I know it's not just about sharpness but I am curious what do you think "it", is about? Dynamic range? Bit depth? Luma/chroma gradients? DOF? Noise?

I distinctively remember medium and large format photographers used to shoot those formats versus 35mm film for the "much higher clarity", "greater sharpness", "real resolving power", "suitable for bigger printing", etc... Funnily most if not all did uae those larger formats for the extra resolution. If there had been a 35mm film stock with MF/LF resolving power we'd be having this rather strange talk of MF vs 35mm IQ back then 50-60 years back.

Mmmmm this should be reviewed and compared to a T/S lens alternative (I wouldn't trust the use of other lenses that are not T/S)... But it really seems unlikely to me that adapters with a "add-on" lens can bring perfect IQ results, and the Laowa 12mm lens just can't support a 50Mpix resolution...

The RAW files in their website may give you some ideas on the image quality.

http://www.venuslens.net/laowa-magic-format-converter-mfc/

very well said, John.

John, there are plenty sharp Sigma 1.8 zooms, yet I see no one adapting on full frame, more likely using a speed booster for smaller sensor.

Availability of many FF lenses is right here downgraded with teleconverter and doesn't make any sense so spend so much on 50MP medium format camera only to dig up FF lenses and zoom in to keep the angle of view somewhat similar. This really defeats the purpose of having large, high resolution sensor. And you will lose the lens speed as well, so bigger sensor collecting more light advantage goes out the window.

Actually, you have seen "APS-C to FF" optical converters. They just aren't marketed as such.

There are quite a few threads where people have found, as expected, that putting APS-C lenses on a teleconverter increased the image circle to cover FF 100% of the time.

"Plenty of sharp Sigma f/1.8 zooms"

There are exactly two, and they seek to replicate the advantage of full-frame in terms of depth of field and noise control- if adapted to full-frame, they'd simply be clumsy equivalents to f/2.8 lenses that already exist.

Ergo, that line of reasoning makes no sense.

And you're outright ignoring two factors in your critique of the FF -> MF adapter, irrespective of degradation:
1. Availability of focal lengths not offered/otherwise available
2. Price

Either or both factors could be motivators for potential buyers; further, they may very well already own the lenses that they'd wish to adapt!

You get the better SNR ratio of bigger sensors, because you use bigger lenses (more mm of lens) to get the same frame. Not because the sensor is larger it self.

For example, if you use a theoretical 100% efficient boost, you could get the same noise levels with FF-lenses on a crop-body. The 1 stop (or whatever) noise advantage, would be there because the f4 lens would count as 2.8 lens efficiently.

Take a magnifying lens, and play with it. What matters is the light that is collected in the begging. How the final beam is converged (narrow and strong, wide and faint) doesnt change the total output.

FF sensors have the advantage we all know, because they use bigger lenses, not because they are just bigger.

Bigger lenses is not what matters at all, bigger sensors is.

Ultimately, it's kind of semantic, because longer FL lenses of a given aperture naturally have larger entrance pupils and so they let in more light. But that argument does nothing at all to explain the image quality advantages of larger formats when the lens is stopped down shooting highly detailed, deep DOF shots at base ISO.

@Deorum You're close, but you're not correct. You're correct that it's all about the light collected. In your magnifying glass example, it's true that as you adjust the glass although the size and intensity varies, the light intensity * the projection area is constant. Where you go astray is that you seem to be operating under the assumption that exposure time is constant. The advantage of the larger format is that it can be exposed more before hitting saturation. Even if you shot an f/8 lens on MF and an f/1.2 lens of FF you can get a higher SNR on MF by just using a longer exposure.

@Androole
Bigger sensor forces you to use bigger lenses. In the end this is what matters and makes all the difference.

@whumber. This is the theory of filling a well, photodiode is a well that is filled slowly. then you take the average.

Maybe yes, but i think it has to do ultimately with the NUMBER of pixels (because the total light has to fall into specific slots, and not the size of pixels itself. The analogy of the well is a bit flawed, not a fact that bigger wells fill slower.
I would argue that bigger wells, fill easied because the collect more light per well.
I am sorry i didnt understand this.
Longer exposure is better if total exposure is the same? 1/100-F2-iso100<1/25-F4-iso100 ?
Stopping down 1 stop Av, and exposing longer gives better SNR (for same iso?) how?

@Androole

Theoretically speaking if we could unlink sensor size-from lenses size, yes i argue that it offers no advantage.
Practically now, it is a different matter. and it is practical reasons (like less strain on lenses etc) that produce a better result. Theoretically the sensor could be as large or small. So still a larger sensor/lens offers better IQ, than same DOF exposure of smaller sensors.
Obvsiously converging the light of an FF lens to a pinpoint size sensor, would yield such a strong light with needs of exposure up to 1/20.000 which is impossible. It would even burn throught the shutter curtain.

This is a tomato / tomahto situation to some extent, but you are putting the cart before the horse with your emphasis on lenses. After all, you can easily put the same "big lens" from a large format camera on your FF camera, or an FF lens onto a 1" sensor camera, and you will get no benefit from it, merely a narrower perspective. So what is obviously most important is to simply have a larger sensor that is able to capture more light.

In your 2nd post about converging the light of an FF lens onto a smaller sensor, from a functional point of view you are literally just referring to decreasing the lens' f-number. Having a wider aperture is the important thing, and is a much more precise way of describing what you want that "bigger lenses."

Focal reducers also do exactly what you are describing, but concentrating the light from a larger image circle. Common in astronomy, and now well known in photography thanks to mirrorless cameras and the Metabones Speedbooster. No burned shutters.

Without a possibility of stopping down... Not much :-(
Hope they add contacts in a production model.

Seeing as their other designs are... oddball, to say the least, I presume this is their own design. Not affecting IQ? Not a chance, but it probably won't be terrible.

@Androole There's nothing inherently bad about the Kenko glass. They're cheap but the quality is up there with the OEM TCs. I do agree that Laowa makes some unique stuff, but there's nothing unique about a 1.4x TC so why would they waste R&D money recreating the wheel? A 1.25x TC would be much more innovative and something more along the lines of what I would expect from their design team. With a 1.4x TC you're actually worse off than shooting the same lens on a FF body.

The 1.4x involve changing in format, which is not the case as a teleconvertor.
so when a 12mm on FF become 17mm in MF, the angle of view is still similar and doesn't really "zoomed in".

I will agree with you, though only temporarily- while Pentax' 645Z is indeed a DSLR in the fullest sense with AF and all of the trimmings, its AF cannot be praised beyond the fact of its inclusion. And for the reasons you cite above, this isn't really an issue; the same for traditional medium-format systems that separate body and sensor back, among others, where AF is typically limited to portraiture at most.

However, by pushing medium format into the 'digital rangefinder' style that Sony first pushed full-frame into at the consumer level, emulating the Leica M-series and surpassing it in many ways, I see Fuji's GFX50s as their proverbial 'A7r', a camera that was limited in so many ways, including AF, but also sparked a revolution in high-quality compact photography.

Here, Fuji would do well to focus (ahem) on autofocus both with firmware revisions and possibly with future Sony sensors that have increased readout speed. As they do so, I would hope that adapter companies keep up.

You're both right? Nobody makes a 1.4x TC that doesn't have horrid effects outside of it's image circle I'd wager though so that's certainly different.