conurus Forum Index conurus
smart adapters and lens mount conversions
 
 FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 

converted 24-85 - light metering issues on 5d2

 
Post new topic   Reply to topic    conurus Forum Index -> Contax N to Canon EF Mount Conversion
View previous topic :: View next topic  
Author Message
arif



Joined: 18 Sep 2010
Posts: 15

PostPosted: Sat Sep 18, 2010 5:56 pm    Post subject: converted 24-85 - light metering issues on 5d2 Reply with quote

Hi,

I have a converted contax 24-85. I love the sharpness and color rendition.

I have been having issues with over exposure though. It appears to me that the light metering is thrown off ?? I've tried it on a 5d2 and 7d with the same result

has anybody else had this issue?

In order to get it to expose correctly, i need to underespose the camera settings by 1 1/3

here is the info from the conversion
http://en.conurus.com/track.php?sn=12701096

any help would be appreciated

thanks
Back to top
View user's profile Send private message
arif



Joined: 18 Sep 2010
Posts: 15

PostPosted: Mon Sep 20, 2010 6:02 pm    Post subject: metering issue Reply with quote

It looks like I have a second generation circuit board

Circuit board# 0820218

Will the new circuit board fix the metering issue?

thanks
Back to top
View user's profile Send private message
conurus
Site Admin


Joined: 15 Aug 2006
Posts: 795
Location: Vancouver, Canada

PostPosted: Sun Oct 03, 2010 12:19 pm    Post subject: Reply with quote

I would have to first confess that the metering of converted lenses has never been great and it can be off by up to half a stop. Whether the circuit board was our old second generation or our new third generation makes no difference. However, your case of 1 1/3 stops off sounds excessive. Please try shooting a uniform blank wall which is white, grey or black and the histogram is supposed to be centered in the middle. Let us know if that is not the case. Thanks!
_________________
I am a bird and I uncovered the E, EF and N-mount communication protocols!
Back to top
View user's profile Send private message Visit poster's website
arif



Joined: 18 Sep 2010
Posts: 15

PostPosted: Mon Oct 04, 2010 12:29 am    Post subject: over exposed Reply with quote

hi

thanks for your reply

I did as you suggested. I shot a wall (it wasn't pure white though)

the histogram is definely on the right side.. not even close to the centre.

ANy suggestions / help would be greatly appreciated

thanks in advance
Back to top
View user's profile Send private message
conurus
Site Admin


Joined: 15 Aug 2006
Posts: 795
Location: Vancouver, Canada

PostPosted: Mon Oct 04, 2010 11:53 am    Post subject: Reply with quote

Was this wide open? If not, at which aperture? Does this happen throughout the entire zoom range?

If there are no problems wide open, I suspect this may be an issue with the aperture diaphragm blades.

_________________
I am a bird and I uncovered the E, EF and N-mount communication protocols!
Back to top
View user's profile Send private message Visit poster's website
arif



Joined: 18 Sep 2010
Posts: 15

PostPosted: Tue Oct 05, 2010 2:13 am    Post subject: Reply with quote

yse,

i tried full zoom (4.5) and full wide (3.5)

both had the histogram spiked to the right Sad
Back to top
View user's profile Send private message
bigkidneys



Joined: 11 Oct 2010
Posts: 8

PostPosted: Mon Oct 11, 2010 8:42 pm    Post subject: Reply with quote

Arif,
Did your issue get resolved? I think I am experiencing the same problem as you. I plan on shooting a wall tomorrow to see what the outcome is. I consistently have to underexpose all my shots in sunny weather to avoid any blowouts.
Back to top
View user's profile Send private message
arif



Joined: 18 Sep 2010
Posts: 15

PostPosted: Mon Oct 11, 2010 9:01 pm    Post subject: Reply with quote

hi

No, I haven't heard back from bo.ming after his last suggestion

I have to set the exposure compensation to -1 1/3 for that lens..

a little dissapointing as I was soo excited to get that lens

dunno what to do

if you figure out something please let me know
Back to top
View user's profile Send private message
bigkidneys



Joined: 11 Oct 2010
Posts: 8

PostPosted: Mon Oct 11, 2010 9:06 pm    Post subject: Reply with quote

Will do. This is my second copy and not at all like the first one I had. I find myself doing the same thing, either using -1 or -2 for exposure compensation. It is a serious pain to constantly have to mess with it in PP so if we don't figure something out I may have to sell it and just stick with my primes. Hopefully it is something easy as I really love this FL and the images are great when properly exposed.
Back to top
View user's profile Send private message
conurus
Site Admin


Joined: 15 Aug 2006
Posts: 795
Location: Vancouver, Canada

PostPosted: Mon Oct 11, 2010 9:11 pm    Post subject: Reply with quote

bigkidneys,

Please observe the aperture diaphragm while you hold down the DoF preview button. Does the aperture blades stop down properly?

arif,

I just conducted some tests on a white, blank wall, in Av exposure mode, exposure compensation = 0 of course, with my own 5D2 and 24-85


FLwide openf/11f/22
24mmunder 1/3under 1/2under 2/3
35mmunder 1/3under 1/3under 2/3
50mmunder 1/3under 1/3under 1/2
85mmunder 1/3correctunder 1/3


I personally have to constantly set exposure compensation to +1/3 stop for the 24-85, but for me it skews to the left side.

If you would send the lens in I would be more than happy to take a look. My only concern is what if it works on my 5D2? But without any better idea you may send it in and I will take a look.


Last edited by conurus on Tue Oct 12, 2010 1:08 am; edited 1 time in total
Back to top
View user's profile Send private message Visit poster's website
bigkidneys



Joined: 11 Oct 2010
Posts: 8

PostPosted: Mon Oct 11, 2010 9:32 pm    Post subject: Reply with quote

Not sure if I am doing it right as I am inside (dark now in Germany) and when I have it pointed at the bedroom light and press the button it does stop down so I am assuming it does so correctly (sorry, new to photography). You can see and hear the diaphragm blades shutting down then releasing back when I let off the button.
Back to top
View user's profile Send private message
arif



Joined: 18 Sep 2010
Posts: 15

PostPosted: Mon Oct 11, 2010 11:29 pm    Post subject: Reply with quote

hi Bo Ming

thanks much for the kind offer

If it works on your 5d2, I would be pretty happy. At least i can sell it with a clean conscience, knowing its only my camera not the lens. that being said, my other lenses (canon and tamron) seem to work fine.

Ignorant (dumb) question.... if i send it in to you, do you think there is anything you can do? is it part of the conversion that may be mis-wired?

just wondering what the chances are that you can help..

a little worried about all thipping the lens may grow through
Back to top
View user's profile Send private message
arif



Joined: 18 Sep 2010
Posts: 15

PostPosted: Thu Oct 14, 2010 1:18 am    Post subject: Reply with quote

hi

just thought i'd attempt to rephrase what i wrote above

IF it works fine for BoMing then its obviously my camera and I'd probably end up selling the lens if thats the case

If not and BoMing thinks there is somthing that he can fix, that would be awesome as the lens itself is sharp and has all the characteristics described for that lens. But if i have to keep under exposing it by 1 1/3 stops.. I'd rather sell it

BoMing, any thoughts?

thanks in advance
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic    conurus Forum Index -> Contax N to Canon EF Mount Conversion All times are GMT
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum

RSS Atom

Powered by phpBB © 2001, 2005 phpBB Group

phpBB SEO