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bong

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Posts posted by bong

    Spotmeter for general use?

    in Large Format

    Posted

    Murray, you're a man after my own heart but if you're not going to develop the roll yourself then you may have to shoot a few rolls to "calibrate" how your local shop soups your film.

     

    You have the right idea about using a spotmeter: read the darkest part of the scene where you want some detail then decrease exposure by 2 stops. If you don't get the detail you want when you print (or scan) the image then you'll have to set your EI lower. If you have good detail but your highlights are blown then you'll have to shoot a few more rolls and ask your lab to develop less until you get both good shadow and highlight details. In the end, it may be cheaper and more convenient to soup your film yourself.

    Am I in over my head????

    in Medium Format

    Posted

    >> Hey Bong, Two questions: I obviously need a spot meter to do this?<br>

    >> And, if there is a 2 stop differance between exposure A and<br>

    >> exposure B why can't I just split the differance and adjust<br>

    >> 1 f-stop...wouldn't that average out the two readings?

    <p>

    No, you don't need a spotmeter. Your center weighted meter should work fine as long as you can get close enough for your metering target to completely cover the metering area. I do have to admit, though, that spotmeters can be quite convenient at times. If you'd like to explore this topic further, I highly recommend Carson Graves' <a href="http://www.amazon.com/exec/obidos/tg/detail/-/0240802039/qid=1055643899/sr=1-1/ref=sr_1_1/103-2821984-5645436?v=glance&s=books">The Zone System for 35mm Photographers: A Basic Guid to Exposure Control</a>.

    <p>

    You can average exposures A and B. If there is a two stop difference between them then the subject you took a meter reading from for exposure A (grass in shade) will end in Zone IV and the subject for exposure B (grass in sun) will end in Zone VI. If bright grass in the sun looks good then that's the right exposure. However, as the difference between exposures A and B increases the average will push the subjects for A and B further into the shadow and highlight, respectively. Things get technically interesting as you near the limits of your film's tonal range. It's easy to give in to your curiosity at this point and start playing with films and developers instead of making photographs especially when you start processing your own black and white films. It is great fun, though.

    <p>

    Shoot slides if you want to see what happens with your exposure choices. Color negatives are pretty forgiving with exposure errors and prints will mask any exposure variations even more. Slides, on the other hand, will show a half-stop change in exposure. Enjoy!

    Am I in over my head????

    in Medium Format

    Posted

    >> Is green grass, medium grey in shade and/or sun???

     

    Both. If everything is in the shade then you can read the grass as your midtone (middle gray). If everything is in the sun then you can read the grass as your midtone. If half the scene is in the shade and the other half in the sun then I would:

     

    1. Take a reading off the grass in the shade. Call this exposure level A.

     

    2. Take a reading off the grass in the sun. Call this exposure level B.

     

    3. Compute how many stops there are between A and B, inclusive. For example, if the meter indicates 1/125 at f/5.6 for the grass in shade and 1/125 at f/11 for grass in the sun then there is a 2 stop difference between A and B.

     

    4. If I get a one stop difference between A and B then I will choose the grass in sun reading (B). The scene in the shade will have one stop less exposure. In Zone speak, I am placing grass in the sun in Zone V and grass in the shade in Zone IV. With black and white film I will use normal development (determined by previous testing).

     

    5. If the difference is more than 1 stop then I will still place the grass in the shade in Zone IV (exposure A less one stop). However, the grass in the sun will end up in Zone V or higher. I can't do anything about this at exposure time. If I develop the (black and white) film normally then the grass in sun will be too dense (its portion on the negative will be darker). Therefore, I will reduce my development time (pull development) so that the grass in sun will not develop as much and hence be less dense. I do this so that when I print the negative, the grass in shade will print at Zone IV and the grass in sun will print somewhere near Zone V without any burning or dodging. Previous testing will have given me an idea of how much to reduce development based on the difference between the grass in shade and grass in sun readings.

     

    The fly in this particular ointment is that if you are using color negative or slide film then you can't decrease or increase development time to make the highlights less or more dense, respectively. For color negative film, I would just place the grass in Zone IV (or whatever zone your experiments show as good grass in shade) and hope that the printers can work their magic to show the grass in the sun as normally exposed grass in the sun. Reverse the rules for color slides because highlights are _less_ dense than shadows. You will therefore want to expose the grass in the sun correctly and hope that the grass in the shade does not turn out too dark.

     

    Isn't this fun? ;)

     

    --bong

    Am I in over my head????

    in Medium Format

    Posted

    You've got some good responses here, Richard. I'll give my vote for an incident meter as well. It's easy to use and you won't have to worry about adding or reducing exposure for most situations.

     

    On the other hand, you may not find any improvement with your exposures even if you got a spotmeter. In fact, you may even get worse results. Having said that, Ansel Adams' Zone System provides a very good explanation of exposure. While I highly recommend investigating the Zone System, it's often too much information for the needs of most photographers. In your case, it may suffice to put a roll of slide film in your N80, use the spot metering mode and find a subject with a relatively wide range of tones (from light to dark) then take a series of bracketed exposures where you take a reading from some part of the scene for each series. For example, measure a highlight and expose at th meter reading, +1.5 stops and -1.5 stops. Keep notes. When you get your roll back, recall where you took the meter reading from and how much compensation you had, if any, for the well exposed frames. When you use your Pentax, you'll have to adjust for the bigger metering area but the lesson you've learned still applies.

     

    Good light!

    Scene metering with Leica M

    in Leica and Rangefinders

    Posted

    Michael, I don't know what set you off but your initial response doesn't offer any more insight compared with all the others. Erik already acknowledged that the Leica's meter sees a bigger area than a real spot meter. If it measured a spot as small as your Olympus SP then your answer is one among may valid ways to use a spot meter. Insulting everyone else in the course of explaining how you do things doesn't make sense. Chill, dude.

    spot meters vs. ambient meters

    in Large Format

    Posted

    I use a spotmeter. I don't take a lot of meter readings. I usually take a reading from the darkest and brightest areas where I want detail. There may be darker and brighter areas but I just acknowledge that I won't get any detail in these areas.

     

    If the darkest differs by more than 5 stops from the brightest area then I know that I will have to pull (contract) development (develop less) to bring down the highlights. If I get less than 5 stops difference then I have to push (expand) development (develop more) to push the highlights further from the shadow and gain contrast.

     

    You can only determine your EI, development, and printing procedures by testing. You can do that systematically or by trial and error. That's how I put the Zone System into practice.

     

    It really doesn't get more complicated than that. There's a strong temptation to take a spot reading from everything but that's not really necessary. You only have to make sure that you get enough detail in the *important* shadow areas -- the rest can go black. You need to take a reading from the *important* highlights because this will give you an idea of how to develop the film. It's not required at the moment of exposure. If you don't find burning inconvenient or difficult then you can ignore the highlight meter reading, develop normally, and burn in the highlights when you print.

    Quest for thinner negatives? Fools errand?

    in Black & White Practice

    Posted

    I have the same scanner and the same results that you had regarding thin negs. If you think of the scanner as another kind of enlarger then you'll find that you have to tailor your negs to fit. Diffusion enlargers need contrastier negs than condenser enlargers. The Acer Scanwit seems to like negs that are softer than negs meant for condenser enlargers.

    Crown Graphic, would you return it?

    in Large Format

    Posted

    I, too, will have to agree with Dave and Don. I bought a very nice Crown Graphic off of eBay for $175. While I had to send my lens off to Steve Grimes for a CLA I was very satisfied with my purchase. I suggest that you bide your time and wait for a really nice item to turn up with a knowledgeable seller. Send it back otherwise you'll just end up envious of the nice Crown Graphics out there. Good luck!

    Density Query.

    in Black & White Practice

    Posted

    Severi,

     

    Your zeal for the Zone System is admirable but trying to control the process to 1/3 stop is indeed frustrating. The whole process itself has so much slop that measuring things beyond a certain precision is almost meaningless. I'm satisfied if I get the negative densities within a 1/2 stop (as long as the error tends towards overexposure) -- printing techniques get me the rest of the way home. This may leave you unsatisfied but try using the Zone System for a while.

     

    Cheers!

    Who wants to volunteer to help photo.net grow?

    in PhotoNet Site Help

    Posted

    photo.net has been an educational and entertaining resource for a long time. I'd like to give something back so, if you'll have me, I can volunteer 5 hours a week.

    <p>

    I can help with any item except for 3, 7, 8, and 9. I'm a programmer by trade and have extensive experience writing distributed applications. I am most fluent with C++ but can pick up a language quickly. I am very comfortable working on Unix with the usual software development tools including CVS. While I don't have Oracle experience, I have enough database skills to read and understand SQL.

    M3 DS shutterspeeds

    in Leica and Rangefinders

    Posted

    I have an M3 DS, too, and the continental shutter speeds annoyed me

    because it threw off the old equation I use to get the aperture and

    shutter speed given an EV: EV = Av + Tv where Av and Tv are the values

    assigned to specific f/stops and shutter speeds:

    <table border=1 width="20%">

    <tr>

    <th>value

    <th>f/stop

    <th>speed

    </tr>

    <tr>

    <td>0

    <td>1.0

    <td>1

    </tr>

    <tr>

    <td>1

    <td>1.4

    <td>1/2

    </tr>

    <tr>

    <td>2

    <td>2

    <td>1/4

    </tr>

    <tr>

    <td>3

    <td>2.8

    <td>1/8

    </tr>

    <tr>

    <td>4

    <td>4

    <td>1/15

    </tr>

    <tr>

    <td>5

    <td>5.6

    <td>1/30

    </tr>

    <tr>

    <td>6

    <td>8

    <td>1/60

    </tr>

    <tr>

    <td>7

    <td>11

    <td>1/125

    </tr>

    <tr>

    <td>8

    <td>16

    <td>1/250

    </tr>

    <tr>

    <td>9

    <td>22

    <td>1/500

    </tr>

    <tr>

    <td>10

    <td>32

    <td>1/1000

    </tr>

    </table>

     

    For example, if I get a reading of EV 8 then I can use any combination

    of aperture and shutter speed that sum to 8, say, f/2.8 (3) at 1/30

    (5).<p>

    To continue using the formula, I computed how many stops the M3

    shutter speeds were from the modern speed settings. These are the

    equivalent numbers I came up with:

    <table border=1 width="20%">

    <tr>

    <th>value

    <th>speed

    </tr>

    <tr>

    <td>2.3

    <td>1/5

    </tr>

    <tr>

    <td>3.3

    <td>1/10

    </tr>

    <tr>

    <td>4.3

    <td>1/20

    </tr>

    <tr>

    <td>5.6

    <td>1/50

    </tr>

    <tr>

    <td>6.6

    <td>1/100

    </tr>

    </table>

    Every 0.3 is 1/3 stop; 2.3 for example means 1/5 is 1/3 stop faster

    than 1/4. Since the 5cm f/1.5 Summarit doesn't have 1/3 stop clicks I

    usually round down (towards more exposure) by a half-stop. This may

    be more anal than you'd like but I'm not perfect <g>. It's

    easiest with a digital meter that can show EV in 1/10 stops. Have fun!

    400 speed films - you say you can see the difference?

    in Leica and Rangefinders

    Posted

    Andy, you've made your point. I do see a difference in tonality

    between the two images.<p>

    I'd say the left hand side was made with the modern technology film

    because it's contrastier. Not to impugn your development process,

    Andy, but it is easier to get a higher CI with TMY than with Tri-X.

    On the other hand, TMY has a higher shoulder than Tri-X which implies

    that the right hand image with more detail in the highlights, the one

    taken with the modern technology film... Ahhh heck, spill it, Andy!

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