Is it really better to not half-press to focus with the Fujifilm X-Pro 1?

Question

Fujifilm's new camera uses contrast-detect autofocus, and the current Internet hand-wringing is over whether this is a horrible critical flaw or not. As often happens in such discussion, a bit of street wisdom has arisen: it's better to just push the shutter the whole way. For example, this blog comment:

AF speed on the XPro isn’t that slow, the problem is that most people use it as they would an SLR/DSLR for focusing, i.e half press the shutter and wait for AF confirmation then press the shutter all the way, in most cases with the XPro and the X100 you don’t need to do this.

And there's at least one thread on DPReview, but as characteristic for such discussions, there's a lot more smoke than fire.

The X-Pro 1 manual says nothing about this, and in fact says:

S (single AF): Focus locks while the shutter button is pressed halfway. Choose for stationary subjects.

In my experience, if the subject is stationary, the half-press method works as it always does, and if it's moving the full-press method isn't as good as using AF-C (continuous autofocus). I've used plenty of point-and-shoot cameras as well, which of course use contrast-based AF, and the half-press focus lock has always served me well.

But then, a lot of people are saying this is a big deal. Is there any reasonable basis, or is it just wishful thinking?

Asked by mattdm

Answer

No, it is not. There is nothing magical about not waiting at the halfway point.

What you read is silly, as if waiting would make the focus take longer or something. It does not work that way. You can press all the way as fast as you want and you'll get a shot in focus or not. The longer you wait at the half-press (in AF-S) mode or before fully pressing (in AF-C mode), the higher the probability the shot will be focused. Waiting too long might make you miss action but it won't make the camera miss focus.

Note, having an X-Pro1 one in hand and, for all I tried, I cannot see how not waiting at the half-press can improve focus.

Answered by Itai

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What is causing the cyan outline in the building in the background of this image?

Question

I took this picture the other day. It's a JPEG from the Fujifilm X-Pro1. The sky is overexposed as was necessary to light Anya brightly — and because I was playing with shooting wide open, and that plus the high base ISO plus max shutter of ¹⁄₄₀₀₀th meant this went beyond what the metering really wanted to do. Maybe a bit much, as we've lost the top corner of her head.

But, never mind that. What I'm interested in here is the cyan blur outlining the Prudential building in the background. A one-for-one pixel-level crop is below the full image....

_{Anya on the Esplanade; photo by me and CC-BY-SA 3.0 in this size only.}

What is causing that blue outline? Is it just a matter of the out-of-focus blur interacting with the overexposed sky? Is chromatic aberration to blame? Or, is it because of the larger-than-normal color matrix used by this camera's unique sensor, and basically an artifact of RAW decoding?

Camera make  : FUJIFILM
Camera model : X-Pro1
Focal length : 35.0mm  (35mm equivalent: 53mm)
Exposure time: 0.0003 s  (1/4000)
Aperture     : f/1.4
ISO equiv.   : 200
Whitebalance : Auto
Metering Mode: pattern
Exposure     : aperture priority (semi-auto)

Asked by mattdm

Answer

The sky on a sunny day is cyan (primarily green and blue with some red). Where the intake of light is really bright, all three color components (red, green, blue) on the sensor chip are fully saturated (at their maximum counter values), which results in overexposure, or pure white in this case.

What you're seeing as a cyan outline is actually the result of that section of the image not being pegged to pure white, because the darkness of the gray building is interfering with (blurring) the ligthness of the sky, and thus preventing the sensor counters from attaining their maximum (e.g, overexposed) values in that region.

If you were to shoot the image again with the same exposure values, but this time with the building in sharp focus instead of the subject, then you would see a sharp line where the building is solid gray-ish and the sky is overexposed to pure white, but no more cyan fringing.

This effect is very similar to the laser bolts in the some of the space battles in Star Wars — where light green or light red charged-particle beams are a white line in the center, surrounded by a beautiful pure color fading out to black. The pure white in the center is simply an artifact of over-exposure; there is no actual white light there.

Note that if you had a light source that was pure red, pure blue, or pure green (such that it perfectly matched the receptor frequencies of your sensor), then you would not see over-exposure toward white, but instead over-exposure to a single color component only.

Answered by Todd Lehman

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If I need the higher ISO anyway, is there any downside in using Fujifilm's extended DR mode?

Question

Fujifilm has an extended dynamic range mode, which is in some way linked to ISO. The X-Pro 1 has a sensor with a base ISO of 200; if I enable "DR 200%", the minimum possible ISO increases to 400, and if I go to "DR 400%", the minimum ISO becomes 800.

I can see — easily, in fact using the DR bracketing drive mode for comparison — that the increased ISO means more noise and less detail. But if I needed ISO 800 anyway for my exposure, is there any detriment in using the extended dynamic range mode?

If there isn't any downside, why isn't it always on when ISO is above the base? (There is an "Auto" setting, but I'm not sure if it simply does that, or if it has a more complicated heuristic taking the actual DR of the scene into account.)

Asked by mattdm

Answer

On this model Fuji's extended DR function doesn't really alter the dynamic range of the sensor (if there were a way to increase DR it would be on all the time).

Instead it gives you more room to recover highlights (which to most people makes it seem like dynamic range has increased) which is done by underexposing the shot. The reason for the increased minimum ISO when using, say DR400%, is that this mode uses the same amplification as ISO200 (it's not possible to underexposure a base ISO shot without changing shutter speed or aperture). This produces a signal underexposed by two stops, which is corrected in software. The advantage to correcting in software is that you can detect when highlights would be clipped and prevent this from happening.

So to answer your question, there is indeed a difference between shooting at ISO800 and shooting with DR400% and ISO800 - the former uses hardware amplification only, the latter uses software amplification only (DR200% uses half hardware, half software). Using software amplification carries with it increased shadow noise. This is because amplification happens post readout so you amplify the read noise, which doesn't happen if you amplify before readout.

If your sensor has very low read noise anyway then the increase in noise when using this approach can be pretty small. But there is still some noise penalty which is why (in addition to the inability to use wider apertures/longer shutter speeds) this setting isn't always on.

Answered by Matt Grum

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Can I change the Fujifilm X-Pro 1's viewfinder magnfication manually?

Question

The Fujifilm X-Pro 1's optical viewfinder mode automatically switches magnification to match the prime lens mounted. There's a "bright frame" electronically drawn as a heads-up display showing the area of the actual frame.

I have the 35mm lens mounted. When I picked up the camera a little bit ago, I discovered that the view through the finder was wider than it has been in my previous few days of using the camera, and that the bright line rectangle was smaller than I was used to. It seems to have switched to a wider view.

After puzzling at the controls and the manual for a while, I couldn't figure it out. I eventually unmounted and remounted the lens, after which everything was back to normal. But the camera seemed to always "know" the right focal length, as it drew the bright frame appropriately.

How did the camera get into this state? A glitch, or something I inadvertently changed? Is it possible to do on purpose? (I can see an advantage in some situations in having less magnification, in order to see more of the surrounding situation.)

I've searched the manual, but found nothing about this. (Unfortunately, the manual is both poorly organized and full of gaps on many points.)

Asked by mattdm

Answer

It seems you pushed the lever that switches from the OVF to the EVF for more than 2 seconds. Doing so will bring the magnification glass on top of the OVF. Try pushing it again for more than 2 seconds to put it back in the other position. That magnification glass is useful for the other lenses...

Answered by sebastien.b

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How does a short flange back distance improve image quality?

Question

In the description for the new lens mount for their X-Pro series, Fujifilm says:

1: Specifically designed to maximize the mirrorless design of the body, the X-Mount has a short flange back distance of just 17.7mm. This means the rear lens elements are as close as possible to the sensor. The wide opening allows the lens to be mounted deeper within the body - up to 7.5mm (approx) from the mount surface - reducing the back focus distance of each lens to the minimum possible, thus achieving high resolution all the way to the edge of the image.

How does this shorter-than-usual distance help "achieve high resolution"? Does it come at a cost? I remember both Olympus and Leica making a big deal about the issues with non-parallel light rays at the edges of digital sensors, and how that caused a sort of vignetting not found with film (where the emulsion is basically non-directional). It seems to me that a shorter flange back distance would force light rays outside of the center of the frame to be even more oblique. Am I misunderstanding how this works?

The Sony E-mount is almost as close. Is this shorter distance all advantage, or does it bring problems as well? (Clearly, it means all-new lenses, but it should also make adapters easy.)

Asked by mattdm

Answer

The short-flange distance gives more latitude to lens designers.

There is no disadvantage at all to a short flange distance because the lens does not have to use it! Case in point, you can adapt almost any lens to a camera with such a short flange distance.

In general, digital sensors prefer light to hit it with a more uniform angle, so lens designers probably wont feel necessary to take advantage of the shorter distance except to create something more compact.

Answered by Itai

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What is the difference between the Instax Mini 25 and the Cheki series?

Question

I'm seriously getting confused.

I'm Googling around for an Instax Mini 25 unit, but I keep getting conflicting results.

• some of the results hint on a distinct difference between the Mini 25 and a Cheki (e.g. Mini 25s come in only white, while Chekis come in a variety of colors)

• some of them show no distinction between the two, as if the two are interchangeable

So here I am. Can anybody tell me exactly what's up with this?

Asked by Richard Neil Ilagan

Answer

Instax Mini 7s and Mini 25 are also called Chekis, they are the same cameras. This article/entry on Photojojo might help to clear it up for you.

Answered by John Cavan

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What is the maximum CF card size for a FujiFilm FinePix S1?

Question

My fiance just got a free FujiFilm FinePix S1. An old camera, I know, but also perfect for helping her learn the basics behind photography.

Anyway, we aren't experts on storage at all. We can see that for SmartMedia cards, the max is 64MB. Does anyone know the maximum for the CompactFlash cards? Does CompactFlash work like that, with the memory limits, the way that SD kind of works? Would a 4GB (or larger) Type I card from BestBuy work? Or does the operating system have a size limit?

Any information at all about this specific camera or CompactFlash in general will be greatly appreciated.

Answer

The file system for the camera (given the era, the cards available at the time and their price) is probably FAT (FAT16). There's no indication anywhere that the camera is capable of using FAT32. If that's the case, you won't be able to use cards bigger than 2GB, and may find that only 1GB is addressable.

While they're not nearly as commonly available as cards weighing in at 4GB and up, you can still find 1GB and 2GB cards at very reasonable prices (under $20). Don't worry about the speed ratings -- all of the currently-available cards will read and write faster than the cards of c. 2000 (except the microdrive, which was really rather snappy).

Unfortunately, Fuji's two non-JPEG formats are TIFF, so you won't be able to get very many shots on a card unless you use JPEG, and there is no RAW format. JPEG Fine should be good enough for most purposes, though, and the bit-depth limitation might actually help to learn about exposure, white balance, etc.

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Why doesn't the background become blurred when I change the aperture on my Fujifilm S4000?

Question

I am sorry if my question is too naive, but I am a complete beginner in photography, and I think I still need to understand well what aperture is. I have a Fujifilm S4000 camera, and I know I can't do with it everything that a professional camera does.

I wanted the background of some pictures to be blurred by changing the aperture, but I don't get the results I expected. I think it also has to do with the focal length, am I right? I took two pictures to show you what I mean.

Picture 1 Aperture: f/4 Exposure: 1/2 s Focal length: 7 mm

Picture 2 Aperture: f/10 Exposure: 2.6 s Focal length: 7 mm

I would like to know what settings I can use to get the background to be blurred. I know that with smaller aperture values, the area around the object in focus will be more blurred, but when I change from f/4 to f/10, it doesn't change much.

Answer

There is NO different at ALL because the physical aperture has not changed.

The Fuji Finepix S4000 simulates a small aperture using an ND filter. When you stop-down, the ND filter slides into the optical path. The Aperture written i the EXIF is adjusted to reflect the transmittance of the ND filter but since the size of the opening has not changed, Depth-Of-Field does not change either.

Not only do such cameras have very small sensors and extensive depth-of-field but they are also extremely prone to diffraction. If the aperture was actually stopped down to F/10, images would get quite blurry.

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Why does my Finepix S2950 not show the image quality I expect?

Question

I am a little confused as to why my Finepix S2950 takes photos like it does. I seem to be able to take great Macro Shots, but not landscapes. I have noticed that if I zoom into a picture enough I can see that the individual pixels are all over the show. Compared with another image that a professional has taken and the difference is noticeable. Here is a part of one of my photos zoomed to 500%. I'm just a little confused as to whether my camera is performing normally or not. It wasn't exactly a cheap camera, but its not a DSLR. My pictures only ever seem to look good when I am zoomed out a bit. They don't look very nice at 100% real size. Not being able to post images is really irritating.

http://i41.tinypic.com/550687.jpg

Answer

A (simplified) Look at Camera Sensors

The sensor on your camera is 14 megapixels and 6.17x4.55 mm in size. By comparison, a Nikon D3100 (an entry-level DSLR) has a sensor that is also 14 megapixels, but its physical size is 23.1 x 15.4 mm.

Even more expensive DSLRs, known as "Full frame," have a sensor that is roughly the size of 35mm film (about 36 x 24 mm).

Why this matters:

Sensor size is important because it tells us something about pixel size. Think of each pixel on a sensor as a rain gauge, basically a small cup that catches water. Photons of light striking that pixel are like individual rain drops. When you take a picture, the camera opens the shutter and allows light (rain drops) to land on the sensor, falling on individual pixels (rain gauges). When the exposure is done, the camera closes the shutter and measures the figurative water level of each pixel, and from that information assembles an image.

Now, what would happen if we make the opening on a rain gauge bigger? Well, it would be able to collect water faster because it would collect more rain drops. That means you could leave it outside less time and collect the same amount of water. Or, conversely, you could collect more water in the same amount of time as you could with a smaller rain gauge.

Now back to cameras:

A camera with the same megapixel count (the same number of pixels) but with a larger sensor will collect more light per pixel than a camera with a smaller sensor. When you are dealing with the high shutter speeds that are typical for hand-held photography, the effect of catching or missing individual photons (raindrops) starts to matter. This effect presents itself visibly as "noise" in the image when viewed at 100%, as some nearby pixels catch more more photons than others (due to their random nature).

The larger the pixels, the less the random nature of light effects your image. You have actually observed this effect for yourself when you say that your pictures look good when you zoom out. By zooming out you are in effect blending nearby pixels together, creating fewer but larger pixels.

The reality of the situation:

Most pictures, even those a professional has taken, are never viewed at 100%. Whether they are uploaded to the web or printed on a photo printer, almost all images undergo some amount of resizing, de-noising, and editing before you see them.

As you will often hear repeated on this site, the quality of a photograph ultimately has far more to do with the photographer than the camera, so you shouldn't worry if your images display some noise at 100%. If it really bothers you, there are some things that you can do to try to decrease the noise you see in your images:

• Pay attention to the ISO your camera is using. This is related to how much light is hitting the sensor, and how much the camera has to scale the values it measures from each pixel to get a bright looking image.

• Post-process your images with a noise-reduction filter.

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What is the production volume for film over the last decade?

Question

How many rolls/sheets of film has Kodak/Fuji/the-whole-industry produced each year for the last ten years?

What has the revenue been?

I've tried googling for the answer but a summary of this information appears elusive.

I'd like to get an impression of whether or not the decline of film has stopped and if it has now stabilized as a niche market.

Answer

I found a graph of Kodak film sales on this page.

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What aftermarket batteries for Fujifilm FinePix X100?

Question

I want to get a spare battery for my Fujifilm FinePix X100. It takes the Fuji NP-95 rechargeable battery. These are very hard to find; aftermarket brands are much more common. I'm hesitant to put an off-brand battery in a $1000 camera, though.

Does anyone (a) have a recommendation for a brand that they have personally tested with an X100, (b) know of a brand/store that guarantees no damage to the camera, or (c) know of a source of genuine Fuji batteries?

Answer

I've written an article about this very thing, http://www.x100enthusiasts.com/discussion/80/batteries-chargers-power-management-finepix-x100-user-guide

I've been using a MaxPower brand generic for 5 weeks now without issue. Other users have reported similar experiences in the comments.

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