Using a dSLR as a light meter

[pete_6109]

I will start with a series of noobish questions:



What do the degrees stand for? What is the practical difference between a 1-degree and a 5-degree meter?

Answer: 1 degree is a smaller, more precise reading of a given tonal area. 5 degrees reads a slightly wider area.



Why do you do that? Wouldn't that lead to loss of detail in those areas, or imply that the meter is off? What kind of results do you get?

Answer: A meter is calibrated to 18% reflectivity as the standard which is "middle gray" or zone 5 in the zone system. Therefore if you were to meter on white snow and then you set your camera to whatever the meter says, your exposure would result in the snow coming out gray in your print. The meter doesn't know you were pointing at something white. The same is true for black and everything in between. So to make things very simple if you meter on light colors or white you need to increase (overexpose) your exposure by 1 to 2 stops and if you meter on dark colors or black you decrease (underexpose) your exposure by 1 to 2 stops. You can do this by selecting a different shutter speed or a different lens aperture.


So basically you are using the spot meter to tell to get a desired exposure for your dSLR. I guess the lightmeter gives you the EV value (never used one, no idea how it actually works), and you adjust the exposure according to it. How do you determine your aperture, shutter speed and ISO based on the EV? Is there some kind of formula to calculate all this, and if there is, could you explain it in detail or link to some more detailed description?

Answer: It depends on what meter you use. Some older meters use a manual dial you set and then read off the aperture and shutter speed.
Digital meters give you exposure values directly on the LCD screen.
I wouldn't worry about formulas. That's why we use light meters.

I hope this helps a little. Best thing for you to do is read about the zone system and take some pics and see how they come out. If in doubt, bracket, bracket, bracket your exposures.

 

[Samriel]

Thanks for all the help and comments guys.

I've been using my dSLR in manual most of the time until now, and I've been judging a photograph on the spot by looking at the photo itself and by looking at the RGB histogram. Concerning LF photography, in the beginning I'll probably shot with my dSLR until I'm satisfied with the result I've gotten on it, and than copy the settings to the field camera. After I've gotten to know the darkroom processes and basic view camera operation a bit better, and after I've done reading Ansel Adams's books, I'll start considering a spot meter and the Zone System.

For bracketing, what would you recommend: +-1EV or +-2EV? I have 3 holders, and I'm thinking of doing 2 bracketed shots (0, -, +) each time, until I get confident in my technique.

 

[DeadEye]

I too am in the process of trying out LF. I have a home studio so it will all take place there. I just ordered a box of fugi 100c 4x5 proofing film "instant" . My idea is about the same as yours for trying it out.

I use the sekonic 385 meter to set up my lights, then shoot with the 1d mk III. So far the exposure has been near perfect every time on the DSLR. I hope for same results with the proofing film witch is 3$ a shot.

I too could use any tips for a LF beginner.

Thanks DeadEye.

 

[pete_6109]

Thanks for all the help and comments guys.

I've been using my dSLR in manual most of the time until now, and I've been judging a photograph on the spot by looking at the photo itself and by looking at the RGB histogram. Concerning LF photography, in the beginning I'll probably shot with my dSLR until I'm satisfied with the result I've gotten on it, and than copy the settings to the field camera. After I've gotten to know the darkroom processes and basic view camera operation a bit better, and after I've done reading Ansel Adams's books, I'll start considering a spot meter and the Zone System.

For bracketing, what would you recommend: +-1EV or +-2EV? I have 3 holders, and I'm thinking of doing 2 bracketed shots (0, -, +) each time, until I get confident in my technique.

I've been doing the same thing you are doing. I view the histogram and then adjust my exposure either up or down, usually in 1/2 to 1 stop at a time. With the zone system you will probably find out that most books will recommend + or - 1/3 stop increments when doing test shots to adjust the manufacturers ISO rating, to calculate your normal developing time, etc.
The zone systems gets very complicated and requires you to shoot sheet film and develop it yourself.

 

[Paul Ron]

There seems to ba alot of confusion about exactly what the zone system is all about here...

The very first thing you have to do is test your meter to film to developer to print and calibrate all of em so you have absolute control of everything. You have to standardize your methods n use the same tehnique everytime.

Take a look at this site and maybe you'll get a better feel for it.... http://www.zone2tone.co.uk/techpagemenu.htm

My meter has a scale on it that I calibrated to read zone 3, shodow with detail. After I take that reading n set my camera for it I read my highlight n take a note of how many stops away form the zone 3 it is. That tells me how to develope my film. The zone system lets you compensate for the range of the scene and allows you to develope for the highlights since they come up the fastest. The the shadows will develope themselves to completion because they are so thin n less active. Now this is where all that testing will take you.... control, living on the edge.

Your meter doesn't have to be an expensive spot meter. I used a Lunar Pro with the spot attachment for many years n it served me fine. The meter is not expensive nor is the attachment. You can still find em for $60 in the classifieds, many people are getting rid of em because they say it's not accurate without the old mercury batteries.. bull! The meter doesn't have to be accurate to another meter... it has to be consistant with your film n developer n printing. Again it's about knowing your equipement n gaining control.

 

[pete_6109]

There seems to ba alot of confusion about exactly what the zone system is all about here...

The very first thing you have to do is test your meter to film to developer to print and calibrate all of em so you have absolute control of everything. You have to standardize your methods n use the same tehnique everytime.

Take a look at this site and maybe you'll get a better feel for it.... http://www.zone2tone.co.uk/techpagemenu.htm

My meter has a scale on it that I calibrated to read zone 3, shodow with detail. After I take that reading n set my camera for it I read my highlight n take a note of how many stops away form the zone 3 it is. That tells me how to develope my film. The zone system lets you compensate for the range of the scene and allows you to develope for the highlights since they come up the fastest. The the shadows will develope themselves to completion because they are so thin n less active. Now this is where all that testing will take you.... control, living on the edge.

Your meter doesn't have to be an expensive spot meter. I used a Lunar Pro with the spot attachment for many years n it served me fine. The meter is not expensive nor is the attachment. You can still find em for $60 in the classifieds, many people are getting rid of em because they say it's not accurate without the old mercury batteries.. bull! The meter doesn't have to be accurate to another meter... it has to be consistant with your film n developer n printing. Again it's about knowing your equipement n gaining control.

Paul,
I agree with you. I bought a Pentax 1 degree spot meter in an antique shop for $10 and it works fine. It reads one stop over my Minolta flash meter IV with it's 5 degree spot attachment. I plan to use the Pentax
meter and put a zone scale on it.

 

[Helen B]

You can use an incident meter instead of a spot meter and still get good results - even use the Zone System. Minor White, in his excellent Zone System Manual explained how to apply incident readings to the ZS, and the same fundamentals were used by Phil Davis in Beyond the Zone System. I find myself using incident readings most of the time. I'll explain the procedure if you wish.

A DSLR can be used as an incident meter simply by reading off a surface of known reflectance such as an 18% grey card or the palm of your hand. Incident meters are, however, cheap enough. Paul has mentioned the Luna Pro - there's also the Luna Pro SBC (also called the Profisix), which is one of the most sensitive meters ever made and it takes readily-available 9-volt batteries. If you want a truly versatile meter, the Sekonic L-758 offers both spot and incident measurement in one, as do a variety of other models.

Best,
Helen

 

[CapnRon]

If your DSLR has a manual mode and you can switch metering to spot, you should be able to determine fairly accurate exposure values.

I have compared my Canon PowerShot A570 in manual mode using its spotmeter with my Pentax 1 degree spotmeter. They compare closely enough that I've started carrying the Canon instead of the Pentax when I'm on hikes and room and weight are an issue(the Canon and my 6x9 folding camera make a pretty tidy medium format package). I've only had a few rolls processed at the local lab but they look good enough to encourage me to try using the Canon for the zone exposure system. I'm currently doing the film speed tests with the Canon as the light meter. We'll see how this works out.

Cheers,
CapnRon