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| Noisy Miner SX70 |
The SX70 is the
latest and best model in Canon’s
Powershot SX(2 digit) series of compact
bridge style superzoom cameras.
Canon has a long history of making this type of digital camera
for the consumer market starting with the S1 of 2004. Since then Canon has changed their naming scheme
somewhat but in recent years the SX(3 digit) models have lacked an EVF while
the SX(2 digit) models have a built in EVF and fully articulated rear screen.
My first acquaintance with the SX(2 digit) series was the
SX20 in 2009. It was a decently good
camera for its time with a good level of specification compared to its peers. I
remember that it had a very smooth, slippery handle and produced large amounts
of chromatic aberration which, by the way is still a weakness of Canon’s
compacts.
The SX50 of 2012 became a firm favourite among SX
aficionados for its good quality lens and overall good picture quality.
Then in 2014 came the SX60. Great was the disappointment on
Canon user forums from the many faithful who found the SX60 a backwards step in
image quality and user experience.
For some reason which I now forget I bought an SX60 and was
disappointed along with all the others. I just could not get decently sharp
pictures out of that camera no matter what strategy I tried at the point of
capture or in post processing. It had a nice handle though…………..
In September 2018 Canon announced the SX70 with the same
body and lens as the SX60 and even more pixels jammed onto the tiny 7.7mm
diagonal sensor.
This did not look promising.
The major review sites such as Digital Photography Review,
Imaging Resource and Camera Labs did not post full reviews. This is usually a
sign that there is, or is perceived to be a problem with the camera. Rather
than post a bad review these sites simply pass onto the next big thing which at
the time the SX70 was released was a bunch of all-new mirrorless full frame bodies and lenses.
The usual suspects including Photography Blog, Tech Radar
and e-Photozine posted their quick so-called “reviews” soon after the camera
was released. Unfortunately I have learned that these sites provide little more
than a re-wording of the published specs together with a few snippets of often
incorrect commentary.
So no help there.
But here is the thing. I find this camera type very
appealing. In one compact relatively inexpensive package you get just about
everything. Wide angle, super telephoto, nice handling, EVF, flippy screen,
close-ups, video ….and so on.
If some manufacturer could get the performance and output
right I would be a happy camera user.
So I bought an SX70 to test it myself.
And….it’s not bad. Not bad at all. Verging on quite good in
fact although with some important caveats which are the reason for this post
and which I will discuss below.
Although Canon made no statement that I ever saw about
improvements to the lens, AF or IS I found in fact that all three of these key
ingredients are in fact considerably improved in the SX70.
In addition they changed the D-Pad from the old
flat-with-5-buttons type to the much more usable rocking saucer type.
There also appear to be numerous improvements to speed and
efficiency of operation.
All this adds up to a camera which looks the same and has
most of the headline specs as the SX60 but which is in fact a much better
camera. It routinely makes better pictures and is nicer to use.
Now let’s get to those caveats.
There are in essence two.
1. The minor one is a somewhat less than wonderful user
experience, particularly for the enthusiast who wants to get the camera
off Auto Mode and take control of
proceedings. The point of my discourse
is that in order to get the best from this camera the user must get off that Auto
setting.
Why ?
2. The reason is the
second and major caveat which is luminance noise which is present in
objectionable levels in the SX70 even at base ISO.
How bad is the noise ?
While testing the SX70 I had available a Lumix FZ80, an
18Mpx budget consumer superzoom with
components mostly carried over from the 2013 FZ70. The FZ80 is certainly no star in the
image noise department.
On my tests at matched output size, the SX70 has about one EV step more noise at ISO
400 than the FZ80.
I also tested the SX70 against my Lumix G85 M43 camera and
found that ISO 200 on the SX70 has about as much luminance noise as ISO 3200 on
the G85.
This is a very poor noise performance the like of which I
have not seen since the Powershot G10 of 2008. I owned one of these for a while. It had a
nice sharp lens but image quality fell apart at ISO 400 with excessive
luminance noise.
So the main consideration in getting best results from the SX70
is to develop strategies for managing that noise.
These strategies involve every aspect of the imaging process
from subject selection and lighting through camera handling and exposure
management to post processing RAW files and final output size.
So with those considerations in mind here are my suggestions
for getting the best possible photo output from the SX70.
Only you can decide whether the effort is worthwhile.
Subject selection
You might think that with a 20Mpx sensor the SX70 would
handle detailed subjects well. In practice however the camera is better suited
to subjects which are not dominated by fine detail. There are two reasons for this
1. In the image processing pipeline you have to deal with
the noise which appears as strong grain. This involves noise reduction
strategies which always reduce the amount of detail available.
2. The lens does a pretty good job for a budget 65x zoom but
let’s be realistic. Outside broadcast TV lenses with this kind of zoom range
cost hundreds of thousands of dollars.
I paid AUD729 for the entire SX70 including the lens. You
don’t gots ultimate resolution here.
Lighting
The only way to fit a 65x zoom lens into such a compact
package is to
a) use the very small smart phone size (7.7mm diagonal)
sensor and
b) restrict the lens to small apertures (relatively high
f-stop numbers) throughout the zoom
range.
So we have a small sensor with a low signal-to-noise ratio
which means the sensor needs plenty of light,
but a lens which is not letting much light through to the
sensor.
Solution ? Take
pictures where and when there is plenty of light. For this camera brighter is
better.
This does not mean the camera is impossible to use indoors
or in low light but doing so does require careful techniques for exposure
management and post processing. See below.
Capture and exposure
strategies
1. Always use RAW output. JPGs apply massive amounts of
noise reduction which is not adjustable. This gets rid of the noise and most of
the detail as well even in bright light outdoors.
2. Use P Mode. This will ensure your aperture is the widest
possible at every focal length. The best aperture is the widest available
(smallest f-stop).
Alternatively set Av and f3.4 at the widest end of the zoom.
The f-stop will increase as the lens zooms out and decrease as you zoom back,
always staying at the lowest available for each focal length.
3. Set Auto ISO upper limit at 200. Yes, 200. That will give
you luminance noise levels equivalent to ISO 6400 on Micro Four Thirds or
25,600 on full Frame.
4. Use the flash indoors. Set flash to -1 stop.
5. View through the EVF when possible. It is easier to hold
the camera steady this way.
6. Monitor your shutter speed. Practice shooting at very slow
shutter speeds. The IS helps a lot with this.
Post processing
This is a fairly arcane topic with each PP enthusiast having
their own special combination of magic moves.
I use Bridge, Adobe Camera Raw and Photoshop. People wax lyrical about other image editing
programs but I notice the one being praised changes quite often. Many
experienced photographers find they get best results when they stick to
Photoshop and learn how to use it properly.
With the SX70 I find I have to apply a lot of sharpening and
a lot of noise reduction, both at the same time. Experience and experiment are
required for the best results.
Overall a much higher level of intervention is required than
would be appropriate for output from larger sensors.
In the Lens Corrections Tab of Camera Raw, I go to the
Profile and Manual tabs to remove purple fringing.
In the Detail Tab:
Sharpening varies from around 60 in the middle of the zoom
range to 100 at the long end.
Radius varies from about 1.5 at the wide end and middle of
the zoom range to 3 at the long end.
Noise reduction is required even at ISO 100 and varies from
30 to around 60.
Sharpening amount and noise reduction have to be balanced
against each other while viewing the image on screen to find the most appealing
result.
Tip: Periodically view at 50% on screen. You will
find that noise which seemed objectionable at 100% is no longer apparent at 50%.
Tip: Never try to remove all the noise. If you do
you will just end up with the melted-plastic-smashed-avocado look of the JPGs.
Tip: Think about how you want to share or display
each image. If the final output size is small then files which looked extremely
grainy at 100% can look just fine.
Summary
The paradox of the SX70 and most other small sensor superzoom
cameras is that the people most likely to use them (casual snapshooters who set
the Mode Dial on Auto and leave it there) are least likely to get best possible
results from the cameras.
On the other hand the enthusiast/expert types who could get
the best results from these small sensor models are more likely to choose
something with a larger sensor.
Such is life.
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