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Image shift on 85mm lens

Adam Rook

Adam Rook

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Hi, guys,

Yesterday I was playing around with my Milvus 85mm on my Scarlet, on a slider. I noticed that when I made a move the image would shift around as if I had a bad Image Stabilization on the camera.

1. Milvus lenses do not have built in IS.
2. The type work I do I use this slider literally every day and I know how to get a very smooth and consistent slide. So it's not me suddenly speeding up or slowing down.

Is there a setting on my Scarlet that could cause it to do that? I notice this particularly when I'm using a long focal length. An no it's not the typical shakiness you can get from shooting on a long lens with no IS. This is different.

I've used this lens many times before and have not seen this. I'm only just now starting to see it.

Thanks in advance!
 
Were you pullling focus at the time?

I am not familiar with Milvus lenses, but we see this sort of thing all the time when using Canons and Nikons. Some lenses are much worse than others, with the longer lenses emphasizing the effect more than wides.

Stephen
 
No not pulling focus. It's not breathing it's a lateral, sudden shifting of the image. If you've ever used a lens with a bad optical stabilizer that kinda hunts around to try to keep things centered it's kind of like that.
I'm not touching the camera or even the fluid head. It happens on longer ends of my zooms or longer lenses. I have a Canon 24-70 that I stopped using because I thought it was the problem. I see the same issue at 70mm.
I have a Sigma 18-300 and forget even trying to get to the end of that thing. I don't see it on my Milvus 50mm or my Tokina 11-20. It's just not there on wider angles. Or maybe it's just not as noticeable.

It hasn't always done this so it makes me question if it's something in the newest firmware? IDK. I'm sort of grasping at straws here.
 
Hey Adam-

I just had a similar issue using a long lens on a slider. I may not have the steadiest hands but when I looked back at the footage, there were these jerky
lateral movements in it too. I was shocked as I thought I would have noticed that while shooting or the director who was monitoring on his own monitor
would have said something. Now I'm wondering if it's similar to what you're experiencing?..I would post some of the footage but all the media is currently
in Europe being edited. I'll see if I can get them to send me a clip as an example. Just FYI I was on a CF Weapon and a 100mm lens. Weapon is on build 6.3.101
 
Sort of a wild-ass-guess here but could it be the jerky shudder that happens when you pan too quickly? RED has a tool to guide how to get smooth pans here: http://www.red.com/tools/panning-speed - which made me think the could be related. Hard to even guess without seeing what is happening.
 
In some cases, if you're really taxing the camera, least compression-max k image quality, you can get a little of this in the recording, what you are describing.
 
If we're talking image shift, i.e. the effect of the optics moving around and the image moving as a result, that is possibly not what's happening.

My first thought is if you are pulling focus, depending on a few factors, the gear could be moving the lens a bit as you're racking which would be noticeable on a longer lens like this pretty easily. This is a slight downside to using EF or F mount lenses instead of PL, but can be remedied via securing the lens one way or another.

If you're pulling with just your hand, all bets are off :)
 
I think it might be a similar problem you experience with judder and pan speeds. When you are on a longer lens the moves need to be that much slower or use a faster shutter to eliminate some of the judder. We were getting a lot of this on some recent commercials I have been directing and we've been moving the shutter angle up to 1/100th on certain moves to combat the judder/stutter that the camera can produce with longer lenses. It might essentially be rolling shutter you are looking at.

David
 
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