I’ve used Mac workstations since the early 1990s. As a professional photographer, it’s important to have a computer that is not only fast, but also scalable. For me, that meant being able to add internal hard drives, PCI expansion cards, and plenty of RAM. By having a computer that I could incrementally upgrade, I am able to extend the useful life of that machine. As a working professional, I consider upgrading my computer system every 3-5 years, depending on my needs.
In 2013, Apple radically redesigned the Mac Pro line to include internal PCI-based solid-state drives and dual video cards. Despite the performance benefits, the new form-factor no longer supported internal expansion of any kind (other than RAM). Although I was not in the market for a new Mac at that time, the immediate consequence of the new form-factor became clear. From now on, any hard drives that lived inside my existing computer would have to be moved to external enclosures.
Apple’s decision to alter the Mac Pro’s form factor suddenly made me start to look at the iMac as a possible future replacement. After all, I’d have to get external drive enclosures either way, as well as a PCI enclosure for my solid-state drive (SSD). My only concerns were processor performance and memory capacity.
I already knew that the Intel i7 processors in the iMac were plenty up to the task of running Lightroom and Photoshop, because that’s the same type of processor that runs my MacBook Pro. It was the 32GB RAM limit on iMacs that had me most concerned. However, when Apple announced the latest update to their 27″ iMacs with Retina display in October, not only did the processors get upgraded, but it turned out that these new iMacs would support up to 64GB of memory. You just need to order the memory from a 3rd-party vendor other than Apple; something I’ve done for years anyway. After much deliberation, I decided to go with the 27″ retina iMac (late 2015), which I ordered from B&H Photo. B&H is an authorized Apple retailer, and you can purchase an AppleCare warranty from them, too (something I highly recommend).
My iMac System
- 4GHz i7 “Skylake” processor
- 8GB memory (which I upgraded to 48GB from here).
- 512GB internal Solid State Drive (this drive only needs to hold my system and applications; all other data are on separate drives)
- AMD Radeon R9 M395X graphics (4GB DDR5 memory)
What about my existing hard drives? Well, I already had a 16TB RAID 5 array for photos in a USB 3.0 enclosure. I picked up a 4-bay Thunderbolt 2 enclosure and an OWC Helios PCI enclosure. I put my internal hard drives into the USB 3 enclosure, and moved the 4-disk RAID set into the Thunderbolt enclosure for even better speed. Note: I set up my RAID using a software utility called SoftRaid. If you have a hardware RAID enclosure you can’t move the disks out of it without breaking the array. With SoftRAID, the RAID 5 array was recognized even though it was in a new enclosure. My existing PCI-based SSD went into the Helios enclosure, and I’m using it as a super-fast scratch disk for Photoshop.
First Impressions: Display
The big deal with these 27″ iMacs is their amazing “5k” Retina display, with a resolution of 5120 x 2880 pixels . The late 2015 models use a different LED backlight technology from the earlier models, one that is supposed to offer a wider color gamut. I calibrated and tested the display with my Spyder 4 colorimeter, and sure enough it measured at 92% of the Adobe RGB color space. I figured this would be no big deal. I was wrong. Suddenly, my other displays looked fuzzy and greenish (despite being calibrated) when viewed next to the iMac. Imagine an iPad or iPhone screen that’s 27″ wide. That’s what this display looks like. Considering that a similar 3rd-party display (and don’t get me wrong, there are good ones out there) would easily cost upwards of $1500, that’s a HUGE value with the iMac.
Frankly, you don’t see the kind of screaming speed improvements with a new computer these days like we did in the 90’s when it seemed like processor speeds doubled every year or two. But I did run my normal suite of tests just to see how it compared to my previous system, a 6-core, 3.33 GHz Mac Pro Xeon workstation, and I was pleased.
Geekbench 3 Scores
In both tests, the iMac running its 4GHz i7 processor beat my 2010 Mac Pro. Single-core tasks were, in fact, 58% faster with the iMac. Not surprisingly, the 6-core machine held its own in multi-core tests against the 4-core iMac. For most photography software, single-core performance will usually be more beneficial than multi-core performance. The notable exception would be video production, which can really get a boost from multiple processor cores. Of course, the Geekbench tests are arbitrary processor benchmarks. Therefore, I also tested Photoshop performance using Lloyd Chambers’ Diglloyd Photoshop Benchmarks.
The Diglloyd benchmarks are useful because they are a repeatable set of Photoshop actions that can be used to compare computer performance doing “real-world” operations like image rotation, blur, sharpen, etc. Here’s how the two computers compared with the three most applicable tests:
In all three of these tests, which run on normal-sized files photographers would be expected to encounter, the iMac beat the Mac Pro. The iMac ran about 25% faster in the “Speed 1” test but only about 14% faster in the “Medium” file test. Again, despite having two fewer processor cores, the iMac handles Photoshop perfectly well. I also haven’t had any issues running Lightroom CC 2015 with the iMac. Even the spot healing tool in visualizer mode is responsive; something that wasn’t always the case with my previous Mac Pro.
Conclusion: Photographers should consider the new iMac
The combination of fast processors, an upper limit of 64GB memory, and a beautiful 5k “Retina” display with a wide color gamut make the iMac a very attractive option for Mac-centric photographers. A comparably spec’d Mac Pro system would cost nearly $7000, and still wouldn’t be faster in many single-core tasks (the multi-core Mac Pros run slower clock speeds). The Mac Pro is essentially a video producer’s dream machine, but for everyone else, I think you’ll be really happy with an iMac system.
Here is the iMac configuration I purchased, from B&H Photo (Save on sales tax outside NY). I was able to use the money I saved on sales tax to help pay for the external drive enclosures from OWC.
I strongly recommend getting an internal SSD for maximum system performance. You can store your photos, music, and mail on external hard drives. Not only does this speed up boot and application launch times, but it also allows you to boot your computer from a different drive and access your data should your internal drive fail.
I purchased my memory from OWC at a significant discount compared to Apple memory. I’ve had no issues with RAM from OWC, ever.