Using B&W film as eclipse filter

xkaes · Mar 31, 2024

+1000 it is!!!

Just use your #1 diopter close-up filter. It's actually a 1,000mm lens. Set it up, all by itself, pointed at the sun -- perpendicularly. Then place a white sheet of paper, etc. 1,000mm behind it. You'll get a very visible view of the sun you can view with the naked eye.

ic-racer · Mar 31, 2024

Last partial solar eclipse I used a cereal box viewer with a pinhole that projects to the bottom of the box. You look in the box to see the image, so you are actually looking 180 degrees from the sun.

I was also using a pinhole on the camera, cranked out to about 600mm focal length.

The ground glass view was pretty dim. You needed a dark cloth to see it well.

As you can see it was overcase, but a circle opened in the clouds long enough to make an exposure.

ic-racer · Mar 31, 2024

xkaes said:
+1000 it is!!!

Just use your #1 diopter close-up filter. It's actually a 1,000mm lens. Set it up, all by itself, pointed at the sun -- perpendicularly. Then place a white sheet of paper, etc. 1,000mm behind it. You'll get a very visible view of the sun you can view with the naked eye.

Yes, it will be bigger than the pinhole projected image in a cereal box.

The grid on my ground glass above is 15mm and the focal length for that projected image was about 600mm.

Cholentpot · Mar 31, 2024

ic-racer said:
What ever you do be careful. I was out testing one of my proposed setups. I had a proper slip-on solar filter on a zoom lens. Essentially the same filter material for the glasses, so safe for optical viewfinder viewing. All was fine until I zoomed and the sliding zoom ring bumped the filter off the front of the lens. For just the fraction of a second until I could close my eye the light was literallhy blinding. Even though the sun only coverd a portion of the focus screen, the entire screen was blindingly bright. Much worse than when a strobe or speedlight goes off and leaves a lasting image.

Also, heed warnings on lenses, some of which warn against internal fires if un-filtered sunlight enters the front element.

It is a little bit of a paradox as a SHORT focal length lens is used to start a fire when camping. But a LONG focal length lens on your camera will burn out your eye quicker.
For example you can't start a fire with a +1 diopter close up lens (1,000mm FL) but looking at the sun through a 1,000mm lens on your camera will damage your eye quickly.

I plan on using a waist level viewfinder like I did last time. Should keep my eyes out of the danger zone

ic-racer · Mar 31, 2024

Cholentpot said:
I plan on using a waist level viewfinder like I did last time. Should keep my eyes out of the danger zone

Waist level view is good for 3PM where I am. For 35mm I'll be using a Rollei 3003 with waist level finder. But, again, if the filter is not on, it is blinding.

ic-racer · Mar 31, 2024

I'll be doing movies with this. I still need to rig up a spotting scope. This lens is 1,000mm equivalent on this format. It is very difficult to find the sun with the filter in place. I found it also challenging without a 90 degree finder which I don't have. I read somewhere the Bolex 90 degree finder looked like one from a Minolta, but it is too late to seek one at this time.

Bill Burk · Mar 31, 2024

Cholentpot said:
Millions upon millions world wide multiple times have used the cheapass cardboards. Is there an epidemic of blindness? I wanna see it with my eyes.

People get Lasik too.

I’m happy looking at shadows and projections.

Cholentpot · Mar 31, 2024

Bill Burk said:
People get Lasik too.

I’m happy looking at shadows and projections.

Lasik has a 99% self reported success rate.

ic-racer said:
Waist level view is good for 3PM where I am. For 35mm I'll be using a Rollei 3003 with waist level finder. But, again, if the filter is not on, it is blinding.

I'm going to attempt with a Mamiya C33 and the 180mm lens for 120. 35mm I have a 500mm mirror lens I might put on my F3 and see what happens. Both camera will have 100 speed film in them. How to meter? No idea.

Bill Burk · Mar 31, 2024

Ask Lasik recipients to describe night time lighting. I’d hate to mess up the stars

Saw someone post that a disco ball would be cool

BobUK · Mar 31, 2024

I think it was for the last transit of Venus across the Sun that I purchased an A4 sheet of Solar Filter Film made by a very well known maker.
After about a forty mile round trip to the shop I inspected the sheet at home. The filter was positively dangerous.
I posted it back, and telephoned the dealer. He agreed it was in no way safe to use. It looked like streaky oil on the sheet with large patches of transparent coating, or lack of coating.
If you luckily get a good sheet check it out for pinholes in a dark room and bright spotlight before putting your faith in the thing.

I have used a welders mask filter occasionally but it has to be a minimum of welders filter strength number 12, denser safer welders filter are desirable if your supplier has them in stock.

Back to the sheet of rubbish filter, I got my money back and ordered a proper Meade Astronomical Solar Filter. A lot more expensive but well worth the peace of mind.

ic-racer · Mar 31, 2024

Cholentpot said:
How to meter? No idea.

My plans, with the solar filter I will spot meter the sun and set at middle gray. Though it could be some zones higher and print fine.
For the 'total' I'm going to follow a chart like this. This is with no filter on the lens

Sirius Glass · Mar 31, 2024

reddesert said:
TLDR: Just get the darn eclipse glasses, from a reliable source.

In the Bad Old Days we sometimes used totally fogged and developed silver black and white film to observe solar eclipses. Like a throughly exposed and developed 35mm leader. Official sources will not recommend this now. Ideally, you should use eclipse glasses purchased from a reliable source (not a random anonymous seller on amazon or ebay), or solar filter film purchased from a reliable source (like Baader or Astro-Physics). These are tested to be effective. If you do take it upon yourself to use a fogged developed film leader, just look for a few seconds, don't stare at the sun for minutes like an idiot.

Under no circumstances should you use something like an R72 filter. The whole point of the fogged film or official solar filter is that the metallic film blocks infrared.

Reasons that official sources endorse eclipse glasses and not fogged developed B&W film include that:
- eclipse glasses are easier to get now, if you order ahead,
- people confuse color and B&W film (undeveloped color film does not have enough silver, and developed color film doesn't have any),
- people confuse silver B&W film and chromogenic B&W like XP2, which has no silver when developed,
- no official source knows your film type or developing practices or whatever and can test or guarantee the opacity of your film leader, even if you are actually using a real B&W film.

Before the 2012 (annular) and 2017 solar eclipses, I tried out a few undeveloped and developed pieces of silver B&W film, observing bright lights and scanning across the sun, and my memory is that the opacity varied a lot, which is not reassuring. In particular, I think undeveloped B&W film (silver halide, not metallic silver) was not opaque enough visually, which suggests worse in the infrared. I got the official solar filter material from Baader and made a filter to go over binoculars.

I've made pinhole cameras to view solar eclipses. It's not trivial because the angular diameter of the sun is small. I used a cardboard box for skis, about 6 feet long. This still makes only about a 15mm diameter solar image. With a maybe 0.5mm pinhole, you have a camera of about f/3600. The sun is bright, but you still need to shade the viewing screen from ambient light (less so during totality).

I agree! Get a proper eclipse glasses from a verified source. Your eyes are worth it. One usually only gets one set of eyes, so properly protect them.

Cholentpot · Mar 31, 2024

ic-racer said:
My plans, with the solar filter I will spot meter the sun and set at middle gray. Though it could be some zones higher and print fine.
For the 'total' I'm going to follow a chart like this. This is with no filter on the lens

View attachment 367048

Thanks!

Ok, you all convinced me. Can amazon get something to my doorstep by the end of the week and what should I get?

BobUK · Apr 1, 2024

WARNING ABOUT TELESCOPE EYEPIECE SUN FILTERS
Never use one.

ic-racer · Apr 1, 2024

I got the cardboard and plastic film ones from B&H and have already tried them photographing with still and cine. They seem pretty safe, the image is quite dim. For viewing I got some cardboard from B&H and also some welding glasses that fit over my perscription glasses better.

ic-racer · Apr 1, 2024

At this point I'm thinking 3 cameras:

8mm with 1000mm eqivalent to film some of the partial and the transition to total.
8mm with wide angle and no filter with intervalometer to film the sky and clouds before during and after. I still need to calculate when to start it and duration between frames and when or if I need to wind the spring motor.
35mm with 200mm lens for stills of partial and total.

RalphLambrecht · Apr 1, 2024

Cholentpot said:
I wasn't sure where to ask this as it's about film but maybe not taking photos.

I've been out of curiosity putting together some solar filters for the eclipse and sun viewing in general. I remember being told as a kid that negatives work. My research has turned up that you need to use exposed and developed B&W film double stacked. However I've seen also that modern B&W films don't have enough silver to filter anything.

I just so happen to have a bulk roll of ancient Tri-X from somewhere in the 70's or 80's. This is 'silver rich' and should work. Now, I have the regular glasses that are ISO rated and will be using those, I'm just wondering if using film would work.

Thanks.

It's fairly easy to expose and develop film to a transmission density of 3.0 and maybe 4.0. that isn't quite enough to filter sunlight safely. metal-foil filters are safer and optically better while still being affordable. Also, they are more color-neutral than welding glasses for example. Using film in layers is out; you'd get annoying reflections and distortions.

Cholentpot · Apr 1, 2024

ic-racer said:
I got the cardboard and plastic film ones from B&H and have already tried them photographing with still and cine. They seem pretty safe, the image is quite dim. For viewing I got some cardboard from B&H and also some welding glasses that fit over my perscription glasses better.

View attachment 367089

Already have glasses. I need something to go on front of camera lenses. I used to have a chunk of welding glass but I seem to have misplaced it over the years.

RalphLambrecht said:
It's fairly easy to expose and develop film to a transmission density of 3.0 and maybe 4.0. that isn't quite enough to filter sunlight safely. metal-foil filters are safer and optically better while still being affordable. Also, they are more color-neutral than welding glasses for example. Using film in layers is out; you'd get annoying reflections and distortions.

I was thinking of exposing it and putting in a tray of Rodinal for a while then fixing it. I have glasses I just want something to go over the front of my lens.

ic-racer · Apr 1, 2024

The solar film in mine looks identical to that which is in the cardboard glasses.

Cholentpot · Apr 3, 2024

All right! Good to go. Glued to the filter of a 500mm f/8 mirror lens and made a makeshift filter cover for the Mamiya TLR 18cm lens. I still have some of the film left so I have to figure out a way to mount onto my EF 200mm without making a mess.

RalphLambrecht · Apr 4, 2024

Cholentpot said:
Hey hey! Take it easy. Would you call me a pitiful fool to my face?

I have the proper safety googles and a nice thick piece of welders glass. I'm not using the homemade thing for the eclipse, I might use it as a front filter for a lens in the future though.

So my cookery of Tri-x in rodinal 1:50 for over and hour would do the job? I'm a DIY guy in general.

I bought what I need back before the rush. I'm no idiot I was just wondering if film blocks the UV rays. I do solar photography from time to time and was just wondering if film would make a good filter. We're getting 83% coverage here. in 2024 we'll be getting 100% though, this is a dry run for me. If what I'm trying works this time, next time I'll get a better lens and plan the whole thing out in advance.

metal-foil-filters are very good but, a pinhole projection is the safest way to observe an eclipse; even then you should wear good sunglasses. the reflection off a white piece of paper is still very bright and the full eclipse cycle takes up to two hours.

Cholentpot · Apr 4, 2024

RalphLambrecht said:
metal-foil-filters are very good but, a pinhole projection is the safest way to observe an eclipse; even then you should wear good sunglasses. the reflection off a white piece of paper is still very bright and the full eclipse cycle takes up to two hours.

So matter what I do it'll never be good enough.

I'll also stay at home under my bed wearing a foam fall helmet and only eat lukewarm mashed potatoes.

You're worried about the light bouncing off a piece of paper? You know, sometimes I drive a few blocks without my seatbelt on. And once in a blue moon I'll ride a bike without a helmet. I hold roman candles in my hand and I'll drink a few bottles of beer and try to sing. I'm Mr. Danger over here.

loccdor · Apr 4, 2024

Well, millions of people are going to be attempting to photograph the eclipse directly. More power to them, but I don't see the point in duplicating their efforts, so if I take a photo, it will probably be of one of the indirect effects, maybe the shadows of a tree or something. I'm mulling over ideas to make an eclipse-related picture more interesting. Maybe use water to reflect the image in some way. Or having something else in the frame. I'm open to suggestions.

Cholentpot · Apr 4, 2024

loccdor said:
Well, millions of people are going to be attempting to photograph the eclipse directly. More power to them, but I don't see the point in duplicating their efforts, so if I take a photo, it will probably be of one of the indirect effects, maybe the shadows of a tree or something. I'm mulling over ideas to make an eclipse-related picture more interesting. Maybe use water to reflect the image in some way. Or having something else in the frame. I'm open to suggestions.

It's a once in a lifetime opportunity to photograph something for me. I like taking photos of things, why should I not jump at the opportunity to take a photo of this thing? It's no different than taking a photo of Niagara Falls, the Moon, Grand Canyon or lighting strikes. It'll be my photo taken by me. There may be millions of other but none like mine.

foc · Apr 4, 2024

Cholentpot said:
You know, sometimes I drive a few blocks without my seatbelt on. And once in a blue moon I'll ride a bike without a helmet.

Thankfully in my country, that is illegal and for a good reason.

Using B&W film as eclipse filter

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