[everydaylife]

Having only ever used apsc I am wondering what the difference is between an image taken on FF and an image taken on apsc. My lenses are all FF compatible. Maybe there is a question mark about my DA" 200 although I remember that when it came out some complained that it was not a new design but only an FA" with new coatings and if that is the case then it should be FF compatible.

Would I be correct in thinking that on FF the field of view would be wider, edges would be softer and that there would be more vignetting? My 200mm lens have the same magnification but would it have the field of view of a 135mm on FF? How much better will the 77ltd or Fa" 85 be for portraits.

[MadMathMind]

In general, yes, you are getting the sweet spot of an FF lens on an APS-C camera. It's probably one reason all those old lenses perform so well. That said, some lenses are sharp corner to corner. At wider apertures, that may not be true, but some of that will be masked by the lower DoF on full frame.

At this point, it's hard to say because the only way to test a Pentax lens on a full frame digital camera is to use an adapter on Canon or Nikon. I think it's possible to use optics-free adapters for Canon because the flange distance is shorter than Pentax's. Nikon's is longer, so corrective optics are needed (and then you can't really gauge the lens itself because who knows what the adapter is doing to the image). One can throw the lenses on film cameras to assess whether they cover the full frame image circle, but the digital performance from film is impossible to assess. As a result, it's really uncertain how certain lenses are going to do. We'll just have to wait and see.

[Adam]

In general, yes, you are getting the sweet spot of an FF lens on an APS-C camera. It's probably one reason all those old lenses perform so well. That said, some lenses are sharp corner to corner. At wider apertures, that may not be true, but some of that will be masked by the lower DoF on full frame.

At this point, it's hard to say because the only way to test a Pentax lens on a full frame digital camera is to use an adapter on Canon or Nikon. I think it's possible to use optics-free adapters for Canon because the flange distance is shorter than Pentax's. Nikon's is longer, so corrective optics are needed (and then you can't really gauge the lens itself because who knows what the adapter is doing to the image). One can throw the lenses on film cameras to assess whether they cover the full frame image circle, but the digital performance from film is impossible to assess. As a result, it's really uncertain how certain lenses are going to do. We'll just have to wait and see.

You can actually test the lenses on the Sony A7 with no degradation, but that's beside the point IMO.

Old lenses will work fine on FF bit there's no question that optical technology has advanced since the film era, and newer lenses will be exciting to try.

[osv]

Would I be correct in thinking that on FF the field of view would be wider, edges would be softer and that there would be more vignetting?

wrt legacy glass, fov is indeed wider, it'll be the fov that the lens was originally designed for.

edges on legacy ff wide lenses will generally be softer than they were on crop, definitely, even to the point of being unusable for some lenses.

but crop glass has the same problem with lenses that were designed for crop sensors... how far do you have to stop a da15 down to make it sharp in the corners, for instance?

My 200mm lens have the same magnification but would it have the field of view of a 135mm on FF?

other direction... 200mm ff lens will be 200mm fov on ff, and give the fov of a longer lens on crop... 200mm x 1.5or1.6(?)crop?

How much better will the 77ltd or Fa" 85 be for portraits.

it's the legacy wide glass that's the problem, anything longer than about ~50mm rocks on ff.

the more dense the mp count of the sensor is, the more that lens defects tend to show up, especially on wide glass.

[UncleVanya]

Having only ever used apsc I am wondering what the difference is between an image taken on FF and an image taken on apsc. My lenses are all FF compatible. Maybe there is a question mark about my DA" 200 although I remember that when it came out some complained that it was not a new design but only an FA" with new coatings and if that is the case then it should be FF compatible.

Would I be correct in thinking that on FF the field of view would be wider, edges would be softer and that there would be more vignetting? My 200mm lens have the same magnification but would it have the field of view of a 135mm on FF? How much better will the 77ltd or Fa" 85 be for portraits.

Ok let's try this slowly...

FOV of a 200mms lens on an (1.5 crop factor) APSC sensor is :
6.9 horizontal, 4.5 vertical, 8.2 diagonal

The same lens on a full frame gives:
10.3 h, 6.9 v, 12.3 d

A 135mms mounted on a crop sensor gives you:
10.2 h, 6.8 v, 12.2 d

So yes what you see when you take a picture on a Pentax APSC camera with a 135mms lens is roughly the same FOV you get from the 200mm on a full frame body.

---------- Post added 02-06-15 at 11:27 PM ----------

other direction... 200mm ff lens will be 200mm fov on ff, and give the fov of a longer lens on crop...

While what you said is true so is what he said. He hasn't ever used ff so his frame of reference is apsc. On those terms when placed on ff, the lenses fov gets wider than he is used to. A 200mms mounted on full frame gives results like the 135 on a crop sensor, just divide by the crop factor.

200/1.5=133

Equivalence flipped around to match the perspective of the user.

[scratchpaddy]

There's a thread with lots of samples of Pentax lenses on any camera with a 35mm (a.k.a. "full frame") sensor. Most of the pictures were taken with the Sony a7 or a7r, but there are a few from Canons and even some on film.

https://www.pentaxforums.com/forums/122-lens-clubs/247282-pentax-lenses-ff-club.html

[everydaylife]

There's a thread with lots of samples of Pentax lenses on any camera with a 35mm (a.k.a. "full frame") sensor. Most of the pictures were taken with the Sony a7 or a7r, but there are a few from Canons and even some on film.

https://www.pentaxforums.com/forums/122-lens-clubs/247282-pentax-lenses-ff-club.html

Thanks for the link. There are many fine samples on this thread

[Digitalis]

you can actually test the lenses on the Sony A7 with no degradation,

The problem is that the sensor stack* on the Sony A7 cameras may be thicker or thinner than what Pentax might settle for on their camera, so it is impossible to be absolutely certain of how a lens will perform until users have that full frame DSLR in their hands.

* this includes the protective sensor cover glass, AA filters, UV/IR cut filters have to be a certain thickness to be of any use at all - Leica found that out the hard way with the Leica M8.

[osv]

While what you said is true so is what he said. He hasn't ever used ff so his frame of reference is apsc. On those terms when placed on ff, the lenses fov gets wider than he is used to. A 200mms mounted on full frame gives results like the 135 on a crop sensor, just divide by the crop factor.

200/1.5=133

Equivalence flipped around to match the perspective of the user.

different lenses, but i think i see where you guys are headed.

if he liked the fov of a 135mm lens on crop, he'd need to be shooting 200mm on ff to get the same fov?

but there are radical differences in actual lens magnification there, regardless of sensor size, so it's not an accurate comparison.

i think that where crop sensor people get further fouled up is because most of 'em fail to take pixel density and 100% view on the screen(object size) into consideration.

here are the basics: DSLR Magnification

the only problem there is that he didn't cover how pixel density affects the view on the screen... this can get rather complicated.

as an example, 200mm on crop is 200mm on ff, period... there is no "magnification", because the focal length of a lens can't be changed.

from there, you can start trying to understand why the picture looks different because of differences in sensor size and pixel density.

...keeping in mind that when 50mp ff sensors hit the market later this year, it going to confuse people who are used to shooting with small high pixel density sensor cameras.

[Nicolas06]

different lenses, but i think i see where you guys are headed.

if he liked the fov of a 135mm lens on crop, he'd need to be shooting 200mm on ff to get the same fov?

but there are radical differences in actual lens magnification there, regardless of sensor size, so it's not an accurate comparison.

i think that where crop sensor people get further fouled up is because most of 'em fail to take pixel density and 100% view on the screen(object size) into consideration.

here are the basics: DSLR Magnification

the only problem there is that he didn't cover how pixel density affects the view on the screen... this can get rather complicated.

as an example, 200mm on crop is 200mm on ff, period... there is no "magnification", because the focal length of a lens can't be changed.

from there, you can start trying to understand why the picture looks different because of differences in sensor size and pixel density.

...keeping in mind that when 50mp ff sensors hit the market later this year, it going to confuse people who are used to shooting with small high pixel density sensor cameras.

Magnification is not dependant of sensor size or pixel density. A macro 1:1 lens stay a macro lense on APSC or FF.

The bigger the sensor, the bigger the field of view, not even a tiny bit the level of details. This is only the pixel density that will affect the level of details.

And so an FF would need 64MP to match the level of details a 28MP APSC sensor (Samsung NX1) or 145MP to match the level of details of a 20MP 1" sensor (Sony RX100).

From practical purpose, if one display the full image on a given physical size (like a screen or a print) the pixel count of the image doesn't count at all as soon as there are enough. That 2MP or less on most screens, 8MP on 4K display, 16MP for a 300dpi "perfect" print 16"x12" print and 150 dpi on an already really good 32"x24" print. Even printing at 75dpi for 64"x48" would be quite ok as to see the details you'll have to look at the picture from nearer distance than what a normal viewer would do.

From a practical point of view if you expect the viewer to see the whole frame at a time from a normal distance, you don't really need that many pixels. Something like 5-10MP is plainty enough.

So what 50MP is for ? To have more latency to crop/reframe the image if needed. For example to extract a pano with enough pixels. Or then to provide perfect quality image for huge image and still be able to go near and see tiny details. But to really do that, 50MP is not even that much, photographers that are after that tend either to use big film camera and scan for 200MP+ or to merge many assembled pictures to have pictures of 1000MP or more.

The only thing to keep in mind from all this crap is the bigger the sensor, the wider the angle of view you'd get out of a given focal length (and the more shallow will be the deph of field for the same apperture). This is conveniant to shoot wide angle landscapes for sure, but this is not that conveniant if at all to shoot from a distance something like wildlife where every few mm had a significant cost and weight to the gear.

[kh1234567890]

The only thing to keep in mind from all this crap is the bigger the sensor, the wider the angle of view you'd get out of a given focal length (and the more shallow will be the deph of field for the same apperture).

Really ?

[tromboads]

Oh jesus getting into bees dicks worth of measuring again. I suppose it's so easy to do. Still, If you want to know what your FF lens are like on FF, buy a $10 pentax Film camera for peats sake. It doesnt really matter what one for that matter, and just shoot a dam roll of film! All this recent talk around being finally able to use the lenses on FF like it's some glorious holy return is all a bit daft really.

[everydaylife]

Thanks for all the replies. All things considered I suppose it was a silly question really because the answer is quite simple. Lenses designed to give optimum image qualities on ff cameras should give a better quality of image on FF than on a crop sensor purely because they were designed for FF.

[Wild Mark]

My analysis is simple. Larger sensor to capture larger image circle. Legacy glass will now perform true to focal length specification.

Will the performance be any good? Well, for starters, a 28mm is now a wide angle lens again. If it is a good lens (i.e. K28/2) then you should get very good performance. If it is a standard ho hum lens, then sure - you get what you pay for.

Today's optics designs are not that much better than 30 years ago. Glass materials and coatings are, so improvements are expected there. How much better????? Unsure ........ judging this is a wait and see exercise.

One thnig to bear in mind. Some of the legacy high end lenses has some fantastically expensive construction, which might cost a small fortune to replicate today .... I wonder if there have been compromises in the name of cost?

[clackers]

Lenses designed to give optimum image qualities on ff cameras should give a better quality of image on FF than on a crop sensor purely because they were designed for FF.

No, by cropping you already get the best part of the lens, Everydaylife.

Going FF can reveal flaws like vignetting and softness away from the centre on the original lenses (especially wide angles).