Output Resolution at Capture

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Today’s Question: How do I shoot to guarantee I am getting a 300 ppi resolution? I have a Sony a7R III.

Tim’s Quick Answer: You don’t actually establish an output resolution in the camera, since at that stage of your workflow the output resolution doesn’t matter. All you really care about is making sure that in general you are capturing the maximum resolution so you have the most flexibility in terms of final output.

More Detail: I’ve been teaching about photography and digital imaging in various ways for about two decades now, and the subject of resolution continues to be one that many photographers are confused by. That is absolutely understandable, considering that resolution is a factor in a variety of contexts.

First off, we have the capture resolution, which basically means how many pixels the image sensor is capturing information for. This is generally described as the number of megapixels for the sensor, or the millions of pixels being captured.

Another type of resolution is essentially the density of information. In other words, how much information do you need in order to be able to produce output of a particular size with good quality. A monitor display requires far fewer pixels than a high-quality print, for example.

With digital displays, you can generally simply refer to the number of pixels, rather than a pixel per inch (ppi) resolution value. So the only time the pixel per inch (ppi) value really comes into play is when you are printing.

You can change the output resolution to any value based on how the image is being printed. Ultimately, all that really matters is that you are providing enough pixels to produce output at the intended print size. That either means having a camera with an adequate resolution, or using software to enlarge the image by adding pixels through a process referred to as “interpolation”.

The appropriate output resolution (ppi) will be based on the specific printer being used to produce the print. In most cases an output resolution of 300 ppi will produce excellent results, though a higher ppi resolution may be helpful in some cases. But the bottom line is that you aren’t really able to alter the final output resolution at the time of capture.

When you’re capturing a photo, the sensor resolution determines how much information is being captured, which in turn determines how large a print you’re able to produce. In other words, the only thing you can really do to ensure the best capture in terms of final output size is to buy a camera with a relatively high resolution, and to make sure you’re using the full-resolution setting for the camera when capturing photos.

Negative Texture

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Today’s Question: After seeing your video about the new Texture adjustment in Lightroom [and Camera Raw], I’ve played around with it a bit. I see that like Clarity it is possible to use a negative value for Texture. Is there ever a situation where you would actually want to use a negative value for this adjustment?

Tim’s Quick Answer: You can use a negative value for the new Texture adjustment anytime you want to reduce the appearance of fine texture in a photo. The most common scenario for this would probably for reducing texture for a portrait of a person, for example. But there may be other types of images where fine texture serves as more of a distraction than a benefit to the image.

More Detail: While many photographers (myself included) will be inclined to only use the new Texture adjustment in Lightroom and Camera Raw to enhance texture, it can also be used very effectively to reduce texture. In fact, that is the reason the adjustment was originally created.

In some cases you may find that significant fine detail in an image can be something of a distraction. This is certainly true for closeup photos of people, but the same can be true with other images as well. If you want to reduce the appearance of texture in an image, until the latest update you could use a negative value for the Clarity adjustment in Lightroom or Camera Raw. But that didn’t provide quite the same effect. Also, in some cases you might want to enhance midtone contrast, while also toning down fine detail.

Now that Lightroom and Camera Raw include a Texture adjustment, there is a solution. As noted in my video covering the differences between Texture and Clarity (among other adjustments), one of the key differences between the Texture adjustment and the Clarity adjustment is the scale at which they operate. Texture operates at a very fine scale, and Clarity operates at a larger scale.

So, if you want to tone down the very fine textures in an image, you can use a negative value for Texture. At the same time, you might want to enhance midtone contrast at a larger scale, and so you could use a positive value for Clarity.

In many respects, you can think of the Texture, Clarity, and Dehaze sliders as all providing options to enhance or reduce the appearance of texture in an image. The difference is that Texture operates at a very small scale, Clarity operates at a “medium” scale, and Dehaze operates at a relatively large scale.

So, depending on your intent in terms of the appearance of texture, detail, and contrast in an image, you can use these various controls with positive or negative values, depending on whether you want to enhance or tone-down detail at various scales.

Note that you can see these adjustments compared in the context of enhancing detail in a video published on my Tim Grey TV channel on YouTube here:

https://youtu.be/H6TMlwYTZd8

Cropped Sensor Changes Image

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Today’s Question: A 105mm lens on a full frame camera in FX mode has the same field of view as a 70mm lens on the same camera in DX mode. However, images won’t be the same. The 105mm lens image would have more apparent compression of distance than the 70mm lens because of the real difference in focal length, and at the same aperture, the 105mm lens would have a shallower depth of field than the 70mm lens.

Tim’s Quick Answer: The compression of the scene is only a factor if the photographer changes position. From the same position the perspective of the full-frame versus cropped-sensor image will be the same. Only if you back away when using the cropped sensor will the perspective of the image change. And there will be a reduction of depth of field when a longer focal length lens is used, regardless of in-camera cropping.

More Detail: Today’s question is a follow-up to one about the option to crop in the camera on some full-frame digital SLR cameras. These cameras essentially let you choose between capturing the full frame, or cropping to only capture a portion of the image circle, matching what you would have achieved with a smaller image sensor using the same lens.

When your camera provides an option to crop the image in-camera to produce a smaller field of view, or you are using a camera that has a sensor smaller than a full-frame sensor, the images you capture will reflect a narrower field of view than you would achieve with the same lens on a full frame camera.

If you do not change your position or adjust the camera settings, you are literally just cropping the image. So with a full-frame camera compared to in-camera cropping or a smaller sensor, if you are using the same lens everything is the same except that the image is cropped.

Note that cropping the image circle doesn’t alter depth of field in the same way that changing lens focal length would. There are factors such as sensor resolution and focal length that affect depth of field. But if the same focal length lens is used on the same camera, and you are merely cropping the image in the camera (such as with the FX versus DX option on some Nikon cameras) the depth of field would not be altered.

The perspective change referred to in today’s question is not really caused by the focal length of the lens, but rather by the change in position by the photographer. If you stay in the same position, the perspective will not change. But, of course, if you are getting the result of a longer focal length in terms of field of view, you would need to back up if you wanted to maintain the same framing of the scene. That would result in a change of perspective.

You can see an example of the effect of your position versus the focal length of the lens in an episode of Tim Grey TV on my YouTube channel here:

https://youtu.be/wFqukptuwmg

“Raw” Capture on Mobile

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Today’s Question: I use Lightroom Classic on my laptop. I downloaded the Lightroom app on my iPhone in order to use the Lightroom camera because it can create DNG files. Is there any working relationship between the Lightroom Mobile app and Lightroom Classic? What is your opinion about the Lightroom Mobile camera versus the iPhone camera app?

Tim’s Quick Answer: Using the Lightroom mobile app for photography on your mobile device can help improve overall quality, since the images can be captured in the Adobe DNG format (rather than JPEG capture, for example). Photos captured within the Lightroom mobile app will automatically synchronize to Lightroom Classic, as long as you’ve enabled that synchronization.

More Detail: The Lightroom mobile app works with both Lightroom Classic and the cloud-based Lightroom CC. With the cloud-based version of Lightroom all photos in your catalog are synchronized to the cloud so they are available on all of your devices or through a web browser. With Lightroom Classic only photos you add to collections with synchronization enabled will be synchronized to the cloud.

As long as you have enabled synchronization on Lightroom Classic, the photos you capture with the Lightroom mobile app will appear in your catalog as soon as they are synchronized. The device (your iPhone in this case) will appear as a separate hard drive, essentially. So if you have all of your photos on an external hard drive, you’ll see that drive listed in the header above all of the folders on that drive in the Folders section of the left panel in the Library module.

Once you have synchronized photos from the Lightroom app on a mobile device, you’ll see a header for that device, with a folder called “Imported Photos”. That folder will contain all images captured with the Lightroom Mobile app, and of course you could move those photos to a different storage location within Lightroom Classic.

The result is that using the Lightroom mobile app to capture photos on your mobile device can provide better image quality as well as a more streamlined workflow.

Lenses in Carry-on Bags

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Today’s Question: Do you pack your 150-600mm lens into your carry-on bag for flights? Or do you put larger lenses in checked luggage?

Tim’s Quick Answer: Yes, so far I have always carried my 150-600mm lens in a carry-on bag for all flights. As a general rule I don’t put any cameras or lenses into a checked bag. I often do, however, put a tripod and various camera accessories into a checked bag.

More Detail: Like most photographers, I’m a bit nervous about putting my important (and sometimes expensive) photography gear in checked luggage for flights. I’m concerned that the luggage will get lost or stolen, or that the gear will get damaged in transit. So I’d much rather have all of my photography (and computer) gear with me in a carry-on bag.

That can certainly add up to a lot of gear and a heavy bag. For example, the lens in question (https://timgrey.me/150600) weighs 4.4 pounds. But I prefer to keep my important gear with me rather than putting it in a checked bag.

Because I generally want to have a bag that works when I’m on the go once I reach my destination, my carry-on is also my camera bag. I prefer to use a backpack as my carry-on bag, and so I need a bag that provides a good balance between providing lots of storage but still being small enough to use as a carry-on bag.

I generally use the Lowepro Fastpack BP 250 AW II, which you can find here:

https://timgrey.me/fastpack250

Note that today’s question was a follow-up from my recent webinar on “Which Lenses Do You Bring?”. If you missed the live presentation, a recording of the full webinar can be found on my Tim Grey TV channel on YouTube here:

https://youtu.be/d1NFXqL__fw

Lenses for Cropped Sensors

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Today’s Question: I see some lenses being promoted as having been designed for cameras with “cropped” sensors, often to provide a wider field of view. But can these lenses still be used with a full-frame camera?

Tim’s Quick Answer: No, lenses that are designed for cameras with “cropped” sensors can’t really be used on full-frame cameras, since the image circle projected by these lenses is not large enough for a full-sized sensor.

More Detail: Lenses in general are obviously designed for a specific camera system, which generally just means a lens will be compatible with the mount for that camera. So a lens might be designed to mount onto a Canon versus Nikon digital SLR, for example, or for a specific mirrorless camera system mount.

With some camera systems, however, different bodies might use the same lens mount but have different sensor sizes. A common example would be various digital SLR cameras that essentially evolved from 35mm film cameras. Some of these digital SLRs have a sensor that is the same size as a frame of 35mm film, which are generally referred to as “full frame” models. Others have a smaller sensor, which are often referred to as having “cropped” sensors because the smaller sensor is cropping a smaller area of the image circle.

Because a “cropped” sensor is capturing a smaller area of the image circle projected by the lens compared to a full-frame sensor, the photos captured with a cropped sensor have a narrower field of view than the same lens would have provided on a full-frame camera. For example, a 100mm lens on a camera with a 1.6X cropping factor due to a smaller sensor would provide a field of view equivalent to a 160mm lens on a full-frame camera.

So, cropped sensors enable our long lenses to provide the field of view of a longer lens. But those sensors also mean you are missing out on the capabilities of a wide-angle lens. For example, a 16mm wide-angle lens on a cropped sensor camera might give you the field of view comparable to a lens with about a 26mm focal length. That can be a big shortcoming.

To compensate for this issue, many lens manufacturers have started designing lenses specifically for cropped sensors. For example, a 10-24mm lens would make up for the loss of wide-angle capabilities, providing an effective range of 16mm to 38mm compared to a full-frame setup.

However, these specialty lenses project an image circle that is smaller than a “normal” lens designed for a full-frame sensor. That means if you used such a lens on a full-frame camera, the edges of the photo would be dark (as in basically black) because the image circle would not cover the full size of the sensor. Therefore, it is important to be aware of not only the lens mount a lens is compatible with, but also the sensor size that is supported.

Sharing Adjustments with Photo

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Today’s Question: Is there a way to send a DNG file with editable adjustments to someone when I want them to see what edits I have made in Lightroom?

Tim’s Quick Answer: Yes, you can export a photo as a DNG (or original raw capture format) and the Develop adjustment settings from Lightroom will be included in metadata. That file can then be imported into Lightroom or opened in Photoshop and the adjustments will be visible (and editable).

More Detail: When you export a photo as an Adobe DNG image or original raw capture format from Lightroom, the Develop settings are embedded in the metadata for the file. In the case of an image exported as a DNG file the metadata will be included in the file itself. If you export a raw capture using the “Original” setting in the Export dialog the metadata added in Lightroom (including Develop settings) will be saved in an XMP sidecar file saved along with the exported image. That XMP file will have the same base filename as the raw capture, with an “.xmp” filename extension.

If you send the DNG file (or the raw file plus the XMP file) to someone else, they can either import that image into Lightroom or open it with Photoshop. In the case of Photoshop that would actually mean the image would be opened via Adobe Camera Raw.

In either Camera Raw and Lightroom, the person you sent the photo to would see your final edited version of the image. The adjustment settings for the image would also be set exactly as you had them at the time the source image was exported. In other words, they would see exactly what adjustments you applied to the photo, and could make changes to those adjustment settings if needed.

Cropping in the Camera

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Today’s Question: If I am using my Nikon D850 with a 24-70mm lens in FX mode, I have the obvious de facto range of 24-70mm. If I then switch to DX mode at a 1.5X crop factor, in theory I would then have extended my range to 105mm. In this scenario am I correct in saying by carrying this one lens only a steep hike up the mountain I have the equivalent of a 24-105mm lens? From an image quality point of view what am I sacrificing when I am operating the 24-70 in the DX mode? What would be the difference between an image shot with my 24-70mm at 70mm in DX mode [105mm effective focal length] versus using a Nikon 105mm prime lens in FX mode?

Tim’s Quick Answer: Put simply, when you make use of this type of option that enables you to achieve the field of view of a longer lens, what you are actually doing is cropping the image in the camera. In other words, the image captured in this crop mode will have a lower resolution. You would get the exact same result in terms of image quality if you captured in the normal full-resolution mode, and cropped the image in post-processing.

More Detail: In this case I’m addressing a question about a specific camera model that offers what is effectively in-camera cropping to a lower resolution, effectively providing a field of view of a longer focal length lens in the process. This feature, however, is available in a variety of different camera models from different manufacturers.

The key thing to keep in mind is that when you switch your camera from full-resolution mode (FX mode in this example) to a cropped mode (DX mode in this case), you’re really just cropping the image circle projected by the lens in the camera. In other words, you’re capturing an image that includes only part of the pixels on the image sensor.

In this specific example, the Nikon D850 has a 45.4 megapixel resolution. When you use DX mode, you are cropping the image that the sensor is recording, and ending up with a 19.4 megapixel image.

You aren’t sacrificing image quality at all in this case. You’re only giving up resolution. You could achieve the exact same result (of using DX mode) by capturing the image in FX mode and then cropping after the fact to the same sizing represented by DX mode (a 1.5X cropping factor in this case).

Of course, you could keep the camera in FX mode, and use a lens with a longer focal length. So you need to consider the impact on resolution in terms of the in-camera cropping.

With the full resolution of 45.4 megapixels, you could print the image at its native resolution to about 18″x28″. That is assuming a 300 ppi print resolution, and no enlargement of the original image. You could obviously print even larger with great quality if you wanted to. For comparison, the DX image would have a native print size of about 12″x18″. Once again, you could print larger if needed.

But the point is that in FX mode the native print size is about 18″x28″, and in DX mode the native print size is about 12″x18″.

In FX mode using a 105mm lens, a capture will have a larger potential output size than if you were using the DX mode with a 70mm lens (105mm effective focal length). That could also translate into slightly better detail in the FX shot, since you have more pixels to work with. But the framing of the two images would be identical. Plus, the DX shot would have a smaller file size than the FX shot.

So, if you need to be able to produce very large prints, you may want to favor FX mode with a longer lens as needed. If you want to favor smaller file sizes (because you are cropping pixels on the image sensor) and don’t mind not being able to print quite so larger, using a shorter lens in DX mode provides a great solution. What that really translates to is that if you’re not intending to ever make especially large prints, you might favor using DX mode most of the time, with shorter (and lighter) lenses to match up with the in-camera cropping. But if you want to be able to make very large prints, you may want to favor FX mode, cropping in post-processing when you need a tighter shot than your maximum lens focal length allows.

Non-Destructive with JPEG?

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Today’s Question: Regarding the advice [from the May 7th Ask Tim Grey eNewsletter] to maintain the JPEG format instead of converting to DNG when importing an image from a smartphone [into Lightroom], is there any other disadvantage other than increased file size? I’m concerned that with a JPEG photo that’s optimized (in Lightroom) and saved through several cycles may degrade due to the lossy nature of the JPEG format.

Tim’s Quick Answer: There is not a cumulative loss of quality caused by working with a JPEG image in Lightroom’s Develop module. The only cumulative degradation in image quality would occur if you exported the adjusted photo as a JPEG, since that exported JPEG copy would have JPEG compression applied to it as well.

More Detail: When you are adjusting an image in the Develop module in Lightroom, that work is non-destructive to the original image. What that means is that you are not altering the original pixel values in the source image file.

Cumulative degradation of image quality in a JPEG image only occurs when you make changes to the actual image data, saving the result as a JPEG image (even if you are simply saving to update the existing file. So, for example, if you apply adjustments to a JPEG image in Photoshop, close the image, then re-open the image, apply adjustments, and save again, the overall image quality would suffer. That is because the compression applied to the pixel data would be performed more than once, reducing overall image quality.

Even that cumulative loss of image quality would not be significant provided you were using a moderately high Quality setting for the JPEG image, and didn’t adjust and re-save the image a very large number of times. In other words, this isn’t an issue you really need to worry about too much in a typical workflow.

This is the reason I don’t really recommend converting an original JPEG capture to a different file format that would result in a larger file size. You aren’t getting a significant quality benefit for the JPEG image, even if you convert it to a higher bit-depth and save it in a file format that avoids lossy compression. There would be very tiny differences, but in most cases not enough benefit to justify the larger file size and slower workflow.

There is certainly an advantage to capturing more data in the first place, such as by opting for raw capture over JPEG capture. But once you have a JPEG capture, the benefit of converting to a different file format in general is rather modest. That is especially true in Lightroom, where your ongoing adjustments are not causing a cumulative loss of image quality.

Moving Lightroom Previews

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Today’s Question: I don’t recall you ever talking about the HUGE space that the full-size previews [for Lightroom Classic CC] eventually take up on one’s computer hard drive. I know how to move the catalog (not that large) to another external drive, but I could not find out how to move the previews to an external hard drive to save space on my computer. My previews take up 100 GB!!

Tim’s Quick Answer: All of the previews for your photos in Lightroom Classic CC are actually stored in a file alongside the catalog file. As a result, if you move the entire folder containing your Lightroom catalog file, the previews will come along with the catalog.

More Detail: Lightroom creates previews of your photos to speed up the process of reviewing images. There are a variety of different previews available, including the option to generate full-resolution (1:1) previews. As the number of photos in your catalog increases, the previews files can obviously get quite large. That is especially true if you generate full-resolution previews for some (or all) of your photos.

The catalog file has a filename extension of “.lrcat”. Alongside that file you will also see a file that contains the previews for your images. That file will have the same base filename as the catalog with the word “Previews” appended to it, and this file will have an “.lrdata” filename extension.

As long as the previews file remains with the catalog file, Lightroom will be able to find the previews that have already been generated. So, you can move the folder containing the catalog file to a different storage location, and the previews will be included with that transfer.

To actually move your Lightroom catalog to a different location, be sure to first close Lightroom. You can then move the folder containing your Lightroom catalog to the desired location. To quickly open Lightroom with the catalog in the new location, you can simply double-click on the catalog file (with the “.lrcat” filename extension) to open Lightroom using that catalog.

Note, by the way, that you can also have Lightroom automatically purge full-resolution previews after a set time interval, to help keep that particular previews file from getting too large. To review this setting, bring up the Catalog Settings dialog by choosing “Catalog Settings” from the Lightroom menu on Macintosh or the Edit menu on Windows. On the File Handling tab you can then select how soon you want full-resolution previews discarded from the popup labeled “Automatically Discard 1:1 Previews”.