How to mark a zoom lens for pulling focus
Posted 14 June 2011 - 07:04 PM
My preferred method is wrapping some tape around the lens and then putting set distances on the tape. This would however require a new bit of tape for the various focal lengths between 24 and 105 since the focus marks would for one focal length would not be accurate for all the others. Is there a more sensible efficient way of doing this, I have googled but cannot find anything so feel I be may be missing the point completely?!
Any advice in the next 6 hours would be much appreciated.
Posted 14 June 2011 - 07:12 PM
This would however require a new bit of tape for the various focal lengths between 24 and 105 since the focus marks would for one focal length would not be accurate for all the others.
I don't know the lens in question but why would this be the case for any normal zoom ?
Posted 14 June 2011 - 07:49 PM
The focus on the lens also has no end points, what is the easiest way of matching the marks on the tape back up with the lens?
Cheers for the advice, im still very much learning as you can tell.
Posted 14 June 2011 - 07:58 PM
Also, does the fact that the lens extends not affect the tape marks or, because it is from the focal plane it does not matter?
One end point will be infinity - the other you could find by putting it at that end point then moving an object until its in focus, then measuring from the focal plane (the circle with the vertical line though it scribed on the camera) to that object.
The focus on the lens also has no end points
Posted 14 June 2011 - 09:15 PM
Posted 14 June 2011 - 10:53 PM
Posted 17 June 2011 - 12:35 AM
1/2" paper tape around the barrel, and using a black stabilo/grease pencil or wet erase pen so you can erase your marks for each setup, and you'll be good.
Posted 28 June 2011 - 04:45 PM
Just to confirm a few things that I experienced:
- The distance marks on the lens were accurate BUT they were few and far between, I think it was 3, 5 and 10 feet which meant that I ended up having to make more marks on the tape than I would have liked.
- There wasn't time to mark up tape all the time so I simply used eye marks as suggested.
- To help with marking the tape I; made sure I marked close focus so that I could always reset the lens back to this for each shot. The focus on the lens has no end stops so you simply have to rotate the focus ring until your close focus mark matches up - remember to rotate the correct way!
- To try and distinguish between marks with more clarity, and to avoid having to change tape so often I used various coloured pens for different set-ups (where necessary).
- I did however have lots of strips of tape already cut so that I could change the cluttered tape when needed.
- Wrapping several bits of tape on the barrel at once can save time, once the top tape is too cluttered simply peel it off and there is another below.
- On this lens the f-stop was f4.0 so depth of field wasn't as much of a nightmare as it could have been but, as some have said the focus mechanism on the lens is not precise compared to cine lens so to make minor adjustments can be pretty difficult.
- One side-effect of doing it is that you can end up shaking the camera because you are always touching the lens. You can try and only bring your hand to the focus ring when an adjustment is made but this can invariably cause a bigger shake when your hand comes back into contact with the lens.
Overall, it was a good learning experience given that I'm pretty new to focus pulling and it definitely help me develop my distance judging.
Posted 01 July 2011 - 12:07 PM
Good practice, yes, but hopefully we'll have to work like this less and less as the DSLR world gets more cine friendly.
Posted 01 July 2011 - 01:48 PM
I'm glad to hear you didn't get completely stressed out over it though. That's good