Jump to content

Red shift with 3.8/18 Super Elmar?


UliWer

Recommended Posts

Advertisement (gone after registration)

On photos with a bright background i recognize a red shift on the edges - especially on the left side - when I use the 3.8/18 with the M8.

 

This reminds me of examples given by Sean Reid in his M9-review, when he found out that cyan shift of the CV4/21 was corrected too much by the manual settings of another lens which resulted to the red shift. So i presume that also in the M8 there is too much cyan correction for the 3.8/18.

 

You can handle it with the tool for lens correction against vignetting in Lightroom, even if the 3.8/18 does not show significant vignetting on the M8.

 

Has anybody made the same experience?

 

I posted two examples of this in a parallel thread in the German forum:

http://www.l-camera-forum.com/leica-forum/forum-zur-leica-m8/98843-problem-mit-dem-super-elmar-18mm.html#post1040024

Link to post
Share on other sites

Are you using the lens without a filter and with UV/IR cut selected in the menu.

Yes exactly. The same situation with the M8/2. I did exactly this (used wrong setting with no filter) on a brief loan from Meister in Berlin. I later got to try the lens for half a day at Hessenpark , this time with a filter and the correct setting. No problems whatsoever.

With new Elmar 18mm, stopped down

18mm stopped down a little

By the way Stefan Daniel has said that the corrections are not aperture dependant.

Link to post
Share on other sites

Yes exactly. The same situation with the M8/2. I did exactly this (used wrong setting with no filter) on a brief loan from Meister in Berlin

 

I tried the 18mm lens without a filter, but forgot to switch off the filter correction. Here's an example - ignore the magenta jiacket and look at the corners...

 

 

[ATTACH]162501[/ATTACH]

Link to post
Share on other sites

Advertisement (gone after registration)

I tried the 18mm lens without a filter, but forgot to switch off the filter correction. Here's an example - ignore the magenta jiacket and look at the corners...

 

 

[ATTACH]162501[/ATTACH]

 

Here's my more dramatic example shot outside the Berlin Leica store. My fault not changing my usual setting on my camera since the lens had no filter. It is actually a pretty good example of how much correction the camera is doing for the filter on wides. All gone on the M9 naturally

My apologies for sharing such a rubbish sample, I didn't even have my 24 finder to frame with on me at the time either.

[ATTACH]162526[/ATTACH]

Link to post
Share on other sites

In the German forum I posted some test-pictures from a white sheet of paper with and without filter and with all settings for the lens detection in the menu:

 

http://www.l-camera-forum.com/leica-forum/forum-zur-leica-m8/98843-problem-mit-dem-super-elmar-18mm.html#post1040405

 

From the extremes you can see: with filter and lens detection off, there is strong cyan-shift caused by the filter; without filter and lens-detection "ON with UV/IR" there is strong redshift, because the cyan-shift is overcorrected. This overcorrection is not so strong but still visible in the first example with filter and lens detection "ON with UV/IR".

Link to post
Share on other sites

Thanks for the heads-up, and careful demonstrations.

 

Leica will doubtless correct this in future firmware. "By indirections we find directions out," as Hamlet said. :)

 

You'll notice that with Sean Reid's M8 measurements, as with yours, the color shift wasn't even. That is, one corner tended to show more shift than the others.

 

That has been my experience as well. Don't know why, but it seems to be a general occurrence.

Edited by ho_co
Link to post
Share on other sites

Thanks for the heads-up, and careful demonstrations.

 

Leica will doubtless correct this in future firmware. "By indirections we find directions out," as Hamlet said. :)

 

You'll notice that with Sean Reid's M8 measurements, as with yours, the color shift wasn't even. That is, one corner tended to show more shift than the others.

 

That has been my experience as well. Don't know why, but it seems to be a general occurrence.

Regarding the firmware, I don't think there is any problem unless the camera is mis-set? I got red corner shift from having the Lens detection + UV/IR ON and no filter.

When I shot with the lens again with filter and correct setting (courtesy of Wolfgang from Leica Akadamie) the lens and camera worked perfectly with no detectable error to red or cyan in any frames I shot over half a day.

Edited by hoppyman
Link to post
Share on other sites

First, make sure you are absolutely square to the target and make sure the lighting is as even as can be (I shoot for variance of 1/3 stop or less). Best to do these at night with only one type of controlled light source - no lights on even in an adjacent room. Keep in mind that the color output of the lights won't always be even either. It's always good to mentally account for the possible confounding variables when doing this type of testing.

 

All that said, a red drift when a lens is corrected is something you'll see in my tests of the WATE and some other wides. Under some lighting conditions with some lenses some of the M8's corrections won't be exact. This is something I've been writing about, in various articles, since shortly after the camera was released. It's not that there's a problem with Leica's programming for this, per se, but that any correction like this will be general - it will work better for some pictures and less well for others. Most of the time it is close enough that one needn't worry about it.

 

But, again, if you read the articles you'll see that I think some of the corrections should be backed off a bit more (for some wide lenses). But the real question is:

 

Is this slight red drift obvious and problematic in your normal pictures? If it isn't I wouldn't worry about it.

 

But the issue itself is, again, something I have been writing about for years. Leica can keep tweaking this but there might then be conditions where the problem is under-corrected.

 

Cheers,

 

Sean

Edited by sean_reid
Link to post
Share on other sites

Thank you everone for the input! For sure I will look after what Sean Reid wrote about his experiences with this issue and other lenses.

 

I did a lot of shooting with the 3.8/18 today always looking for some bright sky at the edges to see what happens. I think the red shift will become more visible if you underexpose. On a wide angle you are keen not to overexpose in the direction of the sun, so underexposure can be the result in the opposite direction (the first example of the landscape I posted in the German forum shows this: sun from the right, no visible red shift on this side, but underexposure and red shift on the left side).

 

Perhaps with the manual lens selection - if it is offered for the M8 - you will be able to avoid the red shift at all, when you select a 21mm setting. (Another argument against an automatic override of the manual setting...).

Link to post
Share on other sites

How's that store's name pronounced?

It’s an acronym for “French Connection UK”, but acronyms, other than mere abbreviations, are supposed to be pronounceable words and a sloppy pronunciation might get you into trouble. As usual, Wikipedia has it all: French Connection (clothing) - Wikipedia, the free encyclopedia.

Link to post
Share on other sites

Merci, mes amis Michael und Uli!

 

There's a US fast-food restaurant chain by the name of "Fuddrucker." It's a name that invites spoonerism (Schüttelreim).

 

But I hadn't seen anything like 'fcuk.'

 

 

 

Couldn't pronounce this one properly, even if I tried carefully.

Better not try. There's no winning with this one! :)

Edited by ho_co
Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...