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-   -   ISO Questions (https://forums.steves-digicams.com/studio-lighting-flash-other-53/iso-questions-132147/)

jvogel71 Nov 10, 2007 1:23 PM

I am taking pictures with the Sony DSC-H7 Cybershot. Have had to have the camera serviced three times already after buying it brand new in July. I have problems with pictures not being very sharp but blurry pictures (with and without zoom) and problems with color saturation/lighting. When I take pictures inside with auto flash and auto adjustment on I get pictures that are very grainy as well. I look at the metadata and the ISO shows ISO400!!! Shouldn't it be more like under 100? Can this cause all the problems I am having? Have you heard of problems like this with using the auto adjustment settings?

Any information would be helpful!

Thanks!
Jenny

VTphotog Nov 11, 2007 7:40 AM

What you are describing sounds as if you are pushing the camera to it's limits. ISO 400 with flash would indicate to me that you are shooting a fairly large area in low light. The blur may be due to the autofocus not working well due to insufficient light. Combined with your comment about color problems, it sounds as if your problems are similar to taking shots of musicians with colored stage lights.

Maybe the people in the Sony camera forum can give you better advice, but it sounds as if you may not have enough camera for the job.

brian

jvogel71 Nov 11, 2007 1:57 PM

Brian,

I am shooting these pictures inside. In my living room with ample lighting in there during the day hours. It doesn't matter if I shoot from 5-10 ft or across living room 15 ft. With auto flash on. Camera still takes pictures with an ISO400 on automatic adjustment. Same results each time. Then pictures do not turn out very good. Have you ever worked with this camera? Now if I take pictures with my Casio EX-Z750 it takes pictures on automatic setting choosing an ISO100 which ends up with good pictures.


Jenny

JimC Nov 11, 2007 2:38 PM

Jenny:

Why don't you downsize one of the photos and post a sample here with EXIF?

How to Post your Photos

Are you sure the flash is even firing? The camera may be deciding that it doesn't need it if there is a lot of ambient light coming in from windows (and just increasing ISO speed instead).

Or, you may have something set wrong. Are you sure you're using Auto (i.e., the green camera on your mode dial)? The A position is not Auto. The A is for aperture priority, and if you have a smaller aperture set (higher f/stop number) , it may need to increase ISO speed to see enough light from the flash.

How about filters? Some filters types (for example, a Polarizer) can *significantly* reduce the amount of light the camera sees. So, it may need to use a higher ISO speed to get enough light from a flash.

If you're sure the mode is correct (you're really using Auto), try resetting the camera back to factory defaults. You'll see an Initilialize menu choice in the camera's setup menu for that purpose.

Of course, the simple solution is just to use the P mode (Programmed Auto), and set the ISO speed to ISO 100, and force the Flash to fire versus using Auto Flash. ;)

But, it sounds more like you've got something set wrong causing it. I'd post a sample for members to look at.


jvogel71 Nov 11, 2007 3:04 PM

1 Attachment(s)
Hi Jim,

Here are some examples. Flash is firing although there was enough lighting in room to do ok without. Without the flash pics were blurry. I had camera set to the green camera setting on the dial set with auto flash. Already reset camera to defaults and did not change anything in picture quality.

Jenny


jvogel71 Nov 11, 2007 3:09 PM

1 Attachment(s)
Here is another pic....

Metadata all shows flash fired, auto white balance and auto exposure.

Jen

JimC Nov 11, 2007 3:33 PM

The second image actually looks pretty good.

That's *much* better than I'd expect from this type of camera's built in flash. That's probably *because* the ISO speed was set higher (letting more ambient light into the image). When a lower ISO speed is used, the flash must provide more of the light.

So, you tend to get far more uneven illumination with a lower ISO speed (if closer subjects are properly exposed, further away portions are usually much darker, and if further subjects are properly exposed, closer subjects may be overexposed. Letting more ambient light into the image (via wider apertures and higher ISO Speeds) means that the flash is contributing less to the exposure and you don't have as many of those types of problems.

The first one underexposed most of the scene (and an underexposed image is going to be noisy and "muddy"). That's to be expected though (because you were shooting directly into a bright light source with the window in the center of the frame). So, it saw so much light coming in from the Window, it didn't use as much flash power to illuminate the rest of the room.

Anytime you shoot directly into a bright light source like that (and there is a *huge* difference in the amount of light coming in from that window compared to artificial lighting in a home), you'll usually need to adjust exposure to compensate (Exposure Compensation is normally used for that purpose, with a +EV setting giving you a brighter exposure). Chances are, the window was throwing off the Autofocus, too.

As for why it's using ISO 400, I don't know. That may just be the way your model normally does it. It's got relatively high ISO speeds available. So, using 400 would not be that out of line (although I see the Auto ISO selected ISO 200 for the flash image in our Samples here).

If you want a lower ISO speed, I'd just use P mode and set it to a lower value. Also make sure you have focus locked on the desired subject (half press and lock focus, then press it the rest of the way down). That's because the algorithms for Flash Exposure are probably taking both focus point and focus distance into consideration.


jvogel71 Nov 11, 2007 3:40 PM

The second pic is a little blurry. I would have expected sharper pictures from this camera.

Do you think there is something wrong with this camera? In that I cannot get sharp pictures in the auto settings?

Jen

JimC Nov 11, 2007 3:46 PM

Not that I'm seeing (I would have expected that kind of result with the image that was underexposed with the Window in the middle of the frame). Now, that one does look soft (but, the bright light source probably messed up the AF, too). That's not uncommon (anytime you have something very bright and reflective like Window glass, it can fool an Autofocus system, and a bright light source in a frame like that will fool a metering system, too).

As for the other image, I see loads of detail in it (it doesn't look soft to my eyes). It would probably sharpen nicely using an editor. Many new cameras are using relatively conservative sharpening by default now (giving you more leeway for sharpening in post processing using software).

Set sharpness higher in the camera menus if you're prefer a sharper image directly from the camera. Or, just sharpen it later using software. I see you have ACDSee from the EXIF. Try a bit of USM (Unsharp Mask) and it should look much better.



jvogel71 Nov 11, 2007 3:47 PM

1 Attachment(s)
Another picture not taken toward door window. Still blurry. Still choosing ISO400 for some reason.

Jenny


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