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Tag: ISO

How to produce smooth timelapse videos.

Posted on January 22, 2019 - 12:01 am by 2
Smooth Waterfall

When shooting a time-lapse, sometimes the footage can come off jerky or jumpy – it is often referred to as the staccato effect. This is when the exposure times for each image in the time-lapse are too short to incorporate enough motion blur to allow the moving elements of the scene to smoothly transition frame to frame. Because there is little to no motion blur, these moving elements in your scene seem to jerk or jump around.

The staccato effect is not to be confused with camera shake, which is when the camera moves during your time-lapse. In order to make sure your time-lapse appears smooth, make sure there is no camera shake. First, make sure you’re using the best time-lapse camera you can afford. Any decent DSLR should have image stabilisation and decent optics.

Place the camera on a solid and secure tripod and avoid moving or jostling the camera while you are capturing your time-lapse. If the camera does get jostled, camera shake will require video stabilization in port production. Don’t jostle the camera and make sure it is securely mounted and this will not be an issue for you.

Exposure Time

The first step to producing smooth time-lapse videos is to make sure that the exposure time will take into consideration the movement between each frame. You want a degree of motion blur to work as a segue from one image to the next. This can be achieved by using relatively long shutter speeds.

Although using smaller apertures is a common way to extend the exposure time for single stills, it is not the best solution for time-lapse. Depending on the lens, it may introduce flicker into your time-lapse. This should not be an issue if you are using lenses with a manual aperture ring, however, if your lens does not have a manual aperture ring, consider using ND filters. Even if you are using a manual aperture lens, ND filters are often an ideal solution to extend the exposure times. They will limit the amount of light coming through your lens, stopping the exposure down. This can allow you to have more control over the exposure times during bright time-lapse shots.

Another means by which you can extend the exposure time is to use the lower ISO numbers available on your camera. This will reduce the sensor sensitivity to light, thereby allowing longer exposures. Often you will be using low ISO numbers and applying ND filters to further extend the exposure times. Low ISO numbers also have generally higher dynamic range – if you can, find out what ISO gives your camera it’s highest dynamic range (the native ISO), and use ND filters with this ISO setting for the best results.

You may also use the aperture but beware. Between each shot, the aperture will automatically reopen to its widest to allow more light to hit the sensor or mirror to make metering and focusing more easy on the user and camera. This often results in each shot having a slight difference in aperture as the blades are opening and then re-closing for each successive exposure, and they often will not produce the exact same aperture size. This is not an issue if you are using the maximum aperture of the lens. Again, if you want to use apertures other than the maximum of the lens, this problem can be solved with a manual aperture lens. Either way, keep in mind that using very high apertures can also produce artefacts in your images. Even small pieces of dust on the lens or sensor are more visible in the higher apertures (around 18 and above), so keep that in mind.

Post Production

If the time-lapse you have already shot is riddled with the staccato effect, then there are some solutions in post-production.

The first thing you’re going to want to do is to reduce flicker. Fir this, the best time-lapse software for the job would probably be LRTimelapse.

For starters, the simplest option would be to create your video, then open that video in a program like Adobe Premiere or Apple Final Cut Pro, and add motion blur. There are two simple ways of doing this in FCP, one would be downloading this motion blur plug-in. This will generate motion blur, however, I think it takes the dropped frames from a sped-up video and makes use of those, so I don’t know how effective it will be when you aren’t speeding the footage. However, if you did speed your time-lapse video, you could apply this effectively, I am sure. Another option is the trails effect in final cut pro. I would give these a try first, as they are simple and quick. There are similar options for Premiere. The echo effect works similarly to the trails effect in FCPX. There is also Pixel Motion Blur available for Premiere.

“The simplest option would be to create your video, then open that video in a program like Adobe Premiere or Apple Final Cut Pro, and add motion blur”

Yet another option will work regardless of the non-linear editor you are using, so long as it supports multiple video tracks and has the ability to manipulate opacity. The idea is to stack multiple video tracks atop one another off-set by one or more frames, with varying opacity. This will create a sort of motion blur by having the previous and following frames composited over the current frame at a lower opacity. You may also use all of these technics together – using multiple video tracks with slightly off-set timing, and including the above-described effects on some of the video channels. There is a good overview of fixing the staccato problem using the Adobe programs Premiere and AfterEffects here. A similar protocol can be followed on Apple programs as well.

Lastly, if you do end up with camera shake, Final Cut Pro and Premiere have tools to remedy these issues as well. Though there are limitations, you will find mild shake can be dealt with using the video stabilization tools in either program. Due to the stabilization filter having to change the position of the image in the video in order to stabilize it, you will likely have to crop the image somewhat after applying the stabilization. This will be true for a large number of other video editing suites in addition to FCP and Premiere.

Time-lapse Flicker Removal Guide

Posted on December 10, 2018 - 10:45 am by 2
Flickering Light Bulb

So you’re here because you need help with time-lapse flicker removal. Flicker is the nemesis of the time-lapse photographer which can often ruin an otherwise silky-smooth time-lapse video, so let’s look at what it is, what causes it, and how you can prevent it or repair it is necessary.

Flicker is the change in brightness or exposure – in this case, of the images taken in a time-lapse stream of photographs – which results in a perceived strobing effect when watched as a video.

There are ultimately two different reasons you could experience flicker – either due to changing light or changing exposure settings. A lot of the time you might not be able to control the light source – outdoor scenes/landscapes – which may introduce flicker which is difficult or even impossible to PREVENT, however, preventing flicker is preferable to having to FIX it.

First, you are going to want to manually set as many of the exposure settings as possible. Automatic shooting will likely result in variations in exposure settings, most notably, aperture, which will easily contribute to flicker.

It is best to shoot in full manual – to set your aperture, shutter speed, ISO, white balance, file format, and focus.

The following assumes you are shooting using a lens with electronic aperture control. If you are shooting on a lens with an aperture ring, then this really won’t apply, as the aperture will remain consistent throughout the shoot.

For aperture, it is a good idea to shoot wide open on your lens if possible, (or, a second choice, at minimum aperture) as mild variations in how the lens and camera will set the aperture between each shot may increase flicker effects. If the lens is at maximum aperture, this can not happen.

Another option is to use lenses without electronic aperture control because these lenses mechanically change the aperture, and because they will not be reset to wide open (for the benefit of the brightness in the viewfinder/autofocus), instead, they will stay consistent. Some suggest unlocking your lens on the mount (giving it a slight turn to disengage the switch), however, the lens will have to be set at the desired aperture first – so you will have to fire a shot; so the camera stops the aperture down, then disconnect the lens DURING the shot, so it would be wise to set a long exposure.

“In an ideal situation, you would shoot with manually set apertures – there are many lenses available with aperture rings”

I have used scotch tape to interrupt the electronic contacts, however, neither is ideal and can sometimes result in the camera resetting the aperture to wide open… Again, not an ideal solution. In an ideal situation, you would shoot with manually set apertures – there are many lenses available with aperture rings – and any lens with a longer flange focal distance than the system your body uses can typically be easily converted to fit your camera mount. There are even aperture adjustment rings that can be added or included into such a scheme if the lens DOES NOT have an aperture ring built into the construction of the lens. For more advice on selecting the ideal lens, see our guide to choosing a lens.

Regarding the image file type, when shooting a time-lapse sequence, it is best to be shooting in RAW. The RAW file format is vastly superior due to the substantially greater amount of detail – especially if you need to push the exposure – allowing the final image to become appropriately exposed. In other words, If you do end up with flicker in your images, RAW will let you adjust the images adequately to allow for appropriate brightness and white balance to a degree which will often cause clipping or other lost color information to reveal itself when the adjustments are applied to JPEGs.

It is a wise decision to use manual focus when shooting time-lapse – not necessarily to prevent the flicker effect, but more to prevent the focus from shifting during the exposure. In addition, if the point of focus is setting the exposure (if the exposure settings are not on manual), then that point becomes shadowed or more illuminated, then the greater scene may change in overall brightness – which will be undesirable if you want to avoid flicker.

It will be preferable to set the white balance yourself – this will prevent the auto white balance setting from changing during the course of shooting and altering the color profile of the final image – this will result in something that will be much like flicker – not in brightness per-se, but rather, in the color shift caused by the changing color temperature.

It is nice to have a static ISO sensitivity, as a varying ISO number will change the sensor sensitivity, which will change the dynamic range, may lead to highlight clipping, ultimately giving reducing shadow detail, and changing levels of shadow noise, which may give a somewhat similar effect – that said, in changing light conditions, this may be necessary in order to achieve a decent exposure.

Setting the shutter speed manually will also help decrease the appearance of flicker, although, with all of the other settings on manual, this may be utilized to adjust to a proper exposure. On a side note, for the purposes of achieving motion blur, which often results in a more smooth motion transition from image to image, it is often suitable to use relatively long exposure times.

In order to off-set long shutter speeds and wide lens apertures, an ND filter may help you achieve the exposure you want. An ND filter, or neutral density filter, is a means to reduce exposure without shifting the color in the resulting image. This is used specifically for outdoor scenes where the light conditions do not allow for the exposure settings you would prefer to use to be possible. It also will help with highlight clipping.

Neutral Density (ND) Filter

But what if the light is changing in your scene?

If you are experiencing changing lighting, then you may need to adjust your exposure settings throughout the shoot. Par exam; a sunset scene – if you begin shooting as the sun is setting, the amount of light entering the lens will decrease through the period of the time-lapse shoot. If this is the case, you could change shutter speeds or even ISO manually, or you could shoot in Aperture Priority (often abbreviated Av) instead of full manual. This will keep the aperture consistent while changing other settings such as the shutter speed and the ISO setting in order to get the right exposure. In this mode, you can set the aperture you want and let the camera adjust other settings in order to get the right exposure.

Still have flicker?

Well, sometimes it is essentially unavoidable – scenes with changing lighting conditions will often result in perceivable flicker even with solid exposures the whole way through, if this is the case, the best solution is de-flickering software. There are several programs available, some free, some come in trial versions, some as plug-ins to Adobe suite applications such as Lightroom, and some as standalone applications.

“There are several programs available, some free, some come in trial versions, some as plug-ins to Adobe suite applications such as Lightroom, and some as standalone applications”

Regardless of whether you are having problems with flicker or not, it is a good idea to familiarize yourself with these programs if you are shooting timelapse – it will likely become an issue at some point, and many of these programs will vastly improve the fluidity of the final presentation of your time-lapse video – and many of them do more than just de-flicker!