I was assuming the same pixel pitch when talking about comparing formats, as well as lens equivalency. Once you bring in other differing factors, it obviously gets more complicated.
douglasf13 wrote:
I was assuming the same pixel pitch when talking about comparing formats, as well as lens equivalency. Once you bring in other differing factors, it obviously gets more complicated.
Yeah, but that's the catch, isn't it? You don't get the same pixel pitch with different sensor sizes. For instance a FF camera with the same pixel pitch as the NEX-7 would be a 54 megapixel camera. Or the other way, if the NEX-7 would have the same pixel pitch as the 24 megapixel D3X, it would have been a a 10.5 megapixel camera.
And the lens equivalency is problematic as well. First unless you keep the pixel pitch constant, you're asking the lens to resolve more - which it will do with reduced microcontrast (i.e. MTF). Second as you use a smaller format you'll have to use wider lenses to get the same angle of view and a high performance 100mm lens is far easier to construct than a high performance 12mm lens.
denoir wrote:
Yeah, but that's the catch, isn't it? You don't get the same pixel pitch with different sensor sizes. For instance a FF camera with the same pixel pitch as the NEX-7 would be a 54 megapixel camera. Or the other way, if the NEX-7 would have the same pixel pitch as the 24 megapixel D3X, it would have been a a 10.5 megapixel camera.
And the lens equivalency is problematic as well. First unless you keep the pixel pitch constant, you're asking the lens to resolve more - which it will do with reduced microcontrast (i.e. MTF). Second as you use a smaller format you'll have to use wider lenses to get the same angle of view and a high performance 100mm lens is far easier to construct than a high performance 12mm lens. ...Show more →
Oh, absolutely. That is certainly the catch, and the further the formats are from each other, the more difficult that it gets.
I've shot a lot of aps-c and 135 digital (with relatively similar pixel pitches,) and the difference between the two isn't that noticeable to me, if they're both printed at sizes that correlate to the size differences. If they're printed at the same size of, say, 13x19, the difference still isn't astounding, but it is perceptible and gets worse as the print size gets larger.
However, I would imagine that, if one compared two sensors that we're a bit further away, say, m4/3 vs. an IQ180, then things really start to stretch.
BTW, I have a question about lens design. I get that a 100mm lens is much easier to design than a 12mm lens, but, does the smaller format of the 12mm lens not influence the ease at which the lens is made? Is it not easier to make a 12mm lens for m4/3 vs. a 12mm lens for 6x6? I assumed that the ease in creating these designs would be somewhat format dependent.
carstenw wrote:
Yes it is easier. You can leave out the corners, which is the hard part
Ha, true! But I guess I'm talking more about making a 12mm lens in proportion to the size of each sensor. i.e. is it really as hard to design a good 20mm lens for m4/3 as it is to design a good 20mm lens for 6x6?? I can't imagine that being the case.
douglasf13 wrote:
I've shot a lot of aps-c and 135 digital (with relatively similar pixel pitches,) and the difference between the two isn't that noticeable to me, if they're both printed at sizes that correlate to the size differences. If they're printed at the same size of, say, 13x19, the difference still isn't astounding, but it is perceptible and gets worse as the print size gets larger.
I've got two pairs of FF/ASP-C cameras that use the same lenses, namely the 5DII and the 7D as well as the M9 and NEX-C3 (with M-mount adapter). What I can say is that I do have a problem with using the same lenses. On crop they just look 'wrong' and very flat. You don't get the same interesting things going on in the edges & corners and the microcontrast is just off. At the same time, I have no problem with my ASP-C X1 (fixed lens) and I don't feel that I'm constantly reminded that it's a crop sensor.
So I think at least to some degree it's a question of matching a lens to the image format it was designed for. I'm guessing that if I used medium format lenses on 35mm FF, I'd have the same issue as when using lenses designed for 35mm FF on ASP-C. I'm also guessing that I would not be as acutely aware of the differences had I not been able to use the same lenses on both crop and FF.
BTW, I have a question about lens design. I get that a 100mm lens is much easier to design than a 12mm lens, but, does the smaller format of the 12mm lens not influence the ease at which the lens is made? Is it not easier to make a 12mm lens for m4/3 vs. a 12mm lens for 6x6? I assumed that the ease in creating these designs would be somewhat format dependent.
Sure, to some extent. Since you are covering a smaller image circle you can use a lot less glass and it gets cheaper. A large piece of high quality optical glass will be much more expensive than a small piece. So you can splurge on materials when building a small lens.
In terms of design, it's difficult to answer. A lens for a larger format doesn't have to be as good as one for a smaller format and usually the MTF curves for medium format glass look worse than equivalent curves for 35mm glass (in the same price range). I say 'usually' because there are quite a few exceptions.
Lenses for smaller formats also tend to be more complex in terms of number of elements, but again I'm guessing it's primarily because you can get away with much more on larger formats.
Luka, I think we're really just getting into personal taste, at that point. I know a lot of shooters actually like shooting larger format lenses on smaller formats, because it avoids all of the edge issues that you prefer. Maybe you should buy some NEX lenses?
douglasf13 wrote:
Ha, true! But I guess I'm talking more about making a 12mm lens in proportion to the size of each sensor. i.e. is it really as hard to design a good 20mm lens for m4/3 as it is to design a good 20mm lens for 6x6?? I can't imagine that being the case.
No, of course not. After all, the LX3 has a pretty darn good 5 mm zoom lens on it that with a whole camera attached costs about $350. You won't get a 5mm lens for 6x6 at any price.
Lens designs scale. In fact, scaling lens designs is often a starting point for a new design. But only a starting point. In general the larger the format (up to a point) the easier it will be to manufacture a given quality lens as far as tolerances go. It will cost you more in materials of course.
Other design parameters complicated the issue. A compact camera can put lens elements arbitrarily close to the sensor, interchangeable not as close, with a mirror even further. A wide angle 4x5 lens for film can be very close in a relative sense.
If you instead look at what is available there are far more of the highest quality lenses available in the larger formats. Theoretical format discussions are kind of senseless if you can't get anyone to manufacture the lens you want!
the shorter flange distance associated with smaller formats often makes the design of lenses easier as well, though obviously this isn't true for aps-c versus FF with the same mount.
wayne: sign me up for that pre-order list too. hopefully X is small, but i doubt it.
douglasf13 wrote:
Luka, I think we're really just getting into personal preference, at that point. I know a lot of shooters actually like shooting larger format lenses on smaller formats, because it avoids all of the edge issues that you prefer. Maybe you should buy some NEX lenses?
The problem being that there aren't any good NEX lenses. Even the new Zeiss 24/1.8 does not seem all that impressive if one goes by the MTF charts. I mean it doesn't look bad, but not interesting enough for me to get it - especially as I only got my NEX as an M-mount backup camera. I have no actual interest in the system except for that purpose. I had some hopes that I might be able to put it to serious use (me likes live view), but I've concluded it's too much of a compromise.
As for using larger format lenses on a smaller format, you gain consistency at edges/corners and lose micro contrast across the frame. Take your pick.
Personally, as I said, I prefer to use lenses the way the designers intended them to be used. I've seen too many instances of a great lens turning into a mediocre one on a different format/body. It's rather interesting but usually not something you want. Take the 21 Distagon that is so popular around here - it's fantastic on a FF camera. Put it on a cropper and it suddenly becomes mediocre. It's still sharp and produces nice colors, but the micro contrast is wrong. Stuff that gets accentuated by a contrast boost (fine detail primarily) on FF doesn't on crop and you end up with a different rendering altogether.
Surely that is just a product of the different sensor tech, pixel pitch and sensor toppings, and not the sensor size, no? If you took the ZM 21 and shot it on your M9, and then just cropped out an aps-c portion out of the same image, wouldn't the crop still have the same micro contrast as the whole frame?
douglasf13 wrote:
Surely that is just a product of the different sensor tech, pixel pitch and sensor toppings, and not the sensor size, no? If you took the ZM 21 and shot it on your M9, and then just cropped out an aps-c portion out of the same image, wouldn't the crop still have the same microcontrast?
Yep, absolutely, it's primarily a product of the pixel pitch and possibly the AA filter.
And in practice pixel pitch is correlated to sensor size with crop sensors having higher pixel densities.
denoir wrote:
Yep, absolutely, it's primarily a product of the pixel pitch and possibly the AA filter.
And in practice pixel pitch is correlated to sensor size with crop sensors having higher pixel densities.
Sure, but it's not as if the pixels on my 12mp A700 or 14mp NEX-5 were THAT much larger than my A900. I'm not convinced that would be enough to do it. Maybe with the NEX-7 vs. A900 it would, although I'll primarily be using the ZM 35/2.8 on the NEX-7, which has great resolution.
The NEX-7 is very interesting, especially with the Zeiss 24/1.8 lens. It's certainly not a full blown system with a lot of lenses and accessories, but if someone is willing to accept its limitations it looks like a neat product that could even serve as a primary camera. I personally like the small size and EVF for manual focus assist and manual focus during videos. To be honest, the idea of exchanging a backpack full of Zeiss and L primes for this little package sounds refreshing. One can get a heart-attack when you add up the cost that goes into FF.
douglasf13 wrote:
Sure, but it's not as if the pixels on my 12mp A700 or 14mp NEX-5 were THAT much larger than my A900. I'm not convinced that would be enough to do it. Maybe with the NEX-7 vs. A900 it would,
You've got AA filters involved as well, which the calculations above don't take into consideration.
although I'll primarily be using the ZM 35/2.8 on the NEX-7, which has great resolution.
It's not primarily a question of resolution but of micro contrast at a given spatial frequency. As the spatial frequency increases, the micro contrast drops. So on the NEX-7 you'd be pushing the lens to do 60 lp/mm where on your A900 you only would have asked for 40 lp/mm. And there is a real difference there.
Here's an MTF example (taken from the Zeiss MTF whitepaper):
pkupcik wrote:
The NEX-7 is very interesting, especially with the Zeiss 24/1.8 lens. It's certainly not a full blown system with a lot of lenses and accessories, but if someone is willing to accept its limitations it looks like a neat product that could even serve as a primary camera. I personally like the small size and EVF for manual focus assist and manual focus during videos. To be honest, the idea of exchanging a backpack full of Zeiss and L primes for this little package sounds refreshing. One can get a heart-attack when you add up the cost that goes into FF....Show more →
But to play devils advocate, the cost of the NEX 7 with the Zeiss 24 1.8 is really not that far away than a FF Sony. The NEX 7 is also going to be expensive to feed it the quality glass it's going to require to really take advantage of it's high density sensor. Thus, I don't see a cost advantage at all. Size and use factors are where it might have advantages.
