Well it is dark all right.
So dark that I can not tell what is in the foreground, that you were trying to photograph.
From the photo, it appears that you are trying to light up a large area. Which you can not do, since the flash on that camera is only rated for 14 feet.
Two photos would be helpful.
One flash shot without the fisheye lens.
One flash shot with the fisheye lens.
The A75 has manual controls and you should experiment with raising the ISO setting.
If you use a tripod or place the camera on a solid surface you can also set the camera to Shutter Priority and experiment with slower shutter speeds.
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I have a canon A75 and since I got a massive fisheye lense, I cant use the flash because it blocks most of it.
http://i149.exs.cx/img149/5061/dark1fn.jpg
In person, the ledges right in front of me were lit well enough to see them. In the photo you can clearly see it is all black, you cant even make out lots of the objects. I dont want to get an external flash, so cant I change some setting to make the photos brighter? ISO?

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