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08-07-2014, 02:44 PM   #496
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Fuji X16 is a micro 4/3 lens, right ? On APS-C it has a field of view equivalent to a 24 mm. And there is already a 24mm f1.4 (in the Sigma world)

08-07-2014, 02:50 PM   #497
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QuoteOriginally posted by goubejp Quote
Fuji X16 is a micro 4/3 lens, right ? On APS-C it has a field of view equivalent to a 24 mm. And there is already a 24mm f1.4 (in the Sigma world)
No, it is an APS-C lens. The Fuji X system is APS-C.
08-07-2014, 02:55 PM   #498
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RE the upcoming Fuji 16mm F/1.4:

QuoteOriginally posted by Wired Quote
And if we did it would probably be massive, heavy, and expensive
Well, I bet the Fuji will be one of those things...

QuoteOriginally posted by goubejp Quote
Fuji X16 is a micro 4/3 lens, right ? On APS-C it has a field of view equivalent to a 24 mm. And there is already a 24mm f1.4 (in the Sigma world)
No. Fuji X-mount is an APS-C mount. So it's 24mm FF equivalent FoV, or 12mm m4/3.

The Samyang 12mm F/2 is another example of the advantage of shorter registration distance for fast wide lenses.
08-07-2014, 03:00 PM   #499
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QuoteOriginally posted by Fogel70 Quote
The advantage of mirrorless it that the retrofocus design get less extreme with shorter register distance, so they require less glass than comparable DSLR lenses.
A question, if you don't mind, Fogel ... why does a mirrorless need a retrofocus lens?

08-07-2014, 03:48 PM   #500
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QuoteOriginally posted by Fogel70 Quote
I really doubt that we will ever see a lens like the upcoming Fuji X 16/1.4 for a APS-C DSLR.
But we could definitely see the equivalent for the FF! In fact there's already a 24mm F/2.0, just a hair faster than the Fuji.

The K-mount is definitely too large for the APS-C sensor, sure.
08-07-2014, 03:55 PM - 1 Like   #501
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QuoteOriginally posted by clackers Quote
A question, if you don't mind, Fogel ... why does a mirrorless need a retrofocus lens?
Digital sensors need lenses of telecentric design, i.e.that ensure low, image-sided, raypath angles. Digital sensors do not 'like' sharp incidence angles of the rays at the edge of the image, which cause vignetting, blur (because of crosstalk) and colour shifts (usually magenta colour shift).

A retrofocus design is an example of quasi-telecentric design.
08-07-2014, 04:19 PM   #502
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QuoteOriginally posted by Mistral75 Quote
Digital sensors need lenses of telecentric design, i.e.that ensure low, image-sided, raypath angles. Digital sensors do not 'like' sharp incidence angles of the rays at the edge of the image, which cause vignetting, blur (because of crosstalk) and colour shifts (usually magenta colour shift).

A retrofocus design is an example of quasi-telecentric design.
And a lot of the reason mirrorless lenses aren't really all-that-much smaller or lighter than DSLR lenses.

The camera is lighter, sure.
08-07-2014, 04:37 PM   #503
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QuoteOriginally posted by Fogel70 Quote
The advantage of mirrorless it that the retrofocus design get less extreme with shorter register distance, so they require less glass than comparable DSLR lenses. So for mirrorless it's possible to design wider and faster wide angle lenses without them requiring extreme amount of glass. DSLR with APS-C sensor have the biggest disadvantage as it use the same register distance as FF DSLR.

I really doubt that we will ever see a lens like the upcoming Fuji X 16/1.4 for a APS-C DSLR.
That said the current DSLR corps excels at telephoto lenses.

DSLR + PDAF + telephoto = market

08-07-2014, 04:38 PM   #504
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QuoteOriginally posted by ElJamoquio Quote
And a lot of the reason mirrorless lenses aren't really all-that-much smaller or lighter than DSLR lenses.
Samyang 14mm F/2.8, K-mount: 530g.
Samyang 12mm F/2, X-mount: 260g.

Faster, wider, and half the weight...
08-07-2014, 05:17 PM   #505
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QuoteOriginally posted by Doundounba Quote
Samyang 14mm F/2.8, K-mount: 530g.
Samyang 12mm F/2, X-mount: 260g.

Faster, wider, and half the weight...
The 14mm is a full frame lens. Samyang hasn't designed a sub-530gram, 9mm F/1.8 lens for APS-C.

So, on the cameras it was designed for, the 14mm is faster + far, far wider. The difference between 9mm and 12mm is huge!
08-07-2014, 06:36 PM   #506
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QuoteOriginally posted by ElJamoquio Quote
The 14mm is a full frame lens. Samyang hasn't designed a sub-530gram, 9mm F/1.8 lens for APS-C.
Neither a 2.8 lens or a 2 lens is an 1.8 lens.
Aperture is not defined from DOF but from exposure. Ie the amount of light reaching the sensor/film.The aperture is proportional to the square root of the light admitted, and thus inversely proportional to the square root of required exposure time, such that an aperture of f/2 allows for exposure times one quarter that of f/4.

Last edited by Pål Jensen; 08-07-2014 at 06:44 PM.
08-07-2014, 06:58 PM   #507
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QuoteOriginally posted by Pål Jensen Quote
Neither a 2.8 lens or a 2 lens is an 1.8 lens.
Aperture is not defined from DOF but from exposure. Ie the amount of light reaching the sensor/film.The aperture is proportional to the square root of the light admitted, and thus inversely proportional to the square root of required exposure time, such that an aperture of f/2 allows for exposure times one quarter that of f/4.
I can take the same pictures with a 14mm F/2.8 lens on a FF camera that I can on a 9mm F/1.8 lens on a APS-C camera. Same exposure time and everything. It's amazing, except that it's just equivalence and it just works.

Honestly if you're trying to convince me you're wasting keystrokes. I have different format cameras. Equivalence works.


I maintain that there's not much difference in weight of MILC lenses compared to DSLR.
08-07-2014, 07:03 PM   #508
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QuoteOriginally posted by Mistral75 Quote
Digital sensors need lenses of telecentric design, i.e.that ensure low, image-sided, raypath angles. Digital sensors do not 'like' sharp incidence angles of the rays at the edge of the image, which cause vignetting, blur (because of crosstalk) and colour shifts (usually magenta colour shift).

A retrofocus design is an example of quasi-telecentric design.
Thanks for the explanation, Mistral!

---------- Post added 08-08-14 at 12:05 PM ----------

QuoteOriginally posted by ElJamoquio Quote
And a lot of the reason mirrorless lenses aren't really all-that-much smaller or lighter than DSLR lenses.
Well, the Fuji wide angles are smaller and lighter, EJ, it was pointed out in another thread, because of the short registration distance.

The teles are presumably harder to engineer.

---------- Post added 08-08-14 at 12:07 PM ----------

QuoteOriginally posted by Pål Jensen Quote
Neither a 2.8 lens or a 2 lens is an 1.8 lens.
Aperture is not defined from DOF but from exposure. Ie the amount of light reaching the sensor/film.The aperture is proportional to the square root of the light admitted, and thus inversely proportional to the square root of required exposure time, such that an aperture of f/2 allows for exposure times one quarter that of f/4.
I think the actual definition is the ratio of focal length to aperture diameter, Pal, rather than DoF or exposure.
08-07-2014, 07:10 PM   #509
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QuoteOriginally posted by clackers Quote
Well, the Fuji wide angles are smaller and lighter, EJ, it was pointed out in another thread, because of the short registration distance.
The thread where one person said they're easier to build because they're easier to build?


I dunno, you can have a short registration distance, but then you need a huge rear element. I haven't seen the Fuji lenses*, but the Sony lenses aren't much smaller or lighter, by-and-large, than a lot of other lenses. They claim huge gains but I haven't seen them. Their 18-55 is about the same weight and size as our 18-55. Their 30mm F/3.5 macro is a bit lighter than our 35mm F/2.8 macro, but is 2/3rds slower and about the same size.

I've never said there's no difference, but I honestly don't think it's all that much of a difference. The 16mm Sony is light, sure, but it has absolutely horrid border performance wide open - basically uncorrected, likely because the rear element isn't large enough, isn't far enough away from the sensors, they didn't use enough elements to correct everything, etc., to minimize size and weight.

Lighter, sure, but not really comparable to a decent wide angle lens IMO.


*don't pay much attention after they lied about their ISO to fool people (ISO6400 was really ISO1000)

Last edited by ElJamoquio; 08-07-2014 at 07:38 PM.
08-07-2014, 07:26 PM   #510
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QuoteOriginally posted by ElJamoquio Quote
I can take the same pictures with a 14mm F/2.8 lens on a FF camera that I can on a 9mm F/1.8 lens on a APS-C camera.
It's true that the Samyang 14mm is FF. Except that all current Pentax DSLRs are k-mount APS-C, not FF! So in real-world terms, I can have a 12mm F/2 250g on an APS-C Fuji X camera or a 14mm F/2.8 560g on an APS-C Pentax K-mount camera. If I understand you correctly, you claim that someone ought to be able to make a 12mm F/2 APS-C-only lens for k-mount that's 250g? If that were the case, I'd buy that in a flash. Please convince Pentax to make such a lens! When I asked why no k-mount for the Samyang 12mm F/2, every one here promptly told me you can't do that kind of lens on k-mount because of greater registration distance, and retrofocal design and so on... So, is it possible or not?
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