[biz-engineer]

I've been thinking about that dilemma over the years, from Pentax K200D to K3, to now K1.

When I upgraded from K200D to K5 to K3, my zoom lenses started to show weaknesses at edges and corners, especially with the K3 higher pixel density sensor. At that time, I bought a series of Pentax limited lenses + DA*300, most (from the 35 macro ltd onward) gave me slightly wider apertures, better color contrast and more even corner to corner sharpness, in a smaller package. The limited lenses lacked the versatility of zooms however, having to swap lenses often, slowing down my shooting, and more opportunities to have dust landing on camera sensor, make use of primes more tricky in bad weather conditions. I sold all this prime kit to buy a K1 and D-FA zoom lenses, getting superior IQ and the versatility of zooms again, downside being the size and weight. Here is the itch, my DFA 24-70 offers great versatility, but I'm not so enthusiastic about edge to edge sharpness even stopped down (fortunately, the DFA28-105 is sharper, but limited to f5.6 and perhaps not quite as good as a star lens). From what I've seem from the K3 mark III, it might be that a DA * 16-50 on a K3 III deliver pictures as good as from a D-FA 24-70 on a K1, given the more recent sensor in the K3III (26Mp + better at high ISO) and more recently designed optics of the DA star 16-50 lens with PLM tech. The same might be observed between image definition from DFA*50 or DFA*85 on a Pentax K1 versus some old FA glass on a 645z, or even a old FA glass on 645z versus much older lens on a 4x5 film... showing overlap between formats depending on quality of the lenses used. For instance, some images are depth of field limited, outdoor flower macros in presence of wind: a sharp fast prime on the smaller format might beat the older lens on the larger camera format, especially in available light where the smaller format allow larger aperture, lower ISO and/or faster shutter speeds. YMMV.

[AfterPentax Mark II]

Whether it is a standard lens, a limited or a star: the difference is the build quality and the choice of glass put in the lens. But in each segment there are lenses that surprise. The DA 35mm f2.4 is one that surprised me, it is sharp and contrasty and amazed me when put on the K-01. So does the 18-135, amazing lens. I recently bought the SMC version of the 77mm (because the good people here accidentally chose the wrong entry I had to buy one) and I am blown away, just as you would expect. Disappointed with an SMC 40mm and pleasantly surprised by the HD version. Thrilled by the 20-40mm. What I mean to say the lenses that I really like and keep on valueing are lenses that when put on my camera did surprise me. Not the star or Limited edition, but just surprise that wow effect that smashed you. So a brilliant lens with a brilliant reputation does not always have to be the lens that is perfect for you. The same goes for the camera, whether it is FF or APS-C.

[Fogel70]

If you have a FF and APS-C camera with same resolution you will most likely see the FF produce higher resolution with a budget zoom lens than a premium prime lens on APS-C, at least in the center of the frame.
In corners of the frame you may get better resolution from a prime lens on APS-C, especially if the lens is designed for FF.

This can often be seen in the LW/PH score in lens reviews.
If the score is based on LP/mm, APS-C score need to be 1.5x higher to produce equal resolution as FF.

But I prefer a lower and even resolution over the whole frame in most my pictures, than a higher resolution only in the center of the frame.

[repaap]

I do suppose that it is not as simple as that. I’m shooting now with K-3III and I have also K-1. What I do notice immediately is that when I use my FF lenses on K-3III it really does need them. What is lowering K-3III performance is old generation lenses(although limiteds show no problems actually, but they are ‘premium’)

What is also different obviously is Fov difference.

Resolution difference is actual when you put images next to each other and give it some PP to lift shadows. This is where K-1 will be ahead. But only if it has the very best lens attached. So, yes. Your conclusion is correct.

What I’m now still after couple months of good everyday use of K-3III, is that I want 11-18,16-50(I have SDM and it is not good enough now with new sensor for edge to edge performance) and if they have 50-135 PLM coming, then that too and DFA 150-450.

I’m propably going sell some FF lenses (not DFA*70-200) as well as limiteds(not 77) and buy 645Z +DFA 35,55 and FA 120 and 6X7 55-100 zoom and use that combo for when ever I want the ‘real’ performance. Looking at the pictures 645Z should still be very good quality. (I want OVF in my photography tools, for video it can be EVF, or screen or…)

That last part I’ll decide when I have seen specs if that new K-1 and it’s performance. When it does come to fun/practical/performance factor, K-3III does deliver. Did I mention renewed accelator, which does make colour really accurate with this new camera too that said, it is not the best landscape camera compared to K-1. Pretty good, but resolution is needed there for my taste(why I’m lusting after 645Z).

[biz-engineer]

This can often be seen in the LW/PH score in lens reviews.

Some FF lenses output 2500 LPPH at edges, similar to the LPPH of a sharp prime mounted on an APSC camera, APSC camera likely to have ISO setting 1 stop lower than FF or faster shutter speed reducing motion blur. So practically maybe no difference.

[Fogel70]

Some FF lenses output 2500 LPPH at edges, similar to the LPPH of a sharp prime mounted on an APSC camera, APSC camera likely to have ISO setting 1 stop lower than FF or faster shutter speed reducing motion blur. So practically maybe no difference.

If you handhold the camera it is often the motion blur that limit resolution more than the lens and camera. Even with image stabilization the blur can be a number of pixels.

[steephill]

Premium lens on larger format, problem solved.

"The sharpest lens you can buy is a tripod."

[biz-engineer]

"The sharpest lens you can buy is a tripod."

or a flash!

[StiffLegged]

I somehow suspect you’re never going to be satisfied. My condolences.

[biz-engineer]

I somehow suspect you’re never going to be satisfied. My condolences.

Not sure about that. My question was more about sharp lens on smaller sensor vs less sharp lens on larger sensor.

[GUB]

Not sure about that. My question was more about sharp lens on smaller sensor vs less sharp lens on larger sensor.

Except it is more about pixel density than sensor size.
If you look at that from my perspective back when I had the K01 it is do I gain more from the smaller pixels of the K3 or the larger format of the K-1.
I felt it was a no - brainer - a 50% increase in image information from increased pixel resolution or a 200% increase in that image information from using more of the image circle.
The flaw to that is it is generally accepted (I think) that currently the lenses are imparting more information than the sensors can handle.

EDIT And if you care to walk forward or backwards to fill the frame in both formats you then have twice the information taken from the lens image circle converted to digital with 50% more information from the sensor when you use the K-1 instead of the K3. That is where the K-1 is miles ahead.

[mikesbike]

From what I've seem from the K3 mark III, it might be that a DA * 16-50 on a K3 III deliver pictures as good as from a D-FA 24-70 on a K1

The new DA* 16-50mm f/2.8 might actually be better edge-to-edge than the D-FA 24-70mm is edge-to-edge. This remains to be seen via test reports. But even if this is so, the sometimes advantage of top-quality APS-C is gone. Then the advantage is for FF due to its superior 36mp resolution, which shows up when the framing is similar by using lenses of similar quality and different FL range to get that same framing and shooting from the same distance. Where APS-C starts to show its advantage is when getting into the tele range where doing this comparison as above becomes more and more impractical due to size and weight constraints. Putting a D-FA 150-450mm on a K-3 III will produce imaging that cannot be duplicated by using a zoom lens of different FL range that corresponds on a K-1 II.... to give an extreme example.

Perhaps a more intriguing question might be, how good is the D-FA 24-70mm f/2.8 on a K-3 III? The edges will no longer be the same. You'd get less WA but still some WA, with more reach.

[GUB]

The new DA* 16-50mm f/2.8 might actually be better edge-to-edge than the D-FA 24-70mm is edge-to-edge. This remains to be seen via test reports. But even if this is so, the sometimes advantage of top-quality APS-C is gone. Then the advantage is for FF due to its superior 36mp resolution, which shows up when the framing is similar by using lenses of similar quality and different FL range to get that same framing and shooting from the same distance.

Haven't you got this logic back to front? If a DA lens is superior to it's FF focal length "equivalant" won't the apsc (K3) pixel density advantage kick in and close the gap between apsc and FF? ie the advantage of top quality APS-C is enhanced?
Isn't this what this OP was about?

[biz-engineer]

The new DA* 16-50mm f/2.8 might actually be better edge-to-edge than the D-FA 24-70mm is edge-to-edge. This remains to be seen via test reports. But even if this is so, the sometimes advantage of top-quality APS-C is gone. Then the advantage is for FF due to its superior 36mp resolution, which shows up when the framing is similar by using lenses of similar quality and different FL range to get that same framing and shooting from the same distance.

Lens optical performance can vary a lot at edges, much less in the center. So, let's say, the FF sensor is 1.5 x APSC size, but the FF lens resolve half of APSC at the edge (MTF50 apsc edge = 80%, and MTF50 @ FF edge = 40%), I would expect similar image resolution. FF can have 36Mpix, if the extra pixels are blurred, doesn't help much. I've seen 100% crops side comparison between K1 and K3 III, it was hard to tell the difference, I'm not sure it that's related to better sensor in the K3 III or the better new DA* PLM lens.

[mikesbike]

Haven't you got this logic back to front? If a DA lens is superior to it's FF focal length "equivalant" won't the apsc (K3) pixel density advantage kick in and close the gap between apsc and FF? ie the advantage of top quality APS-C is enhanced?
Isn't this what this OP was about?

If quality of the lenses are even close, if the the two lenses on these two cameras will present the same FOV and therefore the same framing when shot from the same distance, the pixel density will be greater on the 36mp FF shot than with the 24mp APS-C shot. OTOH, when getting more and more into tele, the FF rig will have trouble keeping up with the framing advantage of the APS-C lens-wise and imaging.

---------- Post added 09-04-21 at 01:57 PM ----------

Lens optical performance can vary a lot at edges, much less in the center. So, let's say, the FF sensor is 1.5 x APSC size, but the FF lens resolve half of APSC at the edge (MTF50 apsc edge = 80%, and MTF50 @ FF edge = 40%), I would expect similar image resolution. FF can have 36Mpix, if the extra pixels are blurred, doesn't help much. I've seen 100% crops side comparison between K1 and K3 III, it was hard to tell the difference, I'm not sure it that's related to better sensor in the K3 III or the better new DA* PLM lens.

Yes, I can see this if there is a great enough discrepancy between the corresponding lenses. If the old DA* 16-50mm SDM lens were being compared on the KP to the DFA 24-70mm on the K-1 II, the FF setup would win hands down, but as to the new DA* 16-50mm PLM, we don't know until tests are run. And even then, even if better, will better be enough to override the 36mp FF advantage for resolution, even at the edges? I guess part of what I am saying here is- is how bad is the the DFA 24-70mm- as bad at the edges on FF as the old DA* 16-50mm SDM at larger apertures on APS-C?