Greetings! I thought these images of stained glass windows would be appropriate tonight. I am posting both the final images & basic snapshots of the churches as they appeared without any in-camera manipulation.
They were taken at night (of course) outside of Trinity Episcopal in St. Augustine, FL & St. Peter's Episcopal in Fernandina Beach, FL. I secured the camera on a tripod & adjusted my settings manually to achieve the desired exposure with a slow shutter speed to allow time for zooming. You will see that I used an extremely small aperture to balance out a shutter speed of approximately 4 - 8 seconds. The order in which I set this up was shutter speed first, aperture second, & ISO third. Take a shot then adjust accordingly, & don't forget you can also adjust the exposure value.
In these particular shots, I strived to obtain a fairly identifiable image at both ends of the zoomed range. I learned through experimentation that you have to linger for a couple of seconds at each end of the range. [NOTE: This is an ART, not a science! - At least that's how I approach it. It is a lot more fun than deriving some formula & applying it.]
You have to determine approximately how far to zoom so that your image remains within the boundaries of the frame. For example, you may go from 135mm out to 85mm (take a few shots to see at what point you lose the image). Look at your hand while you zoom & make note of how far to twist your lens. This is critical as you will not "see" the picture while the mirror is up.
More often than not, one of your "experiments" turns out to be the best shot. So, go with it!
Camera Specs: Trinity Zoom (top left) - Canon EOS 7D, EF-S 18-135mm, 8 sec @ f/29, ISO 400, -2/3EV & St. Peter's (top right)- Canon EOS 7D, EF-S 18-135mm, 5 sec @ f/22, ISO 500, -2 2/3EV
Snapshots of churches as they appeared without zooming are posted below.