Calculating Back-Up Drive Capacity

Not sure if this is a valid question to ask. I am trying to determine an adequate storage capacity for a back-up portable HD. I use a Canon 400D & a Canon G11 to shoot RAW. Although the size of RAW files can vary, is there any basic rule-of-thumb regarding the average RAW file size? If so, I can get a rough estimate of the storage capacity I will need.

Thank you.

Have you considered simply aiming your camera at random scenes and shooting 10 photos, and looking at the file sizes, summing the sizes and dividing by 10 to calculate the average? (Keep in mind that shots at ISO1600 are noisier -- and larger-- than shots at ISO100) According to the Canon user manual, your 400D's average size for RAW file is 9.8MG

Have you considered that guesstimating your requirements is all moot any way? That it's all going to change with your next camera purchase? Or your next big project? Or whatever?

Really, with the price of hard drives these days, my suggestion is to purchase a toaster drive & three 1 TB drives. Load all your images on the first drive, backup to the second & keep them both in your home (the second in a closet, safe or someplace a thief won't be likely to see). Then, backup to the third & keep it offsite (parent or friend's house, safety deposit box, whatever). Update all as needed.

At that point you have 3 copies of everything, one for immediate access if something goes wrong at home & an offsite b/u if you end up with fire, flood, whatever.

When you run out of room, get another three 1 TB drives, rinse, repeat.

As far as how many images you can put on a drive, we use 1 TB drives & with our 1D MkII & IIN jpgs, RAWs & some edited images, there is about 200,000 images on a drive. I expect those numbers will drop with the Mk IV but it doesn't matter. When a drive gets full we'll just get another set of three.

first...you can't have a drive with too much capacity.
second...drives are cheap

So get at least a 1TB drive if not a 2TB drive.

Perhaps as important of a question is ...which interfaces to support. Portable drives can attach via:
FW 400
FW800
USB 2
eSATA
USB 3

What does your laptop or desktop support?

FeXL wrote in post #11929504
Have you considered that guesstimating your requirements is all moot any way? That it's all going to change with your next camera purchase? Or your next big project? Or whatever?

Really, with the price of hard drives these days, my suggestion is to purchase a toaster drive & three 1 TB drives. Load all your images on the first drive, backup to the second & keep them both in your home (the second in a closet, safe or someplace a thief won't be likely to see). Then, backup to the third & keep it offsite (parent or friend's house, safety deposit box, whatever). Update all as needed.

At that point you have 3 copies of everything, one for immediate access if something goes wrong at home & an offsite b/u if you end up with fire, flood, whatever.

When you run out of room, get another three 1 TB drives, rinse, repeat.

As far as how many images you can put on a drive, we use 1 TB drives & with our 1D MkII & IIN jpgs, RAWs & some edited images, there is about 200,000 images on a drive. I expect those numbers will drop with the Mk IV but it doesn't matter. When a drive gets full we'll just get another set of three.

As the OP, I should have been a bit clearer. My question is aimed at acquiring a portable external HD for back-up while traveling. Although I generally subscribe to the maxim that "bigger is better" when it comes to capacity, for traveling a week or two at a time I have no need for huge excess capacity.

Take a look at Canon's file size information in each of your camera manuals. p. 166 for the 400D and 75 for the G11.

Jon wrote in post #11929635
Take a look at Canon's file size information in each of your camera manuals. p. 166 for the 400D and 75 for the G11.

Jon: Good point. Just think how many unnecessary questions could be avoided if people like me took heed to the advise: "read your manual".

size of all 2.5" drives is the same regardless of the capacity being anywhere from 320GB to 2TB these days. you will get more for your money for a 1TB or larger drive. And such a drive size would give you weeks of storage of raw files.

MCAsan wrote in post #11930930
size of all 2.5" drives is the same regardless of the capacity being anywhere from 320GB to 2TB these days. you will get more for your money for a 1TB or larger drive. And such a drive size would give you weeks of storage of raw files.

That's exactly what I am leaning toward. My original queston was driven by the fact that I have decided to swap my ol' Mac laptop for an iPad. But even the 64Gb iPad will have limited image back-up capacity. So for longer trips, a 2.5" external HD would make the most sense for me.

I guess an Ipad needs a USB 2 external drive connected via a docking cable. Can you connect a CF card reader and an external HD at the same time to read/write?

MCAsan wrote in post #11931998
I guess an Ipad needs a USB 2 external drive connected via a docking cable. Can you connect a CF card reader and an external HD at the same time to read/write?

Apple has a camera connection kit accessory to either connect an SD card directly to the iPad docking port or to connect a card reader to the iPad. However, the new iOS 4.2 operating system apparently has insufficient power to drive some card readers. The work-around seems to be a powered reader.

It is my understanding that the iPad will not support an external drive. Disappointing, but I have to remember than Apple didn't design the iPad to compete with a "real" computer.

With those limitations...personal​ly I would go with a laptop.

MCAsan wrote in post #11930930
size of all 2.5" drives is the same regardless of the capacity being anywhere from 320GB to 2TB these days. you will get more for your money for a 1TB or larger drive. And such a drive size would give you weeks of storage of raw files.

It's just a shame that you can't buy 2.5" drives with those sorts of capacity. Realistically 500GB is about all you can get - but that should still be enough for 20,000 7D raw files at 25 MB apiece.

For the OP - check out the Nexto ND2700 for 500GB of portable storage. Or, if you've got more cash, the Hyperdrive Colorspace iPad.

The 2.5" drives are most used inside laptops or other devices. For those the max capacity commonly available is 500GB. For building an external backup HD, you can get 3.5" drives from 1-2TB in the $75-$175 range. An enclosure will be a few dollars more. Pick the enclosure for the desired external internfaces: FW400, FW800, eSATA, USB 2, USB3. If you want the external drive built for speed, put in a 7200rpm drive with a 64MB cache and use an enclosure for eSATA or USB3 (whichever your laptop or desktop will support).

kitjv wrote in post #11929587
As the OP, I should have been a bit clearer. My question is aimed at acquiring a portable external HD for back-up while traveling. Although I generally subscribe to the maxim that "bigger is better" when it comes to capacity, for traveling a week or two at a time I have no need for huge excess capacity.

Ah, understood.

In that case, I have no further suggestions, as we use the laptop for said travel downloads (with a 2.5" FW external as backup).