What will the fujifilm medium format mirrorless camera be like?

Thanks, fujirumors, for sharing the rumour about an interchangable viewfinder for the hopefully upcoming Fujifilm mirrorless medium format. If true, this makes all the difference in the world for the camera and says so much more about what it is going to be like that i can almost give a shot at predicting it.

What the heck, ill give it a try.

(Its been released now, so how did i do? Find out at the bottom.

An interchangable viewfinder, what difference does it make?

When making an interchangeable viewfinder for an EVF camera one have two options. 

1. A detachable EVF.
2. A small sized amoled screen, much like an SLR focusing screen. Lets call it the EFS, electronic focusing screen.

Nr 1 has been used with quite low success but several mirrorless camera manufacturers. All the solutions were technology driven, expensive for the photographer and commercially rather unsuccessfull.

Nr 2 is an modern version of common solution from SLR world, but untried in a mirrorless camera. It is a lot cheaper, especially for a waist level finder that is nothing more than a foldable shade with a likewise foldable looking glass. For the eye-level viewfinder, prisms cost a bit more, but sometimes a cheap mirror may do the trick almost as good. If the EFS thingy is up-flippable within the eye-level finder it may in fact obsolete the prism all together.

With Fujifilm, a release of a new system always seems to come with a twist. Something novelle or quirky, sometimes brilliant, sometimes more or less pointless. I think its because most Fujifilm product lines start with an idea of how to improve or revive a certain aspect of photography with a new solution. It could be another new kind sensor pattern, moster tilt-shift medium formats, 6x8 frame size to fit magazine covers perfectly, reinventing instant photography, very short 120-films to suit drop-in studios, film simulations, yet another sensor pattern or another one again. Nothing has been predicted in the MMF rumours we have heard up until now.

I'd say Nr 2 would make this camera fit right into what to expect from a new Fujifilm product line. At the same time it makes the whole rumour of a MMF a lot more beleavable. It would also be the cheaper way to go and being cheaper than Hasselblad is kind of important here. 

The implications

With a focusing EVF on top of the camera, it will not look like the Hasselblad, the x-t1 or an x-pro2. It will look more like a SLR or a classic MF camera (of which there are many different designs, a bit more on that later).  Whatever they choose, the camera will be deeper than the Hasselblad that is a very thin camera being a medium format. That means that they can fit a focul plane shutter where the mirror would have gone in an SLR, without making it bulky. I know, Fuji do like their leaf shutters, but large leaf shutters are expensive and if you want to make them really fast, they are really expensive. They also make the lenses heavier. Another implication of a deeper camera is that the lenses can be shorter, since the sensor can be a bit further back and some of the focal length can be kept in the camera. I would love a telescopic tube or a TLR-like movable front behind the mount to keep the lenses down to large format size and even allow crude AF with adapted lenses, but i think the R&D and production cost of that would be a bit on the high side unless they come up with a super brilliant solution. I would rather expect a fixed register, something in the range of a regular small frame (D)SLR. Short enough to adapt most medium format lenses, but long enough to keep 44x33 covering optics rather small.

Interchangable viewfinders also limits where you can put the hot shoe and a pop-up the flash. We will most certainly not see a pop-up and the hot shoe may either be left out too, pushed to the left of the viewfinder or put in an unconventional place. Far left is is my guess.

Other conclutions

Sensor

Well, there is only one that would meet the requirements of being not to expensive and good enough. The Sony 50Mp 44x33mm one. Bayer or xtrans then? Rumours sais bayer and so does logic. Fuji will want to go with a perfect colour alternative here. Binning the 50Mp bayer would give true RGB on every pixel on 12,5Mp and a smart demosaicing algorithm would give twice the size with almost perfect RGB and almost 50Mp shapes. Then there is the problem with the current cost of a computer (and internal circuitry) that can demosaic an 50Mp xtrans file in bearable time. There is also the fact that a bayer sensor may still scare off less potential customers than an xtrans.
Bayer it is!

Interface

Fuji allready has a well tested interface of dials, knobs and buttons on the x system. I dont expect them to put resources into another one. We will propobly see the film simulations and most of the menu system duplicated as well. Then there is the question of the screen. If the camera is sold with the WLF as standard, its not impossible that they may skip the big screen in the back. However, i think the first release will be the premium model, a cheaper single screen may come later.

Touchscreen? Not yet, first they need to evaluate that on the cheaper x cameras.

Form factor

SLR-like, TLR-like, HB-like, P-67-like or even GA645-like? Well, i think they will keep the system specs so that they can build most of these in the future. However, for the first model i think its going to look a bit like the Reflex Beauty, but with a grip for the right hand. A small box to house the shutter inside and the EFS on top with a mount for the lens in front and another for the viefinder on the top. The box will most likely be a bit smaller since the 44x33 is smaller than the 55x55 of the beauty reflex. Maybe they will keep the electronic focusing screen at the modern standard 645 size of 56x42mm or their own 645 that is more like 55x43.5mm. Behind the box there would be a fixed back, with electronics, battery and memory card slots, with knobs, dials and buttons much like an x-pro2 or x-t2 and the same screen as them on the back.  All and all like if one would take an x-pro2 and put a small box in front of it and the viewfinder mount on top.

Ofcourse there will be cheaper models if the first one sells well enough. An HB 500c form factor or even a TLR-like camera, but with only one lens at the entry level are viable options in the future.

IBIS

The only reason why Fuji would implement IBIS would be that they were planning to go for a 645 sensor in a future genration so that the lenses were allready 645 prepared. That would actually make some sense here. But the do allready have in-house tech for OS lenses and IBIS is harder to implement the larger the sensor is. So its definetly a no anyway.

Lenses
Three lenses are rumoured to be first released. One normal and one portrait tele plus a wide to normal zoom.

Summary of my prediction compared to the real deal.

• Reflex Beauty style camera
  Not to bad. I didnt see the brilliant move of moving the grip of the camera forward to make it more balanced. But the box is there, just as predicted but its just visible on the back instead of the front.
  
• X system like handling and output
  Was pretty obvious.
  
• 50Mp 44x33 bayer sensor with True RGB binning option
  This is not clear as of yet. We still think bayer and they presented a few tricks of downsizing. More info on this later.
  
• Invention of the EFS, the electronic focusing screen
  Fail! It may still come on a future model.
  
• Small lenses compared to the ones of Hasselblad
  They are smaller, but not super small.
  
• Sadly no bellows, tube or other retractable mount
  Right, sadly enough!
  
• A bit thicker a body compared to the Hasselblad one, but smaller with most comparable lenses mounted
  Spot on!
  
• First body only slightly cheaper than Hasselblads, cheaper ones coming later
  First part is right at least, time will show if the second part is right.
  
• Neither touch nor flippable screen
  Half fail, with no WLF, the flippable screen has to be there. They didnt say anything about touch though.
  
• A focal plane shutter is slightly more likely than leaf shutters
  Right
  
• No IBIS
  Right
  
• Pop-up flash, no
  Right
  
• Hot shoe, far left on top of the camera
  Wrong, sort of. They have an odd hotshoe solution, but its on top of the viewfinder on the regular one. But with the angle finder, where is it then, is there none at all?
  
• Three lenses: Wide-normal zoom, normal and portrait tele primes.
  Kind of wrong. I don't think anyone see them anounce a six lens system.
  
• Weather resistant
  Right.

Oh, im gonna be so wrong...
Well, it could have been a lot worse. What was really wrong was the viewfinder construction and thus also the touchscreen. I'm pretty impressed with what i have seen of the system so far and hope for more (hopefully) cheaper bodies to be released in the future.

Thanks Fujifilm, for releasing such an impressive system!

Purple flares and grid pattern on xtrans: Why its there and how to remove it

There have been a few discussions and posts over the years about a phonomenon on some digital cameras where a grid pattern is appearent in purple flares when pixel peeping. Here is a discussion on the topic from a few years back, that time about a Sony camera.
Now it has become appearant that the effect can occure in xtrans sensors as well. A few months ago Mathieu att Mirrorlessons wrote an article on it. I first read about it on a discussion a few days ago and have been doing some digging since, here is what i know and what have been able to find out the last couple of days.

Purple flare effect in general

Purple flare origins when there are strong light sources in line of sight of the front lens. The source can be, but doesnt have to be, in the frame to cause a flare. If its outside the frame, a well made shade usually helps on a prime. On a zoom lens the shade has to be made to protect only the widest end and if one zooms in, a light source outside the frame can still be in line of sight from the front lens. Filters and dirty front lenses will usually increase the effect.

Flares can usually be avoided, but sometimes they look really good and thats when the real problem occure. If you want it there it has to be well rendered in your photo.

Film vs digital

On film this is usually not a problem unless you scan the negative. If one makes an RA4 copy, a well placed purple flare looks awesome. On a digital camera or a scanned image, things get more complicated. Purple flares over highlights usually work ok, but on shadows, and gray to black highlights in particular, they often become problem. On every camera i have been using (doesnt include sigmas) and every scanner i have used (which are a lot) what always happen is that the post processing latitude turns to almost zero if such a flare is present. Any pushing, pulling, sharpening or even white balance shift will make it look horribly ugly if you dont treat it carefully. Further more, if shot with a digital camera, usually the tolerance for cropping decreases a lot too. To much cropping and one of several kinds of artifacts are bound to appear. It can, for example, be clotting, loss of contrast or that part of the image just gets a different look. On xtrans files is it the grid pattern.

Why?

Mixing bright colour with dark gray is obviously not easy. Try to imagine it yourself. However, when its done right it can look very pleasant. I like to do in postprocessing my darkroom prints. On most papers it doesnt work at all. When it works, its because the papers have a structure like tiny hills and valleys. The black silver then only forms its shade of gray of the photo on the mountain tops in the highlights. Then i can rub colour down in the valleys without desturbing how much silver that should be visible. Even with such a paper it only works in the highlight areas of the photo, in shadow areas the silver reaches down in the shadows and there can be no mix. Digital images face very much the same kind of problems, a single pixel cant be both bright purple and dark grey at the same time. To create something that looks like that, some pixels have to have one property and others the other one. With some clever maths and enough pixels, this is fixable if you start with a picture that have all the colour information for every pixel. But ouch, a digital sensor doesn't have that. Every pixel only have one colour, and its green in 50% of the time on a bayer sensor and even more on an xtrans one. To a green pixel, purple looks almost black. So the amount of pixels the clever maths have to work with is seriously reduced in a purple flare.

The grid pattern

Why does xtrans form a grid pattern? To answer that we have to take a look at the xtrans pattern, so here it is.

As you can see, every fifth green pixel have a different coloured pixel on its side and a green one at its corners. However, four out of five green pixels only have differently coloured pixels at two of the sides. Demosaicing is complecated stuff and ill give you a very very simplyfied version on how it works from one of the green pixels perspective when being faced with purple light.

First it looks to its own information and sees black. Then it asks its longside neighbours. Half of them say black, one says slightly red, and one slightly blue. Including itself, a 3 to 2 majority vote black. Then it asks its corner neighbours and gets the same answer, 3 to 2 for black. The 5th green pixel gets another ansew from its longside neighbours, 4 to 1 majority says its not black which changes its mind.

Now lets look closely at an affected picture converted with lightroom and compare to the xtrans pattern. 

The result is the complete opposite of the prediction, but the pattern remains as the algorithm seems to overcompensate when there is not enough data. I have now looked at the output from several different raw converters including the in-camera one. Every single one creates this reverse pattern in the purple flares. Clearly some tweaking of the demosaicing algorithm in affected areas would be in order. It would still need the mix of brighter and darker pixels to keep the luster, but they have to be scrambled somehow.

Is this a problem worth bothering about?

Yes and no. It only shows this clear when pixel peeping and the kind of screen you use also affects how visible it is. However, when trying to post process a photo with a purple flare by any means to achive sharpening, cropping, clarity, opening up the shadows or changing the contrast, it is always the flare areas that sets the limit of how much one can do. If i was at charge at Fuji, i would dedicate some resources to investigate it and if i was in charge at Silkapix id definetly see it as a chance to show the world i was still ahead of Adobe.

Does it affect my pictures as a photographer? Almost never, and when it does, i know how to fix it in post for almost every case.

The post production solution

Lets start with a picture. This is from the x-pro2 with a 10-24 with a street lamp slightly in front of me, shining down on the camera from above . It wasnt in the frame, but the shade didnt cover my lens enough to keep the light from reaching my front lens. 

Here is a 1:1 crop, it dosnt look pretty at all:
(it uses the adobe standard profile with no modifications but slight clarity and slight dehaze to exagurate the effect)



From lightroom i then right click on the image and chose "Open as smart object in Photoshop". In fotoshop i select the whole image and apply box blur with the minimum strenght of 1, (I use gaussian blur 2 if the pattern appears as diagonal rather than horisontal/vertical). I then close photoshop and click save.

Here is the result that then automatically opens up i Photoshop as a PSD file next to the RAF:

The grid is gone and the loss of detail is much like using a sensor with aa-filter.

Here you can download the before and after pictures side by side. It is a crop at approximatly 1/4 of an xtrans III file.

Happy shooting with purple flares again!

P.S.
In Mathieus article there are pictures with a diagonal pattern as well. I have not been able to recreate that pattern. Could someone, please, mail me (roos@swedish.photography) a RAF of such a photo so that i can investigate it further?