Sunday, 13 March, 2011

Memory cards for Canon 5D/7D shoots

For Canon 5D or 7D shoots, for ad films, music videos, promos, or features, people go into long discussions and arguments about disk storage, RAID etc etc. I have always advocated getting as many memory cards as you plan on shooting. And not erasing and reusing any card, till the shoot is over. Even after transferring the card contents to hard disk for editing and post-production.
That way, one has the data available all the time on the original cards, even if any hard disks fail.

But people tell me that this costs quite a lot. I decided to find out.

First, let's see what media would cost before HDSLRs happened to film-making.

400 feet of film costs about Rs 10,000, and runs about 4 mins, so film is Rs 2500 per minute.
With a shoot ratio of 1:10, a standard Hindi film of 150 mins would shoot 1500 mins of film. This amounts to about 340 rolls of 35mm film or Rs 34 lakhs in film costs alone. Processing extra.

A 40 min HDCam SR tape is about Rs 10,000. So for the same 150 min feature, even at a shoot ration of 1:20 (people tend to shoot more with tape than film). One would use 75 tapes of Rs 7.5 lakhs on tape. And one doesn't erase and reuse tapes even after they are transferred to the edit system.

Now, on to HDSLRs (Canon 5D or 7D)

On a Canon 5D or 7D CF cards are used up at about 3 min per Gb. So, if one shot an entire feature of 150 mins, even at a shooting ratio of 1:30, and shot on 8 GB CF cards, one would use up about 190 CF cards.
At online store,
an 8 GB CF Ultra 200x card sells for Rs 2000. So, if one did not reuse cards, and shot to about 200 cards or 'exposed' 80 hours of video on a Canon 5D/7D, one would spend Rs 4 lakhs.

Rs 34 lakhs for 25 hrs of film, or
Rs 7.5 lakhs for 50 hrs of HD tape, or 
Rs 4 lakhs for 80 hrs of Canon HD video. 

I think its clear CF cards, as a medium, are way cheaper than HD tape or film. And if one does not erase and use the costlier film or HD tape, what reason is there to erase CF cards that cost 1/30th what film costs.

Come to think of it, if you shot with a Canon exactly like film at a shoot ratio of 1:10, you would need only about 63 cards or spend about Rs 1.25 lakhs on 'rawstock'.

So, I don't get the reason for reusing CF cards. Reuse them after the film is released and you've consolidated all your media, but please, stop shooting an entire feature with 2 CF cards erased and used 30-100 times over.


  1. Brilliant!
    unable to digest with the new dogma though :)
    Cards are ought to be formatted :P

  2. I don't understand what you're saying.

    Where have I expressed any dogma?

    "Cards are ought to be formatted" meaning? That cards have to be formatted?
    According to you how many cards should one use for a feature? 1? 2? 5? 10?

    What is the exact reason for reusing cards? Saving money? I don't get it.

    The point of my post is that is you save money by erasing and reusing CF cards, then you will still need to spend money on good storage which is not exactly very cheap.

  3. HI Neil, how r u doing! i once took part in one of ur classes in Andheri. great experience.
    my point is, for a film ... isn't it wise to store all my footage in a storage media than CF cards (i am a 5D addict) ... for future use like editing and DI etc

  4. Pinaki,

    Thanks for the kind words.

    My point in the post was simply that you use hard disk storage for editing digital media, but don't reuse the cards. They become a secondary backup for your hard disk storage.

    A 6 TB RAID drive costs about Rs 1 lakh and is good for editing. But you need a backup in case something goes wrong with this RAID. 6 TB worth of CF cards costs a little more than that. So you don't reuse cards, you save on buying a backup disk.

    If you don't want to have a second backup of your main editing storage, you run the risk of having to reshoot in case of a disk failure - something that is not very rare these days.


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