Do These Photos Look Okay?

Here's a photo of my camera setup


The lights are positioned at 10, 2 and 6. The lights at 10 and 2 can be doubled with both the high (the white Jansjos are about 1 7/8 inches higher) and low (the black Jansjos) on, or on singly (either high or low. I never tried one high and one low light on).

To continue the lighting and aperture comparison I took the following shots...

These first two photos compare the difference in aperture. Both photos are with lights at 10 - 2 in what I'm calling the high position (only the white Jansjos are on)


As expected, the larger aperture size at f/6.3 resulted in a faster shutter speed. The f/6.3 shot seems fairly reasonably exposed, but does seem a bit dark in the 4 - 8 region (lower part of the coin).

Also as expected, at f/8.0 the shutter speed decreased to allow more light to reach the sensor through the smaller aperture size, but the photo looks over exposed. The histogram shows much more light reaching the sensor at f/8.0. As with my previous photos, all of the f/8.0 shots seem to be overexposed. It looks like the camera may be setting the shutter speed too slow at f/8.0 for some reason.

The next two shots compare high and low lighting. Only the lights at 10 - 2 are on. Either both black Janjos (low) or both white Janjos (high).

Here's the high photo (same photo as above)

and the low photo (white Jansjos off, black Jansjos on)


It looks like the lower lights resulted in less diffusion and as a result the shutter speed was faster.

The next two shots compare the effect of adding a light (low) at the 6 position. The 10 -2 lights remain in the high position (white Jansjos are on).

Here's the without light at 6 photo (again same as before)

and with a light at the 6 position

The additional light results in a faster shutter speed, removes the shoulder on the first histogram peak, but increases the second histogram peak as well. To me, this image seems a bit sharper and might look fairly nice with a bit of post processing.

My last comparison is to turn on the additional low lights (the black Jansjos) at the 10 and 2 positions. Here's the 10-6-2 photo again

and one with both high and low lights on at 10 and 2

With the additional lights, the shutter speed once again increased and, to my eyes, the overall lighting of the coin became a bit more even.

I could have thrown in a few more shots at f/8.0, but since they all seem over exposed I didn't include them. It looks like with my camera/lens combo that I will need to apply some exposure bias if I want to use the f/8.0 aperture setting.

It's been a pretty long post, thanks for reading
Any comments are welcome

Ray,

Thanks for the comments.

I agree that it does look like the camera isn't adjusting the shutter speed quite right. Particularly, at the f/8.0 it's leaving the shutter open too long and letting too much light in.

As you indicate, I can change all the settings in post processing. I'm just trying to get the lighting close enough that I can limit the post processing.

As far as the camera goes, it does have the ability to set an exposure bias prior to taking the photograph (you can see in data for each photo that the bias is set to 0 for these shots). You can also adjust the saturation, hue, sharpness and contrast in the camera before taking the photo. I've never thought there was an advantage to adjusting all these parameters prior to the shot versus adjusting in post processing. Do you see an advantage to setting them pre-shot?

Ray,
if you're saving the photos out as JPG files.

I was really asking about RAW (which for some reason Pentax saves as PEF) files. Should have been more clear about that.

It seems like everything that can be set on the camera pre-shot can be adjusted as post processing for RAW files. So, the only advantage that I see is if you're making the same adjustments to all photos, then you might as well do it one time with the camera settings.