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Halide app developer says iPhone portrait smoothing is due to low contrast, noise reduction

4 Oct

The developer of the app, which is billed as RAW Manual Camera and has in one review been described as a “pro camera app”, suggests in this blog post that the smoothing observed (and previously described here) may be a consequence of smart HDR in that HDR always reduces contrast (hence high dynamic range) and therefore apparent sharpness, which may subjectively appear as smoothing. Read more here.

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iPhone XS portrait mode smoothes skin #nooffswitch

1 Oct

Apparently, the iPhone XS and iPhone XS Max have skin smoothing built in when using the portrait mode – in addition to the fake background blur. For the way it looks, I’d say it’s probably done by means of frequency separation as used by many professional retouchers. Customers are now complaining since there’s no know off switch for this – if you want the fake bokeh, you get fake skin thrown into the deal, so the only choice is to not use portrait mode and forego both.

Nikon with banding problems – again

1 Oct

After the D700, D7100, D5200 and D600, the Z7 is the latest Nikon camera to be reported to have banding issues – in spite of having an apparently identical sensor to the D850. It’s apparently due to the holes in the image produced by phase detection pixels – a problem I’ve mentioned several times before. The problem is that phase detection pixels do not precisely measure the quantity of light like regular sensels, so the electronics have to fake the data for those pixels.

z7banding

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Lens equivalence

23 Sep

On the eve (almost) of Canon launching its 32mm f/1.4 lens for EF-M mount (i.e. 1.6 crop factor APS-C), let me point out that in terms of field of view and achievable shallow depth of field, this is roughly the same as a 50mm f/2 on full frame.

I thought it would be useful to write a brief reference for folks to refer to when comparing lenses with different imaging circles (e.g. full frame vs. APS-C), giving specific values for popular focal lengths and apertures.

So in this vein, a 35/0.95 APS-C lens (e.g. Mitakon) is roughly like a 50/1.4 on full frame, and a 50/1.1 for APS-C (e.g. Kamlan) is similar to 85/2 on full frame. So the sometimes affordable 85/1.8 lenses for full frame cameras don’t get you into much better territory than 50/1.2 on APS-C, although you may by this route obtain autofocus at a similar price but at the additional cost of needing a full frame body.

Also note that light equivalence is already taken into account – there’s almost a stop difference between f/1.8 and f/1.2, with a little bit of wiggle room for manufacturer’s specs (aka cheating).

Once upon a time, it used to be true that digital sensors could not work at shallow depth of field very well as the angle at which light would typically fall onto the sensor was typically shallow as well and many of these shallow rays would be deflected off the surface of the sensor, avoiding detection. So on the assumption that that’s still true of modern sensors, working with an f/2 lens on full frame would be preferable to working with f/1.4 on APS-C. One might assume that sensor design has markedly improved in this aspect since mirrorless cameras have to cope with even shallower angles – however, note that mirrorless lenses are typically a little narrower at the aperture and recent lens designs have been very long and heavy, giving an overall less acute angle of incidence, which might be a hint as to the remaining challenges in this area.

If sharpness is what we care about, a full frame camera is generally preferable as the format allows for greater manufacturing tolerances in lenses, and the same lens will, generally speaking, give a sharper image on full frame than APS-C, depending on the sharpness fall-off towards the corners.

And one more thing – if we compare the front element sizes of, say, a 32/1.4 (22.9mm) and 50/2 (25mm), we don’t see a lot of difference, so we might suspect that in terms of the torque needed for autofocus to move elements inside such lenses, there may not be a lot to be lost or gained. So there may not be any particularly convincing excuse for a 35/0.95 lens to not have autofocus, unless we take into account the generally smaller build and smaller battery of a typical APS-C camera compared to a full frame model.

But getting back to the equivalence issue, it’s fair to conclude that most “fast” lenses for APS-C sensors offer nothing particularly revolutionary, this being even more true if they have to be focused manually.

Pentax’ PLM and DC lenses explained

2 Mar

DC (“direct current”) is a kind of focus motor that has been used in Pentax lenses for some time. While it is quiet, it’s not entirely silent. Pentax’ most recent 55-300mm lens features a new type of motor branded as PLM. Here is what Pentax representatives had to say about it in an interview:

The PLM design can quickly activate and allow for faster focusing, but the lens element must be low weight due to limited power (torque).

The DC motor can generate high power (torque) with deceleration mechanisms, which is better for lenses with larger focusing elements. A DC motor can be driven at high speed, but there is an issue that a little sound is generated.

Generally, we use the what we feel is the best focusing mechanism for each specific lens design.

It would be reasonable to suspect that the 55-300mm’s new optical formula and narrower aperture were needed to allow the faster, silent motor to be used, although it should be noted that, like the recent 18-50mm kit and non-kit zoom lenses, the new 55-300mm lens is collapsible to a somewhat smaller size, with the difference between collapsed and uncollapsed size being more pronounced in the 18-50mm.

In the interview, the representatives went on to explain that they do not expect to see PLM in a large aperture lens any time soon, instead putting their money on researching other kinds of motors as well as algorithms to improve autofocus.

Pentax KP, affordable DSLR for low light

28 Jan

Ricoh just took the wraps off the Pentax KP, a rather compact magnesium alloy body DSLR with a 5-stop, 5 axis stabilisation system and ISO 819,200. The body is not particularly beautiful, but inside it waits a noise reduction co-processor that, by first appearances, rivals DxO’s PRIME software, but acts instantaneously. (If you’ve used DxO’s engine, you’ll know what I’m talking about.)

05_kp_black_2040

The Pentax KP
(Source: Ricoh promotional materials)

Technical expose:High ISO images are noisier on average than low ISO ones. The noise cannot be neatly compressed, increases file size and slows down the process of writing files to storage (SD card in most cases). This can affect frame rates. In order to keep the frame rate up, Pentax used to apply noise reduction in RAW from ISO 3200 (several models including at least the K-5, K-5 II, K-5 IIs, K-30 and K-50). This was not configurable and led to mushy images that did not respond well to further noise reduction using other methods. So the way to work with these cameras was to underexpose ISO 1600 by up to three stops, depending on your need – not the best idea if you want to maximise colour tonality, but it got the job done.

screen-shot-2017-01-27-at-12-32-51

Where the magic happens:
the accelerator unit.
(Source: Ricoh promotional materials)

But from samples I’ve seen, the new co-processor, dubbed in the latest press release a “state-of-the-art accelerator unit”, renders such concerns obsolete. In the samples, ISO 6400 looks rather clean, and I’m curious to take a closer look at ISO 12,800. Several in the Pentax community have commented that they might delay their entry into full frame based on this camera’s performance, so the pressure is on for Pentax to bring the accelerator unit and high ISO performance to an updated K-1 full frame camera.

screen-shot-2017-01-27-at-12-37-31

Pure edge detection
in Live View
(Source: Ricoh promotional materials)

Launch price for the Pentax KP is going to be 1100 Euros/Dollars; the Pentax K-70 with similar performance up to ISO 102,400 (also has accelerator unit) is about 400 Euros/Dollars cheaper.

08_kp_silver_2040

Display articulation
(Source: Ricoh promotional materials)

Conclusion: The Pentax KP’s combination of five stops of stabilisation with state-of-the-art in-camera noise reduction will save you money on bodies, lenses, and software, as Pentax leapfrogs the competition. Bring on the night!

PS: Check out the separately posted ISO 819,200 sample image to see what it can do!

PPS: Also check out this comparison of ISO 102,400 after noise reduction in the KP and K-70.

Low light photography? Affordable? Look no further!

27 Jan

Ricoh just took the wraps off the Pentax KP, a rather compact magnesium alloy body DSLR with a 5-stop, 5 axis stabilisation system and ISO 819,200. The body is not particularly beautiful, but inside it waits a noise reduction co-processor that, by first appearances, rivals DxO’s PRIME software, but acts instantaneously. (If you’ve used DxO’s engine, you’ll know what I’m talking about.)

05_kp_black_2040

The Pentax KP
(Source: Ricoh promotional materials)

Technical expose:High ISO images are noisier on average than low ISO ones. The noise cannot be neatly compressed, increases file size and slows down the process of writing files to storage (SD card in most cases). This can affect frame rates. In order to keep the frame rate up, Pentax used to apply noise reduction in RAW from ISO 3200 (several models including at least the K-5, K-5 II, K-5 IIs, K-30 and K-50). This was not configurable and led to mushy images that did not respond well to further noise reduction using other methods. So the way to work with these cameras was to underexpose ISO 1600 by up to three stops, depending on your need – not the best idea if you want to maximise colour tonality, but it got the job done.

screen-shot-2017-01-27-at-12-32-51

Where the magic happens:
the accelerator unit.
(Source: Ricoh promotional materials)

But from samples I’ve seen, the new co-processor, dubbed in the latest press release a “state-of-the-art accelerator unit”, renders such concerns obsolete. In the samples, ISO 6400 looks rather clean, and I’m curious to take a closer look at ISO 12,800. Several in the Pentax community have commented that they might delay their entry into full frame based on this camera’s performance, so the pressure is on for Pentax to bring the accelerator unit and high ISO performance to an updated K-1 full frame camera.

screen-shot-2017-01-27-at-12-37-31

Pure edge detection
in Live View
(Source: Ricoh promotional materials)

Launch price for the Pentax KP is going to be 1100 Euros/Dollars; the Pentax K-70 with similar performance up to ISO 102,400 (also has accelerator unit) is about 400 Euros/Dollars cheaper.

08_kp_silver_2040

Display articulation
(Source: Ricoh promotional materials)

Conclusion: The Pentax KP’s combination of five stops of stabilisation with state-of-the-art in-camera noise reduction will save you money on bodies, lenses, and software, as Pentax leapfrogs the competition. Bring on the night!

PS: Check out the separately posted ISO 819,200 sample image to see what it can do!