I'm trying to guesstimate what kind of continuous shooting speed I could get on my E-PM1 after the buffer fills up, when using various SD Cards that I don't have. Hopefully this will help me to decide whether or not I want to get a faster card, and if so which one. I'm posting my research here in the hope that some kind or curious person or persons might like to confirm or correct some of my numbers if they happen to have the cards in question, or their equivalents. If this info proves helpful to someone, so much the better. Also I find this kind of thing fun. I must be nuts
The resources I'm using for this are:
1) my own testing with my E-PM1 and Sandisk 8GB Class 4 card
2) dpreviews review of continuous shooting performance of the E-M5
3) Giulio Scorios test on his blog
of his E-M5 including the card I have and some that I'm interested in. Giulio didn't record his "buffer-full" shot rate but I think I can extrapolate it from his results by referring to and comparing with my and dpreviews numbers.
4) amazon.co.uk for pricing
I'm making a few assumptions, namely:
- E-M5 jpegs are 11MB
- E-M5 buffer takes 16 jpegs
- E-PM1 jpegs are 8MB
- E-PM1 buffer takes 9 jpegs
Same 4 cards as on Giulio's test minus the eye-fi.
Remember the main thing I'm looking for is a shots per second speed when the buffer is already full.
Numbers and maths follow from here, lets dive in!
Sandisk 8GB Class 4
10 shots in 15.99sec -> 0.63 shots/sec when buffer full on E-PM1
14.37 sec to clear buffer
Buffer cleared just under 56 seconds.
11MB/shot * 16 shots = 176MB / 56sec = 3.1MB/sec = 0.3 shot/sec on OMD, or 0.5 on PM1
So for this card our numbers are much the same, when allowing for timing inaccuracies and rounding errors and whatnot.
Price per speed for this works out at £4.48 / 3.1MB/sec = 1.40£/MB/sec
Sandisk Extreme 4GB 30MB/s
Buffer cleared just under 13 seconds.
11MB/shot * 16 shots = 176MB / 13sec = 13.5MB/sec = 1.2 shots/sec on OMD, or 1.6 on PM1
8MB/shot @ 1.6 shots/sec = 12.8MB/s = 1.1 shots/sec on OMD, or 1.6 on PM1
Again the two sources match up pretty well. Interestingly the buffer-full-shooting write speed is considerably less that the speed written on the card label, but greater that the 'class rating' speed (which is 10 for this card)
Price per speed £8.79 / 13MB/s = 0.67£/MB/sec
Sandisk Extreme Pro 16GB 45MB/s
Buffer cleared just under 17 seconds.
11MB/shot * 16 shots = 176MB / 17sec = 10.3MB/sec = 0.9 shots/sec on OMD, or 1.2 on PM1
I don't have other data to compare for this card so I'll have to take Giulios word for it, but he looks like a trustworthy bloke. As G noted, this card tested a bit slower than the smaller but slower-rated 4GB 30MB/s card.
Price per speed £14.40 / 10.3MB/s = 1.40£/MB/sec
Sandisk Extreme Pro 8GB 95MB/s
Mine - this one was really tested - not just guessing the numbers!
7.8MB/shot * 18 shots = 141MB / 10sec = 14.1MB/sec = 1.8 shots/sec on E-PM1
Sandisk Extreme Pro 16GB 95MB/s
Buffer cleared just under 10 seconds.
11MB/shot * 16 shots = 176MB / 10sec = 17MB/sec = 1.6 shots/sec on OMD, or 2.1 on PM1
Price per speed £32.30 / 17MB/s = 1.90£/MB/sec
Sandisk Extreme Pro 64GB 95MB/s
DPReview didn't post numbers for Large/SFine jpeg/11MB, so from the numbers they did post I guesstimate the E-M5 buffer full rate at 2.2shots/sec so:
11MB/shot * 16 shots = 176MB / 6sec = 29MB/sec = 2.4 shots/sec on OMD, or 3.6 on PM1
Price per speed £128.87 / 29MB/s = 4.44£/MB/sec
It looks like DPRs 64GB card is faster than Giulios 16GB one.
Also DPRs card can apparently write at pretty close to the PM1s continuous shooting speed of 5fps!
The price / performance sweet spot among these is owned by the Sandisk Extreme 4GB 30MB/s card, which for £8.79 should give a buffer-full shooting rate of 1.2 shots/sec on OMD, or 1.6shots/sec on PM1. Above this the law of diminishing returns starts to kick in.
What do you think? Is this kind of thing helpful? Does anyone have any corrections or extra info to add? Did anyone read all the way down this far?