Ask Tim Grey

Today’s Question: My understanding has been that prints made on matte surface, inkjet printing papers are generally more archival than glossy surface papers. Do you agree? And how, if at all, does the coating on coated matte papers influence the print’s life expectancy?

Tim’s Quick Answer: There are a variety of factors that impact overall print longevity. However, in general matte papers will provide the greatest longevity. Glossy papers will generally provide the least longevity, and coated matte papers can be expected to provide longevity that falls somewhere in between.

More Detail: Let’s first assume that all other factors are equal in this case. That’s not a small assumption, of course. There are factors related to the composition of the paper substrate, the degree to which a given paper is acid-free, and many others.

However, among the various factors that impact print longevity is how close the inks ultimately sit to the surface of the paper. The closer the inks are to the surface, the more exposed those inks will be to environmental factors.

Glossy papers generally cause inks to stay at the surface rather than being absorbed. As a result, the inks are more exposed to environmental factors that can cause the inks to fade over time. In other words, with a glossy surface there is a greater risk that the print will fade relatively quickly.

Matte papers, on the other hand, absorb the inks so that the inks can be thought of as somewhat “sitting below the surface” of the paper. That helps to protect the inks, so they are not as prone to fading. Of course, that also reduces the overall color saturation and tonal contrast of the print.

A coated matte paper will generally fall somewhere in between. The matte paper itself is more absorbent than a glossy paper would otherwise be. However, the coating causes the paper to behave a little more like a glossy paper than a matte paper. Thus, in general I would expect coated matte papers to have a print longevity that is longer than that of a glossy paper, but shorter than that of an uncoated matte paper.

Today’s Question: I wondered if you could settle a curiosity for me. Do you know what the rubber rectangle on my camera strap is for? It almost looks like it could fit on the flash hot shoe, but it doesn’t. I can’t figure out what it is for. Help!

Tim’s Quick Answer: The rubber device you’re referring to is a cover for the viewfinder, used to prevent light from entering the viewfinder. You generally need to remove the eyepiece on the viewfinder in order to attach this cover.

More Detail: It seems to be conventional wisdom that during long exposures at night, you should cover up the viewfinder to prevent light from getting into the camera and causing aberrations. In my experience this is not an issue at all. There have certainly been cameras in the past (think large view cameras) where light was an issue in this way. But as far as I’m concerned this is not a concern for modern digital SLR cameras.

However, there is another reason you may still want to cover the viewfinder for night photography (among other situations). While light coming in through the viewfinder won’t impact your photos, it can have a significant impact on your camera’s meter. If you’re using an automatic or semi-automatic exposure mode, or, depending on the camera’s meter to measure the exposure for a night photo, it is a good idea to cover the viewfinder. Of course, it would also be fair to point out that the camera’s meter isn’t incredibly helpful with a lot of night photography anyway.

So, while light can most certainly come in through the viewfinder and affect your camera’s meter, you don’t need to worry about that light in terms of the actual image being captured. More importantly, now you know what that little gadget is on your camera strap!

Today’s Question: Our photography club said not to use IS [image stabilization] on a tripod. With absolutely no movement, the lens will start vibrating to create motion that it can stabilize. I read this somewhere else too, but most people don’t seem to know.

Tim’s Quick Answer: This is one of those bits of advice that has become slightly out of date. With some lenses you can indeed leave image stabilization turned on even when using a tripod. Other lenses include stabilization modes specifically designed for situations where you are panning with a subject.

More Detail: With most older lenses that include image stabilization, it is absolutely true that you should leave the stabilization feature turned off when you are using the lens with a tripod. Otherwise the stabilization technology can actually cause movement that translates into a blurred shot, defeating the whole purpose.

Many newer lenses, however, have stabilization technology that works well even when using a tripod. Some lenses even include special features that enable image stabilization to effective when panning. For example, Canon has incorporated a “Mode 2” option for some of their lenses that is designed for use when panning.

The key is to make sure that the lens you’re using has image stabilization technology that works well with a tripod. But in general you’ll find that with modern lenses the advice to turn off image stabilization is no longer critical advice.

As a general rule, with a static subject when photographing with the use of a tripod, I myself am still in the habit of turning off image stabilization. But in truth, most newer lenses with image stabilization technology (going back to 1999 in the case of Canon lenses, for example) can be used with a tripod even with image stabilization turned on.

Today’s Question: As a part of my workflow in Lightroom, I hold down the Option key [Alt key on Windows] and move the masking slider to adjust the area in the image that I want to sharpen. Sometimes when I am doing this, I think that the result that I see would make an interesting abstract. I think this must be a little like the posterization effect in Photoshop, but when I try to use that approach, it doesn’t seem to produce the same outcome I get with the masking slider. What is it that is actually happening in Lightroom with the masking slider and how could I best reproduce that effect in either Lightroom or Photoshop?

Tim’s Quick Answer: The effect you’re seeing is somewhat similar to a result you can achieve with the Find Edges filter in Photoshop. The approach involves using the Find Edges filter and then creating additional contrast and possibly inverting the result.

More Detail: To get started, open the image in Photoshop. Then create a copy of the Background image layer. From the menu bar choose Filter > Stylize > Find Edges. There are no parameters for this filter, so you’ll simply see the result in the image.

Next, add a Hue/Saturation adjustment layer, and reduce the Saturation completely. This will remove the color created as part of the Find Edges filter, so that you have a black and white version of the image.

You can then add a Levels (or Curves) adjustment layer and drag the black and white point sliders inward to create extreme contrast for the photo. You will generally want to bring these end points very close to each other, possibly all the way until those end points are touching each other. Pay attention to the detail within the photo to help choose where those two end points should meet.

You can then add an Invert adjustment layer if you’d like to reverse the areas that appear black versus white, which will provide the same basic result you were seeing in Lightroom. You may also want to apply a slight blur to the Background Copy layer, using the Gaussian Blur filter.

Note that in some cases you may prefer the effect produced by first working with a lower-resolution image, and then increasing the size of that image to exaggerate the size of the lines created by the effect.

It is worth noting that you could also simply produce a screen capture of the effect directly from the Develop module in Lightroom when using the preview feature (by holding down the Alt/Option key on the keyboard) while adjusting the Masking setting for the sharpening effect. Because the image is abstract, having a relatively low-resolution screen capture won’t have a significant effect on the appearance of the final image.

Today’s Question: I rented a fisheye zoom lens (Canon 8-15mm) to try out, because I’ve never used one. I am not getting the circular images that I was expecting. At the widest zoom setting there is a little vignetting, but the image isn’t a circle. How do you achieve the circular image that to me represents a fisheye photo?

Tim’s Quick Answer: It sounds like you are using a camera with a “cropped” sensor, meaning a sensor smaller than full-frame. To achieve a circular fisheye image, you need to use the lens on a full-frame camera.

More Detail: The Canon 8-15mm fisheye lens (http://timgrey.me/atg815fish) is indeed a genuine fisheye lens, capable of capturing the classic circular images with an extremely wide perspective. I should clarify that the image itself will still be rectangular, but the circular fisheye image will appear within that rectangle, with the rest of the image area being black.

A fisheye lens like this projects a smaller image circle than other lenses, enabling you to capture the circular image effect that is commonly associated with photos captured with a fisheye lens. However, this lens is designed for a full-frame sensor. A smaller image sensor will crop the image circle, so that you aren’t able to see the full circular effect. Instead, at the shortest focal length you will simply see some vignetting in the corners of the image.

This lens includes a “Limit” switch, enabling you to lock the lens so that you can’t zoom out beyond a 10mm focal length. At focal lengths from 10mm onward, you won’t get the vignetting at the corners of the image, because the image circle is effectively being enlarged to more than fill the area of the smaller sensor.

In this case if you want to achieve circular fisheye images you have two options. You can either work with a full-frame camera using one of the various fisheye lens options available, such as the 8-15mm noted above. Or you can use a fisheye lens designed for cropped sensors, such as the Sigma 4.5mm (http://timgrey.me/atgcropfish).

Today’s Question: You had recommended setting your camera [the Canon EOS 7D Mark II] to record to two memory cards at the same time. My camera has this feature, but when I capture video it is still only saved to one card. Photos are going to both cards. How do I fix this for video?

Tim’s Quick Answer: You can’t fix this on the 7D Mark II (or as far as I know on any other digital SLR). While photos can be saved to two cards at once thanks to two cards slots on this camera (among others), you can’t save video to two cards at once.

More Detail: While you can’t record video to two cards, you can choose which card the videos get saved to. The result is that your photos will be saved on both cards, but your videos will only be saved on one of those cards.

In general I would tend to use the fastest media card of the two for saving video. However, I actually opt for the SD card rather than the CompactFlash card as the card that my videos get stored to. That is because my primary computer has a built-in SD card reader. In other words, I prioritize convenience in my overall workflow rather than the performance of the card. And, of course, I use relatively fast cards in any event.

In the case of the Canon 7D Mark II you can choose which card to record videos to from the menu on the LCD. Under the “Set Up 1” menu you can choose the “Record fun+card/folder sel.” option. Then, with the “Record func.” option set to “Rec. to Multiple”, choose the Playback setting and choose the card you want to use for playback. That card will then also be used as the card that video is recorded to.

Today’s Question: You made reference to setting a custom white balance in the camera based on a gray card. How can this be done?

Tim’s Quick Answer: The specific process will vary from one camera to the next, but in general that process is the same. You simply capture a photo of a gray card (or similar neutral object) and then use that photo as the basis of a custom white balance setting in the camera.

More Detail: The concept here is that if you capture a photo of a neutral object (such as a gray card) under the same lighting conditions as the subject you will be photographing, the color of that object as it is captured can be used as the basis of an automatic white balance adjustment for subsequent photos captured under the same conditions.

While a gray card is certainly a great tool to use in this process, it is also possible to employ any other neutral (non-colored) object, such as a bright white sheet of paper. Perhaps the most important part of this process is to be sure you are photographing the gray card (or alternative) under the same lighting conditions that will illuminate your subject.

In other words, this process works best when the lighting on your subject is relatively consistent and uniform. You can then place the gray card in that light, and fill the camera’s frame with the gray card. Once you have captured a photo of the gray card under the lighting conditions for your subject, you can set that photo as the basis of a custom white balance adjustment.

Again, the specific process will vary by camera model, but in general you can simply choose the custom white balance option within your camera’s menu system and then select the appropriate photo as the basis of that custom white balance.

I should hasten to add that this custom white balance option is different from the similarly named option that enables you to dial in a specific Kelvin value for the white balance compensation. The process described above offers a relatively automated approach to compensating for the color of light on your subject through the use of a “sample” photograph captured under the same conditions.

Today’s Question: If you are using Lightroom and you setup your camera for white balance by using a gray card, is it still necessary to use the ColorChecker Passport to setup a color profile the get accurate colors?

Tim’s Quick Answer: That depends on the degree of accuracy you require. For situations (such as product photography) where color accuracy can be critical, I would recommend building a profile based on the X-Rite ColorChecker Passport (http://timgrey.me/checkerpassport). For situations where the color accuracy in the original capture isn’t as critical, using a gray card is generally adequate.

More Detail: When using a gray card (or other color-neutral object) as the basis of a white balance adjustment either in the camera or in post-processing, you’re only applying a simple compensation to the color in the image that will produce a neutral value for that gray card. The X-Rite ColorChecker Passport includes a series of color swatches that can be used to apply a more accurate color adjustment to your photos.

In many cases, especially when you are exercising a degree of artistic interpretation for the colors in a photo, the accuracy provided by the ColorChecker Passport is generally not necessary. By using a gray card to compensate for the color of the light illuminating the scene you’ll be able to get a reasonably accurate result.

What you’ll find is that a gray card enables you to compensate rather effectively for the color of the light source. But the individual color values may still not be quite perfect. Because of the multiple color swatches on the ColorChecker Passport, individual colors will appear more accurate after applying the profile. This will produce a subtle (but sometimes important) shift in some of the individual colors within a photo.

It is worth pointing out, of course, that in some cases you don’t really need to use a gray card or other approach to compensate for the color of light. After all, using this type of approach is focused on removing the color element of the light illuminating the scene, and in many cases that color is a big part of the reason you captured the image in the first place.

Today’s Question: Somehow I’ve accidently activated a ‘Grid’ that is overlaying every image that I open in Photoshop. I have gone into ‘View’ but the ‘Clear Guides’ command is not active (greyed out).

Tim’s Quick Answer: In this case it sounds like it is actually the Grid display option that is an issue, not the Guides. So all you need to do is choose View > Show > Grid from the menu to disable the Grid display.

More Detail: Photoshop provides you with a variety of non-printing display options, primarily aimed at helping you align various objects within a document. Of course, when you enable one of these options by mistake it can become a bit distracting.

For example, one of the other grid options is the Pixel Grid, which can also be found on the View > Show submenu. You’ll find other options as well, some of which you may find helpful from time to time.

There is also an “Extras” option on the View menu, which you can think of as something of a “master switch” for the various display options found on the View > Show submenu. In other words, if you like to enable some of the options found under the View > Show menu, you can temporarily disable (or re-enable) all of them by choosing View > Extras from the menu.

It is worth noting that these various display options can be toggled on or off. When an option is enabled, you will see a checkmark icon next to the name of that option on the menu. When an option is disabled you will not see that checkmark.

Also note that some of these view options have keyboard shortcuts associated with them, which you can see to the right of the applicable options on the menu. Those keyboard shortcuts provide an additional option for quickly enabling or disabling specific options. I suspect that in most cases when one of these options is activated by accident, it happens by pressing a keyboard shortcut unintentionally.

Today’s Question: With reference to your answer about a rule for minimum shutter speed relative to lens focal length, how does the presence of image stabilization in the lens impact this? In other words, can’t I use a slower than recommended shutter speed when employing image stabilization?

Tim’s Quick Answer: Image stabilization technology does provide a benefit that could enable you to employ a slower shutter speed (longer exposure duration) than would otherwise be possible when shooting hand-held (and even when shooting on a tripod in many cases). However, my preference is to treat this benefit as a “bonus” and to continue following the rule of thumb about minimum shutter speed relative to focal length.

More Detail: As a reminder, the rule of thumb about minimum shutter speed relates to lens focal length. More accurately, this rule relates to field of view. With a narrower field of view, any movement of the camera will essentially be magnified, requiring a faster shutter speed to ensure a sharp image. As a general guideline, it is recommended that the lens focal length be used as a minimum value for the denominator in the shutter speed. So, a 100mm lens would call for a 1/100th of a second or faster shutter speed, and a 300mm lens would call for a 1/300th of a second or faster shutter speed.

Image stabilization technology is generally promoted as providing a benefit expressed as a number of stops of light. You might achieve a benefit of anywhere from one stop to about five stops, at least according to marketing materials from various manufacturers. For illustrative purposes, let’s assume a two-stop benefit from a given image stabilization technology.

With a two-stop benefit you could use a slower shutter speed than would otherwise be possible. So with a 100mm lens you could use a 1/25th of a second shutter speed rather than 1/100th of a second. With a 300mm lens you could use a 1/75th of a second shutter speed rather than 1/300th.

While I certainly appreciate the benefit of image stabilization technology, I also realize there are limitations and a variety of other real-world issues that may affect the sharpness of my photos. Therefore, I prefer to follow the rule of thumb about shutter speeds relative to focal length without taking image stabilization into account.

As a result, any benefit caused by image stabilization becomes a “bonus” benefit, further increasing the chances of capturing a sharp photo when shooting hand-held.