Another cracking new feature which I have just discovered in Magic Lantern is the ability to lower the ISO beyond the standard minimum setting of ISO100. It is now possible to reduce the ISO to ISO25, meaning a two stop reduction in sensor sensitivity. Why would you want to do this I hear you ask? Well, there are two reasons I can think of immediately:
1. Shooting outdoors in bright daylight. Unless one has a neutral density filter on the front of the lens, the only way to maintain a short depth of field (wide lens aperture), but avoid over exposure, is to decrease the shutter speed lower than the standard 180 degree shutter of 1/2n, where n = the frame rate. The main issue with doing this however, is that any movement in the shots can become very "staccato". This is often used in fight / action sequences for creative effect, but it is often not desired for normal shooting. Therefore, if one can reduce the ISO to ISO25, the aperture can be opened up two stops, which will help maintain the short depth of field which DSLR video so easily enables. Let's take an example where say the camera is set to ISO 100 and a shutter speed of 1/50s (i.e. standard 25fps shooting). To avoid over exposure, the aperture of the lens needs to be reduced from f/2.8 to f5.6 (two stops reduction). However, in doing this, the depth of field is increased beyond what is required. If the ISO is now changed to ISO25, the exposure will reduce by TWO stops meaning that the aperture on the lens can now be returned to f/2.8, giving the desired short depth of field. Therefore, this new feature acts in a similar way to using a two-stop ND filter.
2. Shooting timelapse sequences using the FRAME RATE OVERRIDE function. If shooting with say a frame rate of 2fps, the shutter speed is also greatly increased, meaning lots of light, meaning potential over exposure, even with the smallest of lens apertures (f/22 for example). However, with the ISO reduced to ISO25, again, one can open up the iris of the lens somewhat higher than its minimum setting.
The DOWNSIDE to this feature, is that some of the over exposed regions can become pink, but this can be corrected in post.
A VERY nice feature!
Wednesday, August 15, 2012
Monday, August 13, 2012
Intervalometer in MOVIE mode / Frame Rate Override
Another test which I plan to carry out this week is Magic Lantern's intervalometer in MOVIE mode. As previously discussed and demonstrated, Magic Lantern has a built-in intervalometer which can be used to automatically press the shutter at set intervals. The resulting still images are then convered into an image sequence using some software such as Quicktime Player 7.
The frame rate override function within Magic Lantern has also been investigated as well which is where the frame rate, in MOVIE mode is lowered to say 2fps, which allows timelapse sequence to be created directly as a movie (this also helps to avoid some of the artefacts caused when using a series of still images too).
What interests me now is using the intervalometer directly within MOVIE mode, which instead of taking a single image every few seconds (for example), will take a 1s movie clip at a user defineable interval. These short 1s movie clips can then be joined together to create a timelapse sequence.
Watch this space for the results......
EDIT: a couple of tests have recently been carried out and the results are as follows:
1. When using the intervalometer in MOVIE mode, the results are decent, however, as the camera is taking a 1s movie clip at regular intervals, the outcome can be quite "jerky". A test was carried out where a 1s clip was taken every 60s for around 2 hours and the results were good, however, when speeding the clip up by 2000%, a much smoother clip was produced.
2. When using the FRAME RATE OVERRIDE function, set to 0.5fps, the results were very good indeed as this basically produced a sequence with the same effect as using a series of still images with a shutter frequency of once every 2 seconds. I did however find that increasing the playback speed by 500% yielded an even better and smoother result. Therefore, if this is the case, it would probably be better to use around a frame rate of 2fps rather than the 0.5fps I tested.
A video of the video discussed in (2), can be found here:
https://vimeo.com/47586109
The main issue with both of these functions is that the Canon 550D can overheat fairly quickly (after around 15 minutes!) but turning off the LCD display on the camera can apparently help increase overheating times quite substantially - again, watch this space!
The frame rate override function within Magic Lantern has also been investigated as well which is where the frame rate, in MOVIE mode is lowered to say 2fps, which allows timelapse sequence to be created directly as a movie (this also helps to avoid some of the artefacts caused when using a series of still images too).
What interests me now is using the intervalometer directly within MOVIE mode, which instead of taking a single image every few seconds (for example), will take a 1s movie clip at a user defineable interval. These short 1s movie clips can then be joined together to create a timelapse sequence.
Watch this space for the results......
EDIT: a couple of tests have recently been carried out and the results are as follows:
1. When using the intervalometer in MOVIE mode, the results are decent, however, as the camera is taking a 1s movie clip at regular intervals, the outcome can be quite "jerky". A test was carried out where a 1s clip was taken every 60s for around 2 hours and the results were good, however, when speeding the clip up by 2000%, a much smoother clip was produced.
2. When using the FRAME RATE OVERRIDE function, set to 0.5fps, the results were very good indeed as this basically produced a sequence with the same effect as using a series of still images with a shutter frequency of once every 2 seconds. I did however find that increasing the playback speed by 500% yielded an even better and smoother result. Therefore, if this is the case, it would probably be better to use around a frame rate of 2fps rather than the 0.5fps I tested.
A video of the video discussed in (2), can be found here:
https://vimeo.com/47586109
The main issue with both of these functions is that the Canon 550D can overheat fairly quickly (after around 15 minutes!) but turning off the LCD display on the camera can apparently help increase overheating times quite substantially - again, watch this space!
Magic Lantern New Version - TODAY
Today sees the latest release of Magic Lantern become available, for all users, for free.
There appears to be some cracking new features available in this latest upgrade, including the abaility to shoot video at a frame rate as low as 0.2fps (equivalent to timelapse shooting of 1 frame every 5 seconds). This is a feature I will definitely be investigating.
Latest version can be downloaded here:
http://www.magiclantern.fm/releasenotes
There appears to be some cracking new features available in this latest upgrade, including the abaility to shoot video at a frame rate as low as 0.2fps (equivalent to timelapse shooting of 1 frame every 5 seconds). This is a feature I will definitely be investigating.
Latest version can be downloaded here:
http://www.magiclantern.fm/releasenotes
Wednesday, August 01, 2012
Timelapse vs. Frame Rate Override
A couple of short timelapse demonstration sequences, one shot using MOVIE mode and the "frame rate override" function to reduce the frame rate to just 1fps. The other shot using a series of still images (lowest JPEG setting), taken every 1 second, strung together in Quicktime Player 7. Both of them were shot over a 15 minute period. (The problem when using such low frame rates is that the camera wants to overheat quite quickly!).
The latest version of Magic Lantern, which was only installed today, enables frame rates much slower than the previous version, which on the 550D, only allowed adjustment as low as 4fps.
The main issue when shooting at such a slow frame rate in MOVIE mode, is that the image can easily be overexposed. With not a great deal of light available, the aperture on the lens had to be closed down to its minimum setting (f/22) to prevent over exposure. Therefore, an ND4 filter was attached to the lens which enabled the aperture to be widened slightly to f/11.
For the timelapse shot with a series of still images, the ND filter was removed to allow the same aperture of f/11 with a shutter of 1/40s. The "LENS TWIST" method was also employed (see previous post), to ensure that the aperture blades were held in the same position for each shot.
On the plus side, using such a slow frame rate would allow fantastic low-light shooting, especially with a fast lens such as the Canon 50mm f/1.8II currently being used for these tests.
Results:
Frame rate override using ISO: 100, 1fps, f/11.
Timelapse using ISO:800, shutter frequency: 1s, f/11.
Higher quality version at Vimeo: https://vimeo.com/46747324
The latest version of Magic Lantern, which was only installed today, enables frame rates much slower than the previous version, which on the 550D, only allowed adjustment as low as 4fps.
The main issue when shooting at such a slow frame rate in MOVIE mode, is that the image can easily be overexposed. With not a great deal of light available, the aperture on the lens had to be closed down to its minimum setting (f/22) to prevent over exposure. Therefore, an ND4 filter was attached to the lens which enabled the aperture to be widened slightly to f/11.
For the timelapse shot with a series of still images, the ND filter was removed to allow the same aperture of f/11 with a shutter of 1/40s. The "LENS TWIST" method was also employed (see previous post), to ensure that the aperture blades were held in the same position for each shot.
On the plus side, using such a slow frame rate would allow fantastic low-light shooting, especially with a fast lens such as the Canon 50mm f/1.8II currently being used for these tests.
Results:
Frame rate override using ISO: 100, 1fps, f/11.
Timelapse using ISO:800, shutter frequency: 1s, f/11.
Higher quality version at Vimeo: https://vimeo.com/46747324
Aperture flicker and other artefacts
Found that when using the 24 to 105 f/4L IS lens, there seems to be quite a lot a movement between the stills in a timelapse sequence and also, there is quite a lot of "aperture" flicker between shots too. Aperture flicker occurs because the aperture blades of a lens return each time a shot is taken and apparently, the camera cannot precisely close the blades by exactly the same amount each time the shutter is released.
Firstly, another lens - the Tokina 11 to 16 f/2.8 was tried and this produced zero movement between shots (which is interesting in itself) and also, the "twist" method to keep the aperture blades on the camera constant was used on the 24 to 105 as well, which is a neat trick:
Aperture fix via "twist" method demonstrated here: https://vimeo.com/30974031
A couple of very shorts tests were carried out with the camera set to take a shot every 2 seconds over a period of approx. 1 minute. The clips below are therefore extremely short, however, they hopefully aid this discussion.
1. Using the Canon 24 to 105 f/4L IS lens, the lens was stopped down to f/8 to close the blades down a little and using the trick mentioned in the video above, the blades were forced to stay in this position. Interestingly, flicker was noticeably reduced, however there was still some slight movement between some of the shots as this very short clip demonstrates.
It might not be noticeable in the video above, but there is some slight movement between some of the shots. There definitely therefore appears to be an issue with lens when used for timelapse sequences.
2. Using the Canon 50mm f/1.8II lens with its aperture blades forced down to f/8, the same short sequence was shot and again, the results were much better, with no noticeable movements between successive shots:
Firstly, another lens - the Tokina 11 to 16 f/2.8 was tried and this produced zero movement between shots (which is interesting in itself) and also, the "twist" method to keep the aperture blades on the camera constant was used on the 24 to 105 as well, which is a neat trick:
Aperture fix via "twist" method demonstrated here: https://vimeo.com/30974031
A couple of very shorts tests were carried out with the camera set to take a shot every 2 seconds over a period of approx. 1 minute. The clips below are therefore extremely short, however, they hopefully aid this discussion.
1. Using the Canon 24 to 105 f/4L IS lens, the lens was stopped down to f/8 to close the blades down a little and using the trick mentioned in the video above, the blades were forced to stay in this position. Interestingly, flicker was noticeably reduced, however there was still some slight movement between some of the shots as this very short clip demonstrates.
It might not be noticeable in the video above, but there is some slight movement between some of the shots. There definitely therefore appears to be an issue with lens when used for timelapse sequences.
2. Using the Canon 50mm f/1.8II lens with its aperture blades forced down to f/8, the same short sequence was shot and again, the results were much better, with no noticeable movements between successive shots:
The power of Vimeo as an e-Learning tool
I've had my Vimeo pages and Vimeo channel for around 2 years now and in that time posted quite a few demonstration /instructional type videos covering AV and in that time received quite a few international comments. Only yesterday, after someone from Norway had viewed an instructional video I had made on "safety recording", did he get in touch requiring some help and guidance; something I was very happy to provide.
There are many user groups within Vimeo and when certain videos are added to these specialist groups, interest in what one is doing starts to increase; the videos on my pages received 50 plays yesterday alone for example.
There are many user groups within Vimeo and when certain videos are added to these specialist groups, interest in what one is doing starts to increase; the videos on my pages received 50 plays yesterday alone for example.
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