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

SojiOkita

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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)
 

OzRay

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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.
 

jyc860923

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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.
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?
 

OzRay

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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?
Correct. That's a pity if automatic correction happens whether you want it or not.
 

SojiOkita

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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.
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.
 
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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.
 

SojiOkita

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The focal lengths for Micro 4/3 lenses take distortion correction into account.
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?

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

OzRay

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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.
 

manzoid

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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.
 

SojiOkita

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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.
 

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HarryS

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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.
 

dohearne

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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.
 

Ulfric M Douglas

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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 ...
 

SojiOkita

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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 ...
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.
 

MAubrey

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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?
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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