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C-Mount
  • PerryWilsonPerryWilson
    OK cant find the answer anywhere so im fishing... I have a bolex c-mount soligor 75mm 1.9... NO VIGNETTE when im NOT using etc mode... at wat focal lenght do we need to start using ETC mode on c-mount glass... will a 25mm fit without using the ETC mode?
  • 23 Replies sorted by
  • sam_sticklandsam_stickland
    I get slight vignetting on my 25mm C-mount. If I use it I prefer to scale the image 10% in post rather than use ETC but in all honesty I brought the 20mm pancake the other day so I can't see myself using this again.
  • PerryWilsonPerryWilson
    how are the optics on that... Im gonna be using Oct-18 cinema glass and need the matchup...
  • sam_sticklandsam_stickland
    The optics are pretty terrible, it's cheapo Chinese C-Mount I bought just for experimenting with, I can't image it even begins to compare to an OCT18. But perhaps the size of the vignette on it serves as a reference point? I've attached a frame from a random video I had lying around - the vignetting is actually greater than I remembered.
    C-Mount 25mm Capture.png
    1553 x 879 - 3M
  • PerryWilsonPerryWilson
    no I meant the 20mm panasonic lens
  • sam_sticklandsam_stickland
    Sorry Perry, I don't think I've the got the experience to be able to answer your question satisfactorily. It looks good to my amateur eyes though!
  • andresandres
    what I´ve tested with 16mm bolex glass up to 35mm there is no vignette. 25mm the corners are to soft and in 16mm I see a circle.
    Oct-18 may well be another story but probably similar.
  • PtchawPtchaw
    It depends entirely on the lens. There is no set focal length where the vignetting becomes acceptable on all lenses. ETC mode crops far more than necessary, so you'll end up with a very close up FOV.

    The 20mm Panasonic is not C mount.
  • PerryWilsonPerryWilson
    right, but the 20mm panasonic is not made for a super 16 image circle... so YES there is a SOLID mm where there will not be vignetting on C-Mount glass... because C mount glass is made specifically for a 16 or S16 image circle
  • davedvdavedv
    The best list of C-mount lens coverage I've found is this one:
    https://spreadsheets.google.com/pub?key=p9kkgjwEQQQ-HJwvNDobeEw

    Some of the 25mm lenses are the shortest focal length on the list with full coverage. But as @Ptchaw mentioned, it really depends on the lens.

    I don't think the list has been updated for a while, and I've seen some reports of lenses others have tried that aren't on the list. Be nice if someone had a list that was more up-to-date ...
  • PtchawPtchaw
    @PerryWilson No, you are mistaken. Firstly C-mount lenses can be made for a 16mm or 8mm format, so depending on the format the lens is designed for, the image circle coverage will vary.

    Secondly, just because a lens is designed for a 16mm format, it does not mean it will cover much outside it; it depends entirely on the design of the lens. Certain 25mm lenses vignette more than others, for example.
  • PerryWilsonPerryWilson
    I stand corrected good sir
  • kazuokazuo
    I bought a 12.5mm Pentax CCTV lens in the hope that it could be used as an ultra
    wide but no luck - 12.5mm is simply too small for the GH2 censor. I ended up with an awful
    iris effect, as if someone was staring down the lens barrel.

    Couldn't use the ETC either cos, 12.5 x 2 = 25 x 2 again, you get 50mm that is digitally magnified.
    I shoot with the Nokton 25mm f0.95: in that light, anything digitally magnified is grainy and a total waste of my time.
  • PtchawPtchaw
    @kazuo It depends on the lens, the Computar 12.5mm f/1.3 has pretty acceptable vignetting, with about 90% coverage. Zooms are by far the worst for vignetting.
  • RRRRRRRR
    Perry: if you search around online you will find quite comprehensive lists of how many common c-mount lenses work on m43 sensor. I remember several lists like that when looking into c-mount glass.. Also, I recall a very comprehensive site for Lomo / Konvas / Kinor and then you should be able to find the information you need.

    I had a deep dig into the world of soviet cinema equipment a while ago, but I can't answer your question straight up.

    Start looking from the model number (of the lens) and there you should be able to find info on what it was designed for.
  • AmandaNLAmandaNL

    Anyone tried this lens?

    http://www.eneo-security.com/item/5000058/5000057/0/101608/c0814mvmp.html

    42039_img_itm.jpg
    203 x 250 - 32K
  • RobertoRoberto

    The M4/3 frame is 13.0×17.3 mm. (actual image area, not the whole sensor).

    16mm Film has a frame of 10.26 x 7.49 mm

    Super-16 Film is 12.52 x 7.41

    If you get a C-Mount lens built for a 16mm or super-16mm camera and it doesn't vignette on a GH2, you're lucky. These are basic questions. I'm happy to read people's anecdotes about being lucky with lenses, but I don't want others to be misled into buying lenses which won't work.

  • RRRRRRRR

    That is a tad melodramatic, Roberto! What works for you might not work for the next guy, and the same goes for everyone!

    Basically, count out using c-mount lenses below 25mm in anything but ex-tele mode. At around 25mm some vignette more heavily, some don't. I recently got a very cheap fujian 35mm cctv lens which is pretty nice, and a lens I've been using quite a bit (both for stills and video) although I have Canon and Zeiss in the same focal length.

    C-mounts usually come with a particular look and are usually not a replacement for cleaner or sharper optics. Most C-mounts look pretty individual and there have been extensive testing on the gh1 and other m43 cams, not so much on the gh2 - just google away to check out individual lenses.

  • RobertoRoberto

    @RRRR Yeah I agree - below 25mm!

  • MeierhansMeierhans

    It should work in ETC, but mos�t likely not without. As written above, 25 mm is pretty much the shortest focal lenght available from CCTV market that does not vignette.

  • RobertoRoberto

    On the other hand, once you use ETC all your lenses seem too long because of the ETC multiplication factor. My Pentax 6mm CCTV lens is the only way I get a medium wide lens with ETC (about 35mm equivalent if you take 50mm as "normal"). Bright & sharp, but no longer as cheap.

  • MeierhansMeierhans

    I am planing to buy the Pentax C22525KP 25mm F1.4. Its the poor mans NOKTON 25mm... check out this clip:

    If you after clinical, sharp images up to the corner and think a lens must not vignette at all this is for sure NOT for you. But if you after some low light shooting for small money you might actually like this lens.

    I found it on ebay quite cheap: http://www.ebay.de/itm/Pentax-C22525KP-25mm-F1-4-22-C-Mount-Lens-W-Locking-Screw-/270878274340?pt=Camera_Lenses&hash=item3f119a7324

    There is only one drawback: Shipping is about 60$! This is pretty anoying. So I am looking out for two other people in germany who want to buy this lense. Then we can share the shipping costs.

    Small calculation

    183 € 3x lens

    63 € 1x shipping

    5 € 2 x DHL (porto für zwei mini päckchen)

    251 €

    /3

    84 € per person (rounded up to euro)

    If you are interested send me a private message. Hope this is ok for you Vitaly, actually I am not trying to make money, but only to save some. If you organize a special deal I would for sure prefer this.

  • producerproducer

    Anybody experienced Fujinon (or Canon) 7.5-90mm 1.4 on GH1/2?

  • MikeLinnMikeLinn

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