[mrNewt]

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?

That is not entirely true. I have tested a few lenses on my a7m2 and as far as I can tell they perform very well. Is all about the quality of the glass you are using.
The lenses that will most probably give you vignette are going to be the ones that are under 35mm.

And 200mm is 200mm - the measurement will never change. Your 200mm is actually 300mm after equivalency on your cropped sensor. So when you will be using an FF body you will see the "true" view of a 200mm - get a cheap Pentax film camera to get the idea.

Really ?

Yes... when you do equivalency, you don't just do the equivalency for the "length", you do it for the f stop as well. So a 200mm 2.8 is actually an equivalent of 300mm 4.2 on a crop 1.5 sensor. And as we all know, a f4 has a "bigger" DoF than a f2.8.

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Last edited by mrNewt; 02-11-2015 at 11:02 AM.

[Nicolas06]

That is not entirely true. I have tested a few lenses on my a7m2 and as far as I can tell they perform very well. Is all about the quality of the glass you are using.
The lenses that will most probably give you vignette are going to be the ones that are under 35mm IF the front element is small(er than what usually an FF lens will be at that length).

And 200mm is 200mm - the measurement will never change. Your 200mm is actually 300mm after equivalency on your cropped sensor. So when you will be using an FF body you will see the "true" view of a 200mm - get a cheap Pentax film camera to get the idea.


Yes... when you do equivalency, you don't just do the equivalency for the "length", you do it for the f stop as well. So a 200mm 2.8 is actually an equivalent of 300mm 4.2 on a crop 1.5 sensor. And as we all know, a f4 has a "bigger" DoF than a f2.8.

As you say 200mm stay 200mm whatever the sensor so there is no "true view" 200mm give a different field of view on APSC, FF, Q or MF. That how it is. No system is more "true" than the others.

if we speak of the field of view a lense has been designed for... Obviously for a DA*200, this is APSC, not FF. In this sense to see the true view of DA*200 you need an APSC body, not an FF.

As for the performance of a given lense on FF even on A7II, one has to be carefull. Yesterday evening I compared the image of say DA35 macro ltd and FA31 and sigma 30mm on APSC. Well none approach the level of detail the DA35 give on APSC (not even FF) borders.

All the DA lenses have been officially tested only on APSC sensors until know. Some have tested the lenses themselve on film where obviously the problem a lense can have is really different.

Some did some tests on their A7; 5D or whatever. so we have some insight on how some lenses might work on FF. So the obvious is known. Some DA lenses don't work wide open, or some zoom don't work at all or on the widest settings. Some lenses have heavy vigneting.

Some look to work well.

For theses, to see how the borders really are, the contrast, the bokeh, the chromatical aberations etc is something that need serious testing to check. Many picture in many different conditions to look for and a formal review as we have for APSC sensor size.

When the Pentax FF is made available, many will do lot of testing, hopefully Pentax will issue some list of compatibilities/incompatibilities and we would see how it truely works.

[zapp]

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.

Best procedure for testing, I agree, but be aware that we have no clue about the new Pentax/Ricoh sensor, design of microlesnes... and software limitations for cropping.
I see many many many DA lenses for sale.

[UncleVanya]

I see many many many DA lenses for sale.

I see many happy apsc owners buying those lenses... 😉

The new ff claims to have a crop mode, and while some will sell the DA lenses many will keep them and buy more!

[Digitalis]

Yesterday evening I compared the image of say DA35 macro ltd and FA31 and sigma 30mm on APSC. Well none approach the level of detail the DA35 give on APSC (not even FF) borders.

There must be an issue with your methodology, your lens or technique - the FA31 is sharp across the APS-C frame at f/1.8-f16. I have no personal experience with the DA35mm f/2.8 - Mike Johnston from TOP considered it superior to the Carl Zeiss distagon 35mm f/2, which is a lens from the past which has always been highly regarded.


Pentax K5IIs- SMCP-FA31mm f/1.8 ASPH Limited

[stevebrot]

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

Yes, often enough. A good example would be my KMZ Helios 44M 58/2. That lens is brilliant on APS-C, but sucks at other than center on 35mm film. This is despite the advantage that lower magnification for a given final image size provides.


Steve

[stevebrot]

As you say 200mm stay 200mm whatever the sensor so there is no "true view" 200mm give a different field of view on APSC, FF, Q or MF. That how it is. No system is more "true" than the others.

Absolutely. I shoot a 210mm on my 4x5 view camera and "true view" for it is basically portrait view.


Steve