Spring is here
Mar 22, 2016 16:33:12 #
Typical New England. I picked this pussy willow bud in the middle of a snowstorm on the first day of spring.
Mar 22, 2016 16:58:12 #
Mar 22, 2016 17:36:07 #
Nikonian72 wrote:
Two LED lamps plus a Sigma ring flash that quit half way through. One problem I see quite often is that the exposure in the focus-stacked image is not the same as in the individual shots.Nice subject. A few hot spots. What is your illumination source?
Mar 22, 2016 17:47:37 #
MACT wrote:
I've not had this happen. As you stack, is the light source also moving? If so, that could be the issue. Inverse square law, or something like that. One problem I see quite often is that the exposure in the focus-stacked image is not the same as in the individual shots.
For this reason, I prefer natural, northern light by a window if I am indoors. When I'm outside, I like to stack on a cloudy day because the light is much more diffused and doesn't go sunny to cloudy which will affect both your white balance and your light intensity.
Mar 22, 2016 18:06:15 #
LoneRangeFinder wrote:
I am working in a basement lab, with no natural light available. I may try a more aggressive diffusion set-up to reduce the hotspot problem.I've not had this happen. As you stack, is the light source also moving? If so, that could be the issue. Inverse square law, or something like that.
For this reason, I prefer natural, northern light by a window if I am indoors. When I'm outside, I like to stack on a cloudy day because the light is much more diffused and doesn't go sunny to cloudy which will affect both your white balance and your light intensity.
For this reason, I prefer natural, northern light by a window if I am indoors. When I'm outside, I like to stack on a cloudy day because the light is much more diffused and doesn't go sunny to cloudy which will affect both your white balance and your light intensity.
Mar 22, 2016 20:24:25 #
MACT wrote:
That's fine. But if you have a ring light mounted on the front of the lens, your light source moves closer to your subject as the camera/lens is moved along the rail, as you collect your stacks. At MWD, this can mean a significant change in the intensity of the light. The only time I use flash to stack, I have it off the camera (synced with an SC-17) so that the flash to subject distance remains constant.I am working in a basement lab, with no natural light available. I may try a more aggressive diffusion set-up to reduce the hotspot problem.
(I have a macro twin flash unit that attaches to the front of the lens. I never use this set-up to stack.)
Mar 22, 2016 20:32:30 #
LoneRangeFinder wrote:
Good point. I will use my remote flash when using the rail and see if it helps.If you have a ring light mounted on the front of the lens, your light source is move closer to your subject as the camera/lens is moved along the rail as you collect your stacks.
Thanks
Mar 23, 2016 01:05:16 #
MACT wrote:
Remember, diffusion is your friend!I will use my remote flash when using the rail and see if it helps.
Mar 23, 2016 17:45:27 #
Mar 24, 2016 19:32:21 #
LoneRangeFinder wrote:
Turns out, it may be a bit more complex. I just ran a trial with no flash, fixed LED lights, and the camera moving on a rail. I still see an increase in illumination: it seems that as the camera gets closer the reflected light has a shorter distance to travel and therefore is more intense. Tomorrow I will try a stack changing the focus, which should keep a constant level of illumination.That's fine. But if you have a ring light mounted... (show quote)
Mar 29, 2016 09:12:02 #
So, there is some difference. With all settings and illumination constant the rail-stack does give an increased exposure compared to focus-stacked.
Mar 30, 2016 06:46:37 #
MACT wrote:
I am not convinced that this is the answer. My understanding is that if you take a light reading of the moon's reflected light it will be the same whether you are standing on the moon or on earth.So, there is some difference. With all settings and illumination constant the rail-stack does give an increased exposure compared to focus-stacked.
As your lens gets closer to the subject then the subject gets larger and so while there is a bigger spread of light I think it is the same intensity. I don't think the distance has much to do with reflected light.
Conversely, if the distance was increasing then the subject would be getting smaller on the sensor as would the spread of light but the intensity would be the same.
Of course, some surfaces/colours reflect light more than others and maybe that is the case with the flower stems.
I hope I am right about this and that some of the physicists we have around will offer their opinion.
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