I'm looking at the 5k iMac with i7 processor, 32 gig ram and 512 flash drive, most likely update to the higher graphics card. This should put me in the 4
Montana Bob
I am using the fastest 5K iMac, 32GB, 1TB Flash, higher graphics card. It was bought primarily for photography from the D810 including doing 100-500MP panoramics.
I considered going the Mac Pro route (again) with a 32" 4K monitor, but given the higher cost of that setup and the fact that the Mac Pro is already out of date, I decided not too for now. The 32GB of RAM is pretty much the bare minimum for me and that was my biggest hesitation with the iMac.
If you have a color critical workflow, there are some reservations with how accurate the iMac is after calibration. For my present needs though, it is adequate.
I use a mix of Capture One/Photoshop CC/Lightroom 5. I also tend to run quite a lot in 5120x2880 mode. Text is quite small, but I like having the interface elements taking up less room on the screen. It also seems to me that Capture One is not making proper use of the Retina Display when in 2560x1440 mode.
I've changed my workflow to more aggressively get rid of non keeper photos, so that more of my work can fit on the 1TB SSD. I am using a 2GB Airport Timecapsule and the 1TB DropBox account to keep everything backed up. The DropBox is nice as my essential work is also mirrored to my Macbook Pro and Mac Mini. They have an extended backup option that keeps track of an entire year's worth of changes without counting towards your diskspace. Older files (that are not that critical to me) I keep on dual USB3 external drives.
On my wish list, is the OWC Thunderbolt dock and a large fast external SSD, such as the 1TB Lacie Little Big Disk. I will put that purchase off as long as possible in hope of better value, performance, and capacity.
Both Capture one and Lightroom are noticibly slower when working at the 5K resolution. I think we just have to live with this and hope the software becomes more optimized. Photoshop performance is excellent. The slowest times are when Photoshop is saving multi gigabyte documents. It seems be more of a CPU bottleneck than an SSD bottleneck. It sometimes takes 2 or 3 minutes for me to save a 4 -8 Gigabyte large format photoshop document. At least Photoshop CC now performs saving in the background.
My workflow is actually Capture One -> Photoshop -> Lightroom. I use Lightroom as a image viewer with the ability to do prints and final image tweaks. Lightroom still isn't able to recognize the Photoshop large document format, so after an image is finished, I make a flattened copy as a 16Bit TIFF. You can go up to 4GB this way. Lightroom is much faster when dealing with these flattened files that are much smaller.
There are some plugins, say Nik Color Efex (etc), that do not seem to use multiple cores at all. The performance becomes very painful once going beyond about 100MP. I doubt any other computer would be significantly faster as the per core performance of the iMac is very high. With my workflow, the 32GB RAM seems to be "just" enough to keep everything from swapping out. My Photoshop sessions do make huge 30GB plus scratch disks, but the SSD seems fast enough to keep the performance up.
I really like the detail of the 5K screen. You can see issues with your photos that normally you might not see until you made a large print of them.
I was pleasantly surprised with how portable the iMac is. I sometimes bring it to different rooms in the house, similar to how you might use a laptop.
. 8gb should be fine and if you need more, just buy some memory sticks later.
