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Comment by dingaling | Hacker News Reader

It's a shame that Lens Rentals had to suffer such material loss, but that report is absolute gold-plated first-hand evidence for my perennial debates with other photographers who insist that they don't need Solar protection for eclipses.

"But I took a landscape shot at midday with the Sun in frame and it didn't melt my sensor". The difference being the length of exposure and the concentrations of energy.

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Just to clarify, there’s no concentration of energy involved with the eclipse itself. The concentration involved is no different than setting a leaf on fire with a magnifying glass on a regular day.

The sun isn’t a garden hose. Putting something in front of it doesn’t make the edges more intense.

There kind of is, because it's darker when the sun is partially covered, so you'll use a larger aperture or longer exposure than you would normally. This is also why it's more dangerous to look at the sun during an eclipse than it is normally: your iris opens wider during an eclipse because it's not as bright.

I think you misunderstood his point, which was: there is no more energy coming from the sun at any given point during the eclipse than in a clear day. The sun isn't "sending" more energy on the path that aren't blocked, nor is the energy blocked going around the obstacle and concentrating on the areas still visibles.

The reason for the damage is entirely due to the receiver behaving/being differently, be it your eyes or your camera, because they get tricked into thinking it's dark and they act like it, being much more receptive and then overwhelmed.

"tricked into thinking it's dark" is kind of misleading, because it is in fact darker, but for some reason unknown to me there the energy from the sun harms you as much. I thought the issue with looking at its sun was its brightness, but i guess it isn't?

During a partial eclipse, part of the sun is hidden behind the moon. So the overall amount of light reaching the ground around you is indeed less, in direct proportion to the amount of sun that is eclipsed.

For example, if 90% of the sun is covered by the moon, then only 10% of the usual amount of sunlight will light up the area around you. So it is quite a bit darker than usual.

However, the portion of the sun that is still visible is just as bright as it would be on any other similar day. If you stare at that remaining portion of the sun, or aim a camera at it, it will cause the same damage as it would any other time, only in a smaller crescent-shaped area instead of a full circle.

The danger to your eyes is even greater, because the overall darkness tricks your irises into opening up wider and letting even more light in than usual.

You're pretty unlikely to stare at the sun for 30 seconds on a normal day. But people do that during a partial eclipse, and that's the problem. Similarly, people don't usually aim their cameras directly at the sun with the lens wide open and no solar filter - except during an eclipse.

A total eclipse is quite a different thing, of course. During totality, the sun's bright photosphere is completely hidden, and only the much fainter corona is visible. This is only about as bright as a full moon, and it's perfectly safe to take pictures with any lens, and to observe directly with the naked eye - even with binoculars.

So I could shine a flashlight into my eyes while looking at the eclipse, and I'd be ok?

That's one of the best explanations I heard about why and how the eye damage can occur. I'm curious how far can you carry that reasoning: If 99.9999999% of the sun were covered during a partial eclipse (down to a single stream of photons), does it damage one single rod on my retina as opposed to a crescent-shaped region? I'm guessing that a single stream of photons from the sun doesn't have enough energy to do any damage.

Now that is an interesting question!

Anecdotally, I viewed the 1979 total eclipse with binoculars (and no filters), and at the end of totality I continued to look through them for a few seconds to see the diamond ring and Baily's beads.

It didn't harm my vision at all, even though there was some fair amount of direct sunlight coming through by then. But it was only a few seconds. The duration of sun exposure certainly is a factor.

The issue is how much light gets focused onto a small area of your retina. When the sun is partially eclipsed, the darkness makes your iris open up to let more light in. That then focuses more light from the visible part of the sun onto the same area of retina.

Your iris reacts to visible wavelengths and not ultraviolet wavelengths. So your iris is open much wider than it ought to be given the amount of UV present (especially given that UV is much more damaging than visible). If you see what I mean :)

It is brightness, but brightness at a single focused point, not total brightness.

> because they get tricked into thinking it's dark and they act like it

This is a really bad example :DDD

I don't think that is totally true for human eye. You can test it by putting a LED spotlight in front of you at night, and have someone else check your pupil before and after you turn on the LED (And remember test it in different distances).

Camera works differently, they have multiple ways (Metering Modes) to test the brightness of a scene. So how it work will depends on the selected Metering Mode.

And camera can collect more light by letting light keep entering the light sensor for longer time. Plus, bigger lens can also collect more light, some people may even mount their camera on a telescope, thus more light entering. So maybe this is the physical reason why so many gears got destroyed?

I understood the point just fine. My point is that there is a greater concentration of energy which is what causes damage, it just happens in the optics rather than at the source.

i was always wondering how a pin hole protects you, and i mean im sure i could have looked it up but just, really wasnt important. dude that tid bit made my day - the more you know

Dingaling is talking about the light being concentrated on certain areas of the sensor. Because the total/average brightness is low, the exposure ends up being much longer then at normal conditions, causing damage to the areas where the light is concentrated. Under normal conditions, the light will be less concentrated on certain spots, so even though there is much more light in total, the camera will choose an appropriate exposure that will prevent damage to the sensor.

You'd have to be incompetent to trust autoexposure during an eclipse.

> The concentration involved is no different than setting a leaf on fire with a magnifying glass on a regular day.

That's what they're saying. Zooming in on the sun vs the sun happening to be in-frame.

Are you saying zooming in on the sun makes damage more likely?

Wouldn't zooming in spread the sun's energy across more of the sensor? Same energy, larger area = less intensity.

The irradiance is determined by the aperture, which is measured relative to the focal length. So with e.g. f/2 you get the same heating of a given area of the sensor regardless of the focal length (i.e. "zoom").

Put differently, longer lenses typically also have bigger absolute apertures, collecting incident light from a larger cross-section. This compensates for the fact that a given solid angle of incident light is spread over a larger area of the sensor.

They have an in-house repair shop that dealt with most or all of it, and they charge the customer for the cost of the repair. From the comments the fact that they don't gouge on repairs is one reason some folks use them.

How do you fix a burnt cmos sensor? I feel like canon would charge you near enough the full replacement price.

I'd imagine it's a fairly common replacement. I've seen event photographers do it quite a few times putting their cameras near lasers.

I'm only a reluctant amateur photographer, but my understanding is that damaged sensors cannot be repaired, and that manufacturers will quote repair costs totalling or exceeding the cost of an entirely new camera.

A quick search online reveals plenty of sources of replacement sensors, at a fraction of the cost of the complete camera.

There do seem to be people selling 7d mark ii cmos sensors for ~$300, while a new body would cost ~$1100.

Someone posted a video of replacing the sensor on the old 7d (https://www.youtube.com/watch?v=udonzfGdW0Y)

Seems it eventually worked for him, after several attempts to adjust the position to get correct focus, but if you read the comments on the video there are many people who've messed up their camera trying to do this.

Might be fun to try though.

They might send that back to the manufacturer to fix.

In the Reddit thread, they talked about replacing the aperture module for some of the lenses; that's just a simple swap, along with cleaning the adjacent elements.

You fix it yourself, most likely using a sensor from another broken camera.

I wish the blog post had talked more about that. I'm curious about their repair process. What capabilities do they have in house? Can they replace a broken sensor?

They blog a lot about their repairs process in general. It's primarily mechanical damage to lenses they appear to normally deal in - the focusing rings, aperture mechanisms or realigning optical elements dislodged by drops and so on. An embedded CCD/CMOS sensor is probably a full logic board replacement I'd assume, as opposed to some kind of sensor only replacement, given it's almost always soldered on.

I know about 12 years ago I blew the firewire connection on my video camera (Canon xm2), and to fix it they would have to replace the full board.

So I feel like they don't make them repairable.

There are a lot of things that a professional repair shop focused on a particular type of equipment may be able to do that aren't practical for anyone else - including manufacturer repair facilities. Louis Rossman is a bit entertaining on this: https://m.youtube.com/watch?v=ocF_hrr83Oc

Yet with a heat gun its an easy fix.

It depends on their expertise

Yup, it all came down to how long the camera was pointed at the sun. I took a bunch of photos of the eclipse including this HDR shot with a Leica 280mm lens and Sony A7R with no filter whatsoever & without any damage to my lens or camera. The thing is, it took seconds to take and I made sure the camera was only pointed at the sun for brief moments:

https://www.flickr.com/photos/patcheudor/35886777354/

I'm assuming the damage Lens Rentals saw was from people who were trying to do time-lapse.

Off topic, but I think here's another image of the same airplane, also taken in Idaho: https://www.reddit.com/r/aviation/comments/6v62nl/plane_cros...

That turned out to be a fake.

https://www.reddit.com/r/pics/comments/6v6y1k/

Oh man that's hilarious considering this: https://petapixel.com/2016/01/29/nikon-awards-prize-to-badly...

I was in North Eastern Idaho and there is a similar looking contrail visible in my wide angle shots at totality so if the point of image capture happened to be just right it would be possible to have it in the frame with the sun.

That one would have been taken about 15 miles or so to the southwest of my location.

You can torch your sensor in seconds:

https://youtu.be/2TO_yZDxryQ

At Lick Observatory, they close the slit in the roof before repositioning during daytime observation (yes, that is a thing) to avoid even the chance of running into Mr. Sun.

Yeah, if you use a super-telephoto lens, then take your camera body off and change the focal point so that you are using your lens as a magnifying glass like they did in the video. No doubt. For the rest of the sane world; however, it's not quite that risky. For reference, that Leica I used in my shot is a one of a kind as it was the first lens to roll off the line when Leitz branding was changed to Leica & estimated to be worth between $12,000 to $22,000. I wouldn't have risked it if there was any risk whatsoever.

No, it is the opposite. A 50mm f/1.4 lens focus the light and the heath much more than a 300mm f/5.6. You were quite lucky with your camera I guess.

Correct.

The flux for the sun on the sensor/film/whatever is:

    Φ/4α² * 1/A²

Where Φ is the sun flux at the surface of the earth, and α is the angular diameter of the sun. A is the f-number of the lens, the only variable in this equation. It doesn't depend on focal length.

The total power over the film is:

    Φ/4πα * f²/A²

which does depend on focal length, but that is usually not the determinant factor, as for surface burns the damage depends mostly on the flux.

Surface damage mostly depends on the power density, not on total power, so it depends mostly on the aperture, not on the focal length. This makes longer focal lengths safer to point at the sun because they are slower lenses. They are also safer if you don't explicitly point them at the sun because they are less likely to catch the sun in the smaller field of view.

Burned shutter cloths on Leica M series cameras with wide angle lenses is a real problem that can happen simply if you leave the camera without a lens cap lying on a table. This is less of a problem on most other cameras, as they use metal shutter curtains.

I wonder if that guy damaged his lens while making that. That lens looks similar to one of the damaged ones in the article.

To satisfy your curiosity, he did not. The lens was borrowed from his workplace (a camera store) for the purpose of the video, and was returned unharmed.

The creator of that video hangs around on /r/photography, his comment is here: https://www.reddit.com/r/photography/comments/6xg8a7/lens_re...

> And of the things returned, we were equally impressed with our customer-base, and their guilt and owning up to the damage.

I thought the renters would be paying for it?

They still probably lose out on some revenue until a replacement is in stock. Having a working lens is always better for business than getting reimbursed to buy a replacement lens. (That's the nature of the business, though.)

LensRentals do all possible repairs internally, so I suspect that the downtime on an expensive lens like that is minimal if possible. Roger mentioned on the photography subreddit that the aperture replacement was a $200 part and 3 to 4 hours -- it only took so long because it was that tech's first time replacing that part.

https://www.reddit.com/r/photography/comments/6xg8a7/lens_re...

He mentions in the article they rented out “thousands” of lenses. I’m guessing the few lenses they have to repair because of this is barely over their normal repair load.

The renters are paying for it. Next sentence:

> Unfortunately, these types of damage are considered neglect

Still, lots of people might feign ignorance.

You can feign ignorance. It doesn't change the fact that the lens has a burn hole on it now.

Deny, deny, deny.

Ah, yes, the Shaggy defense [1]. It's is rarely is successful in practice though.

[1] https://en.wikipedia.org/wiki/Shaggy_defense

It's like denying you murdered somebody when you sent the police the murder weapon with your fingerprints in the victim's blood. Unless you're OJ Simpson, you're going to jail.

lens? what lens?

Presumably the rental place isn't planning to just eat the loss. They have the renters' credit card numbers...

When you hire a lens, you're contractually and personally on the hook for anything not insured.

So yes, somebody owes LR a considerable amount of money for repairing or replacing that £11,000 600mm lens.

The admin of dealing with this crap is built into the rental price. A well looked after lens doesn't depreciate fast.

Worth noting that on the 600mm with melted iris, the user did use a solar filter.

Unfortunately for the lens, the 600mm lens's drop-in filter slot is behind the iris. So the camera was fine, the lens not so much.

http://shuttermuse.com/canon-drop-in-filter-guide/

Why do they even make a drop in filter rated for the sun, if it's going to damage the lens?

What use could you make of this filter?

There is a drop in filter holder that takes 52mm filters designed to screw on to the front of lenses.

(For those unfamiliar - it works this way because the objective element of this lens is far larger than anyone makes filters for. 52mm is a very common diameter, so placing a drop-in mount further along in the focal path means you can use a wide range of filters with minimal cost and inconvenience, and to identical effect - except, of course, in the rare case where you have enough energy coming down the barrel to damage the iris.)

hey astronomy was a wicked hard class and i still dont get it, so maybe this will be a very expensive lesson for them. sadly it probably wont be the right one but that is life. you know that there had to be a couple of smug asshats that were brought down a peg, thats pretty funny. I missed the eclipse.

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