Metering and Exposure
So once the focusing part is done, you've gone through, you've taken care of the critical focus, we now need to get to the part where we're actually getting ready for the camera to kind of get set up. So everything's been locked down, everything's good to go and we now need to load the film holder. Gena, can you bring me a four-by-five film holder? So, when we're loading the film, we've loaded the film, we've put it in there, and one of the things you want to do is, and this is another lesson learned the hard way. You don't have to beat it to death, but what you want to do before you load the film is, and this case, the camera is set up to it vertical. What I want to do is, the film holder's going to go in. This is the bottom. This will be the top. I want to tap this about twice. Just on my hand. And if I was doing a horizontal, the film would be going in this way. I'm going to tap it like that. The reason is, there's enough slush in there to load the film where that film could be load...
ed in the upper part of the track and if I don't do that, the film won't fall and it will be up there and when I pull the dark slide and start the exposure, there's a risk that the film could actually drop and it will cause the slightest bit of out of focus, and if it happens, it will drive you crazy because you will be absolutely sure you nailed the focus and you'll have taken say, two photographs or literally, you took one, you flipped this over, you took the other one, everything looked perfect and great and one's out of focus and one's not and it will be driving you crazy on what happened and it's because the film probably dropped. So just a little bit of a tap and then you're going to go on ahead and load in your film. You're just going to pull this back and push this down. Now one of the other things that happens is people go in and then they stop the first time it hits. You got to push it in all the way down and what's happening is, when it hits the first time, it's hitting the bottom of this. We need it to get over that so that it can actually come in and get the film exposed in the right spot here, so we're going to bring that up and push that down so when you go in, you'll push it in and then it's got to go in until it snaps all the way down and when you look at the bottom, you'll see it's pushed in all the way down there and you can look up here, so you'll know when it's in all the way. At that point, the film's loaded, focusing is done, everything's good and ready to go and now we're actually ready to meter. Metering with a large format camera is a little different than metering with a regular camera, and the reason is, your regular camera, your DSLR, has a massive computer in there that does all of this great, amazing work for you. You are going to be so impressed with your 35 millimeter camera when we're done with the next set of slides because we're going to be talking about how do we actually calculate in meter? The important thing about metering is to know a couple of things before you get started. One, you need to know because we're working with film, the range of film's ability to capture light is unique to each film. Slide film, if you're going to shoot chrome, E6 process film, very narrow range, somewhere between three and six stops of light is what slide films can capture. Color negative film has a really nice, big range. It can cover somewhere between 12 and 15 stops and the beautiful part about color negative film is it is nearly impossible to overexpose. It was designed for consumer use and consumers overexposed film and to make it really easy, they made sure that when we stick that in our camera, it's hard to overexpose. We love that about color negative film. If you're doing night photography on color negative film, you always get these beautiful tones even in streetlights with a really long exposure. It's always able to do that. Black and white has a really huge range, 15 to 18 stops of usable data that are available there, so we need to know that because that tells us how much information is happening in front of us and whether or not we're going to need to apply some filters to offset the range of light. We also have to determine what kind of meter we're going to use, whether we're going to use that incident or reflective meter. We have to make those decisions, but one we have all of that set, we know the film, we kind of know its range, we know which kind of meter we'll use. We're ready to start to get into actually how to do the calculation for exposure. We have to calculate a lot of things when we're dealing with large format cameras. We have to figure out the base exposure. We then need to figure out the filter factors. We then need to figure out the bellows extension, and then we need to calculate for reciprocity failure. Those things added together give us our final exposure. A notebook and a pencil will greatly help you in a lot of ways and I'll tell you why in a second as we get through, but if you're a math person, it's not that scary. It's just a lot of little things you have to add up. So your base exposure basically, this is what you would normally do with a meter. You would meter and I would say, "Okay, I've metered "and it says I need to use a 1/16th of a second." I'd have 22 for my film speed. My film speed's 400, it's 400. If it's 300, it's 300. One of the great things about large format photography versus roll film photography. Roll film, I have somewhere between you know, 12 and 36 exposures on that camera, on that roll of film. Each sheet of large format film can be independently exposed and processed, so if I would need to change the ISO value, it's much easier to do without impacting any other image with a large format camera. If you're metering for black and white, you still want to expose for the shadow. That hasn't changed. If you're coming out of the digital arena and you're used to exposing to the right, film, black and white film, is about exposing for the left. We want to expose for the shadows so we have sufficient detail. If you're working with color film, Sandra Cohen has a great class on color film photography where she talks about metering, but basically, you're metering an average across and if you're dealing with slide film, you got to protect those highlights. So one of the reasons slide film has a great look to it, those beautiful, romanticized look of how we image the world, deep, rich, black shadows because we had to protect those highlights with slide film, so it works more like digital in that regard. So you've got to just figure out what that base exposure is. Once I've figured out the base exposure, I need to write that down because I can't forget that and I'm going to start adding a bunch of numbers to it. The next thing I'm going to add is the filter factor. So if I'm working with a camera and I want to, for some reason I need to put a filter in front of it, I need a neutral density filter. Gena, can you bring me my filters? I want to put a neutral density filter. If I'm doing black and white photography, I might want to put a contrast filter in front of there. A contrast filter is, if I use a red filter, it will darken things that are blue and cyan. It will lighten things that are red, so a contrast filter in black and white photography lightens its own color, lightens its own color and darkens the opposite. I might want to use a neutral density filter. I might want to just be able to put a filter in front of the camera so I can stop and slow down the amount of shutter speed I need. I could also maybe need a split grad because I can't do HDR, because I can't take multiple exposures like I can with digital and assemble them in Photoshop, I would need a split grad indie filter. Those sort of look like, they don't sort of look like this, they actually do look like this. This is actually a split grad. I put that in front of the screen. You can see how the top has got a gray, hopefully you can see that. The top's got a gray. The bottom's clear. Put in front of the camera lens, that's going to allow me to darken the top of the scene or the bottom of the scene to try to bring those ranges of light into balance with one another. I also, if I'm shooting color film, I might need a color correction filter in front of the lens, so there's a lot of reasons why I might need a filter in front of the lens to actually account for all of that. Filters come in different stops. So I have the two split-grad filters here. The top one is a .3. The bottom one is a .6, so that's the filter factor. .3 is the equivalent of one stop. .6 is two stops, .3 is three stops, and they're cumulative, so if I took these two filters together, that's the equivalent of a three stop filter factor. So if I've got my base exposure at say, F and I, at 1/60th of a second and I'm going to apply three stops of filter factor, I've got to now calculate that into the exposure. Now because the F11 or the F22, whatever my F stop is is probably the critical factor here because I've set the focus here already at that F stop. I'm now working with the shutter speed, so I now need three more stops of light. So if I'm at 1/60th of a second, I'm going to go to 1/30th, 1/15th, and 1/8th. So I'm now at 1/8th of a second. That's my now, new basic exposure because I've accounted for the filter factor. The next thing I have to account for is the bellows factor. This is why I mentioned in accessories you're going to need a tape measure and we're going to cover it in a second. Bellows factor is basically, when I talked about we have the camera and we get it set at the infinity point, that's the basic focus for the camera. If the bellows is shorter than that, I'm okay. I don't have to worry about bellows factor, but if the distance from the lens to the film plane increases, I now have to account for that because the light is now traveling farther due to the inverse square law. The light is falling off and I then have to increase the exposure to compensate for that. So the bellows factor is the bellows factor squared divided by the F focal length of the lens squared, gives you the actual number of the bellows factor, which gives you the number of stops. In the bonus material, I have the formula for that. If you have, now, search for a bellows factor equation on the internet, you will find the formula there. It's a super easy formula. To figure out your bellows extension though, I'll find this lens, say, was 150 millimeter lens, that's a six-inch lens. If I measure my bellows factor, I'm going to measure from the lens plane back to the film plane and now that's almost 12 inches, so that's doubled in size. So I've now gone from 6 to 12. I now have to account for that in my bellows factor. I am terrible at math. I don't mean like, sort of bad at math, I'm like, even with a calculator I'm bad at math, so I have figured out a quasi-shortcut. So I could apply the formula. You can also build a table. Like, once you know your lens and your bellows things, you can build a table. In the bonus material, I have tables for a couple of common lenses. You build a table. However, this is what I like to do. Six-inch lens, that is pretty close to F5.6. Close. If I measure 12 out, I measure this out and I'm at 12 inches, I'm like, 12 is really close to F11. F8, F11 is two stops. I need two more stops of light. If I actually run the formula on that, I get a bellows factor of four. I take my lens, divide, square, I get a factor of four, two stops. So I have found this to be close enough and if I need to hedge, I always hedge towards a tiny little bit more exposure. I'd always rather be a little bit overexposed than a little bit underexposed, except with slide film and then I probably would actually do the calculations because slide film's tolerance is so small. But in the normal world, that little piece of closes F stop, measure, next closest F stop, number of stops. That's what I'm going to change. So in this case, I was now at F22 for my setting. I was at 1/8th of a second, I'm now at one quarter of a second, and I'm not at a half a second. That's my current base exposure. I've now calculated for the original exposure, I've added in a filter factor, I've added in the bellows extension. Okay now, I've got to deal with reciprocity failure. Digital does not have reciprocity failure. The closest thing I would equate to reciprocity failure with digital would be if you shoot a higher ISO, you end up with more noise. Reciprocity failure is the inverse of that. If you shoot and don't have enough light, you end up with less exposure. Under extremely low light conditions, a film is less responsive, and what's happening is, photons of light are actually coming in and hitting the silver halide on the film. There is a certain amount of photons that are necessary for that silver halide to actually get activated to create the process for it to turn it into silver for the image to form. If we're under low light enough setting, the meter will tell us we need X amount of exposure, but the light is low enough that not enough photons have actually hit the silver to build up the exposure and this is primarily happening in the shadow detail because in the highlight detail, we do have enough information. To offset that, we have to basically account for the reciprocity failure. Each film has a unique reciprocity failure, so when you start to look for films, you'll see some film like Fuji Acros does not have reciprocity failure up until about 80 seconds. Fuji Provia doesn't have reciprocity failure until about 120 seconds. So as long as you're under two minutes, you don't have to account for that. Anything above 120 seconds you need to add between about 1/3rd or half a stop, up to a stop as you tail a route longer and longer. Black and white films are way, way more susceptible to reciprocity failure outside of that Acros, so Triax, for example, if you take a Triax exposure at 15 seconds, you may actually end up needing to get 45 seconds. A 30 minute exposure is the equivalent of about a three hour exposure, so you have to calculate for the reciprocity failure because if you're under low light and you want to get the exposure you think you're going to get from what your meter said, you've got to take that into account. The most important part of this calculation is reciprocity has to be calculated last. So we've gone through and we've done base, we've done filter, we've done bellows, and then we apply reciprocity. And the reason for that is, if you're at two seconds, say, with Triax film and you apply reciprocity failure, you go to three seconds. Then you add in two stops for a bellows factor, you're now at 12 seconds. But at 12 seconds, Triax actually needs about 26 seconds, so that delta is actually going to be off because you made the decision to choose reciprocity first. So reciprocity is always the last thing calculated. Once you have all that calculation, and that's why I say a little notebook is nice, it's also nice because you have the notes of what you actually calculated so when you get the film back, if something's wrong, you might be able to figure out what actually happened in the calculation of your exposure. Once you have the exposure, we're actually ready to take a picture of the image. So I'm going to pull this lens back on the camera and we'll walk through this. Let me get a because this has got a little bit bigger lens, a little bit easier to see. And Gena, can you bring me an 8x10 holder? Okay, so I'm ready to actually take a picture and so what I've got to do is, everything's all set up. I've got the film holder in. I've got to close the shutter. So I've had the shutter open so that I can see through everything, make my focus decisions. I'm going to close the shutter now. Once the shutter is closed, everything in here is light tight. I then recommend that you cock the shutter and fire the shutter once just to make sure that the shutter is actually going to fire and you don't have a problem. So you just cock it and fire it. It's not necessary, like, it's not going to be problem if you don't do that, but I just recommend you do it so you don't come across any strange surprises. Okay, once the shutter's cocked, at this point, I'm ready to pull the dark slide out. So I pull the dark slide out and then this, I usually just stick, in this camera, I usually stick it just kind of back here under the camera a little bit. On that camera, I kind of set them across here. I just want to make sure that I don't drop it and get it dirty because dust is my enemy with film. Any dust that gets on there is going to be a nightmare of a problem, so I'm trying to keep as much dirt off the camera, off the film as possible. So dark slide's out. At this point, I'm really anal retentive about my exposure, so I do a quick hit of the meter, just to make sure nothing's dramatically changed so did I get F22 at 1/15th of a second last time? Cool, I got F22 at 1/15th of a second. I don't need to worry about my exposure calculation. Shutter's cocked and now comes the part, and I talked about early on, this is an immersive process. This is an experiential process. With a normal camera, you know, we'll pretend this is a 35 millimeter camera. This is the camera to my face, to my subject I'm photographing. So if I'm taking a portrait of you, you see the camera. The interaction is between you and the camera. It's the lens there and that's why big, scary lenses are hard for people sometimes when we stick them up in their face. For this camera in experience to work, I'm now standing here, next to the camera. So this is the part for the camera for me in this experience, this is the payout. All of this hard work, all of this heavy weight, all of these extra steps is all about I am now getting to sit here and if I'm photographing a person, I'm getting to be completely present with the person. Now they're not going to have a lot of movement. I'm can't have them run around and do a bunch of things, but if they're sitting there, I can talk to them and be like, "Oh, so how's this going? "How's that going? "What's this, what's this?" And I can watch for that one gesture here and I can take that picture and we're now in a conversation that's no longer about me, the camera, and the person. It is now about me and the person and the camera really becomes secondary. If I'm out in the field and things are happening, one of my quintessential experiences with a large format camera was, I was photographing and I was trying to deal with a landscape element and these trees were moving. This film is about $12 a sheet, so I'm torching film because the wind keeps moving. I'm taking a picture. I want the trees, the wind moves. Trees, wind moves. But because I'm standing here, now I'm trying to time the wind because I guess I'm arrogant like that, wind's moving. I'm trying to figure that out and then it dawns on me. What if I photograph the wind? How would the wind move through the trees? And all the sudden, I create this beautiful photograph of movement that's then transcended a lot of my work and it's because I was next to the camera experiencing the things going on around me. Minor White has a great quote. He was a large format photographer and somebody asked about how do you know when to take a photograph? And he said, "It's when the object of your affection "acknowledges your presence." For me, standing next to the camera with this action allows me to wait for the acknowledgement to tell me it's okay to take the photograph. So it's this, standing next to the camera becomes really, really, the exciting part. With that shutter cocked though, I'm not going to touch the camera or anything. This is here and I just fire the shutter. Film has been exposed. Now when I loaded the film, I mentioned that we want the white side out. Now I'm going to put it in black side out. So when I put that back in, I push that in all the way and I'll pull this out and I'm going to show you a thing on the top. On the top are these little hooks. These little hooks spin around. They allow you to lick the dark slide so that it doesn't accidentally fall out. So that little piece, I just want to make sure I spin and get locked in on my film. Now with this particular film holder, this one is exposed, but I now know this one is not. So if I go back to my bag later and I pull out another film holder because this is white, I now know I can pick this up and actually use this. When you're first getting started, I usually recommend you make two exposures, so you would just take and flip, make the other exposure so you have two copies of that just in case something goes wrong with the film. So usually, it's one shot for one film holder. As you get more exposed or more exposure and you get more familiar with working with your camera, you may do that less and less. And particularly with my 8x10 camera, I can only carry about three of these in my bag, maybe four and I don't want to take three shots for the day, so I will oftentimes not do that, but if there's one that's critical and I was like, "Oh, this is really cool," I make sure I get two shots of that.