Pages: [1]   Go Down

Author Topic: Why I think a mirrorless system is a great idea  (Read 2847 times)

ErikKaffehr

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 11311
    • Echophoto
Why I think a mirrorless system is a great idea
« on: February 08, 2016, 02:00:42 am »

Hi,

There are lot of mirrorless options in 4/3, APS-C and 24x36. There are a lot of mirrorless options in MFD, too, they are called technical cameras. But technical cameras could do with a lot of more integration. So, I suggest some of the MFD manufacturers should go and build a real good mirrorless MFD camera.

Just to say, there is not a lot of wrong with flipping mirror cameras. But recent innovations from smaller sensors may migrate to larger sensors.

First we need to ask our selves, why do we need that flipping mirror? It was invented to implement "What You See is What You Get" viewing back around 1936. At that time there was a debate between rangefinder shooters and SLR shooters. Rangefinders had a lot of benefits, but SLR went trough a rapid development and came out on top. Still, classical Leica M cameras still had a lot of attraction.

First time I had an amateur video camera in my hand I realised something. It had an electronic viewfinder. That should also work for still cameras.

Now, as mentioned before, original SLR designs had a few issues, but those have been ironed out by nearly 80 years of development.

  • Vibration. The mirror flips out of the optical path before exposure, It needs to move fast to reduce shutter delay. That movement causes vibration on the camera. It cannot be dampened out entirely, due to conservation of momentum. (*)
  • Long focal plane to flange distance that leads to the need of retrofocus lenses.
  • Shutter delay. The mirror needs to flip between two positions, it needs to accelerate, retardate and stop before exposure.
  • Many parts need to be in alignment. Bayonet, sensor, mirror, secondary mirror for AF, AF-sensor and focusing screen. Both mirrors are moving.

On smaller sensors we have seen rapid development of new technologies that go hand in hand with mirrorless:
  • CMOS sensors with very fast readout this is really needed for contrast detecting auto focus (CDAF)
  • On sensor phase detection AF (PDAF) - this eliminates the need of both AF-sensor and AF-adjustment
  • Backside illumination - may solve some problems with beam angle sensitivity of sensors as well depth is reduced
  • Some small size sensors offer thin photodiode layer and have optical insulation between adjacent cells.
  • The new 100 MP sensor from Sony support electronic first shutter curtain.

So, it is quite feasible that next generation of MFD sensors will be better suited to non DSLR designs.

A mirrorless camera can still use an existing lens program with an adapter that is essentially an extension tube. Sony, who make the only 24x36 mirrorless aside Leica have two adapters for the A7-series. One is just an extension tube with electrical contacts and mechanical aperture control, the other contains an AF motor and a AF-module.

Hasselblad has something called the HTS adapter. It can give T&S with most Hasselblad lenses, but it has a built in 1.5X converter needed to make place of the flipping mirror. With a mirrorless design the 1.5X converter would not be needed. It would also be possible to use Canons T&S lenses, as demonstrated by both the Hartblei HCam B1 and the ALPA FPS.

The ALPA FPS and the HCam are forerunners in mirrorless MFD. Both have computer controlled focal plane shutters and aperture control for Canon lenses. The FPS can also control aperture on Contax 645 lenses with an adapter, I think.

The ALPA FPS has some advanced optical viewfinder for viewing and a very long calibrated focusing gear for focus. Best way to focus seems to be a laser rangefinder. The HCam B1 has a motorised sliding back.

Both the FPS and the HCam work well with Canon lenses but Rodenstocks and Schneiders are not fully integrated. A mirrorless camera would need to have full integration.

Live view essentially solves both "What You See is What You Get" viewing and gives optimal focusing capability with actual pixels magnification that ideally can be positioned anywhere.

With next generation sensor we may have on sensor PDAF coming to MFD. If it is designed for mirrorless operation it would work better with non retrofocus wide angles.  But that will not happen as long as flipping mirror cameras dominate.

Best regards
Erik

(*) Conservation of momentum would make it possible to flip the mirror as retarding the mirror would consume the momentum created by accelerating it. But in a coupled system with tripod and lens the forces will cause complex oscillations.
« Last Edit: February 08, 2016, 11:12:07 pm by ErikKaffehr »
Logged
Erik Kaffehr
 

Christoph B.

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 341
Re: Why think a mirrorless system is a great idea
« Reply #1 on: February 08, 2016, 05:11:48 am »

Are you thinking of a camera with a fixed sensor or a removable sensor?

Some big problems I can think of:
  • Battery dependence (think of a hasselblad 500-series and how reliable and sturdy they are without any kind of battery)
  • Battery usage (you'll _have_ to use the EVF in order to see something, so the back has to be turned on all the time)
  • you'll need new lenses and using legacy lenses isn'T going to be a pleasant experience. The distance is much bigger than Sony Mirrorless vs 35mm and in the end it'll be just as long and big as it currently is just with more parts in-between that will likely reduce or remove autofocus or lens communications
  • You'll need lenses with a leaf shutter => they're going to be very, very expensive. Think of how much a current leaf shutter lens costs compared to an old used lens with the same optical capabiliites


In case you were thinking of an integrated solution (sensor is a part of the camera)
  • If the electronic viewfinder fails you have to send in the whole camera, including sensor - while on a SLR-System with removable back you can keep the back, get a spare camera and you're ready to go
  • Cleaning the sensor isn't as easy as it is right now

In case you were thinking of a solution with a removable back

  • You need a new connection between the camera and the back to guarantee a high frame rate and resolution for the EVF - otherwise using it will be uncomfortable and focussing pretty much impossible. So you'll lose legacy support
  • The camera size won't change a lot if you have to account for the additional electronics, new connection ports, processors etc.

The reason why it has worked well for smaller formats is because they have small sensors that don't require a lot of power to work and they are always integrated solutions, the sensor is a part of the camera and everything is connected internally.
On the Sony mirrorless cameras people tend to get around 400 photos off of one full charge - now think about how many photos that would get you with a MF camera.

I think if you want something small, a little point and shoot will do the trick but it doesn't make much sense for a bigger sensor that has to be powered.
Logged

landscapephoto

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 623
Re: Why think a mirrorless system is a great idea
« Reply #2 on: February 08, 2016, 05:52:00 am »

Both Hasselblad and Phase 1 have cameras designed for aerial photography which are, in effect, mirrorless boxes and can mount the existing lenses. Presumably, all what would be needed for an integrated mirrorless system would be an HDMI connection on the backs to mount a viewfinder. I think that viewfinders using an HDMI connection are available off the shelf for video cameras.

So it would basically only be integration work of existing parts, like adapting the aerial photography cameras, etc... It certainly is doable, but the question remains whether there is sufficient demand to finance that work. That we don't know and we won't find out: even if a majority of forum members would be interested, the population on this forum is not representative of the whole market.
Logged

eronald

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 6642
    • My gallery on Instagram
Re: Why think a mirrorless system is a great idea
« Reply #3 on: February 08, 2016, 09:03:24 am »

Both Hasselblad and Phase 1 have cameras designed for aerial photography which are, in effect, mirrorless boxes and can mount the existing lenses. Presumably, all what would be needed for an integrated mirrorless system would be an HDMI connection on the backs to mount a viewfinder. I think that viewfinders using an HDMI connection are available off the shelf for video cameras.

So it would basically only be integration work of existing parts, like adapting the aerial photography cameras, etc... It certainly is doable, but the question remains whether there is sufficient demand to finance that work. That we don't know and we won't find out: even if a majority of forum members would be interested, the population on this forum is not representative of the whole market.

I think we'll find out because the next generation will be mirrorless anyway. It's the obvious engineering route, now, and brings the price of the camera down to the price of electronics, removing most mechanical design issues. Just about any flange distance and image circle become usable, as Alpa proves, so one can use this concept for MF lenses, for 35mm lenses with an adapter, for cine with a different back, for landscape with shift devices, for extreme symmetric wides, for intermediate-size sensors like square 35.

I'm sure there will be a market for a conventional OVF medium format camera, but there is now space for at least one multi-format EVF modular camera system that would resemble Alpa in its universal intent.

Edmund
Logged
If you appreciate my blog posts help me by following on https://instagram.com/edmundronald

yaya

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 1254
    • http://yayapro.com
Re: Why think a mirrorless system is a great idea
« Reply #4 on: February 08, 2016, 09:15:33 am »

Both Hasselblad and Phase 1 have cameras designed for aerial photography which are, in effect, mirrorless boxes and can mount the existing lenses. Presumably, all what would be needed for an integrated mirrorless system would be an HDMI connection on the backs to mount a viewfinder. I think that viewfinders using an HDMI connection are available off the shelf for video cameras.

So it would basically only be integration work of existing parts, like adapting the aerial photography cameras, etc... It certainly is doable, but the question remains whether there is sufficient demand to finance that work. That we don't know and we won't find out: even if a majority of forum members would be interested, the population on this forum is not representative of the whole market.

The iXU-R1000 works with a number of Rodenstock lenses and has HDMI connection already.

BR
Yair
Logged
Yair Shahar | Product Manager | Phase One - Cultural Heritage
e: ysh@phaseone.com |

landscapephoto

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 623
Re: Why think a mirrorless system is a great idea
« Reply #5 on: February 08, 2016, 09:46:29 am »

The iXU-R1000 works with a number of Rodenstock lenses and has HDMI connection already.

I could not find the HDMI connectivity in the specs. Besides, I think that camera can only be released from a computer bus system. But this is the cameras I was thinking about and Hasselblad also has something similar.
Logged

ErikKaffehr

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 11311
    • Echophoto
Re: Why think a mirrorless system is a great idea
« Reply #6 on: February 08, 2016, 02:57:13 pm »

Hi,

Just some comments about the issues you rise:

  • I was mostly thinking about a digital back
  • If you put an MFD Back on the Hasselblad 500 it will be battery dependent anyway.
  • A leaf shutter is not necessary, it is possible to use a focal plane shutter, like Alpa FPS or HCam B1
  • Batteri life on Sony A7 is in part depending on the small battery that is used. How many exposures can you get of one battery with an P or IQ-series back?
  • It just take a smart extension tube to use existing lenses.
  • Size will be similar to flipping mirror camera, but weight will be less.

Best regards
Erik

Are you thinking of a camera with a fixed sensor or a removable sensor?

Some big problems I can think of:
  • Battery dependence (think of a hasselblad 500-series and how reliable and sturdy they are without any kind of battery)
  • Battery usage (you'll _have_ to use the EVF in order to see something, so the back has to be turned on all the time)
  • you'll need new lenses and using legacy lenses isn'T going to be a pleasant experience. The distance is much bigger than Sony Mirrorless vs 35mm and in the end it'll be just as long and big as it currently is just with more parts in-between that will likely reduce or remove autofocus or lens communications
  • You'll need lenses with a leaf shutter => they're going to be very, very expensive. Think of how much a current leaf shutter lens costs compared to an old used lens with the same optical capabiliites


In case you were thinking of an integrated solution (sensor is a part of the camera)
  • If the electronic viewfinder fails you have to send in the whole camera, including sensor - while on a SLR-System with removable back you can keep the back, get a spare camera and you're ready to go
  • Cleaning the sensor isn't as easy as it is right now

In case you were thinking of a solution with a removable back

  • You need a new connection between the camera and the back to guarantee a high frame rate and resolution for the EVF - otherwise using it will be uncomfortable and focussing pretty much impossible. So you'll lose legacy support
  • The camera size won't change a lot if you have to account for the additional electronics, new connection ports, processors etc.

The reason why it has worked well for smaller formats is because they have small sensors that don't require a lot of power to work and they are always integrated solutions, the sensor is a part of the camera and everything is connected internally.
On the Sony mirrorless cameras people tend to get around 400 photos off of one full charge - now think about how many photos that would get you with a MF camera.

I think if you want something small, a little point and shoot will do the trick but it doesn't make much sense for a bigger sensor that has to be powered.
Logged
Erik Kaffehr
 

eronald

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 6642
    • My gallery on Instagram
Re: Why think a mirrorless system is a great idea
« Reply #7 on: February 08, 2016, 04:24:20 pm »

The iXU-R1000 works with a number of Rodenstock lenses and has HDMI connection already.

BR
Yair

Yair,

 Maybe someone should try the iXU-R1000 for tethering in the studio. It might be a different way of working. Or is it the same setup that is sold for repro?

Erik,
 Some CMOS sensor do not *need* a shutter for some types of exposure.  One could probably replace an H50C body with a piece of metal with a lensmount and  a few wires and have a perfectly working camera that can use eg. Hassy lenses  - or with a shorter piece of metal Alpa lenses, or with another piece of metal and some electronics, Canon shift lenses  I would bet that someone could make that piece of metal even now.

Edmund
Logged
If you appreciate my blog posts help me by following on https://instagram.com/edmundronald

yashima

  • Full Member
  • ***
  • Offline Offline
  • Posts: 154
Re: Why think a mirrorless system is a great idea
« Reply #8 on: February 08, 2016, 07:14:10 pm »


The first thing MF digital needs is good image processing engine. Image review and liveview are very washed out at the moment and I refuse to replace beautiful OVF of MF SLR with something like that.
Logged

narikin

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 1371
Re: Why think a mirrorless system is a great idea
« Reply #9 on: February 08, 2016, 09:57:36 pm »

The ALPA FPS and the HCam are forerunners in mirrorless MFD. Both have computer controlled focal plane shutters and aperture control for Canon lenses. The FPS can also control aperture on Contax 645 lenses with an adapter, I think.

The ALPA FPS has some advanced optical viewfinder for viewing and a very long calibrated focusing gear for focus. Best way to focus seems to be a laser rangefinder. The HCam B1 has a motorised sliding back.

Both the FPS and the HCam work well with Canon lenses but Rodenstocks and Schneiders are not fully integrated. A mirrorless camera would need to have full integration.

Live view essentially solves both "What You See is What You Get" viewing and gives optimal focusing capability with actual pixels magnification that ideally can be positioned anywhere.

Yes, I bought an FPS as I saw this coming with CMOS. (as many others did, I do not have ESP!)

It is a shame that Sony didn't build PDAF sites into the new 100mp MF sensor, that really would have taken it to another level, but I doubt Phase One pushed for this, as they have their XF system to promote, which can't take advantage of on-chip focus as yet, and isn't designed, physically, to do so. That would need a clean sheet new body and lens system, so is extremely unlikely. It will take someone else to do this - Pentax, or Fuji (there's rumors!), or Sony themselves, or even Alpa, with their Phase One tie-up.  We may not need actual Auto Focus, a good enough step is on chip focus confirmation at 100% through an EVF, which we are effectively at with HDMI out CMOS (HDMI is a far better signal than Live View - a night and day difference!).  Many people with 'mirrorless' bodies use & prefer manual lenses with magnified live view focus confirmation - note the number of Loxia and Otus lenses sold - and that's virtually here for MF digital, apart from needing a good compact HDMI EVF designed for still cameras, that talks/interacts with the IQ3-100, and I think we'll have that before the end of the year: Photokina...!



« Last Edit: February 08, 2016, 10:01:50 pm by narikin »
Logged

eronald

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 6642
    • My gallery on Instagram
Re: Why think a mirrorless system is a great idea
« Reply #10 on: February 08, 2016, 11:10:21 pm »

The one thing a modular system needs which Alpa lacks is a way to bus signals and power as you snap on modules.
The old low-bandwidth camera/back connection used by digibacks won't cut it.
Look at a video camera, they have so many high-bandwidth connectors one can imagine them being beer spigots in a bar

Edmund
Logged
If you appreciate my blog posts help me by following on https://instagram.com/edmundronald

jng

  • Full Member
  • ***
  • Offline Offline
  • Posts: 150
Re: Why I think a mirrorless system is a great idea
« Reply #11 on: February 08, 2016, 11:59:15 pm »

Well, until Phase or Hasselblad (or someone else) figures this out, this is the MFD mirrorless camera that I'll be using, complete with OVF!  ;)


Logged

ErikKaffehr

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 11311
    • Echophoto
Re: Why I think a mirrorless system is a great idea
« Reply #12 on: February 09, 2016, 12:02:40 am »

Hi,

It used to be said that SWC (and Biogon type lenses) don't play well with digital sensors, can you share your experience?

Best regards
Erik


Well, until Phase or Hasselblad (or someone else) figures this out, this is the MFD mirrorless camera that I'll be using, complete with OVF!  ;)
Logged
Erik Kaffehr
 

jng

  • Full Member
  • ***
  • Offline Offline
  • Posts: 150
Re: Why I think a mirrorless system is a great idea
« Reply #13 on: February 09, 2016, 12:38:41 am »

Hi,

It used to be said that SWC (and Biogon type lenses) don't play well with digital sensors, can you share your experience?

Best regards
Erik

All kidding aside...

The 38mm Biogon, which is a symmetrical lens design, indeed does not play well with digital sensors. From Wildi's Hasselblad manual, the oblique angles striking the sensor glass result in unequal light paths from center to corner. In terms of my own experience using the SWC/Biogon mated to the 60 Mp Dalsa CCD sensor, I find that stopping down to f/16 pulls the corners in nicely, consistent with a previous LL forum post. Together with a LCC adjustment to take care of color cast issues, the images are actually quite nice. But f/16 at ISO50 can be a little restrictive, especially when out shooting at dawn or dusk (I never thought I'd find 2 minute exposures to be limiting when I picked up the IQ160 - who knew?). For greater flexibility and sharpness corner-to-corner, I'm favoring my recently acquired 40mm f/4 IF CFE, which is a beast to say the least. But I'm not yet willing to let go of the SWC/Biogon - it can't be beat in terms of portability and lack of distortion.

Cheers,

John
Logged

ErikKaffehr

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 11311
    • Echophoto
Re: Why I think a mirrorless system is a great idea
« Reply #14 on: February 09, 2016, 12:51:36 am »

Hi,

Thanks for info. There is an additional issue with Biogon type lenses and that is astigmatism, induced by the cover glass of the sensor.

It is discussed on page 12 of this document from Zeiss: http://lenspire.zeiss.com/en/wp-content/uploads/sites/2/2015/09/en_CLB41_Nasse_LensNames_Distagon.pdf

A screendump from the articles is enclosed below.

It is my understanding that the astigmatism can be compensated in the optical calculations and modern glass is normally calculated with extra optical glass in the light path, but older lenses were calculated for film.

Regarding lens sizes, I have the 40/4 CFE (not the IF version) and it is very large.

Best regards
Erik



All kidding aside...

The 38mm Biogon, which is a symmetrical lens design, indeed does not play well with digital sensors. From Wildi's Hasselblad manual, the oblique angles striking the sensor glass result in unequal light paths from center to corner. In terms of my own experience using the SWC/Biogon mated to the 60 Mp Dalsa CCD sensor, I find that stopping down to f/16 pulls the corners in nicely, consistent with a previous LL forum post. Together with a LCC adjustment to take care of color cast issues, the images are actually quite nice. But f/16 at ISO50 can be a little restrictive, especially when out shooting at dawn or dusk (I never thought I'd find 2 minute exposures to be limiting when I picked up the IQ160 - who knew?). For greater flexibility and sharpness corner-to-corner, I'm favoring my recently acquired 40mm f/4 IF CFE, which is a beast to say the least. But I'm not yet willing to let go of the SWC/Biogon - it can't be beat in terms of portability and lack of distortion.

Cheers,

John
Logged
Erik Kaffehr
 

jng

  • Full Member
  • ***
  • Offline Offline
  • Posts: 150
Re: Why I think a mirrorless system is a great idea
« Reply #15 on: February 09, 2016, 01:22:06 am »

Thanks for the article and additional information. I wasn't aware of the effect of the sensor glass on astigmatism. Wildi in his book (7th edition, chapter 11) states that the additional distance imposed on the oblique light beams by the sensor cover glass causes spherical aberration, resulting in field curvature. In any case it all cleans up pretty well by f/16 and unlike the 40mm IF mounted on a 500 series body plus back, it's possible to use the SWC/MFDB hand held.


Sent from my iPad using Tapatalk
Logged

ErikKaffehr

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 11311
    • Echophoto
Re: Why I think a mirrorless system is a great idea
« Reply #16 on: February 09, 2016, 01:43:05 am »

Hi,

You can also check this article:

http://www.lensrentals.com/blog/2014/06/sensor-stack-thickness-when-does-it-matter

I would be in doubt about a flat glass just in front of the sensor would cause field curvature.

Best regards
Erik




Thanks for the article and additional information. I wasn't aware of the effect of the sensor glass on astigmatism. Wildi in his book (7th edition, chapter 11) states that the additional distance imposed on the oblique light beams by the sensor cover glass causes spherical aberration, resulting in field curvature. In any case it all cleans up pretty well by f/16 and unlike the 40mm IF mounted on a 500 series body plus back, it's possible to use the SWC/MFDB hand held.


Sent from my iPad using Tapatalk
Logged
Erik Kaffehr
 

jng

  • Full Member
  • ***
  • Offline Offline
  • Posts: 150
Re: Why I think a mirrorless system is a great idea
« Reply #17 on: February 09, 2016, 02:56:48 am »

My admittedly limited understanding is that the path of the light rays striking at an oblique angle (i.e., at the corners) will have a different path length than those at the center due to refraction through the cover glass. A thicker glass will accentuate the effect assuming the lens was designed for film (which the Biogon certainly was!). I think this is what we're seeing in the mtf charts in the link you sent (thanks for this by the way). Anyway it's been years decades since I've studied optics in college physics so I'll stop there before someone revokes my passing grade!


Sent from my iPad using Tapatalk
« Last Edit: February 09, 2016, 03:06:03 am by jng »
Logged

hjulenissen

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 2051
Re: Why I think a mirrorless system is a great idea
« Reply #18 on: February 09, 2016, 03:16:00 am »

Some of the benefits of DSLR seems to be wasted on the typical larger-sensor crowd. They seem to be typically working at a slower pace where fast tracking PDAF is less relevant, where 100 images per "session" may be sufficient, where wide-angle lenses are really important and where any increase in image quality is worth a lot of pain. It would seem that many of those people would really like the flexibility of movements, though. Is it sensible to make a high-quality, compact, highly integrated mirrorless digital medium format camera with some degree of movement?

So what is the competitive advantages that big players like Canon and friends have been enjoying for the last decade or more?

They have a proprietary system that spans from consumer to professional. Thus, they get huge number of sold units (where tech can be reused), the get user lock-in, the products they design are complex (thus needing a big organization), the products rely on some specialized components (primarily sensor) that either have to be developed in-house or purchased on a more or less monopolized market. Canon presumably have a gazillion software developers, hardware engineers, testers, what not, developing a set of functionality that is shared among several products of a generation and refined/developed from one generation to the next. As long as Canon/Nikon/... does not choose to go into the MF space, and MF is really small, it is going to be hard for the niche MF guys to hire similar numbers of developers, simply because they do not have the massive portfolio/sales figures to cover the cost.

I guess that in the "good old days", it was possible for a mechanical engineer to hook up with an optical engineer and design a good camera in their garage. I wonder if we will get back to that (sort of) when Sony dominates image sensor manufacture at all sensor sizes and cathegories, and embedded development consists of picking Android tablet-type components and writing an "app" on top of that.

-h
Logged
Pages: [1]   Go Up