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D3100 flash controlA basic (understanding) problem with poor exposure  Rating:  Rating
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Posted by Robert: Mon Jan 14th, 2013 02:56 1st Post
Sorry, it's not a D5100, it's a D3100.


I have been using my D3100 to make a pictorial record of my car build.

For the most part it has been very good and has performed well, however...

I normally use 'A' mode, aperture priority, if the lighting is poor I pop the flash up to give the extra light, also to cure camera shake movement blur if I am struggling to hold the camera still.

The problem is when using the built in flash it usually grossly over exposes. I have tried a variety of tactics, reducing the aperture, reducing the ISO and covering the flash with tissue. None of these seem to work well and involve many exposures to get what I want, a quick, easy, nicely exposed image.

In exasperation one evening I tried the green emblem on the mode dial which I think is 'I' (idiot mode) The camera seems to go into a completely automatic mode and when I half press the shutter little lights flash all over the screen. Anyway this mode usually produces perfectly exposed images with rich colours, nicely exposed shadows and no blown highlights, almost an HDR type image, it even pops the flash up automatically.

Why can't I get anywhere near this using 'A' aperture priority? There does not seem to be any way of controlling or reducing the flash intensity.

I can't show examples from the car but I do have this baby pic which I retrieved from the bin, which is typical of the problem.

I can't understand why the flash does not seem to be using any form of auto exposure, nor is flash exposure compensation available. Yet I can get perfect exposures by using idiot mode? I don't remember this issue with the D200 flash, that just works.

It took about six attempts to get an acceptable pic of the baby, I think I ended up at about f32. I was concerned the baby would wake with the frequent flashes.

Attachment: Baby.jpg (Downloaded 16 times)



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Robert.



Posted by richw: Mon Jan 14th, 2013 04:40 2nd Post
Robert, I don't have a D3100 but is it a possible ISO issue. Just thinking the max shutter speed if you are using a flash (and without setting Auto FP) the max shutter speed is probably 1/200 or 1/250 (it could even be set below this).

Is it possible that if you are shooting in Aperture mode the camera can't get the shutter speed up enough to cope with the ISO setting even if it keeps the flash at low power. I'm guessing when you go fully Auto the ISO goes fully auto (if you have a slow shuuter speed fixed for the flash that might get overridden as well) and the camera can therefore expose properly?

Just a guess! (based on similar experience in strong Aussie sunlight)



Posted by Eric: Mon Jan 14th, 2013 07:37 3rd Post
Robert wrote: Sorry, it's not a D5100, it's a D3100.


I have been using my D3100 to make a pictorial record of my car build.

For the most part it has been very good and has performed well, however...

I normally use 'A' mode, aperture priority, if the lighting is poor I pop the flash up to give the extra light, also to cure camera shake movement blur if I am struggling to hold the camera still.

The problem is when using the built in flash it usually grossly over exposes. I have tried a variety of tactics, reducing the aperture, reducing the ISO and covering the flash with tissue. None of these seem to work well and involve many exposures to get what I want, a quick, easy, nicely exposed image.

In exasperation one evening I tried the green emblem on the mode dial which I think is 'I' (idiot mode) The camera seems to go into a completely automatic mode and when I half press the shutter little lights flash all over the screen. Anyway this mode usually produces perfectly exposed images with rich colours, nicely exposed shadows and no blown highlights, almost an HDR type image, it even pops the flash up automatically.

Why can't I get anywhere near this using 'A' aperture priority? There does not seem to be any way of controlling or reducing the flash intensity.

I can't show examples from the car but I do have this baby pic which I retrieved from the bin, which is typical of the problem.

I can't understand why the flash does not seem to be using any form of auto exposure, nor is flash exposure compensation available. Yet I can get perfect exposures by using idiot mode? I don't remember this issue with the D200 flash, that just works.

It took about six attempts to get an acceptable pic of the baby, I think I ended up at about f32. I was concerned the baby would wake with the frequent flashes.

What settings does the EXIf give for the successful image?
If you recreate them in manual mode what do you get?

Pages 83/84 of the manual cover flash compensation.





____________________
Eric


Posted by jk: Mon Jan 14th, 2013 08:39 4th Post
OK. I think this is a case where the camera is too clever.

In Aperture priority mode you also need to adjust the Menus settings so that they are set to TTL for the flash to work with the camera.
This assumes you are using a Nikon SB400, 600, 800, 900. If you are using an earlier Nikon SB models then it should still work.

Also in the Flash menus there is an ability to choose your flash shutter speed.  This needs to be set to 1/60 or if you use the FP mode then it can be 1/250 with the newer Nikon flashes.

Not sure that the D3100 offers this in flash mode but probably.  Also make sure your metering mode is in Matrix not Spot.


If you look at your Menu settings I will bet that they are set to Manual, or Commander or something else.



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Posted by Robert: Mon Jan 14th, 2013 11:41 5th Post
Sorted!

The flash was set to manual changing that to TTL released the flash exposure compensation function.

Many thanks all, I have dropped the ISO back to 400, it was at 800 but the villain was the Manual setting for the flash. I am not used to having to do everything via menus.



____________________
Robert.



Posted by jk: Mon Jan 14th, 2013 11:56 6th Post
Well done Robert.

It is not very clear what the flash settings are as they are all hidden in the menus.



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Posted by Doug: Mon Jan 14th, 2013 16:10 7th Post
Robert wrote:
I am not used to having to do everything via menus.
I thought you were a Mac user...



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Posted by Robert: Mon Jan 14th, 2013 16:20 8th Post
I am used to Macs!

Not used to operating cameras from menus. New dogs and old tricks?

Actually I would say about 80% of my Mac control is via the keyboard, I don't use the menus that much. If I find myself using a menu command regularly I force myself to learn the key chord to select it from the keyboard.

I don't extent that to the command line interface though!!! :lol:



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