Micro SD Card UHS grade requirement question

[Km5er]

Thanks. I suppose I'll have to do a test run on my existing cards as I would prefer not to have to purchase additional cards if practically unnecessary. Sandisk cards have always been reliable and seem to be a good brand. Perhaps I'll order a 64GB class 3 card from Amazon that I can return if not needed.

Is there a way to test the actual write speed of a card in my computer? I have a micro SD reader that is USB3 and a very fast (Alienware) PC (win10)

Yes, there is a way to test the cards but it is a lot of trouble to save $30. Suggest you get at least one V30 card and just use that.

 

[Deleted member 103366]

If you decide you need U3, 64G Samsung Evo U3 are currently around £10 on Amazon UK, I'd guess there is an equivalent price on the USA site

 

[BadWolf1]

Just to make a

If you decide you need U3, 64G Samsung Evo U3 are currently around £10 on Amazon UK, I'd guess there is an equivalent price on the USA site

$9 then Just went to buy an SLR lens - it's the same figure whether the sign in front is a £ or a €

Just been comparing some of my cards. I have San Disk and Lexar U3, and multiple SanDisk U1 a Kingston U1 and a couple of others. The fastest write speed in one convenient bench mark (Your mileage may vary, and it may not represent the speed of the drone) is the Kingston U1. > 50% faster than the Lexar U3. The Kingston is also the second fastest for reads, and the fastest is the Lexar ... The Lexar write speed is less than 45% of its read speed ! All cards read faster than write but the Sandisk in the drone at the moment gets nearly 90%, of the speed.

Based on this wholly unscientific test some U1s are faster than U3s,

 

[Km5er]

Just to make a

$9 then Just went to buy an SLR lens - it's the same figure whether the sign in front is a £ or a €

Just been comparing some of my cards. I have San Disk and Lexar U3, and multiple SanDisk U1 a Kingston U1 and a couple of others. The fastest write speed in one convenient bench mark (Your mileage may vary, and it may not represent the speed of the drone) is the Kingston U1. > 50% faster than the Lexar U3. The Kingston is also the second fastest for reads, and the fastest is the Lexar ... The Lexar write speed is less than 45% of its read speed ! All cards read faster than write but the Sandisk in the drone at the moment gets nearly 90%, of the speed.

Based on this wholly unscientific test some U1s are faster than U3s,

A fluke with the intent to justify the use of a U1 over a U3. It is possible but is it sustainable over the life of the card? and why would they sell a U3 card as a U1 (Or V since that is the measure I use)? The U1 is designed for the lower speed and the U3 is designed for a higher speed. Or is it based on factory tests on the production line as to which get segregated for V10, V30 or V90 and sold as such? It would be interesting to find out. But for me; the bottom line is the spec says V30....and with prices so low nowadays.....why accept the risk or justify based on the shooting mode I think I will be in (like 1080 vs 2.7 or 4K)?

 

[RogerDH]

You need to follow the spec. Spec requires V30 which is same as U3.

Well, U1 cards work just fine, which is not surprising since there's no reason a 40 Mb/s stream should require a U3 -- a genuine U1 should be capable of twice that rate. Looks to me like DJI copied and pasted a spec for a drone that shoots 4K.

 

[BadWolf1]

A fluke with the intent to justify the use of a U1 over a U3. It is possible but is it sustainable over the life of the card? and why would they sell a U3 card as a U1 (Or V since that is the measure I use)? The U1 is designed for the lower speed and the U3 is designed for a higher speed. Or is it based on factory tests on the production line as to which get segregated for V10, V30 or V90 and sold as such? It would be interesting to find out. But for me; the bottom line is the spec says V30....and with prices so low nowadays.....why accept the risk or justify based on the shooting mode I think I will be in (like 1080 vs 2.7 or 4K)?

I'm not trying to justify anything. I have
1x San disk extreme Micro SDXC V30/U3
2x Lexar Micro-SDXC 633x Class 10 V30/U3 [A1] (which is on DJI's list of approved cards

1x Philips Micro-SDXC class 10
1x Sandisk ultra Micro-SDXC class 10
2x Sandisk ultra SDXC (not micro) class 10, U1 "80MB/s"
at least 4x Kingston 64GB 80MB/sec Micro SDXC U1 class 10

I tried them with testing tool which comes with windows. Not guaranteed to be representative of what goes on in a drone, but not exactly a fluke.

I bought the U3s specifically for the drone and everything else with my DSLR in mind. I ordered the Lexars because they're on DJIs list but my supplier couldn't deliver before the drone arrived, so I got the San disk from Amazon. It's useful to know if I can just use the cards as they come to hand or if I need to keep anything less than U3 away from the drone - which is similar to the original question.

One might ask how come Kingston's U1 is faster at writes than Lexar's U3 ? Possibly the Kingston comfortably exceeds the U3 requirement on some counts and doesn't meet it on others, and Lexar meets it on all counts without exceeding it by much.

With Sandisk it seems different cards have been optimized for different things, but a given manufacturing process should always produce the same speed (it was said that at one time all intel chips CPU were the fastest speed and those stamped with a slower speed had failed at high speed). It's not entirely the memory speed - the interfaces have some effect too. It also would not surprise me if using a different reader changed the bench mark results or if some adapters from Micro to full SD were a drag on performance. With each marketing name trying to out do the last we're left pondering if "Ultra" is more less than "Extreme".
When a speed is quoted it's almost always read speed. Great for knowing if your phone can play 4K movies but not so good for knowing if your drone can record them.

With all that said... the mini can't shoot 4K. it's 2720 x 1530 (as near as makes no difference it's double the pixels of 1920x1080 and half the pixels of 4k) so if a U1 card can handle 4K it can definitely cope with the mini's 2.7K.
The rule of thumb seems to be 4K 30 fps needs 10 MBytes / sec (80Mbit/sec) sustained write-speed , which is class 10 / U1. 2.7K 5MBytes/sec , and 1920x1080 2.5MBytes/sec. I must see what the slowest car I have is and what the mini does with it

 

[RogerDH]

(Tl;dr synopsis: A Class 6 card should work, but a Class 10 or U1 is recommended.)

 

[Km5er]

(Tl;dr synopsis: A Class 6 card should work, but a Class 10 or U1 is recommended.)

I disagree with this video. The manufacturer indicates U3/V30 and that is what should be used. Telling people to use a Class 10/U1 is negligent.

 

[RogerDH]

I disagree with this video. The manufacturer indicates U3/V30 and that is what should be used. Telling people to use a Class 10/U1 is negligent.

Suit yourself, but the math and the empirical evidence both say U1s work just fine. Should I believe the spec or my lying eyes?

 

[vindibona1]

Update: For $10 I got a 64GB Lexar U3 chip with adapter. I can always use the other chips in my Canon 5D Mark III as I'm starting to do video recording and editing along side audio recording and editing. At some point I'll test the Sandisk 128GB U1's but for $10 it's not worth it to potentially ruin the first videos I try to take with this drone.

 

[ff22]

I can understand the "waste not, want not" concept and even environmental consciousness of not leaving these older cards to be tossed or gather dust BUT, the drone was $400-$500 and the cellphone similar. $10 or a card that matches the manufacturers suggest specs seems a small price to pay. While I have cards around, the deal I got from Adorama included the "up to snuff" card.

 

[RogerDH]

I can understand the "waste not, want not" concept and even environmental consciousness of not leaving these older cards to be tossed or gather dust BUT, the drone was $400-$500 and the cellphone similar. $10 or a card that matches the manufacturers suggest specs seems a small price to pay. While I have cards around, the deal I got from Adorama included the "up to snuff" card.

I hadn't really looked at the DJI recommended cards for the Mini until today, but in fact there ARE several U1 cards on the list, e.g. the Samsung Pro Endurance, SanDisk Industrial, and Lexar 633x (which is one I have and have used in the Mini). There could be more; I stopped checking after finding those three. So apparently DJI doesn't believe the "U3 required" spec, either. I'll say again, if I was buying a new card, yes, I would definitely buy one of the recommended U3 cards, but if I already had a name-brand U1 (which I did), I would expect it to easily support a 40 Mb/s (5 MB/s) stream -- unless it's a fake, of course, but I test all of my cards with Crystal Benchmark.

 

[Km5er]

Suit yourself, but the math and the empirical evidence both say U1s work just fine. Should I believe the spec or my lying eyes?

My nuclear background and my engineering background says to follow the spec. Also, every card recommended by DJI is a minimum V30. It is good that you feel comfortable using the cheaper cards. Following the spec has less chance to fail you when you are in the middle of the Serengeti without a local store to pick up a replacement. So, the non-spec cards work for you and that is good.....I would rather play it safe when I need the highest reliability such as in the attached once in a lifetime photo. However, when a question is asked in regards to what card a person should use....the spec and manufacturers' recommendations are the most appropriate answer. Take care.

 

[RogerDH]

My nuclear background and my engineering background says to follow the spec. Also, every card recommended by DJI is a minimum V30. It is good that you feel comfortable using the cheaper cards. Following the spec has less chance to fail you when you are in the middle of the Serengeti without a local store to pick up a replacement. So, the non-spec cards work for you and that is good.....I would rather play it safe when I need the highest reliability such as in the attached once in a lifetime photo. However, when a question is asked in regards to what card a person should use....the spec and manufacturers' recommendations are the most appropriate answer. Take care.

At the risk of seeming overly argumentative: U1 and U3 are speed ratings, not reliability ratings; the question I was answering was the one asked in the OP rather than your rephrasing; and as I posted above, some of the DJI-recommended cards are U1s. The question in the OP is a reasonable question, given that there is no logical reason for the Mini to require U3 speed. And since I know it doesn't, that was my answer.

 

[vindibona1]

At the risk of seeming overly argumentative: U1 and U3 are speed ratings, not reliability ratings; the question I was answering was the one asked in the OP rather than your rephrasing; and as I posted above, some of the DJI-recommended cards are U1s. The question in the OP is a reasonable question, given that there is no logical reason for the Mini to require U3 speed. And since I know it doesn't, that was my answer.

It seems that I have inadvertantly been tapped to answer my own question.
I went out to fly this afternoon after doing some video editing this morning from my shoot a day or two ago and absentmindedly forgot to take it out of the card reader in my computer. Who hasn't forgotten to do that at least once? As a professional photographer, I know I was born to do stupid stuff, and was breast fed on redundancy. Of course I packed an extra SD card in my pack!

This was the very same Sandisk Ultra 128GB U1 rated card I was wondering about as I began this thread.
No jumps or glitches as I recorded for 7 minutes. Just as smooth as the Lexar 64GB U3 I bought just to be sure.
I recorded 2.7k 30fps and found zero difference in the quality or smoothness of this micro SD.

 

[ff22]

It seems that I have inadvertantly been tapped to answer my own question.
I went out to fly this afternoon after doing some video editing this morning from my shoot a day or two ago and absentmindedly forgot to take it out of the card reader in my computer. Who hasn't forgotten to do that at least once? As a professional photographer, I know I was born to do stupid stuff, and was breast fed on redundancy. Of course I packed an extra SD card in my pack!

This was the very same Sandisk Ultra 128GB U1 rated card I was wondering about as I began this thread.
No jumps or glitches as I recorded for 7 minutes. Just as smooth as the Lexar 64GB U3 I bought just to be sure.
I recorded 2.7k 30fps and found zero difference in the quality or smoothness of this micro SD.

Yes but when you discover it on your first day in Norway, it can be disheartening! I used the cellphone that first day and purchased an exorbitantly priced card that evening for the rest of the three week trip!

 

[vindibona1]

Yes but when you discover it on your first day in Norway, it can be disheartening! I used the cellphone that first day and purchased an exorbitantly priced card that evening for the rest of the three week trip!

Which is why I forked over money before receiving my MM to get a U3 rated card so I wouldn't get scapled in Norway . But now I know I have two120gb cards and one 64gb that I can use, probably enough to get me through a vacation without having to clear cards.