To be productive you need a fluid experience and unfortunately non of the 2017 i based iMacs will give you that in lightroom. Lets get the elephant in the room out the way first. Lightroom is not well optimized and will not run buttery unless you have high end hardware. This isnt really apples fault as RAW files are fluid in photos but lightroom... not so much. Lightroom has got better but it has a long long way to go and if you work with lightroom on the daily you need to bare that in mind as spending £1500-3000 on a current iMac probably isnt the best way to get that performance needed for fluid workflow.
The mid range iMac is not suitable IMO. Lightroom is a hog and it needs as much power as possible. Sliders can be very laggy, adjustment brushes can be almost unusable. Depends on the files your using so using JPGs will be lass taxing.
It depends what files your using too. My 5DMKIII raw files perform ok, my 6DMKII and 5DMKIV lag a little and my 5DSr files are a pain.
I bought my father the base 2017 iMac with a 2TB fusion as the only upgrade, there is barely any data on it so the SSD is pretty much the only portion used. I exported a wedding as a catalog and was really disapointed at the performance compared to my almost decade old mac pro.
Im a wedding and events photographer and I couldn't do my work on it, lightroom was far too slow. If your editing 500 images and it takes 1-3 seconds every time you zoom to 100% to render a preview even at lower resolution and its laggy as you move around it really slows you down. Say it takes 2 seconds thats an extra 17 minutes on your workflow of 500 images.
The base level iMac performed a fair amount slower than my 9 year old mac pro in my sig, although it benches quicker single and about the same multi its slower because of the display.
My mac pro is mated to a 27" ACD which is 2560x1440 and the difference is night and day.
A lot of it is the graphics card, lightroom will use GPU acceleration on the iMac because its a high resolution display, even when you set the preview size at 2560 it still takes ages to render because the sliders are trying to run at 60FPS and pushing the amount of pixels on the display is GPU and CPU intensive. That 5k display is 14mp as it is.
The iMac pro struggles far less because it has a much more powerful GPU and more cores but a lower clock speed it also lacks the added extras the i series has like quick sync and H265 encoding that helps on the video side. For the money difference I don't think its worth it for me as I do quite a bit of video work too.
I would agree on the SSD portion it definitely worth the money in this application. I never get rid of my smart previews in my lightroom library because I often revisit so I want it to be speedy when I do, lightroom has to rebuild each preview as you work which is annoying. By default Lightroom gets rid of them after 30 days. My 2018 lightroom library is sitting at 200gbs and if you want the best performance put the RAW files on a traditional drive as they cache and its far cheaper (I usually use at least a 4TB hdd per year so SSD storage doesn't make financial sense) and put the stuff that needs the speed like the OS/Apps/library/previews on the SSD.
The fusion only has a 128gb portion so the likelihood is once you have your OS and apps that 128 drive will be full. You can always buy external blade storage like the samsung x5 but they are as much as upgrading the internal storage.
https://www.amazon.co.uk/dp/B07GL8M...t=&hvlocphy=9046623&hvtargid=pla-562941756642
The i7 is the best here, it runs lightroom fairly well from my experience but the fans will start on export and the adjustment brush is still very laggy, again this is a lightroom issue but there are limitations with the iMac hardware.
At the end of the day the iMac is a mid range machine with components like the 5K display that can be more of a hindrance than a help when it comes down to doing actual work, they take a lot of resources to run as it is.
Im waiting for the new mac pro to see what it offers. Ive been thinking about the 5K i7 iMac as an interim but I just cant justify spending that much on an older computer especially when the 9th gen chips are on their way, it doesn't offer too much more than my current machine, loose my storage capability and at the end of the day it throttles and you loose that performance gain because of apples poor cooling solution.
The iMac Pro is better but you still have all the issues of an all in one. ECC ram is a lot less resiliant than normal ram as it error corrects all the time it works much harder. Ive had 4 sticks go in my mac pros since 2008, you just take the faulty stick out and crack on and order another. With the iMac pro you will loose the machine for 2 weeks to apple and who knows what condition it will be in when it comes back.
You could wait for the next iMac but who knows when its coming. People who think they know what they are talking about like
Fishrrman have been telling people for ages but alas all their predictions have been wrong.
What you can draw from the next iMac is that it will be using the newer CPUs the apple K series tend to bench slightly lower than their windows counterparts. The 8700k in PCs is benching between 6-6500 single and up to 30k multi but thats with adequate cooling. But will apple use 9th gen? Who knows but the next high end CPU will be as powerful as the current base iMac pro for probably 30% less money.
It will use Vega which in the macbook pro has seen 20-30% gains over the 5 series which would be a nice addition, the ram is also on the chip making it more efficient. If there is a redesign then possibly no user ram upgrades, who knows what the cooling solution will be like. Maybe they add the iMac pro cooling which is still not optimal the Xeons still run too hot.
Sounds crazy but building a PC with powerful components might be a better option... I also have PCs with my macs, W10 works well and you can get the components you want when you need rather than waiting for apple to give you out of date hardware at top dollar. Then again putting a PC together and matching the 5K display is a similar cost...
Not the best time to be looking at a desktop everything but the mac mini is out of date.
Im interested to see what the mac pro brings, whether it will still be a consumer product or whether it will be in the stratosphere with 50 odd cores and start at 10-15k... we will see.
