I forget: what happens if you use an uncoded lens on an M8?

kshapero

kshapero

South Florida Man
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I have a chance to use an M8 for about a week, but my lenses mostly CV's and a ZM 35mm are not coded. What's the deal?
 
kshapero said:
I have a chance to use an M8 for about a week, but my lenses mostly CV's and a ZM 35mm are not coded. What's the deal?
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One of your favourite body parts drops off :eek:

Just kidding :D

No lens info in the EXIF data. For lenses wider than 50mm, a cyan shift towards the edges of the photo goes uncorrected in JPEGs and there may be some auto-correction fed to the RAW converter that will be absent. Never used one myself - just passing on what I've heard.

...Mike
 
The cyan toward the outer zones comes from the UV/IR Cut filter, so if you don't use the filter, then, well, you trade that problem for the consequences of the sensor's IR sensitivity. Artificial black-dyed fabrics (and even greys) will have a purple/magenta tint, and foliage colors will be slightly off. I found that indoor shots under incandescent light (higher IR emission) was particularly hard to deal with.

I didn't have filters or coded lenses on a trip to Malta, Sicily, and the Canary Is, and for most of my touristy photos there was no obvious effect.

But if you want to go with IR Cut filters (a good idea, I've concluded), but without 6-bit coding, all you miss is the EXIF data and you get the cyan shading. You can deal with that cyan by running your RAW files through CornerFix software.
 
kshapero said:
I have a chance to use an M8 for about a week, but my lenses mostly CV's and a ZM 35mm are not coded. What's the deal?
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As they say in Cantonese (;)) "ist a zukhen vey". The fact your lenses aren't coded isn't nearly as big an issue as whether you have IR-Cut filters for them. Without the filters, green foliage turns yellow or pink, and black clothes turn purple (both commonly encountered in our neck of the woods in S. FL. :D), and it's a nightmare trying to fix it up after the fact.

Once you've got the filters, then you only need to worry about coding for those wider than 35mm (actual, not M8-crop-equivalents) because the IR filters will overcorrect toward the corners and you get a greenish cast. Firmware in the M8 will correct it (applies to DNG as well as JPEG) provided the M8 sees a code. You can code a CV or Zeiss lens as a similar Leica lens and it works fine. However in addition to the code, you have to have the lens bring up the correct framelines, because the two together tell the camera what lens is mounted.

Cornerfix is a great program, but it's a lot more hassle than coding. Panotools works too, and it's a Photoshop plug-in vs a stand-alone, but not as intuitive as Cornerfix.

If you should ever decide to get an M8 for yourself, I strongly suggest coding the CV and Zeiss lenses. On the screw-mount CV's you have to have an adapter that runs full circle because some have a cut-out right where the coding has to be applied. Some Zeiss lenses need a mount change because they bring up the wrong framelines to work with the coding. Coding can be applied temporarily or the mounts can be engraved with little recesses and filled with paint. I did all my <35mm lenses myself by engraving. It is only necessary to have the black recesses, the white ones are optional. At the point you should get an M8 and want your lenses coded, PM me and maybe I can help you out there.

Ben.
 
Ben's summary is pretty good, but I'd add the following: the answer is going to depend in part on your focal lengths, your subjects and whether you convert to b&w or whether you intend to keep the images in color. I think that coding helps with light-fall off in the corners of very wide lenses. In i) uncoded, ii) wide angle lenses, iii) with no IR cut filter you will see some darkening in the corners of your images due to cosine-square light fall off (that is, non-mechanical vignetting) of maybe a stop at the most extreme. I just looked at a photo of mine of a dogwood taken from a low angle with a hand-coded 15mm C/V Heliar and no IR cut filter. The corners of the image that are filled with sky are slightly red. The IR cut filter would have pulled these to a "bluer", more correct tone. This is less of an issue with longer lenses as stated above. If you are converting to b&w the color shift is not an issue, but you still may have to correct the corners of your images if this light fall-off effect bothers you. The items I have had trouble with in terms of color shift are less foliage than synthetic fabrics and, oddly, some women's hair dye, which evidently must throw off more IR than "just hair". The fabrics, I have just left as more purple -- the problem does not come up that often. The women's hair dye though is a really (pardon the expression) bi*** to fix and it is definitely the sort of thing people notice if their hair is purple.

Being susceptible to gadgets, I got a lens coder kit (now available from Tony Rose, I believe) and have hand coded my wider lenses with a Sharpie. As usual: no promises or warranties - you buys your Sharpie and takes your chances, but so far I have not had problems.

In my experience i fyou want to produce color images, the IR filter is more of an issue than the lens coding, but the camera performs better when they are all used together. Now I know there are plenty of folks who see the IR issue as a design flaw, but I got an IR _pass_ filter and have been experimenting with IR photography for the first time. Very cool. We live in a luminous world.

Ben Marks
 
you can get a paper template

you can get a paper template

and code your own lenses with free templates on the web, or the marker kit from Popflash.

I use the UV/IR filters for color, and don't code any lenses. As far as I can tell, it's for EXIF data only, except for possibly superwides (I use 28, 35, 50, 75 and 90).

If anyone can show me M8 RAW metadata that shows coding that affects IQ and/or guesses the aperture, I'd be interested in seeing that.


kshapero said:
I have a chance to use an M8 for about a week, but my lenses mostly CV's and a ZM 35mm are not coded. What's the deal?
Click to expand...
 
ampguy said:
...

I use the UV/IR filters for color, and don't code any lenses. As far as I can tell, it's for EXIF data only, except for possibly superwides (I use 28, 35, 50, 75 and 90).

...
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Slightly OT: should you unscrew the filters from your lenses when using them on film cameras, or can you safely leave them on? I've read about this somewhere but am unable to find it now...:eek:
 
Wideangle lenses with filter will produce some or even severe vignetting due to the angle-sensitive nature of the filters, but theoretically there should be no influence to speak of on longer lenses. Film is insensitive to IR and you don't want UV anyway. the only thing is that the filters may not be 100% neutrally coloured and produce a slight cast.
 
I'm with jappv on this one. You'll a slight cooling (bluer) cast with color film. No BW effect that I can see. Although I can't prove this, my sense is that on an M8, I get sharper pix with the IR cut filters and my theory is that you don't have image forming light (IR) focused somewhere other than the sensor.
 
Fine on film, but more chances for flare

Fine on film, but more chances for flare

They are OK leaving on with film and RD1 (unless you're going to do IR photos...), but of course, any filters might add flare under certain conditions.

CLE-RF said:
Slightly OT: should you unscrew the filters from your lenses when using them on film cameras, or can you safely leave them on? I've read about this somewhere but am unable to find it now...:eek:
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Thanks

Thanks

You could be right, I will check my 35/2 film scans with the UV/IR filter again.

Back to coding and wide - I have not seen any in-camera "fixing" due to coding (assuming filters and latest settings for filter on/off are corrected for), but I'd be more than willing to code, since I can do it for free.

There is a good white paper out there on how the M8 would need to accurately guess (and it might be doing an approximation) the selected aperture, in order to apply (and not over-apply) corrections to WA lenses.

I'm glad the M8 is using the DNG spec, and not some proprietary NEF or Panasonic RAW format, as whatever they are doing with coding and certain lenses for corrections, will likely be figured out.

I'm assuming by wide, you mean wider than 28 or 35? I don't have anything wider than 28, though I'd like a 15, 21 or 24 someday, and would expect that corrections from coding, if any, are going to apply most to those ultrawides.



jaapv said:
Wideangle lenses with filter will produce some or even severe vignetting due to the angle-sensitive nature of the filters, but theoretically there should be no influence to speak of on longer lenses. Film is insensitive to IR and you don't want UV anyway. the only thing is that the filters may not be 100% neutrally coloured and produce a slight cast.
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Thanks all, for the OT replies.

I do not own anything wider than a 28mm at the moment, although I might pick up a Heliar 15mm soon.

Seems I'm in for some DIY coding and filter switching on the wide angles. Yuk.

I'll finally get to use the Tiffen filter purse I bought some time ago, it seems.
 
Nothing happens, in my experience, with lenses from 24mm, 28mm, 35mm, 50mm, to 75mm. I shoot blue skies, white walls, etc., just hoping to have a problem so that I too can get my lenses coded and spend some more money. Yet, to my dismay nothing happens. Or else it's so slight I don't notice. I strongly recommend you try uncoded lenses in a variety of difficult situations--though one rarely photogaphs in those situations--and see if any problems come up. If not, just keep waiting for them to appear like I do.
 
same here

same here

although I've only gone as wide as 28mm.

Only recc. I have is to use latest firmware (release about a month ago), and set properly according to lens detection, and UV/IR filter settings.

Also, test on black synthetics, if you are expecting to shoot in color and require these to come out as black without post processing.

Otherwise filters are not necessary, though lens info. will not show in EXIF metadata.

larryk34 said:
Nothing happens, in my experience, with lenses from 24mm, 28mm, 35mm, 50mm, to 75mm. I shoot blue skies, white walls, etc., just hoping to have a problem so that I too can get my lenses coded and spend some more money. Yet, to my dismay nothing happens. Or else it's so slight I don't notice. I strongly recommend you try uncoded lenses in a variety of difficult situations--though one rarely photogaphs in those situations--and see if any problems come up. If not, just keep waiting for them to appear like I do.
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You go backwards in time to a place where this concern disappears.....

Best regards,

Bob
 
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