Railfan Technology > Digital exposures

Still learning digital photography. Knew Kodachrome well and while we all made some mistakes, we did well with it. I knew to under expose slightly to darken, overexpose to lighten, etc. Now with digital, does it work somewhat the same? I have learned to do a 1/3 under exposure for what seems to be better overall quality. This is especially if there is a lot of trees. How does white balance affect the image? Am I in the right frame of mind?

Rob



Edited 1 time(s). Last edit at 10/10/14 16:17 by SilvertonRR100.

Digi film is extremely cheap, and you don't have to wait for a week to get your shots back.

Learn use your light meter to set your exposure manually, and then test the exposure with a
trial shot. Check that trial shot on the camera's monitor. Your camera's firmware should
have a 'histogram,' and if you're in luck, the histogram will show R / B / G. Learn to use
the histogram to fine tune your exposure.

Also explore shooting in your camera's RAW mode, which will give you a much wider 'dynamic
range.' JPEGS are 8 bits per channel, while RAW is on the order of 12 to 14 bits RAW
shooting will require a digi editor that can process the RAW shots.

HTH.

John.

jkh2cpu Wrote:
-------------------------------------------------------

> Also explore shooting in your camera's RAW mode,
> which will give you a much wider 'dynamic
> range.' JPEGS are 8 bits per channel, while RAW
> is on the order of 12 to 14 bits RAW
> shooting will require a digi editor that can
> process the RAW shots.

+1 on shooting RAW. RAW takes more post processing than JPEG to make a presentable final image, but it gives you far more latitude. One advantage is that you can go back and change the white balance in post processing, and alter it from what the camera may have been set to. This is a big advantage when you grab a shot on the fly, and realize afterward that the white balance wasn't set correctly.

If anything, slightly over expose.
Your best tool is to learn to use, and use your histogram... the lines/peaks that show up on the histogram should be all the way to the right without blowing out the highlights, most camera's will can be set if you "blow out" the highlights. More data is recording on the right side of the histogram (whites) than the left (blacks) thus the reason to expose to the right. Although these images may appear a bit over exposed at first on your computer, that is easily adjusted after the shot... google "expose to the right" for a better and more detailed explanation.
And yes, very much shoot in raw!



Edited 1 time(s). Last edit at 10/11/14 16:32 by skyview.

I agree with the advice to slightly overexpose if shooting raw and post processing with Photoshop or Lightroom gives you more light values to work with. Shooting RAW gives you more ability to refine photos than shooting jpg.

The Kodachrome 1/500 f5.6 standard didn't yield too much depth of field. In digital, you can experiment with higher camera ISO settings so you can shoot in the F8 - f9 range for better depth and sharpness with many lenses. On my camera any ISO 400 or less is indistinguishable in terms of digital noise (grain). ISO is now a variable you can use.

You can experiment with shots that wouldn't work well with Kodachrome - shadow side, dark nose, post sunset, harsh overhead sun, etc. Digital sensors have more latitude, Photoshop can do wonders and pixels are free!

Digital is fun for us old Kodachrome shooters!

Jim B

I'd avoid over exposing, but I would concentrate on keeping the 'area under the histogram'
within the confines of the graph. I'll concede that when absolutely against the wall,
I'll allow a few highlights to burn out so that I don't loose important detail in the
shadows.

John.

I have been advised it is better to slightly under expose. Obviously, I would like to get the exposure as close as possible, but I shoot for a slight underexposure, so as not to blow out any of the highlights. Post processing slightly underexposed images are easier to fix. I have asked around other photographers with far more experience and they tend to agree on the under-exposure. Most don't look at the histograms on a regular basis, they look at the image itself. Just some extra food for thought.

Gary

Overexposed digital images are not your friend. Once the 256, 256 256 threshold is reached all you get in the image is pure white. All detail is gone and there is no way to bring any of it back. This is critical for clouds. If you print a digital image with any all white values then the print has areas where no ink is laid on the paper. Those areas are lifeless. This is what B&W printers avoided by exposing their negatives for the highlights. You had to have detail in the negative in order to have detail in the highlight hence the popularity of graduated neutral density filters to hold back the exposure the skies while opening up the shadows.

With digital images you can recover details in the shadows but any exposure which reaches 256, 256, 256 has absolutely no detail to recover.

Posted from Windows Phone OS 7

Hey I'm no expert but I'd slightly underexpose rather than over expose, you can't get the blowout back but you can boost by 2 stops when you shoot RAW. RAW gives you a + or - two stops, but once fried it's cooked so keep the histogram balanced. A histogram with all the data in the middle is what I like to see.

good luck have fun.

chico

jkh2cpu Wrote:
-------------------------------------------------------
> I'd avoid over exposing, but I would concentrate
> on keeping the 'area under the histogram'
> within the confines of the graph. I'll concede
> that when absolutely against the wall,
> I'll allow a few highlights to burn out so that I
> don't loose important detail in the
> shadows.
>
> John.

A lot of landscape photographers are following the "expose to the right" theory. Basically, you overexpose the image, but just under the threshold for blowing out the highlights. Hence, "expose to the right," versus "up against the wall." The reasoning, is that slightly overexposing lets more light into the sensor, and records more data in the shadow areas. The claim is that colors are better, and correcting "down" to the proper exposure (as long as you haven't blown out the highlights) in post production yields a "cleaner" image, since many digital sensors are prone to "noise" in darker areas of the frame.

To apply that theory to railroad photography, would likely result in a trade off. To slightly overexpose with the same f-stop, you would need a slower shutter speed. Since a lower shutter speed could produce blur of moving objects, the only way to get overexposure with a high enough shutter speed to still freeze the action, and with a small enough f-stop to maintain depth of field, would be by pumping up the ISO. Higher ISO would bring more susceptibility to increased noise, which then defeats the entire reason you would want to use the "expose to the right" practice.



Edited 2 time(s). Last edit at 10/17/14 13:34 by bioyans.

Thanks to all who responded. Personally I have been keeping the exposure right on or if there are a lot of trees, a 1/3 stop underexpose so the train is right on and the trees a tad dark. Appreciate all our thoughts on the matter.

Rob