File size (resolution) degraded with flash on

[VenturaRon]

I'm pleased with my Olympus 1030SW underwater camera. But I've noticed a big difference in resolution when I force the flash to be on. This is a 10.1 Megapixel camera. The file sizes when I use flash can be down in the 55KB range - that can't be compression. W/O flash files can be in the 1700KB range. I usually set the flash to on when shooting people (out of the water) in bright sunlight - so faces don't get shadowed.


Anyone know why I should get such a big resolution degradation with the flash on?

[SmartWombat]

Can you post or link to some examples?

Size of a JPG file is not resolution. The size of a JPG file is related to the amount of detail in the image. Large areas of the same colour can be compressed a lot.
I have found in the past, with other cameras, where there is a lot of black background the file size drops dramatically. I expect the 1030SW will do the same.

[freygr]

Like SmartWombat says it not the file size. The lossyness of JPG is the main reason I stopped using but it's the standard. I would shoot in RAW or TIFF.

I would need to see the photo even to guess what the problem may be. Did you check your menu selections to make sure your settings are still set at the 10 mega pixel size after you force the flash to fire.

[another view]

I have the older 720SW and as far as I know you only have the option of jpeg, but I've really never had a problem with that. Good files can certainly be shot in the jpeg format.

As mentioned, file size is not directly tied to resolution. Two shots of the same resolution can have different file sizes - compare a shot of only a clear blue sky with a shot that has a lot of detail and you'll see a big difference. But one could possibly be (a stretch) half the size of the other, not like 55 vs 1700 - no way.

Something else is going on. I know with mine that some of the scene modes (such as "night portrait" or "underwater") will lower the resolution. Are you using one of them? Are you comparing flash shots where the flash fires automatically vs. not without changing camera settings?

[VenturaRon]

Thanks for all the feedback on this resolution issue. I think I'll do some experimenting with identical scenes, with and without flash. I more closey reviewed the pictures I have that are very similar but have very different file sizes. I thought the only difference was flash and no flash - both in bright sun, taken within seconds of each other. But now I see that what I considered a small change in position and direction of the shots might allow for some, maybe all, the diff in file size.
Thanks again.

[another view]

But now I see that what I considered a small change in position and direction of the shots might allow for some, maybe all, the diff in file size.

You mentioned above 55k vs. 1700k. Are these two figures accurate? 55k would be a shot somewhere around 400x600 or maybe as large as 600x800 pixels. This is tiny in comparison to 1700k. A typo by chance, or something I'm missing?

[VenturaRon]

Re: anotherview, "55k would be a shot somewhere around 400x600 or maybe as large as 600x800 pixels"

You might be confusing pixels with KB of compressed data. I don't think you can directly equate 55KB to 600X800 pixels without knowing the compression ratio - which will in part depend on the complexity of the picture. True, 600X800 = 480,000 pixels. And 55KB = 440,000 bits of data - but it's compressed data. I don't know what the best compression ratio is but I'm sure it's well over 5.

I've run a test of file size and flash. I have had very large file sizes using flash with complex detaild images. So I guess my former examples of small file size with flash was a result of simple, less detailed pictures.

[another view]

Now I'm totally confused... You mentioned file sizes of 55k and 1700k in your original post. I said "somewhere around" 400x600 or 600x800 based on the sizes of images I've posted here in past experience, just as some basis of comparison. 600x800, which is pretty unlikely for any halfway decent looking image at a file size of 55k, is obviously going to be much smaller in pixel dimensions than any decent looking image file that's 1700k.

Compression settings affect file size of course but this isn't even in the neighborhood of 55 vs. 1700. What are the pixel dimensions of both of these shots?