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Not ignored Alan, I can definitely assure you of that, the only issue is the availability of review samples.

Many thanks for the info, always appreciated.

Ideally, I would have run the resolution tets at 800mm as well, but when this review was done the weather was atrocious and I had to have a slot where I could be sure it would not rain and damage the test chart. That chart is large, very large, so for very long lenses we have to move outside. That means a clear day with no wind is needed, and certainly with no rain as any rain would damage the very expensive chart. Doing the 600mm tests was as much as we dared do before the next squall hit, and we were lucky it all held off long enough for that.

We'll get that sorted, many thanks for pointing it out.

Alpha series, A7, A7R etc, and indeed FE mount. It wasn't meant to indicate A mount, but indeed could have been clearer!

Very interesting lenses, for sure, but unfortunately not received for review.

Without actually running a test it's impossible to say for sure, but we can surmise that performance might drop overall slightly when using a teleconverter. However, a 1.4x converter is relatively modest, so it could well still be worth using.

One has been requested for review and it will be added when the review is completed.

The ones listed are the ones that have been reviewed, those being the ones we could pass comment on. We can request one for review and catch up! Thanks for pointing it out.

The real reason was an attempt to be as thorough as possible and to assess each camera from the data generated by the reviews. Leica was included where we had reviewed.

We did all those that we had reviewed and there are perhaps a few that have never been reviewed, which are not included.

You are citing two different forms of measurement, a bit like saying that 20 degrees C looks odd because we can measure 68 degrees F. LW/PH is line widths per picture height, a long way from line pairs per mm.

Hope that helps!

Hi Archie2022, the Sony FE 50mm f/1.2 GM has not yet been reviewed, so we can't give an opinion on it. Thanks for pointing it out though - it may well be on the schedule to do already but we can check to make sure.

The SMC Pentax-DA 50mm f/1.8 is indeed a plastic fantastic, but it isn't a standard lens, being a crop sensor format, so on the APS-C cameras it has a "35mm equivalent" field of view of 75mm, in other words a short telephoto.

Thanks, we'll check that out.

We don't have a reservoir of camera bodies, just imagine the cost of continually replacing them as upgrades become available. The most suitable current body is supplied along with the lens for review purposes. Actually, there are plenty of high quality mirrorless and DSLR bodies around that are 20MP or thereabouts. Excellent results are absolutely possible.

There are plenty of high end top of the range cameras that "only" have 20MP or 24MP and they are capable of superb results. As for lenses, we are measuring their performance in relation to the theoretical maximum for the system as a whole. When we used film the sharpest film (Kodak Technical Pan, ISO 16) could be used in all 35mm format cameras, but there isn't a universal sensor for digital.

It's a great idea. Logistics is what gets in the way as it is very difficult to ensure availability of all these lenses at the same time, plus of course the camera bodies to use them with. To make a proper comparison they would all need to be used on the same camera as well. Sometimes limted comparisons become possible, otherwise I'm afraid we just have the individual reviews to see what the performance of each lens is like.

Thanks Len, it's true that testing very long lenses is a challenge, but it can be done with care, using various techniques, even a second tripod under the lens barrel to stabilise things, and certainly using the delayed action for usually a 10 or 12 second delay. Even better when this raises the mirror on DSLRs before the shutter fires. With mechanical shutters there is also shutter vibration and this can peak at certain shutter speeds, which will then potentially create anomalous readings at that point.

Thanks again for the input, always appreciated.

The limiting factor here would seem to be diffraction, which gradually reduces resolution as we stop down. In theory a "perfect lens" would behave in such a way. I'm not suggesting this is a perfect lens in that context, but it's unusual but what was measured. There may well be other factors in the design affecting the end result.

Thanks for those Mistral75, we'll get that sorted ASAP. I did mean closer focusing, because although it does marginally focus closer than the traditional 0.45m it's a very small difference. Zoom lenses tend to trounce primes for close focusing and just a little more would have been nice. However, not a major point and certainly not a deal breaker.

Availability governs what camera bodies are available at any one time, so the MP counts do vary. However, the decsriptions relate the performance to the theoretical maximum for the particular model. I agree that ideally all reviews should be from the same camera body and this should be as high resolution as possible, but unfortunately that isn't practical.

Thanks for that, I'll pass the info along.

It's always great to see a lens performing well and just a pity that the edges at 12mm let things down a little. In theory, we could re-test every lens with the newest and highest resolution cameras, but of course that is totally impractical.

Thanks Alan, I'll pass that along.

I did realise that it might be very easy to offend Leica enthusiasts, but the objective was to make an unbiased review pitching the lens into the overall world of modern lenses. I would think that no VR was a disadvantage compared to lenses generally as it does limit the ability to hand hold. Likewise the focusing is not particularly close. Both these points may make the Leica lens seem restrictive to, say, a DSLR user who is used to something focusing right down to almost macro distances, as well as VR offering sharp images at ridiculously slow shutter speeds. Hopefully I have also covered what I perceived the strengths to be as well as any disadvantages?

An interesting question. It might of course be that some electronic correction is happening that we are unable to switch off. It might be that there is some edge displacement of the elements so that the figures improve because the aperture is smaller and there is more depth of field and depth of focus. Field curvature could mean that the edges are slightly out but it improves as we stop down. Just a few ideas there.

Many lenses exhibit focus breathing and it doesn't necessarily have much of an impact for stills photography, but of course it can do depending on the sort of photography undertaken. I haven't made any specific note about it for this lens, but being an IF design it is likely to show some focus breathing.

I'm interested to know what photography you have in mind and how focus breathing will affect that?

I haven't examined both these lenses side by side, so can't directly compare them, but I would suggest reading the appropriate reviews and taking some guidance from that. Then perhaps looking wider on the web and seeing what other opinions are. It really depends on your own requirements as well. Questions such as what sort of photography will you be doing, do you need weather resistance, do you need close focusing or long telephoto reach?

What I can tell you is that whatever is measured is measured, and we can't really say that any measurement "should be" lower or even higher, as the nature of a scientific measurement is we have to believe what we see. It's of course true that many scientists over the years have perhaps seen what they want to see to support a particular hypothesis, but that is an aspect of human nature and there are few absolutes. Imatest tell us that very high figures are entirely possible, and when measured they are what they are. Perhaps that supports the description "outstanding" in this case.

We are of course measuring resolution and the resolution at the edges produces a very good level of sharpness, the centre an outstanding level. We can directly compare that to other lenses used at 26MP, and by inference to other resolutions. Other variables will be different sensors and different processing by the camera software, but there's a limit to what we can do. But the edges are still sharp. The rest will depend on the size of reproduction and the acuity of our eyes, as well as the type of subject matter and the way it is lit.