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Author Topic: Fuji X Lenses  (Read 76613 times)

Denis de Gannes

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Re: Fuji X Lenses
« Reply #100 on: January 14, 2015, 08:47:03 pm »

I am old school in terms of photography so when one mentions one stop difference I think only of exposure i.e adjusting f stop, shutter speed and ISO and not DOF.

I agree/understand that DOF is affected/related to f stop, distance from the subject and size of the film/sensor.

If you get correct exposure at F 5.6; 1/500 sec; ISO 100 it will be the same for a FF, APS-C or 4/3 sensor.

The sunny 16 rule, with bright sunlight ISO 100 film; 1/100 sec; f 16 will provide accurate exposure.
So will ISO 200 film; 1/200 sec; f 16
So will ISO 100 film; 1/400 sec; f 8
« Last Edit: January 14, 2015, 09:04:48 pm by Denis de Gannes »
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barryfitzgerald

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Re: Fuji X Lenses
« Reply #101 on: January 16, 2015, 05:25:03 am »

I am old school in terms of photography so when one mentions one stop difference I think only of exposure i.e adjusting f stop, shutter speed and ISO and not DOF.

I agree/understand that DOF is affected/related to f stop, distance from the subject and size of the film/sensor.

If you get correct exposure at F 5.6; 1/500 sec; ISO 100 it will be the same for a FF, APS-C or 4/3 sensor.

The sunny 16 rule, with bright sunlight ISO 100 film; 1/100 sec; f 16 will provide accurate exposure.
So will ISO 200 film; 1/200 sec; f 16
So will ISO 100 film; 1/400 sec; f 8




I don't know where anyone got the 3 stops difference from it's way off the mark
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Slobodan Blagojevic

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Re: Fuji X Lenses
« Reply #102 on: January 16, 2015, 10:44:48 am »

I don't know where anyone got the 3 stops difference from it's way off the mark

It was explained in reply #99, with reference to the DOF table in reply #89.

armand

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Re: Fuji X Lenses
« Reply #103 on: January 16, 2015, 12:45:09 pm »

The Fuji lens lineup, including the upcoming 16 F/1.4, 90 F/2, 120-400 F/4-5.6

http://www.fujifilm.com/products/digital_cameras/pdf/lenses_accessories_catalogue_01.pdf

SZRitter

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Re: Fuji X Lenses
« Reply #104 on: January 16, 2015, 01:00:56 pm »

I am old school in terms of photography so when one mentions one stop difference I think only of exposure i.e adjusting f stop, shutter speed and ISO and not DOF.


I'll call myself middle of the road on the old school thing...

But yes, the whole using stops to equate DOF always seemed strange to me. And I have never heard a LF shooter talk about DOF equivalents between 8x10 and 4x5. But maybe that is just my luck. But then again, my preference is proper exposure first, sharpness (focus/diffraction) second and DOF third.
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Telecaster

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Re: Fuji X Lenses
« Reply #105 on: January 16, 2015, 02:03:17 pm »

But yes, the whole using stops to equate DOF always seemed strange to me.

I think this has more to do with format/brand cheerleading, gear fetishizing & "look at my big(ger) one" than anything else. Consumerist & identity stuff. Not that DOF control is unimportantónot at allóbut seems to me it's typically invoked as a strawman argument to justify preferences held & choices made for those other reasons.

-Dave-
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barryfitzgerald

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Re: Fuji X Lenses
« Reply #106 on: January 16, 2015, 02:33:15 pm »

It was explained in reply #99, with reference to the DOF table in reply #89.

I read the reply and the DOF article (rather the link)
There is nothing there that says APS-C has 3 stops more DOF, as said it's just over a stop APS-C to FF a difference for certain but not really huge at the best of times


Anyway we've wasted enough time covering old ground when the original post was about lenses, but we get sidetracked into talking about formats and sensor sizes/DOF
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armand

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Re: Fuji X Lenses
« Reply #107 on: January 16, 2015, 03:12:11 pm »

Anyway we've wasted enough time covering old ground when the original post was about lenses, but we get sidetracked into talking about formats and sensor sizes/DOF
+1

I was trying to get the discussion back on track with last link that I posted.
That 90 mm F/2 (which is the one that interests me the most) looks biggish, similar to the 55-200?? That's a little too big compared to what I was hoping.

Chris Kern

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Re: Fuji X Lenses
« Reply #108 on: January 16, 2015, 06:57:35 pm »

Anyway we've wasted enough time covering old ground when the original post was about lenses, but we get sidetracked into talking about formats and sensor sizes/DOF

Yup.  This thread is getting blurry.  It needs better focus.

AFairley

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Re: Fuji X Lenses
« Reply #109 on: January 17, 2015, 11:43:21 am »

Yup.  This thread is getting blurry.  It needs better focus.
Yeah, and the bokeh in the blurry parts isn't so good either.
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Slobodan Blagojevic

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Re: Fuji X Lenses
« Reply #110 on: January 17, 2015, 02:15:48 pm »

... There is nothing there that says APS-C has 3 stops more DOF, as said it's just over a stop APS-C to FF a difference ...

Just to clarify my comment about "3 stops." It shall be taken in the context of Manoli's table provided in #89. I am repeating the table below, marking the following:

Full-frame lens @2.8 has 3.37 cm DOF

Fuji 56mm lens @1.2 has 3.70 cm DOF

i.e., still slightly more that the other lens. Hence my estimate that it would take something like f/1.0  (i.e., 3 stops) to match DOF. I said "that is interesting, if true," as I also used to believe the difference was about one stop. Apparently, there are circumstances that contradict that general assumption.

As for the relevance of all this for the thread, I think that DOF issues are very important (at least for me) when one is deciding whether to switch formats.
« Last Edit: January 18, 2015, 10:07:50 am by Slobodan Blagojevic »
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JV

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Re: Fuji X Lenses
« Reply #111 on: January 17, 2015, 03:55:51 pm »

As for the relevance of all this for the thread, I think that DOF issues are very important (at least for me) when one is deciding whether to switch formats.

This thread was about Fuji X lenses though, not about switching formats...

The Fuji lens lineup, including the upcoming 16 F/1.4, 90 F/2, 120-400 F/4-5.6

http://www.fujifilm.com/products/digital_cameras/pdf/lenses_accessories_catalogue_01.pdf

The 16mm/f1.4 and 90mm/f2 both look very provising IMO.

I just hope that Fuji is not going to price them at above $1K again but I am afraid they might...
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armand

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Re: Fuji X Lenses
« Reply #112 on: January 17, 2015, 04:27:25 pm »

Just to clarify my comment about "3 stops." It shall be taken in the context of Armand's table provided in #89. I am repeating the table below, marking the following:

Full-frame lens @2.8 has 3.37 cm DOF

Fuji 56mm lens @1.2 has 3.70 cm DOF

i.e., still slightly more that the other lens. Hence my estimate that it would take something like f/1.0  (i.e., 3 stops) to match DOF. I said "that is interesting, if true," as I also used to believe the difference was about one stop. Apparently, there are circumstances that contradict that general assumption.

As for the relevance of all this for the thread, I think that DOF issues are very important (at least for me) when one is deciding whether to switch formats.

This is in that calculator only. You will not get those results in other calculators, so somewhere there an "interpretation" issue. I guess you can open a new topic to additionally explore this. Btw, this is the part that I was referring to when I said it's confusing.

PS. As similar as Manoli and Armand are, it's not quite the same thing
« Last Edit: January 17, 2015, 04:29:18 pm by armand »
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BJL

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Taking as an example the Fuji 56/1.2 and comparing it to a FF 85/1.4 - both focused at 3M,  Bart's on-line DOF planner gives the following DOF measurements: ...
Those numbers are very different from what I see on other DOF calculators like http://www.cambridgeincolour.com/tutorials/dof-calculator.htm
which gives
- 14cm for 56/1.2 in the Fujifilm "1.5x" format
- 14cm for 85/1.8 in 35mm format, and
- 22cm for 85/2.8 in 35mm format.
- 14cm for 85/2.8 in 1.5x format.

There the first two numbers fit the rule of thumb of just over one stop difference (1.5x in fact): adjust aperture ratio in proportion to focal length and format size to get equal DOF and equal FOV from equal distance.

The last number suggests that the numbers you give are computed with same "allowable circle of confusion" [CoC] for both formats, which is only of practical interest if you plan to display and view images at sizes proportional to the format size while viewing them from the same distance.

If instead you compare images of the same size, the ones for the smaller format are enlarged more, so the circles of confusion recorded on the sensor are enlarged more for display, and so the OOF effects are more visible: DOF decreases with this extra enlargement. To correct for that, every DOF calculator I know of allows for adjusting the CoC in proportion to format size.
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armand

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The last number suggests that the numbers you give are computed with same "allowable circle of confusion" [CoC] for both formats, which is only of practical interest if you plan to display and view images at sizes proportional to the format size while viewing them from the same distance.

If instead you compare images of the same size, the ones for the smaller format are enlarged more, so the circles of confusion recorded on the sensor are enlarged more for display, and so the OOF effects are more visible: DOF decreases with this extra enlargement. To correct for that, every DOF calculator I know of allows for adjusting the CoC in proportion to format size.


Thank you, this was the information I was looking for.

Manoli

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Those numbers are very different from what I see on other DOF calculators ...

I did say in #89 that I prefer to use the term 'critical focus', as its more descriptive of what we're actually measuring. The reason they're different is because, as CambridgeInColour says:

Quote
An acceptably sharp circle of confusion is loosely defined as one which would go unnoticed when enlarged to a standard 8x10 inch print, and observed from a standard viewing distance of about 1 foot. [Ö] A different maximum circle of confusion also applies for each print size and viewing distance combination..

Bart's figures are based on a max output size/ppi figure for a selected 'quality' setting. In the case of the Fuji that comes to a print size of 16x12 inches, approximately, at 291 ppi. Not 10x8. Bart's calculator is far more extensive both in the number of inputs and variables (almost to the point of confusion for us lesser mortals) as well as the consequent output.

If I were to insert the 10x8 print size the DOF does indeed change, though still not quite as deep as the Cambridge ones. 

One may vary the CoC, but I believe Bart is initially using a CoC quite close to the sensel pitch of the camera. For the Fuji thats about 4.8 microns  but the CoC diameter is automatically updated based on the sensor / pixel pitch, output quality requirements, print size and camera settings in [Section2]

The basic tenet is that for a given max output size the DOF will be in accordance with his calculator. Any smaller sizes will obviously have greater apparent DOF. A quick search on Bart van der Wolf's posts re DOF will explain a lot more than I'm able to do in a quick post.

Practically speaking though, and assuming an output size of A2, I've found Bart's figures far more representative of real life 'critical focus', at least as far as portraiture is concerned.

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Slobodan Blagojevic

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Re: Fuji X Lenses
« Reply #116 on: January 18, 2015, 10:09:00 am »

.... PS. As similar as Manoli and Armand are, it's not quite the same thing

Sorry, unintentional. Corrected.

BJL

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"equal PPI DOF" (aka "critical DOF") vs "equal print size DOF"
« Reply #117 on: January 19, 2015, 02:16:33 pm »

I did say in #89 that I prefer to use the term 'critical focus', as its more descriptive of what we're actually measuring. ...
Bart's figures are based on a max output size/ppi figure for a selected 'quality' setting. In the case of the Fuji that comes to a print size of 16x12 inches, approximately, at 291 ppi.  I believe Bart is initially using a CoC quite close to the sensel pitch of the camera.
I get it now: this is what I above called "minimum DOF": measuring what part of the image appears to be in focus even under the closest scrutiny, due to any OOF effects being below the resolution limits of the camera.

So this depends on pixel size as well as format (along with various aspects of the composition) and the numbers you give are comparing Fufillm's 16MP, 24x16mm sensor to what you would get with a 36x24mm sensor of the same pixel size (so 36MP) and then displaying at equal PPI and viewing from the same distance distance.

I have no problem with that as one useful way to think about DOF; it all depends on viewing intent.  But some (like Slobodan) should beware of taking this as a DOF difference due to format difference alone! For example, if one compares that Fujifilm camera to the Nikon D4s, with about the same 16MP but in 36x24mm format, Bart's method would get us back to the traditional rule of DOF at equal aperture ratio differing by the format size ratio of 1.5x, and so slightly over one stop higher needed with the D4s to get equal DOF.

So, here are some options that do not require changing format or f-stop:
- if you want more "critical DOF," use a lower resolution sensor, or down-sample (or use a lens of very poor resolving power);
- if you want less "critical DOF", use a higher resolution sensor.
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armand

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Re: Fuji X Lenses
« Reply #118 on: January 30, 2015, 08:51:37 am »

Didn't play much with it but seems interesting: http://fujifilmxmount.com/comparison/en/

armand

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Re: Fuji X Lenses
« Reply #119 on: April 16, 2015, 12:29:00 pm »

Fujifilm 16mm F1.4 announced: http://www.fujifilm.com/news/n150416.html

I am telling myself I will not buy it but that's what I said about the 14mm F2.8 (too wide), about the 56mm F1.2 (too expensive for how often I need it, I already have the 60mm), about the 10-24mm F4 (too wide, I already have the 14) and about 23mm F1.4 (I already have the 10-24mm). They seem to be pushing a lot of "right" buttons. It is quite expensive though to buy without some actual need.

EDIT
here is a first look: http://www.fujirumors.com/first-look-xf16mmf1-4-r-wr/
« Last Edit: April 16, 2015, 12:46:18 pm by armand »
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