topic Re: solar eclipse in EF & RF Lenses

solar eclipse

MichaelLichtman — Tue, 14 Mar 2017 19:11:32 GMT

going to be directly in the path of the total solar eclipse in Aug. shooting with a 500f4 lens. will Baader film taped to the hood, be strong enough to shoot partial> full eclipse without harming the lens?

Re: solar eclipse

kvbarkley — Tue, 14 Mar 2017 22:01:52 GMT

I don't know what Baader film is, but I had good luck with these:

http://thousandoaksoptical.com/solar.html

If you are lucky, you might not need a filter:

Re: solar eclipse

MichaelLichtman — Tue, 14 Mar 2017 19:50:55 GMT

did you tape this on?

Re: solar eclipse

kvbarkley — Tue, 14 Mar 2017 22:02:18 GMT

The thousand oaks filter comes with a metal ring that I slipped over the lens hood of my 150-600 and secured with tape.

Re: solar eclipse

Waddizzle — Tue, 14 Mar 2017 22:25:11 GMT

@MichaelLichtman wrote:
going to be directly in the path of the total solar eclipse in Aug. shooting with a 500f4 lens. will Baader film taped to the hood, be strong enough to shoot partial> full eclipse without harming the lens?

Do a web search for "solar photography filters". They sell threaded filters that screw on your lenses in many standard sizes. An 5.0 ND filter is what I have found.

Re: solar eclipse

ebiggs1 — Wed, 15 Mar 2017 16:04:54 GMT

For $3 or $4 bucks you can buy welding glass. You need to shoot RAW because the welding glass has a green tint which must be corrected in post. Easy to do.

You will probably need to tract the Sun, too.

Re: solar eclipse

kvbarkley — Wed, 15 Mar 2017 17:26:03 GMT

If you need to track, you have too much filter. Both my filtered and unfiltered exposures were reasonable. You do need a tripod, though.

Re: solar eclipse

Waddizzle — Wed, 15 Mar 2017 18:20:37 GMT

@kvbarkley wrote:
If you need to track, you have too much filter. Both my filtered and unfiltered exposures were reasonable. You do need a tripod, though.

My favorite NYC online superstore has a small selection of "solar eclipse" [5.0 ND] filters, including "clear" filters.

Re: solar eclipse

RobertTheFat — Wed, 15 Mar 2017 19:28:25 GMT

@kvbarkley wrote:
If you need to track, you have too much filter. Both my filtered and unfiltered exposures were reasonable. You do need a tripod, though.

And you probably wouldn't want to track. You're not photographing some distant galaxy. Eclipses happen fast, and a tracked image would be blurry and confusing. Maybe OK as a work of art, but not as an accurate record of a once in a lifetime astronomical event.

I hope you'll be luckier than I was. I was literally at the best possible location to view the total solar eclipse of 1964. The American Astronomical Society was there too - invited by my uncle, who was head of the Astronomy Department at the University of Maine. Clouds obliterated the entire event.

Re: solar eclipse

John_SD — Wed, 15 Mar 2017 20:23:40 GMT

@MichaelLichtman wrote:
going to be directly in the path of the total solar eclipse in Aug. shooting with a 500f4 lens. will Baader film taped to the hood, be strong enough to shoot partial> full eclipse without harming the lens?

Harming the lens? I'd be a little more concerned about going blind. If you are going to bet your eyesight on a piece of tape, then I wish you the best. If it were me, I'd be using a proper solar filter.

Re: solar eclipse

Waddizzle — Wed, 15 Mar 2017 20:49:44 GMT

@MichaelLichtman wrote:
going to be directly in the path of the total solar eclipse in Aug. shooting with a 500f4 lens. will Baader film taped to the hood, be strong enough to shoot partial> full eclipse without harming the lens?

Harm the lens? Make sure that the light is properly filtered before it enters the lens, and there is very little to go wrong.

Re: solar eclipse

RobertTheFat — Wed, 15 Mar 2017 20:58:12 GMT

@John_SD wrote:
@MichaelLichtman wrote:
going to be directly in the path of the total solar eclipse in Aug. shooting with a 500f4 lens. will Baader film taped to the hood, be strong enough to shoot partial> full eclipse without harming the lens?
Harming the lens? I'd be a little more concerned about going blind. If you are going to bet your eyesight on a piece of tape, then I wish you the best. If it were me, I'd be using a proper solar filter.

True enough. One point that people often overlook is that not all dangerous radiation is in the visible spectrum. So the fact that a particular filter darkens the light doesn't ensure that it removes all radiation that can damage one's eyes.

However, it's worth noting that looking at an eclipse via live view is probably not dangerous. What you're seeing is not the original light, but rather the sensor's reaction to that light. And the intensity of light that emanates from a camera's LCD screen isn't nearly sufficient to burn one's eyes.

Re: solar eclipse

MichaelLichtman — Wed, 15 Mar 2017 22:27:39 GMT

eyes are fine..i can buy eclipse glasses on Amazon. when the eclipse is full, you do not need a solar screen or glasses to see the corona. It's the time before that, when it's partial, that you can burn your retina or fry the lens

Re: solar eclipse

MichaelLichtman — Wed, 15 Mar 2017 22:47:18 GMT

thank you for that great info

Re: solar eclipse

John_SD — Wed, 15 Mar 2017 23:26:30 GMT

@MichaelLichtman wrote:
eyes are fine..i can buy eclipse glasses on Amazon. when the eclipse is full, you do not need a solar screen or glasses to see the corona. It's the time before that, when it's partial, that you can burn your retina or fry the lens

I don't understand how an eclipse can "fry the lens"? I could see how it could damage the image sensor, but destroying the physical lens? How?

Re: solar eclipse

kvbarkley — Wed, 15 Mar 2017 23:28:33 GMT

Ever used a magnifying glass to light something on fire?

Re: solar eclipse

Waddizzle — Wed, 15 Mar 2017 23:33:07 GMT

@John_SD wrote:
@MichaelLichtman wrote:
eyes are fine..i can buy eclipse glasses on Amazon. when the eclipse is full, you do not need a solar screen or glasses to see the corona. It's the time before that, when it's partial, that you can burn your retina or fry the lens
I don't understand how an eclipse can "fry the lens"? I could see how it could damage the image sensor, but destroying the physical lens? How?

Heat can buildup and literally fry a lens. Consider how a greenhouse can heat itself in the dead of winter. A camera lens pointed at the sun really isn't all that different from a greenhouse. Heat can potentially buildup to the point where internal electtronics and motors can be damaged.

Also, remember the basic principle of how a lens works. A lens gathers parallel light waves, and focuses it at individual points. The danger comes from the intense, broad spectrum of light that is being focused through the lens elements.

Re: solar eclipse

John_SD — Thu, 16 Mar 2017 00:12:42 GMT

@Waddizzle wrote:
Heat can buildup and literally fry a lens. Consider how a greenhouse can heat itself in the dead of winter. A camera lens pointed at the sun really isn't all that different from a greenhouse. Heat can potentially buildup to the point where internal electtronics and motors can be damaged.

Also, remember the basic principle of how a lens works. A lens gathers parallel light waves, and focuses it at individual points. The danger comes from the intense, broad spectrum of light that is being focused through the lens elements.

I follow you. I would just never view an eclipse without a solar filter on. But maybe it isn't needed at the precise moment of a total eclipse?

Re: solar eclipse

RobertTheFat — Thu, 16 Mar 2017 01:36:53 GMT

@Waddizzle wrote:
@John_SD wrote:
@MichaelLichtman wrote:
eyes are fine..i can buy eclipse glasses on Amazon. when the eclipse is full, you do not need a solar screen or glasses to see the corona. It's the time before that, when it's partial, that you can burn your retina or fry the lens
I don't understand how an eclipse can "fry the lens"? I could see how it could damage the image sensor, but destroying the physical lens? How?
Heat can buildup and literally fry a lens. Consider how a greenhouse can heat itself in the dead of winter. A camera lens pointed at the sun really isn't all that different from a greenhouse. Heat can potentially buildup to the point where internal electtronics and motors can be damaged.

Also, remember the basic principle of how a lens works. A lens gathers parallel light waves, and focuses it at individual points. The danger comes from the intense, broad spectrum of light that is being focused through the lens elements.

A greenhouse isn't a very good analogy. Greenhouse heating occurs because light entering a greenhouse is absorbed by relatively dark objects inside and re-radiated as heat. But the whole point of a lens is to pass as much of the light as possible, not allowing it to be absorbed along the way. A properly designed lens should absorb very little light and not heat up too much.

What is more like a greenhouse is a camera body. A lot of the light that comes in does get absorbed. A fair amount gets reflected out through the viewfinder (so keep your eye away from that when the lens is pointed at the sun); but in live view, which is what you'd probably use to photograph an eclipse, that mechanism isn't available. So in terms of something overheating, I think I'd worry more about the camera than about the lens.

Re: solar eclipse

ebiggs1 — Thu, 16 Mar 2017 08:46:15 GMT

You guys have never shot the sun. Have you?

When viewing or photographing the partial phases of a solar eclipse or the maximum phase of the annular eclipse, you must use a solar filter. Even if 99% of the sun is covered by the moon, the remaining 1% is dangerous to view with the naked eye.

What I mean is, if you want the sun to appear as large as the moon in your pictures, which most people photograph a lot, you need the same focal length lens. Make sense?

The moon's apparent size is about the same as the sun's. It has roughly the same total brightness as the corona. A series of exposures will show potential problems with focus and can necessitate the need for tracking. The sun moves throughout the eclipse. If you start photographing just before it begins and stop after it ends you'll have been working for more than two hours. If you're planning to do a time-lapse you need to bear this in mind when you're composing the shot. Even if you're not making a time-lapse you'll need to adjust your framing a few times to keep the sun in the image. Depending on the exposure settings you choose and the focal length of the lens plus the necessary filter the SS can be anywhere from 1/2000 to 1/30. It also depends on what part of the eclipse you are shooting.

Unless the mirror is locked up any light coming through the lens will reflect off the mirror up in to the view finder. Not on the sensor! Plus you should have your totally covered lens aperture so the light will be safe in the camera.