Weening off of "Auto" - a Mushroom experiment

Discussion in 'Photography Beginners' Forum' started by TwoRails, Nov 23, 2008.

  1. TwoRails

    TwoRails TPF Noob!

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    Weening off of "Auto" - a Mushroom experiment

    I noticed how the darker stem of this mushroom was in the shadows, yet the brighter head (in comparison to the stem) was catching a ray of sunlight. I like shooting mushrooms and figured this would be a good time to learn a little and practice shooting other than in auto mode. I was so busy thinking of settings that I had a 'dooh' moment and didn't think of manually focusing for a better DoF.

    As expected, the head came out like a neon sign in Auto mode. I played with the EV settings and went down one stop, but those are washed out, too. Test one is straight out of the camera.

    After about 12 shots, I switched to manual (ISO Auto) and stopped down to f7.1 from Auto's f5.6. That was the only shot that wasn't washed out on the head, but I didn't notice I somehow had the shutter cranked up so the Auto ISO was maxed out at 1600. The shot was fairly noisy. So Test 2 has some PP noise reduction applied and the shadows cranked up a little as they were too dark. No color or contrast adjustments as I wanted the head to be pretty much "as-is" for comparison to Test one.

    (After the shots, I read a thread here about using AE lock --- gotta learn that as I probably could have gotten a decent shot by reading the head and let the rest be dark. Seems like it would have served the same purpose... Yes? No?)

    Comments, suggestions, C&C welcome!!

    Test one: Auto mode showing total washout of the head, stem's nice:

    [​IMG]


    Test two: manual mode, minor editing as noted above:

    [​IMG]

    .
     
  2. Big Mike

    Big Mike I am Big, I am Mike Staff Member Supporting Member

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    The second one really is a 'better' exposure.

    A shot taken at F8, 1/125 @ ISO 100, will be the same whether it's in Auto, aperture priority, shutter priority or manual. So it doesn't really matter what mode you are in. The difference is just how you use the modes to get your exposure.

    In the 'auto' modes, you can use EC (exposure compensation) to adjust the exposure away from the meter reading. In manual (without auto ISO), you just adjust the settings how you want, but you can keep an eye on the light meter 'scale'.

    A common practice is called bracketing. That is where you take several shots but change the exposure for each shot. One at the meter reading and some under and some over etc. Then you can look them over later and pick the best one.
     
  3. gsgary

    gsgary Been spending a lot of time on here!

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    And turn off auto iso
     
  4. TamiyaGuy

    TamiyaGuy No longer a newbie, moving up!

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    I quite like the second one, although it lacks a little saturation boost. Also, Auto ISO, while it is good at times, should generally be turned off. But otherwise, I say it's an experiment well done!
     
  5. TwoRails

    TwoRails TPF Noob!

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    Thanks for the reples!!

    That makes sense.

    EC, if I understand you correctly, it is when you set the "+" or "-" on the "EV" ? If so, I have messed with that several times just to play with it. Very handy! Just got to learn to put it into practrice, though.

    I've read threads here on HDR shots, and I tried a bracketed shot, but I obviously have to read the manual on it. I pushed the button to do it, had the camera in bust mode, but got three identical shots... so I did something wrong. My understanding here is where one part is washed out (the 'head') and the rest either reasonably correct exposure or a little under then HDR would be the "trick" to get the shot. In fact, all of the shots, except for the last shot, came out looking pretty close to each other which was not expected. Some are a little less blownout, but all are "not good."

    Lots to learn. I didn't even think of that! Heck, like I mentioned above, I didn't even think of using manual focus... I was too 'busy' thinking (or trying to :)) of the other stuff. Now that I think it, not setting the ISO is probably the reason that the shots, with all the different settings I played with, came out so close to each other. The only darker one is #2 above. For some reason my editor doesn't pick up ISO settingns so I copied back and read it in the camera: it was red and reading 1600, and a shutter of 400. So I'm thinking that my messed up settings were beyond what the camera can do, so it came out underexposed, in a sense.

    Glad you like it. In 'real life' it was a pretty cool looking 'sroom.' I did like the challenge it presented, and somehow I didn't think of waiting for the sun to go down some to try another set of shots on it: I was too busy "playing" with settings. I'll try to remember turning off Auto ISO. Yes, I could boost things a little but I did want to leave things as reasonably close to the first shot for everyone to critique, not to mention it's a grey mushsroom with a white head.

    Again, thanks for the comments :)
     
  6. prodigy2k7

    prodigy2k7 No longer a newbie, moving up!

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    Two different lighting conditions...How can you compare?

    The second image has very little direct sunlight.
     
  7. TwoRails

    TwoRails TPF Noob!

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    On the contrary, both where taken within a minute or three of each other. That was my "experiment" ! :) I wanted to see if I could get a shot with a "spot light" on the head and the rest in a shadow. The sun light was coming thru the bushes / trees and the same foliage was casting a shadow on the rest.
     
  8. prodigy2k7

    prodigy2k7 No longer a newbie, moving up!

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    your images say it was 3 minutes apart. :) The sun can move a lot within 3 minutes at that angle.
    The reason why the second doesnt have its head washed out is because its underexposed compared to the first one...
    There is a lot more detail in the first one than the second one.
    The second is underexposed by 2 full stops compared to the first one, am i correct?
    The second should have 1/100 F/2.2 to get the same amount of light.

    The light has changed in 3 minutes, especially at that angle, so its hard to say if the metering was off or if the light changed, or both.
     
    Last edited: Nov 26, 2008
  9. TwoRails

    TwoRails TPF Noob!

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    Yes, the sun can move a lot in several minutes. I don't "think" it changed that much, though. The first shot was on Auto, aimed at the darker stem. I'd bet that if in the last shot I did the same, the head would be also washed out.

    As far as the differences in settings, I just loaded both shots in my editor and here's what the EXIF says (something else I'm learning):

    #1:
    1/60 shutter
    f5.6 aperture
    ISO unknown (it doesn't read for some reason)

    #2
    1/400 shutter
    f7.1
    ISO unknown (but it was at least 1600 as mentioned above as I loaded it back into the camera to read ISO)

    A full stop is a doubling of shutter speed, yes? And for aperture, it's the number on the lens, such as 5.6 to 8, to 11, yes? So how do you calculate the stop value from 5.6 to 7.1?
     
  10. epp_b

    epp_b No longer a newbie, moving up!

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    You didn't say what you were shooting with, but, with that kind of noise at ISO 1600, I'm assuming it's the D40 or something of that sensor era.

    For ISO Auto, I set it the minimum shutter speed to what I can comfortably hand-hold while standing and set the maximum ISO to whatever I feel gives me acceptable amount of noise (in the case of the D40, that's ISO 800). I leave it on unless I want deliberate control over the ISO, which is usually in manual mode, because, annoyingly, Nikons don't switch off ISO Auto in manual mode like they should.

    That sounds about right for auto-mode on a D40 or similar. The D40/D40x/D60/D80 all overexpose in auto by at least 2/3rds of a stop. I usually shoot in P mode and dial in 2/3rds of exposure compensation to the right (darker).

    Let's do some math:

    1/400 is about 2 and 2/3rds of a stop darker than 1/60th. f/7.1 is 2/3rds of a stop darker than f/5.6. You've now exposed your second image 3 and 2/3rd stops darker than the first. The Auto ISO now recognizes that and cranks up the ISO from 200 to 1600 (that's 3 stops, from 200 - 400 - 800 - 1600) because it will be very underexposed. So, now you have an image that is 2/3rds of a stop darker (because of the Auto ISO was configured, it couldn't go another full stop to 3200 and the ISO doesn't adjust in fractions of stops on your camera) but very colourless and noisy because of the high ISO. See what said before about dialing in 2/3rds of exposure compensation?

    Yes and yes.

    I think it adjusts aperture in 1/3 stops and it goes from 5.6 - 6.3 - 7.1 - 8, so f/7.1 would be 2/3rds of a stop darker than f/5.6. So, you'd need 2/3rds of a slower shutter speed to get the same exposure.
     
    Last edited: Nov 27, 2008
  11. TwoRails

    TwoRails TPF Noob!

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    Those were taken with a used D70 I recently picked up from a friend. He said it has a firmware update as some D70s had problems and I have no idea what problems they had. The second shot had "auto" noise reduction applied in my editor (Paint Shop Pro x2). I guess I'm stuck on "auto" - LOL. In the full sized shot I can see the noise but have to admit my eyes are not "in tune" enough to easily spot noise in the small shots above; more I have to learn. The in-camera noise setting is set to whatever he has it set at...

    Now that I think of it, I don't even know how to turn it off. I just now played with it and I can hold the button in and turn the dail, but it still flashes "auto ISO" when I release the button. Time to get the manual out (and to learn how to bracket, too.)

    Thank you for that! The 'math' put it in much better perspective. I don't have it down yet, but I can see it better now. So much to learn :)

    Again, thanks :) - very helpful and informative.
     
  12. epp_b

    epp_b No longer a newbie, moving up!

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    OK, well the D70 is an older model than the D40, though of the same generation, I think. It probably performs pretty much the same or maybe slightly worse than the D40 in terms of noise.

    Eh, I find noise reduction pretty useless. I just try to make shots without noise in the first place.

    It will be in the menus. I'd dig out my D40 and just tell you, but I don't know if it's the same on the D70.

    Yup, it's all math. It's just canceling or balancing one out with another. Once you have the aperture f/stops memorized, it's easy. Shutter and film/sensor speed are just a matter of doubling or halving numbers (or calculating their fractions in between for half and third stops).

    So:

    1/250th shutter at f/5.6 at ISO 200 will give you the same exposure as 1/500th at f/4 at ISO 200 and the same as 1/60th at f/8 at ISO 100. Because each variable of exposure (shutter, aperture, film/sensor speed) has an secondary effect on the image (shutter and motion, aperture and depth of field, film/sensor speed and grain/noise), you want to adjust each one according to the photo you want to achieve.
     

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