Showing posts with label 5. Part 4: Light. Project: The intensity of light. Show all posts
Showing posts with label 5. Part 4: Light. Project: The intensity of light. Show all posts

Monday, 18 February 2013

Higher and lower sensitivity

January 2013

I decided to take some photos of our local town market. Having waited for cloudy weather and researched when local markets happen, I set out with my camera.  Disappointingly, there were not many stalls or customers. I think the time of year had something to do with it – a midweek market just after Christmas in the recession with shop closures happening weekly.The weather was cold and misty, and only just above freezing. I considered whether to retake the photos on a different day, but thought that because I could draw some learning from this exercise, I would just bear the ISO exercise in mind next time it was cloudy.

I took a couple of photos and a street views.

IMG_1725 web IMG_1729 webIMG_1734 web
F11 1/8 ISO100 80mm   f11 1/30 ISO400 80mm   F11 1/60 ISO800 80mm

At ISO100 it was difficult to attain clear shots. People were blurred all the way through the scene because of the slow shutter speed. There are some shadows under people’s feet.

At ISO400, people are still motion blurred and it was difficult to handhold the camera because of the long shutter speed (although not as long as ISO100). The foreground is more in focus than at ISO100. There is some grain in the photo but it is acceptable.

By ISO800, the faces of people are still not crystal clear. There is less motion blur. I was able to handhold the camera. I think the graininess is still acceptable.

IMG_1701 webIMG_1702 webIMG_1709 web

F11 1/8 ISO100 35mm  F11 1/30 ISO400 24mm F11 1/60 ISO800 28mm

IMG_1711 webIMG_1715 web IMG_1717 web

At ISO100, the shadows are even and defined.There is motion blur as I was unable to handhold the camera at this shutter speed.  By ISO400, there is still movement of people. The shadow detail becomes grainier. By ISO800, the shadows are quite grainy.

In my opinion, increasing the ISO is an option to allow me to handhold the camera as there are times when using a tripod may not be practical. I think in portrait photography it is acceptable because I have seen photos on grainy paper and there are times when grain accentuates detail such as in black and white portraits. I think the subject matter is also important in the decision making process. For example, on my fungus photography morning in October 2012, I was unable to get into some nooks and crannies with a fully extended tripod. I increased the ISO to 400 and had acceptable results. At ISO800, the ISO made the photo appear grainy, and because the photo was taken with a lens that is 1:4macro, the graininess became apparent at 100% enlargement. (My fungi do not have much shadow detail as most of them were well hidden under the tree canopy.)

fungus 41 fungus 21
F4 1/45 ISO400                               F8 1/20 ISO800

Sunday, 9 December 2012

Measuring Exposure

7th December 2012

In the following photographs I have used partial metering and exposure compensation to make the photos deliberately lighter or darker than average.
 
1/125 F13 ISO200 Focal Length 24mm Exposure Compensation -1
 
By setting the exposure to 1 stop less than the camera suggested, I was able to make the blue sky darker than it looked to contrast against the silver birch trunks and branches.
 
1/350 F13 ISO400 Focal Length 105mm Exposure Compensation -1
 
Some of this pond was still icy and there was a little contrast between the blues and browns. By altering the exposure, I was able to make the colours richer and have a more even exposure than I would have achieved using the camera's recommended meter reading. I used a high ISO as it was very windy which helped to stabilise the reeds as the shutter speed was faster. 
 
F180 F13 ISO400 Focal Length 105mm Exposure Compensation -1
 
This composition requires 2 very different exposures to create what the eyes sees. Because of this I decided to concentrate on bringing out the yellow of the gorse which meant that I would loose the detail in the sky giving it a 'blown out' effect. Even though the exposure is -1 stop the sky is 'blown out' because the gorse is darker and therefore needs a longer exposure.
 
1/1000 F13 ISO400 Focal Length 40mm Exposure Compensation -2
 
This sign is made from a reflective metal, and when the sun shines onto it, it becomes difficult to see. When experimenting with this subject, I found that the faster the shutter speed, the more balanced the exposure was. Below 1/750sec, the photo became overexposed.
 
1/125 F6.3 ISO200 Focal Length 105mm Exposure Compensation +2/3
 
I took this seed head photo earlier in the year as an experiment with snow exposures. There is still room for improvement as the snow is blue in places. Having read around the subject a little, I need to be more confident and practice setting the exposure compensation at up to +2 and expose accordingly. I will also experiment with the white balance in future. I was pleased with the direction of light through the flower. It rim lights some of the feather like flower. 
 
1/125 F6.3 ISO200 Focal Length 105mm Exposure Compensation +2/3
 
This thistle picture was an experiment with high key which I took earlier in the year. It has a blue colouring which would probably disappear if the exposure compensation was set at up to +2 and expose accordingly. I will also experiment with the white balance. The brown of the seed head is a focal point for the photo and the stem provides direction for the viewer.  
 
For the following photos, I have used evaluative metering.


Savoy Cabbage
 
The central exposure is what I saw when I set this picture up. As the shadow falls on surface of the cabbage, it looks slightly too dark in the centre. I think the +1/2 Exposure Compensation gives a more even contrast of the cabbage and the background. I like the light being a little luminous at the bottom of the cabbage.
 
 
   IMG_1280 overexposed  1 web IMG_1281 overexposed  .5 web  
1 sec F8 ISO100 Focal Length 70mm                      0.5 sec, F8 ISO 100 Focal Length 70mm Exposure Compensation +1                        Exposure Compensation 0


IMG_1281 overexposed  .5 web
  0.7 sec, F8 ISO 100 Focal Length 70mm Exposure Compensation +1/2

  IMG_1283 -.5 exposure webIMG_1284 underexposed -1 web 
                     0.3 sec/F8/ISO 100/FL 70mm             1/4 sec/F8/ISO 100/FL 70mm
                     Exposure Compensation -0.5               Exposure Compensation-1            


 Gingerbread Men
 
The central exposure was the scene in front of me. The camera set the same speed for the shutter on what it thought was the correct exposure and the –1/2 exposure compensation. The glitter and white piping on the –1/2 is less bright making the overall picture more evenly exposed.
 IMG_1301  1 overexposed webIMG_1300  .5 overexposed webIMG_1297 normal exposure web
  1 sec F8 ISO100 96mm       0.7 sec F8 ISO100 96mm      0.5 sec F8 ISO100 96mm
Exposure Compensation +1  Exposure Compensation+1/2 Exposure Compensation 0 
 
IMG_1302 underexposed -.5 focus web0.5 sec F8 ISO100 96mm Exposure Compensation -1/2
 
IMG_1299 -1 underexposed web1/4 sec F8 ISO100 96mm Exposure Compensation -1
 
Pot Pourri
I noticed that the normal exposure was fairly bright. By stopping down –1/2 stop, the brightness was lost from the picture which allows more detail to be seen.
 

IMG_1307 crop overexposed  .5 web
IMG_1308 crop overexposed  1 web
 
2 secs Exposure Compensation +1               1.5secs Exposure Compensation +1/2                                
F8 IS0100 Focal Length 58mm               
 
 IMG_1304 crop underexposed -.5 web
0.7 secs F8 ISO100 Focal Length 58mm
Exposure Compensation –1/2
 
 
IMG_1305 crop underexposed -1 web
IMG_1304 crop altered to normal exposure compensation web
0.7secs  Exposure Compensation 0                              0.5secs ExposureCompensation –1
                                                       F8 ISO100 Focal Length58mm                       
 
 
 
Shiny flowerpot with black background
I thought this would challenge the camera to focus on three different subjects – shiny flowerpot, white bubbles and black background. I expected the bubbles and background to become grey with an incorrect exposure.I focused on the bubbles so that they would stay white with the correct exposure.The best exposure was +1/2.
 
IMG_1319 overexposed  1 web IMG_1318 overexposed  .5 web
1sec +1 Exposure Compensation   0.7secs +1/2 Exposure Compensation  
 
F8 ISO100 Focal Length 88mm           
 
 
IMG_1315 normal exposure webIMG_1316 underexposed -.5 webIMG_1317 underexposed -1 web
0.7secs 0 Exposure Comp     0.3secs -1/2 Exposure Comp  1/4 sec Exposure Comp
 
F8  ISO100 Focal Length 88mm                  
 
Reflection of cooking utensils in saucepan lid
The normal exposure shows balanced shadows and contrast and colours. As the exposure time becomes shorter, the picture becomes too dark and shadow depth is increased. As the photo becomes overexposed, detail is lost. Normal and –1/2 are acceptable.
 
IMG_1350  1 evaluative metering webIMG_1349  .5 evaluative metering webIMG_1348 normal exposure web
0.7secs Exposure Comp +1 0.7secs Exposure Comp+1/2  0.5sec Exposure Comp 0
F8 ISO100 Focal Length 105mm
 
IMG_1347 -.5 evaluative metering webIMG_1346 - 1 evaluative metering web
0.3secs Exposure Compensation –1/2          1/4sec Exposure Comp -1
F8 ISO100 Focal Length 105mm
 
Tea set
The normal exposure is what I expected it to be. The exposure is still acceptable at –1/2 but by –1 the white shows the reflections and the painted detail loses definition.
 
IMG_1361  1 eval meterIMG_1360  .5 eval meter web
3secs Exposure Comp +1     2secs Exposure Comp +1/2
F8 ISO 100 Focal Length 60mm
 
IMG_1357 normal exposure web
 
 
IMG_1358 -.5 eval meter webIMG_1359 -1 eval meter web
1sec Exposure Comp –1/2   0.7secs Exposure Comp -1
F8 ISO 100 Focal Length 60mm
 
 
 
 
               
1.5secs Exposure Compensation 0 F8 ISO100Focal Length 60mm