> ## Content Index > Fetch the complete content index at: https://blog.tonalphoto.com/llms.txt > Use this file to discover other available public pages before exploring further. # Phocus 4.1 Ultra HDR Export Bug: Memory Leak Can Cause System Crash - URL: https://blog.tonalphoto.com/phocus-4-1-ultra-hdr-export-bug-memory-leak/ - Published: 2026-01-10T12:00:36.000Z - Updated: 2026-08-18T18:02:36.000Z - Description: Phocus 4.1 leaks ~50 MB per Ultra HDR export, eventually crashing your system. Here's what causes it and how to work around it. - Author: Konrad Michels - Tags: Bug Reports So I'd been playing around with Phocus 4.1 since I discovered it was available, trying to figure out what they had fixed, but not noted in their release notes. There were some memory leakages in v4.0.1 which I'd already reported, which were now moot given the new version seemed to have remedied them. Undaunted thought, with some creative testing, I managed to get Phocus 4.1 to consume **94 GB of memory** before macOS decided enough was enough. Up to that point it had been bravely paging out to the swap file, but obviously hit a tipping point. What was I doing to get it to do this? I'd found memory leak in the Ultra HDR export pipeline that accumulated with every image and never released, even after hours of idle time. I just kept doing UltraHDR exports until everything came to a complete stop. If you're batch exporting Ultra HDR JPEGs in Phocus 4.1, or even just exporting Ultra HDR JPEGs at all, you need to know about this. --- **A note on support:** This post represents my personal exploration and testing, not official technical support or guidance from Hasselblad. If you need assistance with your Hasselblad equipment, please contact Hasselblad directly: [customersupport@hasselblad.com](mailto:customersupport@hasselblad.com) for global support, [support.us@hasselblad.com](mailto:support.us@hasselblad.com) for the Americas, or visit hasselblad.com/support for regional options. --- 💡 Key finding: Phocus 4.1 leaks memory during Ultra HDR export. Batch-exporting 30+ files causes RAM usage to climb until the app crashes. Workaround: export in small batches of 5-10 files and restart Phocus between batches. ## **How the Phocus 4.1 Memory Leak Works** Every Ultra HDR export leaks approximately 50-55 MB of memory. The Ultra HDR encoder allocates buffers for the conversion but never deallocates them. This memory wasn't released when the export completed, wasn't released during idle time, and wasn't released until I quit Phocus entirely. Export 30 images? That's 1.5 GB gone. Export 500 images from a wedding shoot? You've leaked 25+ GB. ### **Discovering the Leak** I first noticed something was wrong after exporting a batch of 30 [3FR](https://blog.tonalphoto.com/hasselblad-fff-vs-3fr-why-renaming-doesnt-work-and-why-thats-good/) files to Ultra HDR. Phocus was sitting at 12.5 GB (not unusual for modest editing in Phocus, as it turns out) but it stayed there long after the export finished. Ten minutes idle. An hour idle. No change. So I pushed it: 471 more exports. Because why not, right! ### **The Numbers** | Ultra HDR Exports | Memory Consumed | System Impact | | ----------------- | --------------- | ------------------ | | 30 | \~12 GB | Normal operation | | 100 | \~15 GB | Phocus now lagging | | 471 | \~51 GB | Heavy swap usage | | 942 | \~94 GB | System freeze | The leak scaled linearly. Every export added to the pile, and nothing cleared it. Have you seen the guide? I've published Essential Phocus 4.x for Mac - 85 topics across 250 pages covering everything from HNCS color science to HDR workflows. It's the reference manual Hasselblad hasn't updated since 3.8\. It's $49, and updates are included. [Get it here ](https://payhip.com/b/6pqAt?ref=blog.tonalphoto.com) ### **The Overnight Test** After hitting 51 GB, I left Phocus running overnight to see if it would eventually clean up. I monitored memory every hour for nine hours. Result: **zero bytes released**. The footprint stayed locked at 51.2 GB from 9 PM to 6 AM. The leaked memory was permanent until quitting the application. ### **What Happened When Memory Ran Out** The next morning, just because I'm from an engineering background and like testing limits, I exported another batch starting from that bloated 51 GB baseline. At 94 GB, macOS threw up the *"Your system has run out of application memory"* dialog and paused every running application. Phocus was consuming **90x more memory** than any other app on the system! I'll be the first to admit that this is an unlikely edge case. Let's be honest, you'd need a lot of shots to get 942 HDR images you want to export as keepers. It was more about the principle, and curiosity about seeing just how far macOS would let it go. Force-quitting Phocus was the only recovery option. --- ![green circuit board close-up photography](https://images.unsplash.com/photo-1562976540-1502c2145186?crop=entropy&cs=tinysrgb&fit=max&fm=jpg&ixid=M3wxMTc3M3wwfDF8c2VhcmNofDF8fHJhbXxlbnwwfHx8fDE3Njc1NzM1NTN8MA&ixlib=rb-4.1.0&q=80&w=2000) Photo by [Harrison Broadbent](https://unsplash.com/@harrisonbroadbent?ref=blog.tonalphoto.com) / [Unsplash](https://unsplash.com/?utm%5Fsource=ghost&utm%5Fmedium=referral&utm%5Fcampaign=api-credit) ## **How Much RAM Does Phocus 4.1 Actually Need?** The Phocus 4.1 readme specifies 8 GB minimum RAM with 16 GB recommended. You don't need to be particularly good at mathematics to realize that in practice, these numbers are somewhat optimistic. During my testing, I tracked memory usage through normal editing workflows - importing images, scrolling through thumbnails, clicking to generate previews, applying edits. Here's what I saw: | **Activity** | **Memory Usage** | | --------------------------- | ---------------------------- | | Phocus launch | \~875 MB | | After importing 467 images | 7.5 GB | | Click first image (preview) | 9.6 GB | | Click second image | 10.6 GB | | Normal editing workflow | 10-12 GB stable | | HNNR/HNCS operations | Up to 17.8 GB temporary peak | The cache did seem to be working correctly - once it filled to what appeared to be a 10-12 GB working set, it stabilized there rather than growing unbounded. But that baseline was already above the stated 8 GB minimum. ### **On an 8 GB system** You'll likely hit swap the moment you start clicking through images. Basic operations will be sluggish. The "8 GB minimum" lets you install and launch Phocus, but not use it productively. And that's ignoring memory required by the OS, even if Phocus is the only app you have open. Researching and writing the blog and page posts I produce takes up a lot of my time and costs me money for software subscriptions, tooling, and other incidentals related to running a business. Please consider a paid membership to help me keep the lights on and pay the bills - it is only a fraction of the cost of an X2D II and a lens. Click on the button to go to the membership page to see the options available. [Support the blog. ](https://blog.tonalphoto.com/membership/) ### **On a 16 GB system** After macOS takes its share (kernel, system processes, wired memory that can't be swapped), you're left with roughly 12-13 GB for applications. With Phocus's 10-12 GB working set, you're already running at or near capacity during normal editing - before any Ultra HDR exports. macOS will manage this through memory compression and preemptive swapping, but you're operating with essentially zero margin. Any Ultra HDR exports will immediately add memory pressure. **If you're on 16 GB:** Keep Activity Monitor open during Ultra HDR exports. Restart the moment you see memory pressure climb or compression ratios spike. Until Hasselblad patches this bug, 16 GB users are probably starting from a deficit. **My recommendation:** 16 GB is the realistic minimum for Phocus 4.1\. 24 GB or more is comfortable for larger image sets and HNNR/HNCS processing. --- ## **The Workaround** Until Hasselblad patches this, **restart Phocus between Ultra HDR export batches**. Conservative limits before restart: | System RAM | Safe Ultra HDR Exports | | ---------- | ---------------------- | | 16 GB | 50-100 | | 32 GB | 150-200 | | 48 GB | 300-400 | | 64 GB | 500-600 | Monitor Activity Monitor during exports. When Phocus approaches 80% of your physical RAM, quit and relaunch before continuing. **Note:** This leak only affects Ultra HDR exports. Standard JPEG and TIFF exports don't seem to exhibit this behavior. Update (June 2026): the leak is fixed in Phocus 4.2, which also removed the dedicated Ultra HDR JPEG presets in favor of automatic gain-map export. Details in [Where the Ultra HDR JPEG Preset Went in Phocus 4.2](https://blog.tonalphoto.com/phocus-4-2-ultra-hdr-jpeg-preset/). --- ## **Technical Details** For those interested: macOS profiling tools (leaks, heap) identified the culprit as uhdr\_encoder\_private objects creating ROOT CYCLE leaks (circular references that prevent deallocation). Each export spawned new encoder instances that were never cleaned up. I've submitted a detailed bug report to Hasselblad with profiling data, overnight monitoring logs, and reproduction steps. --- ## **Summary** Phocus 4.1 has a critical memory leak in Ultra HDR export. Each image leaks \~50 MB permanently. Large batch exports will eventually crash your system. Restart Phocus between batches until a fix arrives. --- ## Sign up for The Tech Behind the Frame - Hasselblad edition Subscribe Email sent! Check your inbox to complete your signup. This bug was fixed in Phocus 4.1.0\. See all tracked Phocus issues for current statuses. --- *Tested on Phocus 4.1, macOS Tahoe 26.2, Apple M4 Pro, 48 GB RAM. Test files: 467 3FR images from X2D II.* For current statuses on all reported Phocus bugs, see the [known issues tracker](https://blog.tonalphoto.com/phocus-known-issues/). This bug was fixed in Phocus 4.1.0\. See the [full version history](https://blog.tonalphoto.com/phocus-version-history/) for all releases. --- **Setting up your own HDR pipeline?** A prepaid consulting hour gets you a written setup review calibrated to your gear and targets. $195 per hour. [See details →](https://blog.tonalphoto.com/work-with-me/#hasselblad-workflow-consulting)