Nikon D80 - DOF in program mode with flash issues.

Discussion in 'Nikon' started by david_rice, Nov 26, 2010.

  1. Last night at Thanksgiving dinner I took about 100 photos of family and friends with flash. Reviewing them today I found many with depth of field issues. Sharp focus at the focus point but other areas are soft due to limited DOF. All are shot with flash, auto ISO and program mode with a 18-135 3.5-5.6f DX Nikkor lens. 90% of the exposures the camera selected 100 ISO and a aperture of F4. My question is why does the camera select ISO 100 with such a wide open aperture limiting the DOF? The sensor is certainly capable of great images at much higher ISO's. Seems like in program mode it should favor a smaller aperture and a higher ISO to give a less shallow DOF. Do I need to shoot in aperture priority with flash so I can force the camera to choose a higher ISO?
    This is my first digital SLR. I cut my teeth on all manual cameras back in the film days. Automation is a mixed blessing. It gets things right a lot of the time but also requires babysitting to make sure it does not make bad choices.
     
  2. The camera can't read your mind. It has no idea what you're shooting, or which of many factors you consider important.
    When you shoot with auto-everything, the camera just follows its program. You can find exactly what it's doing detailed in the instruction manual.
    If you want something else, you have to tell it so, like selecting the ISO yourself and/or shooting in aperture priority mode.
    - Leigh
     
  3. you have really answered your own question, it seems to me. the camera's computer has no way of knowing what's important in the frame; it just judges the optimum exposure based on ambient light. be more proactive with aperture and then let the camera's computer do the rest.
     
  4. If you want to have specific depth of field with flash, set the camera to Aperture priority mode, set aperture to f5.6 or f/8 etc. The automatic iTTL stuff will look after the flash. You don't really need a higher ISO with the flash unless you are set to TTL-BL (fill flash). The base ISO, (in your case ISO 100 ) gives the best image dynamic range and least amount of noise.
     
  5. I am not positive as I have not handled a D80 for a while but I believe like other Nikon bodies, you can select the 'base' ISO when shooting with Auto ISO on.
     
  6. I wouldn't call that an "issue", is what one could expect from a camera in program mode. Everything but what you want.
     
  7. Thanks for the all the responses. I was just surprised that program mode would use a "wide open" aperture in that situation. On the D80 you can pick a maximum ISO in auto ISO mode. I don't see a option for a base ISO. I will be using program mode less now and the semi manual and manual modes more often now.
     
  8. David, I believe the Auto ISO function is separate from your ISO selection, so the ISO you have your camera set at is the base ISO. For example, if you have your camera set as ISO 800 with Auto ISO on, the camera will select ISO 800 or higher, but never lower than 800. This is the way I believe all Nikon DSLRs with Auto ISO work. And I am pretty sure this applies to the D80.
     
  9. I think the D80 only allowed to set the maximum ISO and minimal shutter for Auto ISO....
    Either way, the full auto mode makes these kind of silly selections. In P mode already, you have some influence since you can alter the shutter/aperture. So, to go to P, A or S mode would already give you what you need, I think.
    Auto ISO is nice under constantly changing conditions, but if you are and stay indoors with flash (=similar condition all the time), I would just set it manually. I think I'd choose ISO800, which will balance the amount of flash a bit nicer, and which gives good noise performance on the D80.
     
  10. ShunCheung

    ShunCheung Administrator

    On Nikon DSLRs, avoid the P program mode at all cost when you use flash. That is a combo that will cause a lot of problems.
     
  11. Are we talking about the built-in flash here? Keep in mind that these have very limited range. They are intended for fill-flash of fairly close subjects, not rooms full of people. The Program mode is doing what it's supposed to do, within the limitations imposed. I don't have the same camera myself, but most are similar in that regard. It can only sync with a certain shutter speed or below, but at the same time, the Program will try to choose a reasonable balance between the effective distance of the flash, the focus distance, the flash sync speed and hand-holdable speed, and the largest available aperture it can use so as to avoid limiting flash range. The range is actually so short that DOF indoors may not be a big consideration anyway. If you have used a compact camera with flash, it's different, because unlike the SLR, the compact camera has almost unlimited DOF whether you want it or not and no matter what the aperture is. The DSLR doesn't work like that.
    If you force a higher ISO, it will only give you more flash range. It probably won't change the sync speed in P mode, nor change the aperture that much. You would have to choose slow sync, but then you might need to use a tripod. Other than that, you would have to set an aperture yourself. SLRs are like that. If you want more out of flash, you have to get a more powerful Speedlight (higher guide number, so much more range). With the pop-up flash, even using manual exposure settings won't give you much more than what you' ve already got with P mode.
     
  12. I was using a flash mounted on a flash bracket. I had a TTL cord from the camera shoe to the flash. In auto iso mode you can select the max ISO in the menu. You can then select the min ISO by holding the ISO button on the back of the camera and rotating the command dial. I learned about the min ISO setting today. If I force it choose a higher ISO by setting the min ISO higher it does choose a higher aperture number for more DOF.
    All this automation is new to me as I came from shooting a Nikon F3 ten years ago. I began to trust P mode because it worked great for the most part outdoors on a bright sunny day. But for flash indoors where the flash provides most of the light for the exposure it chooses poorly. I just have to learn a the nuances of the automatic modes. I also think I will be using A, T and M modes more often in the future.
     
  13. I've shot my D80 and D90 in A mode 80% of the time, S mode 15% on the time and manual only when those modes failed me - mainly when using flash in aa tough lighting condition.
    A and S mode are very similar to P mode but YOU select either the apeture or shutter speed and the camera takes care of the rest.
     

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