Blackmagic Forum

I’m coming from a late 2013 Mac Pro 6 Core 64GB RAM and found my fusion comps to be getting difficult to work with.

Assuming my machine was a bit old for it all I bought an 8core iMac Pro to help as it had the highest single CPU speed which I believe is what Fusion prefers. It seems to be about twice the speed of my 2013 Mac Pro, but twice the speed of 5 miles per hour is still only 10 miles per hour.

For the huge outlay I can’t see its worth the cost performance benefit. Assuming more cores as I stated isn’t going to help am I ultimately going to have to go the PC route to see better performance? I do appreciate that the iMac Pro will perform much better in other areas but I’m not really struggling with those with my late 2013 Mac Pro.

More cores will help. The 8 core has the SLOWEST single core speed, not the highest. And most operations in Fusion are multithreaded.

The problem with the iMac Pro is that it's 2+ years old. Even so, you won't see much more than a 2x performance boost for the money by using modern PC components. You'll get the option of adding additional GPU's, however, when Fusion adds support for that.

What are your performance expectations based on?

On Apples site it lists the 8 core as 3.2GHz with the higher core counts getting progressively lower but with turbo getting higher. I assumed the turbo would be a seldom used aspect? So I’m a little confused there.

I remember reading on Puget’s website (who build custom PCs for Fusion users among others) that more cores weren’t going to do much though I appreciate it depends on the tool you’re using.

The comp I was working on was a panning shot which required a fair bit of removing people and cars from the scene during the pan and after panning. All outside a location. I had to split it into different sections using the time speed tool to create static textures (basically rebuilt the background sans cars etc) tracked it and ‘sat’ it into the scene. So a fair bit of paint but static paint. The comp was previewing about 1 frame every 9 seconds. I ended up rendering over and over agin only to see faults, correct them then render again rinse and repeat. I could really have done with being about to render in the comp but it was taking 15 minutes every time. I ended up just noding together small sections to get better previews but ultimately made the assumption my machine is just old.

I did see improvements for the iMac Pro but I couldn’t justify the cost for their size. I’m only working in HD, I’m sure a 4K situation would benefit more from the iMac Pro. But you reckon a ten core would be even better?

Think yourself lucky... The solve on a 3D camera track I did on Sunday took 3 hours to complete (each time). Managed to get the solve error down to less than 0.3 though so it was worth it. Interesting that the CPU was only 15% utilized during the solve operation, with all the cores doing "a little bit" to help. Hard to say whether more cores or more IPC would be a better way to go -- but it's obvious that something else (memory bandwidth?) was the bottleneck on this.

If this is on a paid job, it's definitely worth considering getting Syntheyes. It's not crazy expensive, but it is crazy good (and fast) out of the box with much more options to finetune your tracks.
In cases like this it will pay for itself in one or two jobs.

+1 for Syntheyes. It's very good, super fast, very flexible and plays well with Fusion. Scott Andersson, the developer, is very responsive to customer needs and very helpful in a crisis. And there's loads of tutorials and reference on Scott's website.

Russ Andersson

Interesting stuff thanks!

Realistically, I would 100% not buy a iMac Pro at this time. Lease? Maybe for a year. If you can afford to pay for it with your current work, great, but it's just not a good deal, especially for the future.

When the iMac Pro came out, 5K displays were expensive. They aren't now. 18-core CPUs were expensive. They aren't now. NVMe SSDs were expensive. They aren't now.

For the same price as the iMac Pro, you could get 2x the CPU cores, 2x the memory, 4x the storage, and 2x the GPU power. And you get the added benefit of being able to expand/upgrade to 3x the CPU cores, 8x the memory, 32x the storage, and 8x the GPU power.

Good points, in my head they seem a recent addition.

As it is I sent mine back and I'm back on my trash can Mac which is doing alright mostly given this is a HD project. Looking at the stuff I have coming up it shouldn't be much more taxing for it. I've grown quite attached to this little machine actually for the hate it gets.