For a straightforward Sony a5100 memory-card purchase, choose a full-size 64GB SDXC card marked Class 10 and UHS-I. A reputable U3/V30 card also meets that speed-class requirement, but the camera does not need an expensive UHS-II card to record its supported video formats.
The important detail is the camera’s XAVC S requirement: a fast 32GB SDHC card is still the wrong card type for that setting. Sony specifies SDXC with at least 64GB for XAVC S, and its original a5100 guide documents testing SD cards up to 64GB. This guide therefore centers on that well-documented capacity rather than promising compatibility with every larger card sold today.
A specific card to consider
SanDisk Extreme PRO 64GB SDXC UHS-I, SDSDXXU-064G-GN4IN
This full-size card is a sensible specification match for still photographs and the a5100’s HD movie modes. The exact version here is the 64GB SDSDXXU-064G-GN4IN, supplied as one card, with Class 10, U3 and V30 markings. It is not a microSD card, a two-pack or a camera-branded reader bundle.
SanDisk Extreme PRO SDSDXXU-064G-GN4IN, 64GB SDXC UHS-I, 1 Card
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SanDisk advertises up to 200MB/s reading and up to 90MB/s writing for this 64GB version. Those are manufacturer maximums under compatible conditions, not measured a5100 performance. The enhanced transfer rate relies on compatible equipment; spending more for a large number printed on the packaging does not make the camera write at that rate. See the manufacturer’s model and performance notes.
Choose the correct capacity and suffix when comparing offers. Product pages can combine several capacities and generations, and a retailer’s selected option may change the item in the basket. Check the card count, seller, returns and exact model at checkout. No current price or stock level is assumed here.
Which card does each shooting mode need?
- Still photographs: the a5100 supports SD, SDHC and SDXC media. A 64GB Class 10 UHS-I card is a convenient choice if you also want video.
- AVCHD and MP4 movies: Sony’s card guidance lists Class 4 or faster SD media. Buying a Class 10 card avoids choosing a slower card just for these modes.
- XAVC S movies: use the specific SDXC, capacity and speed requirements above. Capacity, format family and speed all matter.
These requirements come from the ILCE-5100 memory-card guide, not a compatibility chart for a newer Alpha camera. Sony also lists compatible Memory Stick families, but a full-size SDXC card makes sense if you are buying into a common card-reader workflow now.
What the symbols mean when shopping
Start with the terms that answer separate questions. 64GB describes capacity. SDXC identifies the card family. UHS-I describes the bus interface. Class, U and V speed markings describe performance classes; they should not be confused with a package’s maximum transfer-rate headline. A listing that mentions only “high speed” is less useful than one that shows the actual markings and model number.
The SanDisk example supplies more speed-class headroom than this camera’s minimum. That can be useful when sharing a card with other compatible equipment, but it is not evidence that a more expensive card improves image quality. A card records what the camera produces; it does not increase sensor resolution or add new recording formats.
Does a 4K-labelled card make the a5100 shoot 4K?
No. The a5100’s movie format menu offers XAVC S HD, AVCHD and MP4. Marketing on a memory card describes uses supported by that card in suitable devices. It does not upgrade the recording capabilities of the camera holding it. Buy for this camera’s requirements, rather than for a prominent 4K badge.
How much video fits on 64GB?
Sony’s recording-time table estimates a total of 2 hours 35 minutes for its 50Mbps XAVC S settings on a formatted 64GB card, with Dual Video REC off. That is total storage across clips, not a promise of one continuous recording.
The same guide gives an approximate 29-minute continuous recording limit, with shorter operation possible depending on temperature and settings. Battery life and camera temperature remain separate constraints. For an interview or event, plan clip changes, power and backups as well as card space. Test the complete setup before the important session rather than relying on capacity alone.
Format safely before a new shoot
- Copy any existing photographs and video to another storage location and confirm that the copies open.
- Insert the card in the camera correctly. Do not force a card that resists or appears damaged.
- When you are ready to erase the card, use MENU, Setup, Format, as described in Sony’s formatting instructions.
- Take a few photographs and record a short clip in the movie format you intend to use, then play them back and check your computer import workflow.
Formatting permanently removes all data, including protected images. Do not use it as a first response when a card contains the only copy of a valuable recording. A computer asking to format an unfamiliar card is also a reason to stop and investigate, not immediate permission to erase it.
If XAVC S will not record
Read the front of the card and the selected product variation again. A common shopping mismatch is an SDHC card that is fast enough but below the specified SDXC capacity. Check free space and whether the card has been prepared in the camera. If a known suitable card fails, preserve its files first and try a second known-good card before assuming that a more expensive speed tier will fix the issue.
Keep cards in a protective case, avoid touching the contacts and maintain more than one copy of important work. A card’s weather-resistance claims do not turn it into a backup system. For most a5100 owners, the useful purchase is one clearly identified 64GB SDXC UHS-I card and a reliable transfer routine, followed by a spare when the shooting schedule warrants it.
Image note: AI-generated generic editorial illustration; not a photograph of a named or tested product.
