M9 Freedom from 6-bit Code???

[Reddot9]

Reading an article at:

http://www.kenrockwell.com/leica/m9/lens-compatibility.htm

I was somewhat surprised when the author stated that:

"Your M9 reads 6-bit lens coding, but doesn't need to.…Leica suggests you turn off the M9's automatic 6-bit code reader when using uncoded lenses to prevent the LEDs from reading spurious signals off the chrome…"

Is this correct? Remotely correct? or totally wrong?

Has anyone a specific Leica source for that comment?

 

[splitimageview]

Probably a good idea to turn if off with uncoded lenses, as that would indeed prevent such a scenario. I don't know what the odds are of that actually happening, though.

 

[sepiareverb]

I tell the camera which lens is on it manually most of the time as only half my lenses are coded. Is this turning it off?

I also forget, and shoot plenty of things with the 50/2 when the camera believes it's wearing a 35/1.4 pre-ASPH or a 90/2 AA. I can often tell with the DNG files when I've screwed up with the 35/1.4 and the wrong code- when the camera knows it is one of the finest lenses I've ever shot. Surprisingly sharp and good color all the way out to the corners in darn big prints.

 

[swoop]

I leave mine on the 35mm cron all the time. It works well that way. I remember doing some comparisons and the off setting left everything a bit dark and off color.

 

[250swb]

I think he's misreading the Manual (Page 124).

As a Note after a paragraph on what coding achieves EXIF, flash compatability etc, it says

'When using lenses without 6 bit coding the identification function (which I take to mean 'Auto') must be switched off to prevent malfunctions and the lens type entered manually.'

What that means is that if you put a non-coded lens on and the Auto detect function is set things like a TTL flash will malfunction unless you enter the correct lens manually, because it won't know what the lens is. Thats all. If you put a non-coded lens onto a body that isn't coded the EXIF will not record what it is, but that is all, nothing malfunctions.

As regards Rockwell over egging the pudding by suggesting it is spurious reflections that can cause problems, well I think he just misunderstood the whole thing and made it up. There is on real substitute for reading the Manual yourself.


Steve

 

[Ben Z]

Putting on an uncoded lens with the detection set to AUTO is the same as turning the detection to OFF in terms of what the in-camera processing defaults to. Reflections off the chrome will cause nothing...in fact, all my lenses I DIY coded I only engraved where the black codings go, not the white ones. They are place holders, that's all. The reason they're needed with a flange that has 6 recesses is because the code reader will usually mistake un-painted recesses as black one's. If the flange is smooth, shiny chrome, the code reader is blinded to it. However some older Leitz lenses have a flange screw opposite the code reader, which when lens detection is in AUTO, the camera will mistake for a black code, and set itself for whichever lens has a black code in that spot, along with the frameline choice. By pure coincidence, the "Thin" 90 Tele-Elmarit will register correctly because of it's flange screw.

 

[Mudman]

according to leica, sometimes there is a screw on the mount of uncoded lenses that can interact with the 6 bit coding and cause a mis-read.

 

[dogberryjr]

I only have one coded lens, so I leave it set for manual entry.

 

[Peter Klein]

I have an M8, which doesn't have a lens selection menu. I leave the coding detection on all the time. My 35mm and wider lenses are coded, my 50mm and 90mm lenses are not.

It works fine, with one execption. Occasionally my M8 thinks that a 90/3.5 VC lens with a VC adapter is really a 21mm, resulting in pink corners of the picture. It's happened all of twice the entire time I've owned the camera. So I'll turn off the conding detect for that lens. Coding helps prevent cyan corners with lenses 35mm or wider, and these corrections are written to the RAW files. For lenses longer than 35mm on the M8 (and *maybe* 50mm on the M9), coding really doesn't matter much.