Stepless exposure change with D600 and D810?

[chuck]

I am trying to do time lapse sunset photos on autoexposure aperture priority so the sequence tracks changing ambient light. However, you can see a noticeable exposure change from one frame to the next in the sequence whenever the camera makes a 1/3 stop aperture change. The result is the time lapse has a distinct strobe effect.

 

Can either D600 or D810 be set to do stepless adjustments instead of 1/3 stop adjustments?

[Dieter Schaefer]

When in aperture priority (A) mode, the shutter speeds are controlled steplessly (the 1/3 steps in the shutter speed are just for display purposes) - the flickering you see is most likely due to inconsistencies in the reproducible control of the aperture opening for each shot - are you using a G lens (as the solution is to use a lens that allows to control the aperture directly). Flickering could also come from inconsistencies in the shutter speed - the solution usually is to go to longer speeds.

[rodeo_joe1]

You could grade the frames individually; maybe automating the process with a set of actions in PS.

 

First thing I'd do though, is examine the EXIF data to see where any variation is. Aperture, shutter speed or what.

[mike_halliwell]

There is a program that smoothes these slight variations. IIRC it's called LRTimelapse. It works on RAW files so makes use of all the info recorded.

[ilkka_nissila]

For the most consistent exposures, if possible, use a lens with a physical aperture ring (and set the aperture on the lens).

 

A lens with electromagnetic aperture (E lenses) would also do well provided that it's not very cold. In extreme winter conditions I've had problems with E lenses but most of the time they work fine.

 

G lenses (or other non-E CPU lenses if the body is set to control the aperture) can produce some variation from shot to shot. Software correction is probably the best approach in that case.

[mike_halliwell]

I guess something like the older PC lenses with the preset aperture ring at the front of the lens would work?

Would a D810 work in A mode with one? Not sure how it meters with no tab.

[Dieter Schaefer]

First thing I'd do though, is examine the EXIF data to see where any variation is. Aperture, shutter speed or what.

There is a program that smoothes these slight variations. IIRC it's called LRTimelapse. It works on RAW files so makes use of all the info recorded.

If the EXIF data record a change in exposure value, the light has changed and concomitantly the exposure had to too. Inconsistencies in the reproducibility of aperture or shutter speed is not recorded in the EXIF and hence can't be examined or utilized in some software correction scheme.

[mike_halliwell]

The software effectively looks at the RAW file, maybe the embeddedJPEG?, and determins the variation frame to frame. Pop to the website and look at the tutorial. They explain it much better:) Edited August 12, 2018 by mike_halliwell

[rodeo_joe1]

"Would a D810 work in A mode with one? Not sure how it meters with no tab."

 

- It'd work... provided the non-CPU lens aperture was set to f/2.8 or smaller. At apertures above 2.8 the metering doesn't register through-the-viewfinder brightness levels properly, and LiveView is generally too battery hungry to use for timelapse.

 

If the timelapse application is close-focus or macro, then using a non-Nikon, or MF Nikon lens on a bellows will allow the aperture to be fixed. Good quality enlarging lenses are great for macro BTW.

 

However, the issue may be with the metering itself. There's no guarantee that the subject exposure will be kept constant under varying lighting conditions using averaging or matrix metering. Spot metering centred on an important part of the subject (or a grey card) is likely to be more consistent.... except that then the BG lighting will doubtless vary distractingly.

 

It's for the above reasons I suggested examining the EXIF data, not to look for small aperture or shutter variations.

 

The only surefire solution is to control the lighting by using flash or building a light-tent around the subject to diffuse natural light and get rid of hard and varying-angle shadows.

Edited August 12, 2018 by rodeo_joe|1

[ben_hutcherson]

FWIW, cameras like the D810 and D600 can be set such that they will meter in aperture priority mode according to the position of the aperture on lenses that have one, even if dealing with a CPU lens. I have both my D800 and D600 set that way, as I prefer setting the aperture according to the aperture ring.

 

This avoids the hassle of using a pre-set lens, but should, as said, be more repeatable than letting the camera stop down the aperture according to the position of the stop down lever.

[BeBu Lamar]

I think new Nikon still do stepless shutter speed in A and P but some Canon owner swear that his Canon does it in steps. I myself prefer the stepped approach.

[Matthew Currie]

I use a preset lens a lot of the time with a D7100, and it seems to meter fine within the normal range of apertures, but I've never checked it for absolute accuracy or repeatability, so now I'm wondering about the statement that such a lens will not meter properly at any aperture but wide open. If the camera is designed to meter correctly with a natively slower lens, is there some reason I have not thought of why it would not meter correctly with a preset lens set within that range?

[BeBu Lamar]

I use a preset lens a lot of the time with a D7100, and it seems to meter fine within the normal range of apertures, but I've never checked it for absolute accuracy or repeatability, so now I'm wondering about the statement that such a lens will not meter properly at any aperture but wide open. If the camera is designed to meter correctly with a natively slower lens, is there some reason I have not thought of why it would not meter correctly with a preset lens set within that range?

 

For the Nikon matrix metering system it has to meter with the maximum aperture. The reason is that the meter needs to know how bright the scene is and not how bright the image is projecting on the sensor. There is an algorithm in the matrix metering system that it will not expose for anything brighter than EV16 or so at ISO 100. It deems such a scene is not possible and there must be some kind of light source that fools the meter.

[Matthew Currie]

Interesting. But how, with a preset lens, does the meter know that the lens is stopped down, rather than just that the scene has become darker? How about other metering modes?

 

I've only fooled a little with this, but even with a pretty consistent subject, matrix metering varies a little from one setting to another with both the preset and AF lenses, but with spot or averaging metering, it's more consistent, and It appears that the preset lens gives close to the same exposure at different apertures, and without caring much what "non-CPU lens" info the camera is using.

 

What would happen if you used a preset lens and set the Non-CPU information to match the aperture the lens is using? Set the lens at, say, F8, and specify to the camera that it's an F8 lens?

[BeBu Lamar]

Interesting. But how, with a preset lens, does the meter know that the lens is stopped down, rather than just that the scene has become darker? How about other metering modes?

 

I've only fooled a little with this, but even with a pretty consistent subject, matrix metering varies a little from one setting to another with both the preset and AF lenses, but with spot or averaging metering, it's more consistent, and It appears that the preset lens gives close to the same exposure at different apertures, and without caring much what "non-CPU lens" info the camera is using.

 

What would happen if you used a preset lens and set the Non-CPU information to match the aperture the lens is using? Set the lens at, say, F8, and specify to the camera that it's an F8 lens?

 

Yeah that's only applied to matrix metering. With others it doesn't care.

[mike_halliwell]

You gotta think Matrix might be most easily fooled in a timelapse sequence which tend to cover large areas. I guess spot on a featureless place is ideal or maybe full average?

 

It's that compromise between the real brightness changing, but in a short term way, a frame or 2 maybe, and the sun going down in a linear darkening way.

 

Mechanically induced errors, ie stopping down variations, can be eliminated by presets. After that it's electronic metering etc.

[Andrew Garrard]

Belatedly, I believe there's a setting somewhere in Premiere Pro for balancing the lighting. I've used it for time lapse and long videos outdoors where clouds briefly affected lighting.

 

Not that it's rocket science to average the frame exposure and scale it. I did it manually (well, a short program) on a high frame rate sequence back in the 1990s to undo the 50Hz lighting flicker. I'm sure several bits of software can do it, and probably more effectively than any mechanical variance in the exposure.