Speed Booster Aperture Control

V

VMT

Well-known member
Question for Metabones Speed Booster Nikon - m43 users out there. Just got one and found it difficult to judge F-stop using the aperture control ring. How do you get a precise aperture opening/reading on a lens like the Sigma 18-35? Is it all just guessing work?
 
Each number is one stop. So full open is same as the lens, each step down is one stop. If the lens has less stops than graduations on the speed booster you will notice looking down the lens barrel that nothing happens to the iris if you keep going beyond the limit. Different lenses have different ranges so you'll have to mentally map each lens to the booster stop markings.
 
You could use your camera's meter to estimate the F-stops, or simply forget about F-stops and use the Metabones index scale on the adapter as your guide.
 
The only way to know for sure is to compare IRE readings on a plain frame vs. another lens at known f-stops, then write up a simple table of what hash mark correlates to what f-stop. It's not a direct correlation on either of my Metabones adapters with any NikG-lens.
 
WhatAndGiveUpShowBusiness said:
This nice review/test of the Metabones Speed Booster at http://www.slrlounge.com/near-full-...-metabones-speedbooster-nikon-adapter-review/ (about 2/3 of the way through the article) discusses the fact that the booster's F-stop marks are not necessarily linearly related to the lens's F stops
Click to expand...

That's an old article. The original version was non-linear. A couple of months after its release the design was changed with a completely different and more robust cam design that is linear. The easiest way to tell the difference is that the original non-linear version is marked 1-8, while the newer linear version is marked 0-7.
 
I have one of each - one SB marked F-8, one normal marked F-7. Neither has a direct stop-to-stop correlation.

Here's what I get for the Sigma 18-35 (Nik):
With the booster, stops are at: F, 1.5, 2, 2.5, 3, 4, 5.5, 8
Without the booster, stops are at: F, 0.5, 1, 2.5, 4, 5, 6

With the Sigma 50-150/2.8:
SB: F, 2, 2.5, 3, 3.5, 4.5, 7
N: F, .5, 1, 2, 3, 4.5

These are compared vs. a Voigtlander 17.5/0.95 (aperture clicked) and Leica R 90/2
 
You must log in or register to reply here.
Back
Top