FS7: Metabones + Canon 16-35 f/4 IS darker when zooming

M

Martin.G

Well-known member
Anyone else have this issue?

My Canon 16-35 f/4 IS gets darker when zooming in. Or brighter when zooming out.

Pictures perfectly exposed at 35mm gets blown and overexposed when i zoom out to 24mm or 16mm.

This practically makes the lens much or less useless for my needs.

FS7 latest firmware
Metabones Speedbooster Ultra latest firmware
Will test Metabones Mk2 when i get the time

(Anyone have the Sony 16-35 f/4 OSS and can comment on that lens?)
 
All of the constant aperture Canon L zooms do this except for the 70-200. The Sigma 18-35 actually maintains a constant aperture.
 
cpreston said:
The Sigma 18-35 actually maintains a constant aperture.
Click to expand...

I have the Sigma 24-105 (before they stopped making it) as my main lens. Zero change in exposure when zooming, and great reach and T-value combined with Speedbooster. Very nice.

But im starting to become ready to move 100% over to Sony lenses, together with Sony a7 DSLRs for my photography needs as well.
 
cpreston said:
All of the constant aperture Canon L zooms do this except for the 70-200. The Sigma 18-35 actually maintains a constant aperture.
Click to expand...
Unfortunately, the Sigma 18-35 (Art 1.8 lens anyway) is not even close to being par focal w/ MB adapter on the FS7. A bit bummed about that.
 
markfpv said:
Unfortunately, the Sigma 18-35 (Art 1.8 lens anyway) is not even close to being par focal w/ MB adapter on the FS7. A bit bummed about that.
Click to expand...

It is a matter of individual units. There are probably some variations between the lenses themselves but I'm sure the adapters are not made to high tolerances. That's why ENG camera lenses have back focus adjustment and when it comes to Super 35 and S16 zooms they have to be collimated. Having said that, I'm lucky because my 18-35mm f/1.8 is near parfocal on FS7, perfectly parfocal when stopped down to f/3.5
 
I don't remember my 18-35 being way off either. Not perfect but not wildly off. I tried the Sigma 24-105 and that was too unparfocl for my taste
 
Not many if any still zooms are made to be par focal. One could just be very lucky sometimes.
None of my Canon 24-105 have been par focal, and they all lost a stop or half at the long end. Really annoying when they claim f4
 
Yoak said:
Not many if any still zooms are made to be par focal. One could just be very lucky sometimes.
None of my Canon 24-105 have been par focal, and they all lost a stop or half at the long end. Really annoying when they claim f4
Click to expand...

My Canon 24-105 did the same. Sigma 24-105 did not, and i find my Sigma to be "pretty much" parfocal. Not perfect, not for 4K going 24mm all the way to 105mm, but for run and gun in HD it works.

What alternatives is there to true 16mm (Sony FE 16mm becomes 24mm so its not really wide on crop sensor FS7) with OSS? Sigma 18-35 does not have IS OSS or VR.

Allthough, i dont really run and gun it with the 16-35. But it gets really dark at 35 nonetheless. Rules out low exposure stuff... Things to consider wether to keep it or not
 
That's interesting about the sigma being near par focal. I would have chosen that over the Canon if the copy I tried had been . Mine was wildly out. Otherwise its abetter lens than the canon all the way round. Maybe I should try another one. I find I use my Tamron 24-70 most of the time simply because its a better lens than the Canon 24-105 even though the range is shorter.

Who knows though as we are both using adapters how much that is affecting the issue.
 
the only lens that i know that is 100% parfocal - Sigma 50-150 f2.8, also have not seen it gets darker..... seems like ok with it as well, the only issue - breathing

what about canon 24-70 II f2.8 or F4.0 IS? does it get darker when zooming?
 
anatusa said:
the only lens that i know that is 100% parfocal - Sigma 50-150 f2.8, also have not seen it gets darker..... seems like ok with it as well, the only issue - breathing

what about canon 24-70 II f2.8 or F4.0 IS? does it get darker when zooming?
Click to expand...

Which version on 50-150mm Sigma are you referring to?
 
This is intriguing. My Canon 24 -105L f/4 is really close to being par focal (on both MB SB Ultra and Mk IV) ... but I do think Canon exaggerates the f/4 on the long end of this lens. (I've used it years on 5D to shoot stills and noticed the same thing - but honestly my FS7 has given this lens a whole new life.)
I may try and purchase a cheap EF - E dummy mount... and see if it's more the Mk IV adapter that makes my version of the Sigma Art 18-35 f1.8 very un-parfocal.
 
anatusa said:
the only lens that i know that is 100% parfocal - Sigma 50-150 f2.8, also have not seen it gets darker..... seems like ok with it as well, the only issue - breathing

what about canon 24-70 II f2.8 or F4.0 IS? does it get darker when zooming?
Click to expand...

my 24-70 f2.8 mk I doesn't get darker
 
You must log in or register to reply here.
Back
Top