(06-03-2020, 07:12 PM)thxbb12 Wrote: This MFT lens is not equivalent to a 24-70 f8 FF lens, but 24-90 f8 FF or 16-60 f5.3 APS-C.
I see it mainly as a landscape lens given the limited DOF control, but given the limited range, it's not very interesting.
The only selling point would be a tiny size or a potentially interesting range (hence the 10-45 I mentioned earlier).
I see it as a missed opportunity. For instance, I see zero incentive to get this over the already very good 12-40 f2.8.
Stupid mistake I made, of course it should be 24-90mm and 16-60mm. Thanks for correcting me.
(06-04-2020, 05:14 PM)wim Wrote:
(06-03-2020, 07:00 PM)Brightcolours Wrote: What I do not get... Not many would consider getting a 24-70mm f8 zoom lens for FF. Nor a 16-46mm f5.6 lens for APS-C.
Yet, somehow there appear to be enough MFT users prepared to get such a lens and pay a "pro" price for it. Like getting a "meh" zoom and stopping down to f8 by default to get good results..
The lens is sharpest wide open, Not that strange, as past f4 diffraction softening limits the resolution (as you see with f8 on FF and f5.6 with APS-C).
You should really stop your "comparisons with different formats, oit is getting boring beyond annoying.
When you try to make comparisons like this, you need to state clealry that you are talking about equivalent FLs, and equivalent apertures for DoF.
It still is an 12-45 F/4 lens. And lens diffraction is the same for all lenses, whatever the format they are covering, and is only limited (or caused) by aperture, nothing else.
Sensor diffraction is different, obviously, because the EM-5 Mk II has an equivalent sensel density as a 64 MP FF camera. You therefore cannot say that F/4 diffraction is the same as F/8 on FF, and F/5.6 on APS-C, not for the lens on itself anyway.
You really should stop your incorrect posts.
(reference to your first rude line
I do not have to type "equivalent" when I talk about a comparable FF lens or APS-C lens, it is a given and should be apparent. The lens is not just a 12-45mm f4 lens, it is in fact a 12-45mm f4 lens with a lens diameter LIMITED to MTF use by design, not suitable for APS-C or FF or any other bigger format.
The diffraction softening you see is dependent on the print size, or the MTF measurements. The lenstip review that I responded to shows that on a 16mp MTF camera diffraction already has set in wide open and limits resolution with every stopped down stop extra.
You would see a similar trend with a 16mp FF camera with an f8 zoom lens. Or with a 16mp APS-C camera with a f5.3 lens.
So not sure what your point and/or objection is about.
When you print a photo at a certain size, you will see similar diffraction softening for a MFT combo at f8, a FF combo at f16, or an APS-C combo at f10.7 for instance.
Again not sure what your point or objection is, diffraction softening you see or measure is similar for different formats when using equivalent f-stops.
There is no such thing as "sensor diffraction", I assume you meant something like capturing diffraction impact on sensor level? The MTF measurements I mention above.
It is totally pointless and nonsensical to compare a MTF f4 lens and a FF f4 lens. So no, no sense in comparing a 16mp MFT and 64mp FF camera that way.
Again, you print at a certain size. If you see diffraction softening on an image from "MFT" 16mp f5.6, you will see the same diffraction softening from "MFT" 160mp f5.6. Just like you will see similar diffraction softening from "FF" 20mp f11.
I also see that you state that diffraction is the same for every lens, and that is not quite right. Diffraction happens at edges light passes. So, in the lens light diffracts a bit at the front element, a lot at the aperture, and depending on element sizes and lens construction, at other lens elements at back element where "mechanical vignetting" might be an issue.
Light diffracts the same amount at the same aperture size, for every lens. So, with a 50mm lens with an f2 aperture the same as with a 100mm lens with an f4 aperture. Ponder about that for a moment.
How much the diffraction impacts sharpness at the image plane, depends on the size of the aperture, and the distance of that aperture to the image plane. Twice the distance of the aperture to the image plane means twice the diffraction softening. That is why on average a 50mm f4 lens and a 100mm f4 lens show similar diffraction softening, the 100mm aperture will be further away than the 50mm aperture.
Not every lens design will have the aperture at the same distance, so sometimes you come across a lens that shows less diffraction softening than you would expect (in respect to other lenses).
So, in short, there is nothing wrong with comparing different formats. Especially comparing different formats with equivalent lenses (equivalent focal lengths and f-stops) makes a lot of sense and puts things perspective.
And as such, me wondering about a "pro" f4 MTF zoom and akin it to f8 FF actually makes a lot of sense, too.
Hope I cleared a few things up.
Kind regards, Brightcolours.