follow focus question

C

charliemcdanger

Well-known member
I'm piecing together a 15mm rig and just added a follow focus. It operates excellently, with one snag: the pressure of the gear against the barrel pushes the barrel away from the follow focus, and consequently it slips.

On my Canon bodies (7d and t3i), is there any way to keep the body in line on the quick-release plate? All I can think of so far is to rubber band the lens barrel to the follow-focus, which seems ridiculous and bush-league. Thanks in advance for solutions.
 
Your rig is not stiff enough, or something is not tightened as it should be. Neither the FF nor specially the camera should move at all when you change focus.

BTW this is all relative: my rig works fine in general but I'd have that same problem with my CZJ 300mm f/4, because it's a huge lens with a pretty stiff focus ring.
 
Samuel H said:
Your rig is not stiff enough
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Man if I had a nickel for every time... Anyway, I guess tightening the screw on the quick release plate is the obvious answer. It just seems like these bodies don't provide a lot of friction, i.e. are easily twisted on the plate.
 
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I can't stand it any more.

Why do people have "follow focus" devices when there is the option of a remote that does focus, iris, zoom and on/off?

I bought a gadget from Studio 1 Productions with two wires that plug into my AG-AC160A and I have been as happy as a clam ever since. Am I missing something?

It may be that remotes work on a cam with a fixed lens but not with cams that accommodate interchangeable lens.
 
kwkeirstead said:
I can't stand it any more.

Why do people have "follow focus" devices when there is the option of a remote that does focus, iris, zoom and on/off?

I bought a gadget from Studio 1 Productions with two wires that plug into my AG-AC160A and I have been as happy as a clam ever since. Am I missing something?
Click to expand...

That works for traditional camcorders sporting fixed lenses with electronic controls of focus and servo zoom. DSLR cameras do not have these kinds of controls on their interchangeable lenses, as focus is completely mechanical and manual.

Further, the follow focus is not a new concept; it has been used for decades in major motion pictures with film cameras and interchangeable cinema lenses.
 
You can by an electronic "follow focus" for DSLRs that plugs into the USB port but there is something with the USB protocol that only allows for step motor focusing which isn't very smooth. The other benefit of a true follow focus is the tactile feel and control of it..something you loose with LANC systems.
 
kwkeirstead said:
I can't stand it any more.

Why do people have "follow focus" devices when there is the option of a remote that does focus, iris, zoom and on/off?

I bought a gadget from Studio 1 Productions with two wires that plug into my AG-AC160A and I have been as happy as a clam ever since. Am I missing something?
Click to expand...

You're missing the fact that this is a DSLR thread... I use focus controllers on my AC130, but I'd never shoot something I wanted to look "beautiful" with that camera. I'd go DSLR, BMC, Red, etc., and I'd need gears and an FF.

There are electronic solutions for Canon, but they're herkyjerky affairs.

It's taken me a lot of work to sort out FF on DSLRs with still lenses. The camera can spin (no "DV pin" - someone does make a plate for some cameras that wraps around the front of the body to prevent spin).

When still lenses were designed, it didn't matter if the lens barrel shifted a bit when it was touched; most of my still lenses will have a tiny amount of play when grabbed, which doesn't matter for stills but can ruin a motion shot. I find an FF can "lift" the lens up as well, esp. larger heavy glass.

What's worked for me:

Get a decent FF to start - actually the Fotga DP II (or whatever??) is amazing for under $200. It's on Amazon, and so are spare gears and stop screw spares - and they're reasonably prices as well.

For god's sake, don't use a battery grip on rails!!!

Use a lens support for any lens that has the room, and put some upward tension on the lens - don't go nuts and mess up the mount, just enough to lock it in place, and don't store it that way.

See if your QR plate is stiff enough - if you can rock the camera up/down, or twist it, you need help. There's just not much real estate under there. I've found folding a couple layers of blue tape into a shim has fixed my problems (along with a lens support). Others cut a slice from a rubber bike inner tube.

Most DSLR rod setups are crap and will flex like mad. You need to come up with a solution that has fore and aft rod supports for the tripod section, and the same for the camera mount section - 8 points of contact (4 per rail). Or a baseplate that has a very long sleeve that the rods slide into. There are plenty out there, but they're made for video cameras - I think it's critical that you have battery access on your rails. I've cut chunks out of baseplates in the past, I've bought two of those Fotga plates and turned 'em into one system, etc.

Don't just cram the FF gear into the lens gear - there's a sweet spot where the gear moves easily. When you mount the FF and slide it towards the camera, hold the sliding area down so it's level, and turn the knob until it meshes with the gears, but not so tight it starts pushing the lens to the side. It will spin much more easily that way.

Keep your hand on the FF if your shot requires a pull - often just the moment you touch the knob things will rock a hair.

Use a focus whip and keep your hand on it - the whip can make a huge difference - sometimes it'll solve all your problems for the day.

Look at the setup below - that camera is going to flex up & down like crazy. The camera stage needs a second support under the camera body:

SIDE.jpg

I use this style lens support - I like that it can be raised or lowered by the center knob, so I can fine tune the pressure under the lens. If the lens is too short for a support, it probably doesn't need one.This item has made a world of difference for me, since 80% of the time I'm using a Nikkor 28-70 2.8, also known as "the beast"...

support.jpg
 
charliemcdanger said:
Man if I had a nickel for every time... Anyway, I guess tightening the screw on the quick release plate is the obvious answer. It just seems like these bodies don't provide a lot of friction, i.e. are easily twisted on the plate.
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Dslrs have a major design flaw in the single screw hole = follow focus spins the camera

First try some gaffa under the camera - no luck? consider a cage or RRS L bracket..

S
 
morgan_moore said:
Dslrs have a major design flaw in the single screw hole = follow focus spins the camera

First try some gaffa under the camera - no luck? consider a cage or RRS L bracket..

S
Click to expand...

In reality, I've had almost no trouble with camera spin. Tighten the screw before every shoot, check it during the shoot. Get some rubber under there if needed - bicycle inner tube material is pretty good.

And there's this - looking at my D7100, there are several post-holes (I think for aligning the battery grip) that would work fine as DV pin holes, if a plate were made for the camera.

I've "milled" aluminum to make an offset plate once (well, I only have a drill press, it looked kind of like a metal abortion but worked fine). But I really think 3D printing is the answer to a lot of this stuff.

Sketchup is free for Mac or PC. It's absurdly easy to learn (I have a decade of 3d modeling and rendering, certainly not at some hollywood level - but the concepts of simple modeling and using one shape to add or subtract to another are simple). You could print a test camera plate from one of the mail-order "maker" places for $15 or so (you upload your 3D file). If it doesn't fit, learn what's off and do it again, another fifteen bucks.

I've been working on a dovetail plate to fit a nightvision harness - I want to mount an HDMI VF to my head for steadicam work in the sun, essentially. My first shot at it was $15, sizing was off but I expected that and knew this would be my "dial in the fit" piece. even if I have to do that 2 more times, I'll be under fifty bucks for a custom part.

Someday we'll all have 3D printers in our homes and we'll buy things by downloading the files and printing 'em. But just using sketchup and a service right now is... well, it's like "this is the f*cking future!!!" And I'm just a civilian as far as this 3D stuff goes, but if you DIY stuff - download sketchup, watch some tuts, and give it a try.

THAT SAID... FF/DSLR issues are really much more sag and droop from your rails, and the fact that still lenses and mounts aren't built like cinema gear. My list a couple posts above served me very well.
 
morgan_moore said:
Dslrs have a major design flaw in the single screw hole = follow focus spins the camera
S
Click to expand...

i had this problem with my 7D, and then my blackmagic production camera. it was a huge issue when trying to pull on a follow focus with a long lens like a 70-200. the lens is so long and there is so much leverage near the end that the camera would sometimes [dangerously] slide loose. the only 100% sure way that i could lock the camera down was with a cage that used multiple fastening points. do yourself a favour and buy a custom cage that fastens in at least two points on the camera body.

this one is top notch, but im sure there are cheaper versions out there.
http://woodencamera.com/Quick-Cage-DSLR-Large.html
 
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