Rokinon / Samyang 14mm 2.8

[wayn0i]

Im trying to implement a workflow where my imaging programs can automatically pickup the lens, focal length, fstop etc. information from the exif data, only problem is my Rokinon (seaming) 14mm doesn't have a CPU. I can use Exiftool to add the correct Exif data however Im not sure exactly what the data should be and it needs to be correct for the imaging software to pick it up.

Does anyway have an image from a chipped 14mm Samayang / Rokinon? if so could I receive it off the camera so I can have a look at the exif data please. Or has someone already walked this road and can tell me what needs to go where.

Cheers

Wayne

[ameerat42]

Hmm! I certainly don't have one of those, Wayne. But, when I was using fully manual lenses I would set the f-stop manually on the lens AND THEN also dial it in on the camera.
Of course, what I set on the camera had NO EFFECT on the lens operation but it DID record in EXIF.

--Ahh! Now a thought occurred to me: you can't set it manually on your lens?

[wayn0i]

ameerat42,

Thanks for your reply

The aperture is the oddest thing actually, so the lens I have is the cine version so the aperture runs from 3.1 - 22 but is reflected in the camera display as 22-90. Not sure why that is the case???

[ameerat42]

Strnge indeed!

[Cage]

Wayne, I have the Samyang 14mm in Nikon mount.

From memory it seems to pick it up in EXIF as a Nikon 14mm.

Anyway if you tell me what sort of shot you need I'd be more than happy to assist.

[wayn0i]

Kev,

Mate can you send me any image, even a black pic leaving all the exif data in place.

Cheers

Wayne

[arthurking83]

I feel your pain Wayne, adding exif into images can be a real annoyance.

What I would seriously recommend tho .. instead of mucking about with this workflow every time you use the Samyang, you'd be better off getting yourself a dandelion chip for the lens.
With these electronic chips, they basically turn non cpu'ed lenses into CPUed lenses, so exif is added automagically every time you take the image.
In the long run this HAS to be the better option, rather than the repetitive struggle of batch editing files after the fact.

Anyhow, there are a few more advantages in having the dandelion chip installed onto the lens.

The installation process looks as easy as can be, where you simply glue the chip onto the rear of the lens(well .. maybe after some simple pre-prep work!).
But, compared to the amount of work required in adding these chips to Nikon mount lens!!! ... I can only dream of a simple glue job. On two of my fave manual lenses .. I can't even get the screws off the mount, as some idiot had tried before me, and rounded the screw heads

If my manual/non chipped lenses were Canon mount, and not Nikon mount .. they'd all have been chipped years ago(due to the ease of mounting these chips)

Anyhow ... I can't recommend these chips highly enough for these types of manual lenses.

I'm not entirely sure what lens value exif data it will give you in your images tho.
I assume that, because the chip needs to be programmed from scratch, it just gives a generic lens value.

That is, where the Samyang lens for Nikon is already chipped at the factory, Samyang will have programmed the CPU to a specific type. Going on Cage's info, this appears to be set as a Nikon 14mm f/2.8 lens .. etc, etc.(ie. and not a Samyang 14mm f/2.8 ... etc)

With the dandelion chip tho, you don't get an option to program a manufacturer into the lens .. it will simply be 14mm(focal length) f/2.8(max aperture) .. etc.
Programming is easy, and is done via the camera once the chip is finally mounted to the lens.

Here is a site where you can find out more info about these chips(scroll down to the image of the chip just below the last image of the lens mount conversion)
.... and also a link on how to fit the CPU to the lens


With current exchange rates .. 19 Euro is about $28(ish) AU using a currency converter(the actual conversion will be different but not far off), so reckon on about $30 or so.
Also note that you can also find these things on ebay too.

Lastly(almost), this dandelion chip was invented by a Russian, in Russia.
I've read that someone in China has also weighed in on the industry(at least for Nikon mount lenses) .. but haven't seen/read any info on this Chinese version as yet ... just in case you do more research and come across any.

I've had one, which I mounted onto one of my lenses. The thing is brilliant in some of the things it can do, compared to the limited ability of manually adding lens info into the camera.
(the problem was that I stuffed it tho .. I broke it)
But while it worked, it also gave the ability to do focus trapping. That is, with the camera in focus priority shooting mode, you hold the shutter down, focus slowly manually as normal .. and as soon as the image is focused(as recognised by the camera's focus system) .. the shot is exposed.
It's a sort of pseudo AF for manual lenses. The only negative aspect of this method is that you can't shoot in continuous mode.

Finally(lastly). I don't know how Canon stuff works .. but I'll explain the way the Nikon system works(so I assume that Canon do it kind'a similarly).
With this type of CPU added to a manual lens, depending on the lens type you get a few situations with respect to aperture control.

On a normal coupled lens(where the lens has an aperture tab for the camera to control) .. without the CPU, you can't use the camera to set aperture. Aperture HAS to be set via the lenses aperture ring.
The camera controls the actual aperture via the aperture tab, but setting the required aperture value is only done via the lens.
With a CPU added to the lens, the camera assumes it's a new modern lens, so it subsequently allows you to set the aperture value now via the cameras control dials.

On lenses without aperture couplings tho, every thing is done manually. So if the lens is f/2.8 and you want f/4, you can only set the aperture value via the lens. Of course, the issue with this is viewfinder darkening because as you stop the lens down, you do so in real time. The camera has no control over the aperture.
Using non CPU lenses in this way is tiresome and cumbersome. I have many that I use for macro, and the annoyance is in keeping up with what image had what aperture value set .. etc.

The dandelion chip added to such a lens(ie. non coupled) allows you to set a (pseudo) aperture value via the camera tho!
That is, you can seemingly set an aperture value via the camera, but it has no effect on the aperture of the lens. That is only ever done manually on the lens. I've noted a few exposure issues tho in doing this.

--EDIT:-- got interrupted and forgot to add what this actually means in real usage:
If you have a full manual, non coupled lens, you can set the actual shooting aperture via the camera, so that the exif relates what actual aperture was used.
With such lenses without a CPU, while you can set the aperture to a lower than maximum value, it won't be recorded as such in the exif.
eg. you have an f/2.8 lens, but shoot at f/8.
with the non cpu'ed lens, the exif may be recorded as f/2.8 as the camera doesn't know what other value to record(non coupled)
with such a lens with a CPU, you set f/8 on the lens, and then set f/8 via the camera too. exif is then recorded as f/8, as it's been set in the camera.


Also! .. what computer system are you invested in? If Apple ..I can't help, but if Windows, there may be a better way to add info into the images rather than using an exif editor to do it.

[wayn0i]

arthurking83,

Mate thankyou for all that information, I will give it a go.

Ive got the Exif copying process down pat but DxO still doesnt recognise the images and ifx distortion autmoatically, not sure why as the exif on my image is now the same as Kevs and when the two images are offered to DxO his is lens corrected automatically and my doesnt????>?

Anyway just part of the journey.

Cheers

Wayno


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[arthurking83]

Aha!
Now it makes sense why you want the lens data in the exif!

I don't use DxO so can't really help ... but if you do a manual correction on one of exif edited images of yours .. doesn't this then allow you to save it as a job lot/batch job, or allow you some other way to auto apply a lens correction adjustment to the rest of those files that are similar?

I'm assuming that as you have a Canon, and Kev's camera was a Nikon, that this must be some sort of obstruction in DXO's auto correction feature

Also .. what's your exif editing process?
I'm assuming that you are not fully copying Kev's sample image exif data onto your images .. only the lens data in the exif.


I reckon for $30ish and a bit of strong glue .. having the lens chipped for DXO to auto correct the distortion is going to be the easier way forward.

[wayn0i]

Arthurking,

Thanks for your message, just to clear something up I have a Nikon also a D610.

I've now ordered the chip, interestingly the Nikon chip with postage was about $55, more expensive to be a Nikon owner it seems.

I started copying specific exit data from Kevs image then after a while copied everything possible, but still no luck.

I've chatted to DxO about manually selecting a lens correction but they refuse to go in that direction even at the expense of losing customers, plenty of disappointed people online, strange business model.

The exiftool app is a simple but powerful command line tool. Check it out online its cross platform which is nice, you can also script it which automates the process which I like.

Anyway let's see what this chip achieves otherwise I might sell the lens and grab a chipped version

Cheers

Wayne


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[arthurking83]

Ah! .. Ok.
This D610 I didn't know.

So the Rok is a Nikon mount(I'm now assuming),

This changes a bit.
If you are a little 'engineering' minded, and don't mind a bit of cut'n'shut, grinding .. filing, sanding, estimating, guessing, smoothing ... and have a steady hand to go with all that ... then adding a a dandelion chip to any Nikon lens other than the 500/8(or 1000/11) mirror lenses .. is probably a great challenge, you may relish!

Like I said, I have a few Nikkors I will eventually chip, but the biggest hurdle at the moment is removing those bleeding impossible to remove mount screws.
Just for the sake of completely understanding that I haven't lost my nerve or something .. I've removed the mount off a couple of perfectly good .. still under warranty, and (for me) expensive lenses.
So I know I haven't lost my nerve(or ability) .. it's just that those maddening screws are simply not going to come out without some 'gentle force'
So I've given up a bit on trying.
But this is a bit of a hurdle for some folks ... cutting up a perfectly good lens mount.

The Canon version of the dandelion looks so much easier to mount, by comparions.

I know exiftool .. helped me a bit, many moons ago. commandline hurts my already worn down fingers(have you seen how long my replies are on AP! )
I graduated to exiftoolgui some time ago.

Have you tried PTLens(for lens distortion correction). I never have(but only because I tend not too do lens distortion correction anyhow).
Many peeps say it's the bees knees for distortion. allows you to do whatever you want. Just had a quick peep and there is a free trial available. It's US$25 to purchase.

Anyhow, back to the topic of the lens/cpu/chip ...
Have you entered the lens into the camera non CPU lens database?
(if you don't know about this)

Go to the Setup Menu(spanner con)
Scroll down to the Non CPU lens data.
Move cursor across and set lens to number 1.
move the cursor around and alter the lens data to reflect your lens .. obvious 14mm for focal length and f/2.8 for aperture.
You must press OK for it to accept the data.

Anytime you mount a lens with no CPU(or if you shoot the camera with no lens attached) the camera assumes that you have a 14mm f/2.8 lens mounted.
The camera doesn't know if you have or don't have a lens mounted!!! it just assumes it's mounted.

So lets say you find another manual lens to fit .. a 500mm f/8 lens. If you don't set this lens data up as either another lens memory(eg. #2 or #3) or edit the 14mm non cpu lens data .. and you stil have the 14mm f/2.8 lens data set .. the camera sets the 14mm f/2.8 as the lens instead of the 500mm and f/8 lens that it should be.
the camera is not smart with respect to this info .. you have to help it along.
But once you set this data, the data is automagically inputted into the exif by itself... no need to use exif tool to do it all 'manually'

there are some handy features to this non CPU lens data feature too. You get spot metering, but only on the central spot. So if you set one of the AF points to any of the AF points that is NOT the central spot, you don't get spot metering on that point .. only the central AF point does spot metering with non CPU lenses mounted.
You do get matrix metering tho
And you get AF confirm via the green dot too.
And you get aperture control from the camera. That is, you set aperture to whatever value you need via the lenses aperture ring, and the camera does auto stop down(if you have set it stopped down).

Hope that helps.

[wayn0i]

AK
Thank you I've set that up now, so atleast now I have the correct aperture and focal length, well almost there's no 14mm setting
Cheers
Wayne


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[arthurking83]

Ah!!!

mongrels(Nikon).
Yeah, I forget about that.

The lens focal length input is centred around a lot of Nikon's old lenses.

They made a 13mm lens in Ais mount, and a few different 15mm lens as well.
So they've programmed the ability to load a lenses focal length, by their own database of acceptable lenses.

Your reply just twigged my memory of it all(I have a full range of lenses already loaded into this feature .. and so haven't really looked at it for a long while)

So as an example of what the above means .. if the lens is a 'strange one' in Nikon's history of old lenses, even tho it's one of their own lenses, it may not be included in the focal length database.
The obvious one that stands out here is an old non Ai 7.5mm fisheye lens they once made which can't fit onto any DSLR without lots of mods and mucking about.
This focal length is not a part of their database embedded in the camera.

Yet, if you check the 50-ish and 85-ish mm range .. they have a setting for 43mm and 86mm. This is because Nikon once made lenses that incorporated those focal lengths that can be fitted to their DSLRs.
(there are a few other 'interesting' focal lengths available too)

While Nikon made a 14mm prime lens .. as it's a modern AF-D lens .. there's no need to load it into the cameras non CPU lens memory.

As for what focal length to load, if you want to give it a go .. either 13mm or 15mm makes sense .. I know the 13mm was supposedly a very low distortion lens .. but know nothing of the 15mm lenses.
And even if DxO did have either of those two Nikon lenses as a part of their database .. my guess would be that the distortion would probably be incompatible anyhow.

But, having just looked at some exif info, for some of the lenses I have:
It seems that while focal length is recorded in the exif, the camera doesn't translate this info into comparable lens data in any way.
Looking at any (specific)lens info in the exif, when a manual lens is used via the non CPU database .. the only recording of any specific lens data is simply listed as MF.
That is the lens is simply MF.

But when I had the dandelion chip on the 500/8, the data in the lens area of the exif is more detailed, and lists the lens as a 500mm f/8 and that's it's a G type lens, focus distance(even tho it's totally out of whack), exit pupil distance, (bogus) lens ID No. .. etc.
There is no manufacturer or brand description tho.
With that same lens without the dandelion chip, even the max aperture listed in the lens specs is convoluted .. it's listed as 1.0(not even f/1) ..

So my guess will be that even if you got the correct lens data in the camera, as the lens doesn't transfer any 'lens data' to the camera(the camera just records some basic lens info) ... in a sense, the exif may be incomplete for DxO to use the lens data it may need to apply the distortion correction anyhow.


FWIW tho, with a dandelion chip, you program the relevant lens info from the camera and it's quite detailed in many ways.
It's a bit tedious, but once done .. it's done, and the lens is 'CPUed'

Anyhow, going by all the info you have now given .. I'd say you're best off getting the chipped Samyang 14mm lens, rather than doing a dandelion conversion on it.

[wayn0i]

I'll let you know how it goes
Cheers
Wayne


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