What is the 9-18 mm "effective" field-of-view (after correction)?

Discussion in 'Native Lenses' started by SojiOkita, Nov 14, 2014.

  1. SojiOkita

    SojiOkita Mu-43 Top Veteran

    619
    Feb 23, 2014
    France
    In my current m43 lens set-up, I miss an Ultra Wide Angle.
    On my Canon APS I loved my 10-22 lens.

    I'm considering buying the 9-18 because it is small, lightweight and not so expensive (and the IQ seems to be correct - not very different from my 10-22 which is also soft in the borders/corners).

    However, I'm afraid the 9 mm would be too long.
    I don't shoot JPEG, but Lightroom applies automatically the same distorsion correction to the RAW files.
    That's a pity because most of the times for landscapes, distorsion is not an issue.

    Do anybody knows what effective field-of-view is the 9 mm (after correction)?

    If I calculate correctly, theoretically, 9 mm in micro four thirds corresponds to:
    - 100° diagonal (compared to 106° for the 10-22)
    - 72° vertical (compared to 73° for the 10-22)
    - 88° horizontal (compared to 96° for the 10-22)

    Even without correction, the 9 mm corresponds approximately to an image with the 10-22 cropped in 4/3 ratio. That's already a bit long.
    After correction... it will we worse, but how much worse?

    Do any website measure that type of things?
    (field-of-view is a very important data for an ultra wide angle lens)
     
  2. OzRay

    OzRay Mu-43 Legend

    Jan 29, 2010
    South Gippsland, Australia
    Ray, not Oz
    I use a 7-14mm lens and LR doesn't do any correction whatsoever, so I don't understand why it would do so with the 9-18mm.
     
  3. jyc860923

    jyc860923 Mu-43 Hall of Famer

    Feb 28, 2012
    Shenyang, China
    贾一川
    It's probably because that most MFT lenses come with built-in correction info, so that it can be applied automatically in supported converter software.

    Ray I'm assuming you're referring to the FT 7-14?
     
  4. OzRay

    OzRay Mu-43 Legend

    Jan 29, 2010
    South Gippsland, Australia
    Ray, not Oz
    Correct. That's a pity if automatic correction happens whether you want it or not.
     
  5. SojiOkita

    SojiOkita Mu-43 Top Veteran

    619
    Feb 23, 2014
    France
    The automatic correction is automatic, so you don't see if it is applied or not;)
    (you can see it when comparing to another RAW correcter like DxO where you can really disable the correction).
    Anyway, I'm not sure this applies to four thirds lenses.
     
  6. The focal lengths for Micro 4/3 lenses take distortion correction into account.

    FWIW, I went from a 10-20mm lens on my APS-C Canons to the 9-18mm on Micro 4/3 and never really felt that it wasn't wide enough.
     
  7. OzRay

    OzRay Mu-43 Legend

    Jan 29, 2010
    South Gippsland, Australia
    Ray, not Oz
    Does this automatic correction happen with Olympus Viewer 3 as well?
     
  8. SojiOkita

    SojiOkita Mu-43 Top Veteran

    619
    Feb 23, 2014
    France
    Are you sure of that?
    Focal length is supposed to be an optical data, it's not related to how you crop the image.
    That would mean than the focal lengths written on the lenses are "equivalent" focal lengths and not real focal lengths?

    That's an interesting feedback.
    Coming from the 10-22, are you happy with the 9-18 (in terms of Image Quality, range, etc...)?
     
  9. OzRay

    OzRay Mu-43 Legend

    Jan 29, 2010
    South Gippsland, Australia
    Ray, not Oz
    You could always consider the 4/3 9-18mm f4-5.6 and adapter, then you'd get no automatic correction. And you can probably get these cheaper off eBay new than the m4/3 version, and it may well be a better lens.
     
  10. SojiOkita

    SojiOkita Mu-43 Top Veteran

    619
    Feb 23, 2014
    France
    Will the autofocus be a problem?
    I have an E-M10, not an E-M1.
     
  11. manzoid

    manzoid Mu-43 Regular

    137
    Jun 9, 2011
    I can't remember where (and therefore, how trustworthy the source), but I do remember reading that the angle of view is after the distortion correction. It does make sense otherwise the quoted angle wouldn't mean so much if each one needed to be adjusted differently.

    According to BH, the angle of view is 100-62 degrees.
    http://www.bhphotovideo.com/c/product/674724-REG/Olympus_261503_M_Zuiko_Digital_ED_9_18mm.html

    That seems to agree with your calculation. Have you factored in the different aspect ratio to your calculations of vertical and horizontal?

    If you want superwide, cheap, sharp and compact there is always the 7.5mm fisheye. Lack of focus really is a non-issue, and it is possible to defish easily enough. This does lead to resolution loss in the corners and a narrowing of the view, but you are starting out with 180 degree diagonal.

    I have both lenses, but no experience with the 10-22mm.
     
  12. SojiOkita

    SojiOkita Mu-43 Top Veteran

    619
    Feb 23, 2014
    France
    I already have the 7.5 fisheye. It's a great lens. I use it a lot more that I thought. (I bought it only because the 9 mm BCL was out of stock at the time).
    It's very sharp and I love the results with a stereographic correction.

    However, fisheye & ultra wide are very different.
    A couple of times, I used a rectiliear projection with the 7.5 and the results are acceptable (after cropping the borders), but in order to frame my pictures correctly, I need to see the rectilinear image in the viewfinder.
     
  13. jrsilva

    jrsilva Mu-43 All-Pro

    Nov 1, 2012
    Portugal
    Jaime
  14. HarryS

    HarryS Mu-43 Top Veteran

    920
    Jun 23, 2012
    Midwest, USA
    The 4/3 9-18 AF might be an issue if you need it faster than yesterday, but shooting WA zooms generally doesn't require fast AF.

    You might look at this review, which shows the comparative sizes.

    Big lens, in a relative sense.
     
  15. dohearne

    dohearne Mu-43 Regular

    49
    Apr 23, 2013
    Vermont, Virginia
    Dave Hearne
    Like you I debated the question of the O9-18mm as a wide angle for my mft (E-M5). I was coming from a Nikon D300 with a 10-24mm Tamron. I usually shot the Tamron at 10-12mm and was concerned that the 9mm would be wide enough fov. For me the 9-18 has proved to be a good landscape lens and I am getting what I consider to be the 100 degrees expected when brought through LR. I have been satisfied to give up some fov for the ability to easily add ND filters. Until I recently bought the O12-40/2.8, the 9-18 was my walk around lens.
     
  16. Ulfric M Douglas

    Ulfric M Douglas Mu-43 Hall of Famer

    Mar 6, 2010
    Northumberland
    The autofocus on my adapted 4/3rds 9-18 is quite fast, even on the oldest m4/3rds bodies.
    It is not one of the 4/3rds lenses which does a long jiggle, just a short jiggle.
    I like it although it isn't svelte ...
     
  17. SojiOkita

    SojiOkita Mu-43 Top Veteran

    619
    Feb 23, 2014
    France
    • Like Like x 2
  18. SojiOkita

    SojiOkita Mu-43 Top Veteran

    619
    Feb 23, 2014
    France
    Yes, it is quite big. With the adapter, it is nearly the size of my Canon 10-22, and I choose m43 to have a more compact system...
    The optical perfomance seems to be better than the M.Zuiko lens.
     
  19. MAubrey

    MAubrey Photographer

    Jul 9, 2012
    Bellingham, WA
    Mike Aubrey
    Corrections are provided in the metadata of the image. And more than that, it is the final corrected image that will correspond to 9mm. The uncorrected image that you can only access with an unsupported RAW viewer (e.g. DCRaw) will actually be wider than 9mm. That's par for the course for μ43 lenses. For example, the 14mm f/2.5 is closer to 13mm uncorrected.

    See: http://www.lenstip.com/273.6-Lens_review-Panasonic_G_14_mm_f_2.5_ASPH._Distortion.html
     
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  20. peter124

    peter124 Mu-43 Regular