Welcome to our community

Be a part of something great, join today!

Register Log in
  • Hey all, just changed over the backend after 15 years I figured time to give it a bit of an update, its probably gonna be a bit weird for most of you and i am sure there is a few bugs to work out but it should kinda work the same as before... hopefully :)

Soft Focus at Infinity with Epic and Tokina 11-16 f/2.8 II - Any Solution?

A

Andy Maser

Well-known member
Joined
Jan 18, 2012
Messages
140
Reaction score
6
Points
0
Location
Portland, OR
I've seen other threads about this, but haven't seen any good solutions yet. Has anyone figured out a way to resolve the issue of soft focus with a stock Tokina 11-16 Canon mount lens with the Epic? Only really noticing the issue at infinity and have tried rolling the focus back slightly from infinity, which doesn't resolve the problem.

Is this an across-the-board issue with Tokina f/2.8 11-16 II lenses, or are their duds out there? Does the Duclos process resolve the problem? I've been on the wait list for a while and bought the stock version to use in the meantime. It's absolutely indispensable so I'd love to get the stock version working properly...


Thanks!
 

Attachments

  • Epic_5khd_11_16.jpg
    Epic_5khd_11_16.jpg
    98.7 KB · Views: 0
Ouch. Looks bad even as a jpeg. I have used a Duclos 11-16 for a couple of years now, never had a problem with infinity focus. It does look like a back focus adjustment or possibly an internal optics misalignment... Maybe it is a dud. Good luck. I'm sure you will love the Duclos PL lens when you get it.
 
It looks like you have good sharp focus at the close grass. That means your back focus or flange depth are long. Maybe both.
unfortunately it's hard to tell which without more info.
check the lens on the collimator and the camera with a back focus tool like our Optimator and you'll know which one to adjust.
IQ seems fine on the lens otherwise...
 
I don't have focus issues with any of my other lenses--does that eliminate back focus as a potential issue? Is flange depth a lens adjustment issue or a camera adjustment issue?
 
That is not good. I have both duclos and tokina and don't have that issue. I did have a problem with my tokina, my son was hand holding a skate board shot and slammed into a rock, and http://www.thkphoto.com/ replaced the front element and tweaked it. They did a great job. So if you find your flange is set properly try these guys.
 
Pay Matthew Duclos to convert it properly to PL.

My Duclos is one of my favourite lenses and i shoot with it quite often.
 
Andy Maser said:
I don't have focus issues with any of my other lenses--does that eliminate back focus as a potential issue? Is flange depth a lens adjustment issue or a camera adjustment issue?
Click to expand...

flange depth/distance is the proper term for back focus.
 
flange depth is backfocus haha. backfocus is the incorrect term though. Flange depth is distance between sensor to rear element of lens. So adjust your camera flange distance as a test first. If thats not off it's the lens.

http://en.wikipedia.org/wiki/Flange_focal_distance
 
Haha lovely :)
Don't you just love internet forums?!!!
 
I sometimes have had that happen with some lenses. Have you try and back off the focus just a bit? That seems to bring things back into focus sometimes.
 
Some Black Magic CC users are complaining about that same problem with that lens. Mine works fine.
 
Ok, so let me see if I have this right. Even though all but one of my lenses produces sharp results throughout the focal range, there's still a chance that the issue is with my camera? Not that I'm an expert at back focus issues, or really have any real understanding of it, but that seems a little fishy to me.

I'll try it on my Scarlet tomorrow and see if I have the same problem.
 
It's your back focus in relation to that particular lens.

Wide lenses are particularly tough critics - you can often fudge it on the long end and get a sharp image.

I would say adjust the back focus with a collimator as suggested by several people here - or adjust the camera so that infinity on the Tokina works, and then see how your other lenses fare in terms of marks after that.

I have witnessed this problem before with a Duclos 11-16 on an epic.

I blamed the lens because I thought backfocus had been correct. Sure enough it was not correct even though "seemingly" correct with an 18mm Zeiss.

Tough lens, Tough crowd. Tough situation.
 
Les Dittert said:
Some Black Magic CC users are complaining about that same problem with that lens. Mine works fine.
Click to expand...
I have seen the problem on the EF version of the BMCC. I had planned to use the Nikon mount Tokina with an adapter, but don't know yet if it also is soft.

It's a real problem for the BMCC, since there are so few ultra wide/fast lenses. Anyone had similar issues with the Sigma 8-16mm?

Cheers.
 
Jacek Zakowicz said:
It looks like you have good sharp focus at the close grass. That means your back focus or flange depth are long. Maybe both.
unfortunately it's hard to tell which without more info.
check the lens on the collimator and the camera with a back focus tool like our Optimator and you'll know which one to adjust.
IQ seems fine on the lens otherwise...
Click to expand...

What Jacek said....SOLUTION:

Setup your backfocus with a Backfocus (burst) chart at say 5 to 6' and lots of other stuff IN BACKGROUND at 20' and more.....then hook up HDMI to a very good monitor/television AND use your onboard 5" touchscreen---put it in one of the focus assist modes--can't recall--but one that has nice sharp lines when in focus--AND use focus assist where you get a green square when in focus...setup all of this on a tripod AND begin working your bacfocus screw...For me it usually takes 10-15 mins to go back and forth sometimes 15-20 turns...to over what seems like the focus mark and then back again....to go the other way to sort of bracket the AREA of where IN FOUS is....then fine tune by going back and forth with your large monitor AND your smaller monitor---HAVE your 1:1 button set so you are zoomed in....once you get the chart AND background in best focus you can, that's it..IF you can't get infinity in focus, then as Jacek pointed out your flange depth on the actual mount may be off....could be so so small....but if you cannot get in focus, then mount could be the issue...BUT try another lens as well.
 
Noel Sterrett said:
It's a real problem for the BMCC, since there are so few ultra wide/fast lenses. Anyone had similar issues with the Sigma 8-16mm?

Cheers.
Click to expand...

Yup, got the problem on the BMC. All other glass I own, from Zeiss primes to Nikons, Samyang, Tokina 12-24 and even exotic vintage lenses on cheapish China adapters are razor sharp from front to the back though.

It also doesn't look that bad if I bolt the 11-16 on a DSLR - I run out of ideas. Think I give it back.

Frank
 
You must log in or register to reply here.
Back
Top