# Why have full frame DSLRs "only" full frame sensor and not bigger?



## climber (Jul 11, 2014)

I have one technical question for those of you, who understand those things well.

Full frame format is 36 x 24 mm large. But we know that larger sensor gives better image quality. (here I speak about physical size and not about number of MP)

So, what is the reason that manufacturers don't make DSLRs with a slightly bigger sensor? I don't think that they should be as big as medium format, but something in between let say. Is an obstacle for that in lenses? Should be lenses entirely redesigned, if they want put in a larger sensor?

Thanks for making me smarter


----------



## privatebydesign (Jul 11, 2014)

A lot of "medium format" sensors are not much bigger than 135 (FF).

The mirror box and flange distances won't allow much/any bigger sensors with current lenses.

A new line of lenses would be very expensive.

The market would be small, lets face it the vast majority if DSLR's are still 1.5/1.6 crop cameras.


----------



## Mt Spokane Photography (Jul 11, 2014)

climber said:


> I have one technical question for those of you, who understand those things well.
> 
> Full frame format is 36 x 24 mm large. But we know that larger sensor gives better image quality. (here I speak about physical size and not about number of MP)
> 
> ...




Camera makers do not make a slightly bigger sensor because it means all new bodies and lenses. The current 35mm system is carefully matched. If you had a bigger sensor, everything needs to get larger, and the mirror would hit the back of the lens.


With a mirrorless system, it would be possible to make slightly larger sensors, if you did not mind the poor quality image at the edges, or having it cut off entirely by the lens.


----------



## Don Haines (Jul 11, 2014)

The way I see it, it's not worth making anything larger than FF unless you make something significantly larger than FF...at least 4 times the sensor area.

Anything larger, even a few percent, means a whole new set of lenses and they will be expensive. You can depend on technology being updated far more often in the smaller bodies, so they will usually be ahead of MF... so if you want MF to be better, you have to give it enough sensor area to really make it worthwhile...


----------



## Lightmaster (Jul 11, 2014)

well yes lenses have to be designed.
and it´s expensive.

but i would be interested in a affordable fixed zoom lens medium format camera. 

like a sony RX1 on steroids.


----------



## privatebydesign (Jul 11, 2014)

Lightmaster said:


> well yes lenses have to be designed.
> and it´s expensive.
> 
> but i would be interested in a affordable fixed zoom lens medium format camera.
> ...



You and about 12 other people, which would put it at about 100x affordable!


----------



## Mt Spokane Photography (Jul 11, 2014)

privatebydesign said:


> Lightmaster said:
> 
> 
> > well yes lenses have to be designed.
> ...




The key word is "affordable" Bill Gates might consider $200K affordable, but I don't.


----------



## mrsfotografie (Jul 11, 2014)

climber said:


> I have one technical question for those of you, who understand those things well.
> 
> Full frame format is 36 x 24 mm large. But we know that larger sensor gives better image quality. (here I speak about physical size and not about number of MP)
> 
> ...



The well known company with the red dot makes such a camera:

http://us.leica-camera.com/Photography/S-System/Leica-S 

It _is_ medium format too so bring lots and lots of $$$$$$$$$$$$$$$$$$$$$$$$$$.


----------



## Tugela (Jul 12, 2014)

There is also the small issue of very few people having a need for a larger sensor. If they did make cameras like that, they would not sell many.


----------



## Famateur (Jul 12, 2014)

One other thing to mention, the larger the sensor, the fewer sensors yielded per silicon wafer. This, and the increased waste (wafers are round, so the larger the sensor, the larger the wasted fragments on the edges) translates into much higher cost for sensor production.

Someone feel free to correct me if I'm mistaken on this...


----------



## 9VIII (Jul 12, 2014)

Famateur said:


> One other thing to mention, the larger the sensor, the fewer sensors yielded per silicon wafer. This, and the increased waste (wafers are round, so the larger the sensor, the larger the wasted fragments on the edges) translates into much higher cost for sensor production.
> 
> Someone feel free to correct me if I'm mistaken on this...



That's correct, but defects are equally concerning.
The reason it gets ridiculous really fast is you're pretty much guaranteed to have a certain number of defects per wafer (usually caused by dust), so in the hypothetical case that you get ten defects on a wafer but you're only producing really small sensors, all ten of those defects will only cause you to throw out a very small portion of the wafer.
If you were to try to make a sensor so big that you could only fit four on every wafer, at ten defects per wafer you'd pretty much be wasting your time as the chances of getting a single functional sensor out of it would be very low.
I remember reading a comment that Canon had to drastically improve air quality when moving to full frame production.


----------



## tolusina (Jul 12, 2014)

Famateur said:


> ......(wafers are round, so the larger the sensor, the larger the wasted fragments on the edges) ........


Hmm, then why not round sensors, round like lens elements are round. Waste can then be transferred to the end user should they choose to print round. 

Or, why not square sensors, 36mm on a side, would that still fit in the same image circle as 24 x 36? Crop later if you want landscape or portrait.


----------



## Spectrum (Jul 12, 2014)

tolusina said:


> Famateur said:
> 
> 
> > ......(wafers are round, so the larger the sensor, the larger the wasted fragments on the edges) ........
> ...



That was my thought. Other than the bottom line, why not put a round sensor in some cameras? The image circle of lenses is round and all the current sensors capture a rectangular section of it. I know it would be a niche item, but that would be perfect for circular fisheye lenses. Or better yet, add a switch to go between circular and rectangular formats.


----------



## privatebydesign (Jul 12, 2014)

This comes up regularly.

Cutting round sensors out of a bigger round sensor is way more wasteful than squares or rectangles that can be cut edge to edge.

You can't use a bigger than 24mm on the short side sensor for our lenses image circle, the image below has the image circle our lenses make, the pink rectangle is our FF sensor, the big square is what people think they could get, the small square is what you can actually cover.

The 24mm short side is dictated by the image circle and flange distance needed to clear the mirror (don't start on mirrorless!). The guys that designed this stuff did actually think about it first.


----------



## mr_hyde (Jul 12, 2014)

As already mentioned,

a round sensor would not help as one would waste a lot of space on a silicon wafer as chips have to be cut in squares or rectangles. 

And a 200 mm or 300 mm (which are typical wafer diameters) sensor would not really make sense nor could somebody afford it. In addition to that one would probably see huge variations over the entire wafer/image.


----------



## LetTheRightLensIn (Jul 12, 2014)

tolusina said:


> Famateur said:
> 
> 
> > ......(wafers are round, so the larger the sensor, the larger the wasted fragments on the edges) ........
> ...



They were also limited by how many MP they could process in a certain amount of time. People tend to shoot other than square more often so you'd be wasting res more often than not.

Plus film did it that way so you still run into problem of a taller mirror (from wide to square) hitting back of many lenses. In films days they probably chose rectangle since it was a decent average shape and you didn't have to bother with getting you square images and trying to cut them as much and plsu film would've cost more per shot and it was bad enough as it was.


----------



## Don Haines (Jul 12, 2014)

dilbert said:


> Why don't you have round sensors?
> 
> Where would you display a round picture?
> On your round monitor?
> ...



I could pass it around on facebook


----------



## 9VIII (Jul 12, 2014)

dilbert said:


> climber said:
> 
> 
> > I have one technical question for those of you, who understand those things well.
> ...



I still like the idea of a sensor that covers the entire image circle (with "circular" image lenses) just so we can get rid of the whole concept of "portrait" and "landscape" orientation while holding the camera. It allows for conversion from one to the other on the fly in post.
A waste of silicon? Sure, but it's not like we're saving humanity with our cameras as it is.


----------



## Orangutan (Jul 12, 2014)

9VIII said:


> I still like the idea of a sensor that covers the entire image circle (with "circular" image lenses) just so we can get rid of the whole concept of "portrait" and "landscape" orientation while holding the camera. It allows for conversion from one to the other on the fly in post.



Exactly. And also get rid of those stupid vertical grips.


----------

