Monday, September 27, 2010

DAM - Digital Asset Management


There's not really a right or wrong answer to "looking after" all of the assets which make up a project, but the need for a decent asset management strategy, especially when using double system sound is very important. Students often run into problems when moving from one edit suite / studio to another, and often leave some of their files behind. I have therefore created a basic flow chart which discusses a solution (not THE solution) to help make asset management easier.

This video http://www.vimeo.com/14840608 which I thought was excellent, runs through some really useful methods; my flow chart is attached here too, with a couple of extra stages added if necessary, such as setting up the scratch disc and exporting to ProTools for further sound editing .... (please click on the picture to open it and so that you can read it properly).

The flow chart (and video) makes use of Final Cut's MERGE CLIP feature when using double system sound and this has been discussed and demonstrated on this Blog previously. Equally, PLURALEYES could be used for the automatic sync'ing of clips if a clapperboard of some kind of sync point was not used......

First Electronic Viewfinder for DSLR

Redrock micro have jsut announced the world's first HDMI electronic viewfinder for HDSLR cameras:

http://www.dslrnewsshooter.com/2010/09/26/redrock-micro-launches-the-microevf-for-hddslr/

Sunday, September 26, 2010

Monopod

Went out with the camera this morning to a local nature reserve to have a further play with my new 70 to 200L f4 lens. However, this time I also took a monopod and what can I say, these things are great and help take the weight incredibly well. When normally holding the camera with the lens at its maximum focal length, it's so tiresome to hold it steady; not with the monopod!

Great!

Friday, September 24, 2010

Audio drifit issues

Found a very interesting article here discussing a "glitch" in Final Cut Pro which sometimes can cause separate audio to start drifting from the picture:

http://brucesharpe.blogspot.com/2009/06/dslr-dual-system-audio-999-solution.html

I intend to make a demonstration video discussing this shortly.....

Thursday, September 23, 2010

ZOOM H4N Output Level Settings

Carried out a little test the other day to compare the output levels of the Zoom H4N when input to the Canon 550D. The audio output is on its own too "hot" for the 550D to handle and as the 550D has no gain controls for its audio input, a PAD cable needs to be employed. Luckily Pink Noise Systems manufacture a custom mini jack to mini jack cable with built in -25dB attenuator to prevent the input on the 550D from overdriving. I wondered however what effect changing the audio output level on the Zoom H4N would have.

With the audio output on 50 (i.e. half way), there was quite a lot of noise present, but compared to a setting of 75 and 100, it sounded far more transparent without any nasty AGC (automatic gain control) kicking on the Camera. I am not interested in keeping the audio any way as I would use separate sound recorded by the Zoom any way, it's just that I wondered how the quality of the audio recorded by the camera would be affected.

Results here: http://www.vimeo.com/15159957

Tuesday, September 21, 2010

Zoom H4N Limiter Settings?

Just been playing around with the three different LIMITER settings on the ZOOM H4N. The manual doesn't give any information as to what level the limiter actually kicks in at, so I decided to quickly test the three. It appears that on "LIMIT 1" it kicks in at around -9dBFS, "LIMIT 2" at around -6dBFS and "LIMIT 3" at around -3dBFS. I think to try and keep recordings as transparent as possible, I will therefore use LIMIT 3 from now on. Recording at 24 bits, it is not necessary to get as close to 0dBFS as possible, so as long as sufficient headroom is left, the limiter at this level should very rarely kick in; only when the signal is getting very close to 0dBFS....

Monday, September 20, 2010

Sensor Size vs. Depth of Field

Just had a thought - yes, the sensor size does affect the camera's field of view, but does it also have an impact on its depth of field?

Let's take a 35mm camera (such as the Canon 5D MKII) which has a full frame sensor. If we stick on an 80mm lens set with an aperture of f/4, then the diameter of the iris at this setting would be 80mm / 4 = 20mm. However, with a cropped sensor of 1.6, the same effective field of view would be obtained from a 50mm lens (i.e. 80mm / 1.6 = 50mm). Therefore, with this, the diameter of the iris, again at f/4 would only be 12.5mm, i.e. smaller than for the uncropped sensor. So, to obtain the same aperture diameter of 20mm, the f number would need to be 50mm / 20mm = f/2.5 which is more than one f stop larger.

Looking at it another way, if the aperture of 80mm lens on the 35mm camera was set to 12.5mm (i.e. the calculated diameter of the 50mm lens on the cropped sensor), its f number would only need to be 80 / 12.5 = 6.4.

Or putting it another way, the equivalent f number rises or falls by a factor equal to the SQUARE of crop factor:

f/4 on 1.6 cropped sensor = f/2.5 on full frame

f4 on full frame sensor = f6.4 on 1.6 cropped sensor.

This is very interesting as it means that to get the same depth of field that say a 50mm f1.4 lens would give on a full frame sensor, one would need a 31mm lens with an aperture of approx. f0.55 (1.4 / 1.6^2)!

It can therefore be seen that using a full frame camera yields not only a change in the field of view, but also a decrease in the depth of field.

Saturday, September 18, 2010

The Road to Coronation Street

Found an interesting article discussing the recent BBC4 Drama "The Road To Cornoration Street" in that it was mostly shot on the Canon 5D MKII Digital SLR:

http://www.4khub.co.za/node/82

Friday, September 17, 2010

Final Cut Issues

Spent an age today trying to compile a demonstration video whereby some footage was 1080p ProRes from the Camera and others were MP4 screen grabs from Quicktime Player X. Firstly, I was unable to get the screen grab footage to load into Final Cut Pro, so I tried transcoding it to ProRes and HDV but neither of these would still load into FCP? Any way, eventually, after using EXPORT TO DV within MPEGStreamClip, I managed to get some footage to load. However, I didn't realise until after several exports of the finished edit, that my sequence preset had been set to PAL DV 720 x 576 due to the format of some of the clips being brought in. This was fine, or so I thought, because I could simply amend the sequence preset from within the settings window. After having changed the sequence preset back to ProRes(LT) 1080p 25fps, the strangest thing happened to all of my footage in that its dimensions drastically reduced, even for the native 1080p footage from the camera? To cut a long story short, the only way to get round this was to re-add each of the pieces of footage back onto the sequence? Very strange??

Thursday, September 09, 2010

Vimeo

Have just registered with Vimeo so will be posting higher quality videos there too from now on....

Home page:

www.vimeo.com/digitalvideoslr

Channel:

www.vimeo.com/channels/audiovideotraining

Lilliput HDMI field monitor


Another new toy for rig (well toys as I have also upgraded my Tripod Head to a Manfrotto 501HDV) is the Lilliput 668 HDMI field monitor.

There are many very expensive HDMI capable field monitors out there, but this caught my eye because it was so much cheaper than all of the others. It came supplied with everything required including mini HDMI to HDMI cable, ball levelling hot shoe adaptor, sun screen and battery. I highly recommend this little screen and is great for reviewing footage on and for focussing. Its resolution isn't true HD (800 x 480 pixels) but it more than does the job for me.

See it here:

http://www.carcomputer.co.uk/shop/monitors/hdmi-monitors/lilliput-668gl-70np-h-y-7-hdmi-field-monitor-non-touch-screen

Canon 70 to 200 f4

Just bought a new lens - the Canon 70 to 200 L F4. Absolutely delighted with it and yesterday I carried out a test to establish how the lens performed under different aperture and shutter speed settings. The lens isn't amazingly fast being f4 only, but it is a constant f4 throughout the zoom range and its image is razor sharp.

The test settings used were a constant focal length of 200mm and wide open at f4. As I was shooting in daylight the only way to avoid over exposure was to increase the shutter speed to 1/400s. This is not ideal and I have ordered some cheap ND filters to help bring the useable shutter speed down to 1/50s (for 25p) but these haven't arrived yet. Any way, I then lowered the aperture down to f5.6, f8, f11, f13 and f16, changing the shutter speed to compensate. Interestingly, the "proper" shutter speed of 1/50s could only be obtained with an aperture of f13.

Video here....

Tuesday, September 07, 2010

Slow Motion

Shot some 720p video using the NTSC format the other day (so that 60fps) can be used. Clip captured and transcoded to ProRes(LT) 1280 x 720 @ 60fps and then slowed down to 42% (i.e. 25 / 60) of its original speed in Final Cut. The "frame blending" option was also unticked.

Example here....

Monday, September 06, 2010

Slow shutter speed, in high light with Shallow DoF - how?!

Recently I went to film a Lancaster Bomber on a Taxi run and I wanted a short DoF, setting my lens to f2.8 or sometimes f4. It was daylight, so light levels were high and due to the wide aperture setting of the lens, the only way to obtain the correct exposure was to increase the shutter speed. Everything looked fine apart from the fact that the propeller blades of the plane appeared to be almost stationary; the high shutter speed of (probably) 1/1000s saw to that!

The problem with shooting at a high shutter speed is that the it sort of takes away the "film" look of the footage, where the shutter speed is always set to TWICE that of the current frame rate being used (as each frame is only exposed to light for half of the time). Therefore, at 25p, a shutter of 1/50s should be utilised. Similarly, when shooting at say 50p, a shutter of 1/100s should be used. So therefore, if you want to use a wide aperture setting for shallow DoF, gain the correct exposure and only use the optimum shutter speed, how you can achieve this; there are no more variables to play with!

The answer (after some research!): some kind of Vari-ND filter attached to the lens which enables the user to control the amount of light actually entering the lens to begin with. Philip Bloom, and others, recommend the Singh-Ray filters (http://www.singh-ray.com/varind.html), but these are very expensive. Therefore, I have found a DIY alternative whereby two polarising filters can be bought and one reversed: http://www.petapixel.com/2010/08/27/how-to-build-a-cheap-and-simple-variable-neutral-density-filter/

Not sure how well it works, but worth a try :)

Friday, September 03, 2010

Rode NTG1 vs. Rode NT1 microphone test

Knocked up a quick demonstration video to compare the tonal difference (if any!) between the Rode NTG1 shotgun mic and the Rode NT1 studio mic. Obviously there are differences in the pick up response between the two mics and I wouldn't want to use the NT1 outdoors, but inside and on axis, they both sound good. There is slightly less "room noise" on the NTG1 but this is down to its hypercardioid pickup. Didn't mention in the video, but both mics were approx. 18" from mouth.

The video itself was shot with the 550d camera and Tamron 28 to 75mm f2.8 lens to give nice shallow DoF. Audio was handled by Zoom H4N and sync'd up with picture using Pluraleyes software (although a hand clap and Final Cut's MERGE SEQUENCE function would have worked just as well).

Exported from Final Cut with a 2.35:1 "widescreen" filter applied. Black bars removed by exporting to MPEG4 (3000kbps) using a resolution of 1920 x 816 (i.e. 2.35:1) and aspect ratio maintained by "crop" option.

RIGS

Really getting into DSLR video now and all its toys. I have been looking into supports and rigs for a while now and whilst the likes of Zacuto are extremely good, they attract a premium. Their "Striker" retails for about £800 alone which is too rich for my blood.

I have therefore been looking at the "Half Inch Rails" website which details more of a DIY approach but who sell really well engineered and light kits. For a complete solution, together with rail mount for an HDMI field monitor etc., and a simple follow focus which can be accessed via your thumb (so no need to move hand away from grip), you're probably looking at about £600, which whilst expensive does allow the option of quickly moving the whole rig onto a tripod. For this, the Manfrotto 577/501 plate combination is recommended. I am looking at the possibility of a 501HDV video head for my tripod, together with a 577/501 plate for the rig so that they can easily be interchanged.

I am also looking at another new lens for my camera and for me, I think it's got to be the Canon 70 to 200 f4 L lens. I cannot find a bad review about this lens any where and, with the cropped sensor of my 550d, would give a zoom range of about 112mm to 320mm and a constant aperature of f4. Ideally, the f2.8 version would be better, but this costs much more and weighs a lot more too! The IS (image stabalised) version is also recommended but again, I'd rather not spend £1000 at least on a lens! Therefore, I think the non-IS f4 lens will be great for me.

The whole rig, when finished, should comprise the Half Inch Rails rig, together with Zoom H4N for audio, some kind of HDMI field monitor and tripod. I already have the LCDVF viewfinder as well.

Just need that lottery win :)