SONY ALPH A A750

[Greg Beetham]

If it comes true there will be a few happy campers, but I think there will be quite a few more not so happy ones, (it's got to be more expensive surely), especially if the video capability interferes with it's still taking attributes in any way. There will probably be no sound, unless Sony provides an isolated boom mike, so it can't pick up the focus motor noises etc.
It might only have LV on the rear screen perhaps, from the main sensor, and that is a copy of what is going to the memory card....maybe.
Greg

[David Kilpatrick]

The latest rumours refer to a pellicle mirror, and boy are the dPreview posters in a mess over this. I can not post there to put them out of their misery, as no-one seems to understand anything about this at all!

First of all, pellicle and 'thin film' are not interchangeable terms. Pellicle mirrors are specifically a stretched plastic film with as close to zero thickness as possible, vacuum coated with a semi-silvered mirror on the front face. This can be done with glass, but the glass has a thickness and a refractive index which means that when placed at 45° in the image ray path, it causes loss of sharpness by adding some unwanted colour aberration. The pellicle film avoids this. 'Thin film' is a different technology and refers to the coating, which can be applied to glass or plastic; it does not refer to the plastic film used for the pellicle mirror.

Secondly, it is not possible to have an exposed sensor for live view along with a pellicle mirror for an OVF. Light can enter through the eyepiece and degrade the image (which is why pellicle mirror cameras use a blind to cover the focusing screen or cap the eyepiece during exposure). Even having the focusing screen exposed as a surface in the darkchamber is a bad design feature, normally a matt black shutter blind will cover it. Clearly that can not be done for video filming through the finder.

Sony may have been able to create a design using polarisation to prevent incoming light through the eyepiece, or they may have been able to build a 24fps eyepiece shutter into the OVF to synchronise with the video capture frequency; or they may have another secret I can't guess at. But they are very unlikely to have a normal pellicle mirror OVF together with an uncovered sensor.

Next item - phase detect AF. Since this requires a secondary mirror in normal use, it's not possible with a pellicle mirror using existing designs. This secondary mirror does not have to be attached to the main mirror, and could be a periscope system (like Corfield Periflex but operating from the well of the camera, not the top). However, this could not be in place during video filming as it would be in front of the sensor.

Many years ago when Polaroid made a unique digital camera, they used a design I had already sketched as a teenager for SLRs - a straight through optical path for the viewfinder, but the sensor (film!) off to the side and a 45 degree mirror aiming the image at the sensor. With film it would have meant a mirror image. With a sensor, that is irrelevant; it just gets turned the right way digitally. So a pellicle mirror and a radical rethink could be possible, with the image path to the sensor unimpeded, and the AF/viewfinder image path shared instead. All the rubbish - metering cells, AF secondary mirror and cells, focusing screen, image inverting optics, eyepiece - would live behind the mirror; the sensor would live where the focusing screen is in current SLRs.

A final possibility is that the camera has no OVF, and the pellicle mirror serves only to feed an AF phase detect sensor array. Since it would be a full sized mirror, the AF array could be much larger ad cover the entire frame - even more points, and wider spread, than the Nikon MultiCam 3500. The sensor would feed an EVF of very high quality placed as for a normal prism eyepiece, so the camera would look much like a regular DSLR. The beamsplitter mirror could remain in place for video with continuous AF, and for action still shooting with the same - OR it could flip like a regular mirror, out of the way, for one-shot AF with zero loss of light to the sensor and zero loss of image quality (no mirror to pass through).

This last solution would be how I would design such a DSLR if an EVF was felt acceptable to replace OVF entirely.

Anyway, the mention of pellicle mirror has got people thinking Canon EOS RTS style - mirror used for OVF - without considering other ways in which a pellicle mirror could be used, such as this last option which solves the video AF problem.

Finally, there is no reason why a dual mirror assembly could not be used, with a regular SLR/secondary AF system for still shooting which rises and locks under the focus screen (as normal) when video shooting. This leaves room for separate hinged pellicle mirror to move into place feeding the AF sensor only, and covering the entire sensor field. In this mode video with phase detect AF would be possible, but the normal DSLR operation would remain unaffected.

David

[mike2008]

The idea of having the best of all worlds in terms of PD AF, good high iso etc. with a flippable pellicle and no OVF seems like a very interesting idea. There is a new high res EVF just released by Seiko/Epson, so perhaps there is something to this plan... See here: http://www.eetasia.com/ART_8800590564_4 ... 56f795.HTM

What is missing though is more silent AF SSM lenses, particularly wide ones... You could imagine the marketing department having a field-day with this though, as many people would need to buy new ssm lenses if they wanted to use video.

[bfitzgerald]

The idea of no OVF seems like a not very good idea to me!
It's too risky in a segment such as the A700, which is not consumer based, but aimed at "photographers"
I don't see any major desire from folks I know to move to EVF based systems, esp so for an add on feature such as video.

If Sony do decide to play experiments with this type of camera, they will find themselves in a whole world of trouble, the market is simply not ready for EVF's esp not ready for semi pro level machine in this stable.

[peterottaway]

To Barry I would say that with the wind around here at the moment landscape is very much a high speed if not a high fps game.

With what Olaf was saying about high fps for equestrian events, I think it all depends on your shooting style and what sort of horse events you are trying to cover. Most of my experience is with polocross and usually I have found some anticipation and single frame shooting works for me. Some years back Perth hosted the Womens World Hockey Championship and I managed to get a day off to shoot some games. Apart from the last few minutes of a game that was heading for a draw and both teams needed the win , I was using single frame for the matches. Yes this was in film days but I was using two cameras and a bag full of film.

[bfitzgerald]

I've shot equestrian events with a 3fps Km5d, sure more fps is better, but few really need 10fps
So nah, I ain't convinced about a need for ultra high FPS models. Might be some market for it, in fact there is. But not a DSLR like the A7xx.

The main issue is the viewfinder, IMO it's a poor trade to get AF in video by giving up the OVF.

Why not just work on getting contrast AF better and faster? Seems a lot easier. If Sony are planning something big and a mega revolution, they had better do it well, or face some serious flak. This all seems a bit too far fetched, why not just make a really good camera, with sensor LV, and slap a contrast AF video mode in? So 01af is right, I am narrow minded, because I ain't interested in a video camera, just a stills one done really well! What's so bad about that then?? lol

[bossel]

Now what about that 1/2 or 2/3 stops of lights you use by having a semi transparent mirror?

Maybe the eyepiece sensor is high-resolution and the final pic is a merged one from the two sensors?

[David Kilpatrick]

EVF feed from main sensor. The A550 proves it can be done. No eyepiece sensor.

David

[bossel]

The A550 has no significant loss of light due to a semi-transparent mirror!

Then they should dump the mirror completely and find a super fast way for contrast based AF & metering. Could this be done with some extra circuitery on the main sensor? Kind of a hybrid sensor, where a few pixels here and there are sacrificed for AF cirquitery...

Still leaves open the issue of the OVF. Must be a helluva EVF to convince most of us.

[Dusty]

Vague rumors about what it might have when no-one has seen it yet. And it starts arguments about how good/bad that design is.

I'm with Barry in that I want a still camera, video in a DSLR is of no interest to me. I'm with Olaf in that high frame rates - IF they don't compromise something else - are great. I got by with a 2FPS power winder in MD film cameras, but I was also paying for film! Since digital pics are essentially free, more FPS mean I may get some better action shots.

I've rarely used MLU, but did like that option, but it's not a make or break feature for me. Then again, autofocus is a gimmick I'm forced to pay for and don't need.

An EVF is like electric windows in the car - just something else to break that also cost us money to have. The manual (OVF) method is pretty foolproof.

High ISO is another feature I only want for specialized functions and don't want to sacrifice my low ISO quality of ability to use it. It's one fo the great negatives of the 550 for me.

Perhaps Sony will come up with an expanded line of very similar models with different sensors for different needs - a 750 that's just an updated 700, a 780 that has all the video gizmos, and a 600 series that offers low ISO, MLU, essentially a 700 series made for the landscape shooter or studio shooter.

Man do I wish I was running Sony's DSLR division!

Dusty

[bossel]

Man do I wish I was running Sony's DSLR division!

Man am I happy you're not! No AF, no Video, no MLU, no power-windows. You just slashed 95% of Sonys sales

[Dusty]

Man do I wish I was running Sony's DSLR division!

Man am I happy you're not! No AF, no Video, no MLU, no power-windows. You just slashed 95% of Sonys sales

Well, it's too late to do away with AF, and I would put MLU in all but the entry series. Video would have it's own separate series, or reserved section in a series - e.g. 750 would be sans video, 780 with it. I'd put in a 400 series as well as a 600 series, and make sure that every non-beginner system had Program Shift. (Beginners want P mode to do everything, and often get confused when they have any manual control in P mode!)

I would try to get a sensor in an old x700 just to see how it would do!

But you're right in that I'd stay away from power windows!

I think that if you build modular systems, and just swap a few sensors and firmware tweaks, you can economically produce cameras that will appeal to a wider array of photographers for very low cost.

What if you had a 750 that was essentially a 700 with faster frame rates and better sensor - maybe 16 MPs and better high ISO response. Then you also had the choice of a 740 that was the same except for a base ISO of 25 that tops out at 1600? What else is missing, except video? The 400 series could be a 700 'lite' - plastic instead of mag alloy body, slower frame rates, but same features and sensors.

I would also expand the FF line-ups, but with all higher end features.

Maybe we need a new subject for all of this. Of even a new category: Design The Next Model SONY DSLR

Dusty


Perhaps the 600 series would be all video gizmo'ed up.

[bfitzgerald]

Interesting, reading through some of my late 80's/early 90's books.

Describing AF as a "useful tool" but no more than that, aka not bulletproof. Have to say AF was a major deal back then, and it's well stamped into users minds. I sometimes like a play on older MF bodies, with their nice viewfinders and even a range finder. Sadly most modern bodies are not too great for MF, still.

I am with Dusty in that it's pretty much essential that we retain "camera ist" designs, and that there be no compromises made simply for adding non essential stuff like video. I don't care much about it, but I think they have to put it in, don't even care if it's non AF crippled video, these are cameras, and need to serve the market for those users. Once you start trying to make hybrid type cameras that try to be good cameras and video machines, the danger is master of none. Whilst some video people like stills photos, and some photo people like video..IMO I have not met that many of them. Most stick to their own interest, they share only a few areas, and are very different in their final presentation. Stuffing up a DSLR to please a soccer mom, isn't my idea of fun...

[01af]

... but few really need 10 fps.

Actually, many do. Especially when it comes in an affordable package. Apart from that, what's your problem anyway? No-one will force you to keep shooting at 10 fps all the times.

... IMO it's a poor trade to get AF in video by giving up the OVF.

And just why do you keep fantasising about giving up the optical viewfinder?

-- Olaf

[bfitzgerald]

01af sorry but you are not very convincing.
I can see how some action shooters might want 10fps, or even more, but not everyone does action photography, and I will put money down right now, that they are a minority of shooters, and very few really need that speed. I don't have a problem with it, just it's a tad simplistic to think a camera is just "FPS" and nothing more, it's one of many areas. If only Sony put as much effort into their last 2 models as they did FPS, and we might have got somewhere.

I have made my preference for an optical finder well known, it's simply that, my own personal view. I have tried better EVF's, including the G1, and IMO it's not a patch on a good OVF. Not bad, but too much lag in low light, flickering problems with indoor lighting, and relatively poor DR in the VF, esp notable lack of shadow details. It might suit some, but it's far from what most would demand. It's not a fantasy, it's just a viewpoint. Not everyone shares your desire to have an EVF shoved on them.