a selection, however, this behavior changes. If you add an adjustment layer while in Quick Mask mode, the layer mask associated with the new adjustment layer will not reflect the active selection. Instead, there will be a “blank” (all white) layer mask, meaning the adjustment layer will affect the entire image.

The workaround is to make sure you are in the “normal” selection mode before adding an adjustment layer (or otherwise adding a layer mask). You can still use Quick Mask mode to modify your selection, of course. But then when you’re finished you can exit Quick Mask mode (by pressing “Q” on the keyboard) to ensure you’re in the normal selection mode before adding an adjustment layer or otherwise adding a layer mask to an image.

Today’s Question: I have come across several images that have received extensive editing and now are marked with an arrow icon in the upper right corner of the image in the grid view. When I click on this icon I get a message I don’t understand:

“The metadata for this photo has been changed by both Lightroom and another application. Should Lightroom import settings from disk or overwrite disk settings with those from the catalog?”

I assume that this may be the result of editing in Lightroom after editing in Photoshop, but I’m not sure. I’m also at a loss as to what the different outcomes of the choice I’m being asked to make.

Tim’s Quick Answer: The message indicates that changes have been made to the metadata for a photo outside of Lightroom, which in turn means that the embedded metadata for the photo does not match the metadata in the Lightroom catalog. The options presented to you are asking you to choose which metadata you want to keep, and therefore which metadata you want to lose, in order to synchronize the metadata between the image and the catalog.

More Detail: There are a variety of ways the metadata in an image file might get updated so that it no longer matches what Lightroom is expecting based on the information about a photo in the Lightroom catalog. For example, if you browse a photo in Adobe Bridge and add a keyword, that keyword would not be reflected in the Lightroom catalog. As a result, there would be a metadata mismatch.

In general you can avoid these types of mismatches by making sure that everything you do with an image is initiated in Lightroom. If you always make a point of performing all updates in Lightroom, it will also be easier to know which option to select if a metadata mismatch should occur.

The options available to resolve a metadata mismatch in Lightroom involve choosing which metadata you want to keep and which metadata you want to lose. Unfortunately, it isn’t possible to simply merge all of the updates that might have been applied within Lightroom versus outside of Lightroom.

Let’s assume you have a photo of a bird captured in Florida. If you add the keyword “bird” in Lightroom and the keyword “Florida” in Bridge, you will have a metadata mismatch. In Lightroom you’ll see “bird” as a keyword, but not “Florida”. And in Bridge you’ll see “Florida” as a keyword but not “bird”. To resolve the metadata mismatch you will have to choose which of those keywords you want to keep.

Choosing the “Import Settings from Disk” option means that you want to retain the metadata added outside of Lightroom, and bring that metadata into Lightroom. In the process you’ll lose some of the metadata in Lightroom since it will be updated with outside values. If you choose the “Overwrite Settings” option you’ll preserve the metadata in Lightroom and save that information to the image file, replacing the metadata that had been included in that file.

Again, if all of your metadata updates have been applied within Lightroom, you can be reasonably confident that any mismatches are not critical. That, in turn, would mean that you could always choose the “Overwrite Settings” option to resolve the metadata mismatch by prioritizing the information in your Lightroom catalog.

Today’s Question: In Lightroom if you edit a raw file and save as JPEG I understand the edits are nondestructive to the original raw file. If you then re-edit the JPEG, are the new edits destructive to the JPEG file?

Tim’s Quick Answer: All of the adjustments in the Develop module in Lightroom are non-destructive to the source image file you are currently working on. That includes JPEG images (among other supported file formats) in addition to raw captures.

More Detail: When you apply an adjustment to an image in Lightroom’s Develop module, the changes you apply aren’t actually altering the source image file on your hard drive. Instead, your adjustment settings are essentially metadata updates stored in the Lightroom catalog. This approach ensures Lightroom will be non-destructive to the information in your source images.

When you export an image, you are creating a new file and the adjustments you applied will be incorporated into the pixel values for that image. So, for example, if you export a JPEG image based on a raw capture you’ve adjusted in Lightroom, the source raw file remains unchanged, but the JPEG will reflect the adjustments you applied.

If you import that JPEG image into your Lightroom catalog, you can of course apply new adjustments to that image. Those adjustments will still be non-destructive, meaning the source JPEG image file on your hard drive won’t be altered based on the new adjustments you applied. Of course, if you create a new JPEG based on the existing JPEG using the Export feature, the adjustments will be incorporated into the pixel values for that new JPEG version of the image.

So, in a way, you can think of the adjustments in Lightroom as always being only metadata updates that are non-destructive to the source image. However, exporting a new copy will cause the adjustments to be incorporated into the pixel values for the new image file created as part of that process.