Not quite understanding manual exposure

[Rob MacKillop]

Despite the wonderful tutorials on this forum and elsewhere, I still have uncertainties when trying to set my manual cameras for best exposure.

Question 1:

Both the Mamiya C330 and RB67 apparently ignore the film sensitivity, ISO or ASA. As does my Zeiss Nettar.

I've been using the Weston Master IV light meter, for which I have to set the ASA to match the film I'm using. Depending on the subject, I use incident or reflective methods. I then read off the shutter speed for the f.stop I want to use.

But why this apparent need for accuracy, when the camera doesn't recognise the ASA of the film?

Question 2:

The shutter speeds on the Nettar range from 25 to 125. If I decided to use the Sunny 16 rule on a sunny day (we do get one or two a year) but I'm using 200 or 400 film, how do I set the shutter speed when at f.16?


As only the right side of my brain seems to have any life in it, please keep the technicalities, algebra and calculus to a minimum

My exposures are often overexposed or noisy. I can make digital adjustments in pp, but would rather get it right when shooting. I often forget to bring the Weston, and just guess, with varying results. As I want to spend more time with these cameras, I want to get to grips with the techniques for good exposure.

 

[Rob MacKillop]

Writing that out helped. I suppose the answer to 1 is, it doesn't matter that the camera does not recognise the ASA, as long as the light meter does.
And 2., I have to increase the exposure time? Or is it decrease?!

 

[Beth Carter]

keeping math at a minimum i suggest downloading a stop calculator app on your phone. you plug in the settings you have and tell it to adjust for whatever iso or shutter speed you need to use and it tells you the rest.

i have one that also gives me hyperfocal distances.

the more tedious answer is to figure out how many stops of light difference there are between what exposure values you're being told to use and what you need to use, adjust either shutter speed or aperture to compensate.

so for the sunny 16 rule with iso 400 film you would use the exposure settings of f/16, iso 400, 1/400s. but you have to use 1/100s because your camera settings don't allow you to use anything faster (i didn't use 1/125s to keep the math easy). that's a difference of 2 stops more light, so after setting the shutter speed to 1/100s you need to make your aperture 2 stops smaller to let it less light, f/32.

or you can compensate with an nd filter. stack them until you get the stops you need.

 

[Rob MacKillop]

My phone is too basic. I have an iPad, and it has an app called FotometerPro, which is really cool. Bit of a pain carrying that as well, though, but possible.

I don't have f/32 on the Nettar, but do on the other two. Bit of a problem if I have in mind an aperture of f/2.8 for a nice dof.

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I suppose I just need to slip my Fuji XF1 into my shirt pocket, put that on aperture mode, iso 200 (or whatever) and see what it suggests for the shutter speed?

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Seems like cheating, somehow!

 

[Rob MacKillop]

Sorry...please bear with me.

My Nettar settings - F stops 6.3, 8, 11, 16, 22 and Shutter Speeds 25, 50, 100, 125 B and T

Now, I'm trying to set up a picture of the wall opposite me right now.

The XF1 camera has iso 200 (same as the film), f/6.4 (closest to the Nettar's 6.3) - and it is showing a shutter speed of 1/4, which is nowhere near the 25 of the Nettar. Or is it exactly the same - one quarter second = 1/25. So, I'm getting mixed up between decimals and fractions?

So, if I increase the aperture to f/7.1 on the XF1, it gives me a shutter speed of 25. At f/8 (the next Nettar f stop) the XF1 gives a reading of 1.6.

What settings to I put on the Nettar?

Sometimes when I write things out, they become more clear. Sometimes they just confuse me further!

 

[David Mitchell]

Be aware when using older cameras it can be quite hard to get the correct exposure due to the limited shutter settings, an example being the Kodak autographic camera I gave my mate has a setting of either 1/25 or 1/50, the manual calls for the use of ISO 40 film - which would have been common at the time but now the slowest speed is ISO 50 (with the Pan F).

I have downloaded this:

Squit Photo

Its like a slide rule for the sunny 16 rule which I am using on my Bessa and got good results, it gives you options at a glance and rather useful.

 

[Beth Carter]

or you could print out a chart showing the stops

http://www.photographytipscorner.com/wp-content/uploads/2012/04/Exposure-Chart-copy.png

 

[Paul Lange]

Rob, from what you say I believe the critical connection you need to make is the relationship between F stops, shutter speeds and ISO.

Set you camera aperture to 6.3 and imagine that a certain amount of light is reaching the film. you don't have to quantify it, just imagine some light going through the lens and reaching the film. Now set the aperture 8. You have just reduced the amount of light reaching the film by half.

It is the same relationship with shutter speed. Change your shutter speed from say 100 (1/100 of a second) to 50 and you have again just reduced the amount of light reaching the film by half.

It is the same relationship again with ISO. Change ISO from 400 to 200 and the camera is now half as sensitive to light as it was before.

You will not that shutter speed and ISO increase by a factor of 2 or decrease by half for each step. Aperture on most cameras goes something like 2.8, 4, 5.6, 6.3, 8, 11, 16, 32. These numbers do not increase / decrease by 2 for each step. This is because aperture is referring to the open area of the iris in the camera. Imagine that your aperture is 2.8 centimeters in diameter (this is an imaginary situation) if you want the area of your aperture to double so it can let in twice as much light you multiply diameter not by 2 but by 1.414. (2.8 x 1.414=4).

This doesn't answer all of your question but it should set you on the right path you if can get your head around it.

 

[Rob MacKillop]

Yes, I kind of understand that, Paul, and thanks for it. But, I've downloaded an app called Expositor Lite, which looks just like the slide rule printout thing which David kindly referred me to above. Now, it is easy to use. The ASA I'm using is 100 (Acros Neopan) and the weather is cloudy. That gives me a few apertures each with a corresponding shutter speed. F/8 and 1/125 is the one I would chose in this instance. Fine. But...when I check that with the Fuji camera, with the same iso, it says f/8 and 2.5 seconds - an eternity by comparison. That's what is confusing me.

And, by the way, the FotometerPro app gives me a 1 second shutter time. Different again.

And the Weston gives me 1/130, which is close to the slide rule reading. All for f/8 and ISO 100.

Which would be the best?

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Paul, you say...

<It is the same relationship with shutter speed. Change your shutter speed from say 100 (1/100 of a second) to 50 and you have again just reduced the amount of light reaching the film by half.>

One hundredth of a second is a shorter duration than one fiftieth, so why are you letting in less light when at 50? I would have thought it was the opposite?

 

[Beth Carter]

sounds like the real questions is which device/rule is right for your nettar. shoot a couple of frames using the exposures your various tools have told you. take notes so you know which frame had which exposure.

if you check out the chart i posted above you'll see apertures, iso and shutter speeds listed, the bold ones indicate full stop increments. count the number of stops between the shutter speed your tool's calculated and the one you need for your camera, then adjust your aperture the same number of stops.

 

[Rob MacKillop]

Thanks, Beth. I couldn't see that image when I was on my iPad, but I can see it now. It's another way of notating the same thing, and I understand the method of adjusting for the camera. Thanks for that. I'll laminate it!

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I'll also do your first suggestion. Good idea.

 

[Paul Lange]

Yes Rob you are right about the shutter speeds, I put them the wrong way around. Sorry about that, also for misunderstanding your question.

Dare I say anything else to incriminate me but.............

The Fuji is basing it's exposure on light reflected off of your subject. Your Sunny 16 guide is based on the light actually falling on the subject. Have you tried just taking both exposures with your Fuji and comparing the results?

 

[Rob MacKillop]

Yes, they are different. So, not much point in using it. I think I'm getting there now. Luckily the film allows some latitude. So far, I've been able to get good and maybe some not so good results by guess work, and there have been a few complete failures. But overall I'm pretty much getting it. But the task is to get it perfect, and to do so every time! That would be worth working at.

Thanks for all your help.

 

[David Mitchell]

If you use a Trip 35 it does it all for you

 

[Rob MacKillop]

That's why it became so popular! And it's one of the reasons I enjoy the challenge of these old meterless cameras. There is no option. You have to get it right, although, as I said earlier, there is some latitude. No through the lens metering or AE. Just you, the world in front of you, and light falling onto the film. It's wonderful to feel that connection. And it is worth the effort to think it all through, so that you can get to the point where you don't have to think. That's where the art happens. My problem is that I want to get there right now, or yesterday; get straight to the art bit. But sometimes you've got to work at it, figure it out, ask questions, dumb or otherwise.

 

[David Mitchell]

Yeah, most of mine are meterless, I used that slide rule sunny 16 and it worked out pretty good, some of my cameras have very very limited settings which is always fun lol

 

[Brian Moore]

Modern emulsions have a lot of latitude, Rob. (Except for slide film maybe.)

For your 200 ASA film I would guess that 1/125th would be close enough. The 400 ASA might be too much in some circumstances, but again some emulsions are said to be good shot at 1, 2 or even 3 stops slower (or faster, depending on the film) so you might get away with it. For example, I think I read a few posts on other sites in which people were waxing lyrical about the latitude of Portra 400. Check the film manufacturer website for their recommendations for the emulsion you plan to use.

By the way, I've shot Kodak Tri-X 400 and Ilford HP5 (400asa) in my Brownie Hawkeye with no problems. (Its one shutter speed--about 1/40 I think) and one aperture (about f8 I think.) Same with my Kodak No.2 Hawk-Eye Model C. 400 ASA film turned out just fine. (It think its about 1/40 and f11.)

Anyway, I wouldn't worry a great deal about it. Or,... just shoot slower speed films with those old cameras.

Ain't this fun?

 

[Rob MacKillop]

It is fun. I wasn't really awake to the fact that it is better to use slower-speed film, so I've got some Portra 400 (not opened yet), HP5, FP4, and Acros 100. Must get some Ilford Pan F which has an ISO of 50. Any slower films?

 

[David Mitchell]

I think Ilford Pan F is the slowest you can buy, I am planning to try out some slower films as I now have a tripod lol I like less grain and don't need the faster speeds as I don't shoot in low light. The only way you can go slower is to use older alternative processes, but ISO 50 should be slow enough lol. My FM2n can meter down to ISO 12, but I've never seen any film that slow so I am guessing that might be used for pushing and pulling film.

Its also why I shoot my D3100 on the lowest possible ISO, usually keeping it around or under ISO 200 as digital noise is worse than grain lol.

Edit -

Just checked the manual, its suggesting you use 32 ASA (ISO) film, so you can see what I mean about the difficulties with older camera settings as they aren't designed for very high ISO film. You probably find that when the camera was built the super fast films were something like ISO 100 lol.

Suggested settings at ISO 32:

Outdoor bright - f8 1/100
Outdoor overcast - f5.6 1/50

 

[Rob MacKillop]

Interesting, David. I guess it's essential to use a tripod with slow film, unless you are doing deliberately out of focus, shakey stuff (not that I would ever do that )