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At very wide angles the danger is much less and taking photos with the sun in the field of view doesn't normally harm the camera or lens. When the sun is very low on the horizon the energy is also reduced as there is much more of Earth's atmosphere to absorb much of that energy between an observer on the ground than when the sun is high in the sky.

More importantly, with wider angles of view it probably doesn't do any harm to the photographer's eyesight. Keep in mind, though, that to the best of my knowledge NO manufacturer of cameras or lenses has ever said anything to the effect of, "It's okay to look at the sun through our camera's viewfinder." If in doubt, use Live View. You can replace a camera. You can't replace retinas cooked by the sun's infrared light!

With narrower angles of view provided by longer focal length lenses it's an entirely different story. You can damage your camera in mere seconds. You can also permanently damage your eyes. Your retinas have no pain receptors. Even looking at the unmagnified sun for a relatively short time period with your naked eyes can damage them. Human pupils have a minimum opening of only about 2-4mm when fully constricted. Now take a high powered telephoto lens, such as a 200mm f/2.8 - the entrance pupil is over 70mm wide! The amount of sunlight, including infrared light, striking a circle 70mm wide is 320X as much as the amount striking a 4mm circle, and over 1,200X as that striking a 2 mm wide circle! Multiply that energy times 4 for a 400mm f/2.8 or a 560mm f/4 or an 800mm f/5.6. All of that energy is being refracted and focused into a much smaller area and coming out the back of your viewfinder in about a 3mm wide light field which your cornea focuses down to a very small area. You can literally cook your retina in little more than an instant with the infrared light from the sun through such a lens.

Be sure to protect your eyesight and do not look directly at the sun through the viewfinder at all when it is at or near full brightness high in the sky!

At very wide angles the danger is much less and taking photos with the sun in the field of view doesn't normally harm the camera or lens. When the sun is very low on the horizon the energy is also reduced as there is much more of Earth's atmosphere to absorb much of that energy between the sun and an observer on the ground than when the sun is high in the sky.

More importantly, with wider angles of view it probably doesn't do any harm to the photographer's eyesight. Keep in mind, though, that to the best of my knowledge NO manufacturer of cameras or lenses has ever said anything to the effect of, "It's okay to look at the sun through our camera's viewfinder." If in doubt, use Live View or a camera with an Electronic View Finder (EVF). You can replace a camera. You can't replace retinas cooked by the sun's infrared light!

With narrower angles of view provided by longer focal length lenses it's an entirely different story. You can damage your camera in mere seconds. You can also permanently damage your eyes. Your retinas have no pain receptors. Even looking at the unmagnified sun for a relatively short time period with your naked eyes can damage them. Human pupils have a minimum opening of only about 2-4mm when fully constricted. Now take a high powered telephoto lens, such as a 200mm f/2.8 - the entrance pupil is over 70mm wide! The amount of sunlight, including infrared light, striking a circle 70mm wide is 320X as much as the amount striking a 4mm circle, and over 1,200X as that striking a 2 mm wide circle! Multiply that energy times 4 for a 400mm f/2.8 or a 560mm f/4 or an 800mm f/5.6. All of that energy is being refracted and focused into a much smaller area and coming out the back of your optical viewfinder in about a 3mm wide light field which your cornea focuses down to a very small area. You can literally cook your retina in little more than an instant with the infrared light from the sun through such a lens.

Be sure to protect your eyesight and do not look directly at the sun through an optical viewfinder at all when it is at or near full brightness high in the sky!

Epilogue:

Lensrentals.com has posted a blog entry in which what happened to some of their rental equipment that were used without proper solar filtering during the recent total eclipse in the United States is shown in photos of the damaged equipment.

Damage to a shutter curtain:

Damage to a sensor:

Damage to the aperture diaphragm of a 600mm f/4 when the user used a rear positioned drop-in solar filter:

With narrower angles of view provided by longer focal length lenses it's an entirely different story. You can damage your camera in mere seconds. You can also permanently damage your eyes. Your retinas have no pain receptors. Even looking at the unmagnified sun for a relatively short time period with your naked eyes can damage them. That is with pupils with an opening of only about 2-4mm. Now take a high powered telephoto lens, such as a 200mm f/2.8 - the entrance pupil is over 70mm wide! The amount of sunlight, including infrared light, striking a circle 70mm wide is 320X as much as the amount striking a 4mm circle, and over 1,200X as that striking a 2 mm wide circle! Multiply that energy times 4 for a 400mm f/2.8 or a 560mm f/4 or an 800mm f/5.6. All of that energy is being refracted and focused into a much smaller area and coming out the back of your viewfinder in about a 3mm wide light field which your cornea focuses down to a very small area. You can literally cook your retina in little more than an instant with the infrared light from the sun through such a lens.

Thank goodness this camera wasn't in Live View with the shutter curtains open for the 1 minute it took the sun to do this through a 600mm f/4 lens during a flare test, during which the sun was just out of the frame but obviously just inside the lens' image circle, by Bryan at The-Digital-Picture. If the light that fell on the edge of the light box had been focused on the sensor or shutter curtains (in viewfinder mode) the camera would likely have been rendered unusable.

With narrower angles of view provided by longer focal length lenses it's an entirely different story. You can damage your camera in mere seconds. You can also permanently damage your eyes. Your retinas have no pain receptors. Even looking at the unmagnified sun for a relatively short time period with your naked eyes can damage them. Human pupils have a minimum opening of only about 2-4mm when fully constricted. Now take a high powered telephoto lens, such as a 200mm f/2.8 - the entrance pupil is over 70mm wide! The amount of sunlight, including infrared light, striking a circle 70mm wide is 320X as much as the amount striking a 4mm circle, and over 1,200X as that striking a 2 mm wide circle! Multiply that energy times 4 for a 400mm f/2.8 or a 560mm f/4 or an 800mm f/5.6. All of that energy is being refracted and focused into a much smaller area and coming out the back of your viewfinder in about a 3mm wide light field which your cornea focuses down to a very small area. You can literally cook your retina in little more than an instant with the infrared light from the sun through such a lens.

Thank goodness this camera wasn't in Live View and pointed directly at the sun with the shutter curtains open for the 1 minute it took the sun to do this through a 600mm f/4 lens. It happened during a flare test conducted by Bryan at The-Digital-Picture with the sun just out of the frame but obviously just inside the lens' image circle. If the light that fell on the edge of the light box had been focused on the sensor or shutter curtains (in viewfinder mode) the camera would likely have been rendered unusable.