MILC 'shutters'.....Sun Damage?

Whenever you see a lens-off shot of a mirrorless body you can plainly see the sensor, albeit behind a filter stack of some sort.

 

Many of these same cameras also have what is referred to as a 'mechanical shutter'. Where is it?

 

On a connected note, if you happen to leave your mirrorless camera pointed* at the sun with a long lens on, does it damage the sensor?

 

In a DSLR it can send the light beam back out of the OVF via the main mirror and penta-prism/mirror.

 

* or the sun moves around to shine down the barrel of a once-safely placed camera.

Most of them have a mechanical shutter in the usual place, but often leave the shutter open when the camera is powered off - this makes sensor cleaning easier (or at least less prone to the shutter blades slamming shut on the cleaning equipment). It also makes it more likely that dust will land on the sensor when you change lens, and there's a trade-off for whether lens changes are better scraping a mechanical shutter or a sensor stack.

 

And yes, you can burn a sensor, although it's a lump of metal that is at least partly heat sinked* so you have to try. I suspect the filters would go first, but I don't know.

 

(* sank?)

In a DSLR it can send the light beam back out of the OVF via the main mirror and penta-prism/mirror.

 

Incidentally, only some of it. You're still frying the AF system and the meter. And lensrentals showed a big telephoto with burned aperture blades from a recent eclipse.

 

I've always been a bit confused that people seem to worry more about reflectors than refractors when it comes to pointing them at the sun, unless I'm getting an odd impression. I'd expect a refractor to be more likely to be a sealed unit and to have internal heat build-up. I'm disappointed during pending eclipses that the Sky at Night doesn't deliberately fry something with a (small) telescope as a way of impressing on people that looking at the sun through magnifying optics is a bad idea - I've never known them to do it.

 

Belatedly: found the link - mangled aperture blades, burnt shutter blades, burnt sensor. On rare occasions, adding more light does not make photography easier!

Not something that's currently robbing me of sleep.

Not something that's currently robbing me of sleep.

 

Because at night the sun won't damage the sensor?

 

Allegedly one reason for metal shutter blades was because of all the Leica owners who'd left the camera lens pointing up and found holes burned in it. You have to try a bit harder with titanium blades, but to a big enough telephoto, everything looks like an ant. One thing I picked up in the recent Apollo celebrations was that Apollo 12 had a colour TV camera that the carried onto the moon surface - but accidentally fried it by pointing it at the sun while setting it up.

 

There was at least one mirrorless camera series that had the shutter blades closed by default, but I've forgotten which one it is. I'm worried that I'm going to feel silly, and it's the Z series.

There was at least one mirrorless camera series that had the shutter blades closed by default, but I've forgotten which one it is. I'm worried that I'm going to feel silly, and it's the Z series.

 

Update: That's going to bug me, and I really shouldn't waste the rest of my work day finding out. If anyone happens to remember, please put me out of my misery.

There was at least one mirrorless camera series that had the shutter blades closed by default, but I've forgotten which one it is

IIRC, the it's one (or all?) of the Canon R Series mirrorless (when the lens is taken off).

 

EDIT: It's the EOS R: The EOS R has a clever mechanism to protect the sensor when you change lenses (power must be off): the mechanical curtains close to prevent dust or other particles of reaching the sensor. (Canon EOS R vs EOS RP – Five key points analysed)

 

Never been easier to damage the mechanical shutter while changing lenses:rolleyes: - but who is turning the camera off to change lenses anyway?

Edited September 6, 2019 by Dieter Schaefer

IIRC, the it's one (or all?) of the Canon R Series mirrorless (when the lens is taken off).

 

Thank you - that was going to bug me. I skimmed an R review, but it didn't mention it.

 

EDIT: It's the EOS R: The EOS R has a clever mechanism to protect the sensor when you change lenses (power must be off): the mechanical curtains close to prevent dust or other particles of reaching the sensor. (Canon EOS R vs EOS RP – Five key points analysed)

 

Thanks. Interesting that the RP doesn't do it - it seems to backtrack on several of the more "interesting" features that the the R tried to introduce (notably also the touch bar). As various fora point out, it stops dust hitting the sensor, but it doesn't stop dust hitting the shutter blades; I'm not sure how much of a problem this really is, since I can't imagine the mirror is that great a shield on a dSLR. Interesting that the aperture blades close to stop the shutter blades getting fried (if I read correctly), but to my mind raises the question of what's stopping the aperture blades from getting fried; I suppose, at least, the sun probably wouldn't be in focus. I suspect cleaning the sensor is more immediately inconvenient than any tiny dust spec near the shutter blades, and however good a sensor shaker is at removing dust, I'd expect a shutter slamming around to be better at it.

 

Never been easier to damage the mechanical shutter while changing lenses:rolleyes: - but who is turning the camera off to change lenses anyway?

 

I'm sure I historically read something about turning off the camera during lens changes with the idea that an "on" sensor tended to carry an electrostatic charge and attracted dust. I'm not sure how scientific it is, but I've usually been turning my camera off for lens changes anyway. I'm less good at remembering to turn VR off on the lens before turning the camera off.

If dust lands on a closed shutter, won't it be shaken off when that shutter violently opens? And then float around in the camera, only to ultimately land on the sensor anyway?

Lens cap? Also does a good job of protecting the front element...

 

 

I tend to switch off when changing lenses, partly because it just seems like a good idea with anything electronic, but also because I have my cameras set to do a sensor clean on startup, so hopefully any dust that got in when changing lenses, gets shaken off straight away.

Not something that's currently robbing me of sleep.

 

Humm... CURRENTLY sounds worryingly prophetic......;)

 

Guess when you can't find a fire-extinguisher to put out your smouldering Z7 that might change??

Lens cap? Also does a good job of protecting the front element...

It's that casual 'pop it down on the table for a moment' whilst looking for your spare battery or memory card that's wriggled it's way down one of those mesh pockets that act like the fabric version of a grappling hook.

 

With anything longer than my 300mm, the element is protected by the huge CF hood, but if i forget to put the baggy thing over it and the sun moves around....:(

 

Obviously it does very occasionally happen, I was just curious about mirrorless being worse than mirrored.

- but who is turning the camera off to change lenses anyway?

I do, its only sec.

If dust lands on a closed shutter, won't it be shaken off when that shutter violently opens? And then float around in the camera, only to ultimately land on the sensor anyway?

 

I was under the impression that dSLRs tended to have something sticky in the bottom of the mirror box with a view to catching stray dust and fluff, but now I say it, I have no idea where I got that from. I did find

of a D50 mirror box tear down, which didn't mention it, but is quite interesting. I've not looked to see whether there's a full explanation for the difference between the D6x0 and D8x0 shutter/aperture lever mechanisms, which I'd still like to understand better. I always point my lens throat down when changing lenses to try to fend off fluff, since most of my lens rear elements are exposed anyway and fluff is easier to, er, spot and blow clear. If there's a massive hair inside the recessed rear element of my 300/4, I'm unlikely to know until too late. (I'm temporarily between cats, but normally the fluff-to-clear-air ratio in my house is high, which is why I don't do my own sensor cleaning and don't really know what the inside of a mirror box looks like - and why I'm cross my wife let a foster cat into my study.)

 

It's that casual 'pop it down on the table for a moment' whilst looking for your spare battery or memory card that's wriggled it's way down one of those mesh pockets that act like the fabric version of a grappling hook.

 

With anything longer than my 300mm, the element is protected by the huge CF hood, but if i forget to put the baggy thing over it and the sun moves around....:(

 

Obviously it does very occasionally happen, I was just curious about mirrorless being worse than mirrored.

 

I often end up with lens caps hiding in a pocket. There was the time I was trying to work out how my 70-200 had managed to acquire so much mould haze before I realised I'd just dumped a load of pocket fluff on the front element. They're usually on, but I've been known to drive around with the cap off so I can grab the lens in a hurry if I'm somewhere scenic. As Mike alludes to, the soft hood on my 200/2 takes an appreciable amount of time to use (you have to invert the hood, then pull it over the front, arrange the draw strings, support everything else with your fourth hand... my old 500mm AI-P was even worse, since the hood would slide off if you didn't do it right). I don't really know what was wrong with a "normal" lens cap for these things - it doesn't stop you rear-mounting your filters.

 

Mostly it's the "don't want to have to reattach the hood in order to take a shot, so I can't easily attach the lens cap" argument, for me. I do sometimes put the cap on, but it takes longer to remove it with the hand inside the hood, and I always worry about scratching something when reattaching it.

 

Titanium shutters solved the "shorter lens with the camera lying on its back" problem that was probably more common. Whether digital sensors are any better at surviving small bright spots of sunlight than cloth shutters were, I don't know. I don't think I've fried anything yet, but then I've taken a photo of a transit of Venus with a telephoto lens pointing straight at the sun (through cloud cover) and got away with it - although I knew full well that I'd need good reactions if the sun came out. I hope nothing nasty happened to me in infrared.

I've usually been turning my camera off for lens changes anyway. I'm less good at remembering to turn VR off on the lens before turning the camera off.

Same here - I generally turn the camera off when changing lenses - and I always forget to turn VR off beforehand.

I do, its only sec

On most mirrorless it seems takes a bit longer for the camera to come back to life:oops: - but it is indeed good practice to turn the camera (and lens-based VR) off before changing lenses.

I've taken a photo of a transit of Venus

Before the last partial eclipse there was an 'advisory' about how to watch it. Oddly, looking at it via your phone was a no-no.

 

Apparently, it's not the looking at the screen that's the problem (really..? (sarcasm!)), it's the aiming needed to see the sun on the screen means you're looking directly at the sun if/when it peeks around the edge of the phone, ie perfect alignment for blinding!

and I always forget to turn VR off beforehand

I understand failing to do this, 'killed' the OS on some of the early OS equipped Sigmas.

Before the last partial eclipse there was an 'advisory' about how to watch it. Oddly, looking at it via your phone was a no-no.

 

Apparently, it's not the looking at the screen that's the problem (really..? (sarcasm!)), it's the aiming needed to see the sun on the screen means you're looking directly at the sun if/when it peeks around the edge of the phone, ie perfect alignment for blinding!

 

Eugh. It's a little known fact that you can accidentally look at the sun without going blind. (Well, I think so. I stared at the sun as a kid and now I can't see very well, but I don't think the effects took thirty years to show.) If you use a telescope to look at your phone, I'd understand it. (Well, I'd understand the blinding bit.) It may have been more a warning from those who didn't want their eclipse experience ruined by people waving phones around.

 

I do like the occasional secondary warning from the telescope community not to forget your finder scope, though: stories of people with a filtered telescope finding that the finderscope had set something on fire. I wonder if rangefinders ever had this problem with auxiliary finders? (Not that I suspect there were ever many telephoto ones with fast apertures.)

I understand failing to do this, 'killed' the OS on some of the early OS equipped Sigmas.

 

Speaking for the 150-500 OS, it deserved to die. Not that I'm bitter.

Damage to the shutter or sensor at the image plane is plausible, even likely, because the sun's image is focused at or near that point. I suspect that melted diaphragm blades are the result of something other than pointing the camera at the sun.

 

In a compound lens, the diaphragm is usually placed between the front and rear nodes, where light rays entering the lens from any angle are parallel, hence not concentrated. Heat from the sun's light would be no more concentrated than what you would feel with an outstretched hand in daylight.

 

Cardinal point (optics) - Wikipedia

 

I suspect that these cameras were used on a telescope as a digiscope, with both the camera lens and telescope eyepiece in place. This would concentrate the light (and heat) entering the lens greatly. In the focusing process, the image plane and diaphragm could coincide. Even momentarily would be enough to cause damage. A solar filter would prevent this from happening, if placed on the objective of the telescope (not just the lens). (Protective glasses won't work with a telescope either. A 4" telescope will put over 200 times as much light through your eye than without, about 7 stops worth.)

Most of them have a mechanical shutter in the usual place, but often leave the shutter open when the camera is powered off - this makes sensor cleaning easier (or at least less prone to the shutter blades slamming shut on the cleaning equipment). It also makes it more likely that dust will land on the sensor when you change lens, and there's a trade-off for whether lens changes are better scraping a mechanical shutter or a sensor stack.

 

And yes, you can burn a sensor, although it's a lump of metal that is at least partly heat sinked* so you have to try. I suspect the filters would go first, but I don't know.

 

(* sank?)

 

Unlike the DSLR, the MILC spends mot of its time with the shutter open. It only closes the shutter briefly just before the exposure. and/or only after the exposure if they use first curtain electronic shutter.

In a compound lens, the diaphragm is usually placed between the front and rear nodes, where light rays entering the lens from any angle are parallel, hence not concentrated. Heat from the sun's light would be no more concentrated than what you would feel with an outstretched hand in daylight.

 

Is this not ignoring the telephoto-ness of the lens? The aperture blades on big telephotos are certainly not the size of the entrance aperture, which suggests light being concentrated.

 

I suspect that these cameras were used on a telescope as a digiscope, with both the camera lens and telescope eyepiece in place.

 

I imagine you're right about the 20mm Panasonic. I can't imagine the 600/4 being used as a secondary lens, though.

 

A solar filter would prevent this from happening, if placed on the objective of the telescope (not just the lens). (Protective glasses won't work with a telescope either. A 4" telescope will put over 200 times as much light through your eye than without, about 7 stops worth.)

 

Yes; I imagine some were careless enough to use a conventional filter that still allowed IR through, and in the case of the 600/4 may have been really dumb and tried using the rear filter. I've never been in the right place for a total eclipse; when I eventually get the chance, I'll certainly be filtering properly.

Solar filters for telescopes are large enough to fit over even the largest camera lens. They're made of a plastic dichroic foil, and appear wrinkled. However the filter element is very thin, and the wrinkles have no effect on the image quality.

Solar filters for telescopes are large enough to fit over even the largest camera lens. They're made of a plastic dichroic foil, and appear wrinkled. However the filter element is very thin, and the wrinkles have no effect on the image quality.

 

Yes. I gather, though, that people have an unfortunate habit of forgetting to fit them, or tearing them (or getting holes in them, but I'd hope that's less a problem), or they fall or blow off because they're fitted loosely. The "forgetting to filter your finder scope" thing is pretty understandable too. There was a fuss a little while back that people were selling eclipse glasses that weren't actually blocking the light (especially IR) properly, and I imagine the same has happened when the unscrupulous or idiotic have tried to cash in on selling filters.

 

The drop-in Nikon polariser for my 200/2 appears wrinkled, too. I don't think this affects the image quality, although I mostly use that lens indoors and don't have many test images; none of my other polarisers have this appearance.