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Astro Long Expo Low Light Cameras

Crossing datas from four sites to choose the Best Cameras :

BDP : Brendan Davey     DPR : Digital Photography
Dxo : DxoMark Sensor Test    P2P : Bill Claff

APSC DSLRs - with 4/3 or 1" stills Crop Modes ?

For Astro, Birds Photography, there are not so many APSC cameras available with a
Crop Mode down to 4:3 or 1" format for stills. Now that they all get Fully Addressable
CIS, CMos Image Sensor, RoI - Region of Interest - is a totally CostLess Option, but
very useful for AstroPhotography of Deep Sky Small Objects or Birds photography !

Let's examine 2 pairs of APSC DSLRs through, a Used and a New one :

Astro Low-Light Long-Expo APSC Cams
Click Image, Ctrl+ to Enlarge

Used APSC Cameras : Pentax K-5(II(s)) betters the Eos 60d in every characteristic,
except for the Read Noise where the 60d's slightly better. Canon DSLRs were Champs
of the Conversion Noise : Eos-60d = 8.5 vs PK-5 = 0.6 ! Red Layer especially suffers
from that Huge Conversion Noise level : a Stock Pentax K-5 with an UHCS filter shows
at least equivalent Red Performance than an Expensive Eos-60dA, the proofs here :
Note that the 52mm secondary mirror of my 200/1000 SkyWatcher is way too narrow !
Pentax K-5's body is Weather Sealed, its specified min.operating temperature is -10°C.
The Pentax K-5 also has a very low Dark Current level so that you can Expose until 30
minutes at ISO 80 by 12-25°C ambient Temperature and get so Clean Raw files that the
Bias Maps, Dark Frames are useless and, in most cases, you'll only need 3-8 Raw files:
17 min Exposure through an UHCS filter to darken the target, then pushed 6 Ev :
Not a bit of Banding, nor any Fixed Pattern Noise.
The Pentax K5 is IsoLess, far better results are achieved by stacking ISO 80 subs to get
a High SNR picture that you can easily Push a lot than shooting at ISO 1600 as you have
to with a Canon camera very Noisy at base ISO. 1st exceptions the last Eos R5 and R6 !

the imx071 exmor sensor inside the PK5 is so fine that chinese camera assemblers did
not hesitate launching their Asi071, Qhy168C and so on, at the high price of $3000€ = 3
times, 3x the Price I bought my Pentax K-5 New in Spring 2011 ! Some models are still
available at ~half their launch price, see how Low is their imx-071's Dark Current level:
- first CMos Exmor sensor: ~15 years on the market and still In the Race.
QHY 168C Medium Size Cooled CMOS Camera
The very 1st sensor w/o any Amp-Glow.

Dxo 4 DSLRs APSc
Click Image, Ctrl+ to Enlarge

New APSc Camera: if I had to buy an APSc camera for Long Exposure in Low Light
or Astro-Photo today, I would certainly choose a Nikon D7500 over a Canon Eos 80d
- the Eos 90d has not yet been tested by DxoMark. Pentax K3 I, II, III are Not at the DR
level of the K5 ; they do Need Hard Raw Smoothing to follow Modern Dual-Gain BSIs.
Proof, the K3-3 Mono w/ imx571 doesn't need that Strong Raw NR to gain 2+ Ev DR.
The Eos 80d, now very close to the Pentax K5 is a high progress over the Eos 60d(a).
The Nikon D7500 beats them all in all characteristics except for Long Exposure Noise.
The Pentax K5 is still the Long Exposure King, far less Noisy than either the D7500
and the D500 which share ~very similar sensors, if not exactly the same. Canon Eos
80d is roughly in between both for long exposures, but way more noisy than both the
Nikon and the Pentax for Exposures of 30 seconds or shorter.

DxoMark 4 APSc DSLRs
Click Image, Ctrl+ to Enlarge

Now DxoMark don't allow comparing more than 3 camera. But that wasn't too difficult
for me to add the Canon Eos 60d over the screen shots of the 3 APSc DSLRs, Canon
Eos 80d, Pentax K5 and Nikon D7500, here sorted by their IQ performance rate.

~~~~~ tbc... ~~~~~

Pentax K5 v 24 Mpx High-End 24x36 FF Cameras

Let's compare the Pentax K5 APSc to - 4 Full-Frame 24x36 High-End 24 Mp DSLRs :

Pentax K5 vs 24 MPx High-End 24x36 Full-Frames
Click Image, Ctrl+ to Enlarge

Incredible, the Pentax K5 beats all these Flagships in almost every criteria measured by
DxoMark ! Exception, the Nikon D3x is better of 1 bit Color-Depth in Portrait Mode,
but, was launched at $8800 in the UK - more than 8x the price I paid for my new K5 !
The better ISO score of the Full-Frames is logical, it's because their 2,33x sensor Area,
all other things being equal, the Dxo-ISO score is function of the sensor's 2 dimensions :
Low-Light Photography and Sensor Sensitivity Comparison Tools for Astronomy
You see the 24x36 are far from reaching ISO 2707 ! The Sonys are only 1,2x the K5 !
Dynamic Range: the ability to show NoiseLess Details, even in the Deepest Shadows,
and here, the Pentax K5 shines : 2,4 Ev better than the 2012 Eos 5D III, 1,8 Ev better
than the Sony Alpha-900, first camera to implement an On-Sensor ADC, an Analog to
Digital Converter which prevents aSaP the Signal to be Polluted by Conversion-Noise :
External ADC, Weak Filtering Power Supply, Weak Shielding ruin the Dynamic Range

Comments from DxoMark, plus their Review for the Pentax K-5 :
DxOMark Review, Comparisons of the Pentax K5
« The best APS-C in all tested fields »

~~~~~ tbc... ~~~~~

FF (mf) cameras w/ APSC (ff) stills Crop Mode ?

For Astro, Birds Photography, there are not so many MF cameras available with Crop
Modes down to FF + APSC formats for stills. Now that they all get Fully Addressable
CIS, CMos Image Sensor, RoI - Region of Interest - is a totally CostLess Option, but
very useful for AstroPhotography of Deep Sky Small Objects or Birds Photography !

Let's examine 4 FF 24x36 DSLRs at, the reference being my old Nikon D600 :

Astro Low-Light Long-Expo FF Cams
Click Image, Ctrl+ to Enlarge

Comparing these 4 Full-Frame DSLRs, you see the old Nikon D600 could still be a
winner. 14+ Ev Dynamic Range, i.e. 76+ e- Full Well Capacity vs Low Noise levels,
especially the Conversion noise level which is as low as the value of the Nikon D850.
DR is 2~2.5 Ev better than 2012 Eos DSLRs, D600 Low Light's ~664 ISO better :
If you are buying a D600, a D610 just spend a little more for a D750, it will beat the
D600, D610 in the Long Exposure Sensor Testing of Brendan Davey Photography :
You may also enjoy shooting with this D750 at a High ISO setting - but, don't forget
the imx-128 isoless Sony Exmor sensor is at its Best between ISO-100 and -400 !

Here is M-42 in 6x 8 min. from my D600 at ISO-200 through an F/6.7 refractor :
Long Exposure in the Night : 42 shades of Blue, Purple and Red ( D600 )
The Green layer level has been significantly lowered to that effect :
M-42 Orion + Running-Man in Blue, Purple and Red

Asi128MC-Pro & Qhy128C-Pro Astro cams launched at ~$6000€ are easy to find
discounted or used for ~35-60% that price with imx128 really stunning performances

I find those Best FF Cameras don't show that much improvements over my 9 years old
Nikon D600. So I put my wishes in a " Blue Dream Camera " at the right of the 5 DxO
rated 100 from 3 different brands, with my old Nikon D600 as a Reference at left :

Click Image, Ctrl+ to Enlarge

Note that if the D600 has an overall score of only 94, this is mainly because of its lower
Pixel Count, 24 versus 45 for these 5 recent FF cams. Plus 24 MP gives only 10 MP in
APSC crop mode, this is Not enough at the time where Recent APSC cameras get 20,
24, 26, 28 MPix. D600's Color Depth is only 25 bit vs recent FF cameras are over 26,
but despite its lower Pixel Count, D600 is still " in the race " for its Very Good Dynamic
Range, especially at ISO 200, and Good Low-Light-ISO score.

How about the Signal to Noise Ratio, SNR, of these 5 Top Ranked FF cameras :

Click Image, Ctrl+ to Enlarge

SNR is one of the main criteria for Long Exposures in Low-Light, Astro-Photography.
If you plan to Print Large Posters, compare camera's Screen Modes, vs if you expect
the benefits from DownSampling, then compare cameras in Print Mode. Blue Curve
show my expectations for a FF camera with More than 48 dB SNR at ISO 100.

How about the Dynamic Range score of these 5 Top FF cameras w/ a rating of 100 :

Click Image, Ctrl+ to Enlarge

Due to their very Low Noise levels, CMos Image Sensors, CIS cameras show much
improved Dynamic Range vs older, mainly APS-C CCD cameras with Lots of Noise.
Dynamic Range: the ability to show Noise-Less Details even in the Deeper Shadows.
If you plan to Print Large Posters, compare camera's Screen Modes, vs if you expect
the benefits from DownSampling, then compare cameras in Print Mode. The Blue dots
show my expectations for a FF camera with more than 15 Ev of DR at ISO 100.

How about the Color Sensitivity score of these 5 Top Ranked FF cameras :

Click Image, Ctrl+ to Enlarge

For Long Exposure in Low-Light, Astro-Photography, Color Sensitivity is not the most
important characteristic to take into account when choosing a new camera, nevertheless
if you are also interested in shooting Architecture, Landscapes, Portraits, etc with it, you
have to take this parameter seriously too. The Blue Curve shows my expectations for a
Full Frame camera with More than 27 bit of Color Sensitivity at ISO 100.

Finally, I expected a Low-Light score of ISO 5680, this is computed from the DxoMark
ISO value of both the Pentax Q and Q-10, first averaged : (183 + 189 ) /2, then divided
by their sensor dimensions : /4,6 /6,15 mm, finally enlarged up to FF size : *24 *36 mm.
Sensor Sensitivity Comparison Tools for Astronomy and Low-Light Photography
ISO 5680 is the sensitivity of a Full-Frame sensor that would have the Same Sensitivity
/ mm² than the averaged value of both Pentax Q and Q-10 :
Pentax Q, Q10, 2 little Marvels with DxoMark ISO-5680 BSI sensor

Signal to Noise Ratio higher than 48 dB, Dynamic Range better than 15 Ev, Color Sen-
sitivity higher than 27 bit, Low-Light ISO score better than 5680 ! Are my expectations,
too high ? I don't think so, if you aren't ambitious enough to exceed your limits and usual
limits, don't bother, buy any camera, else always buy the best tool for your requirements.

Now, I just have to keep waiting for a camera that'll reach these IQ performance levels...

A good way to evaluate the DxO ISO value of an unknown camera sensor, is to apply a
rule of 3. Let's compute an ISO value for the Gfx100s' imx411 CMos, the closest sensor
by Pixel Design recently tested by DxoMark is the Pixii A1571's imx571. Its ISO sports
score is 1939. I will only keep 85%=1648 due to the fact a 4x bigger sensor has to fight
more against Heat, Amp Glow, etc. The calculation from the dimensions : 1648 / 23.5 *
44 / 15.7 * 33mm = 6486 for the Fuji Gfx100s' sensor. The same rule of 3 I used on 16
April 2014 to evaluate the DxO ISO value of the Pentax 645z. I was very close : "4500"
instead of 4505 published by DxoMark 3.5 years later. I was optimistic for the Dynamic
Range, 15 ev instead of 14.7 ev and dead on for the Color Depth, 26 bit exactly ! Here
are my Forecasts after the Pentax 645z announcement published by DPReview
Pentax 645z : my sensor rating Forecasts, April 16 2014

Pentax 645z My sensor rating Forecasts
Click Image to Enlarge

Pentax 645z results, finally published by DxoMark, November 14 2017

Testing a MF camera instead of a FF one ?

I'm actually testing the Fuji GFX 100s, and it seems to meet my expectations IQ wise.
Here are the results of my first night testings during Christmas & New Year's day WE :
Fujifilm GFX 100s, the first 7 night-tests edited

Shooting, everything was shot Handheld from GFX-100S JPGs with GF 32-64 f/4.
ISO Sensitivity : ISO 800-1000 - all in HCG mode range.
Aperture : f/5,6-6,4 - SS : 1/10, 1/13-1/15 sec. thanks to the IBIS system.

Building, Stock Exchange, Wheel : perspective straightened in Elements 3.
Editing, Size reduct°, 100% Crop insert°, USM, Save to JPG 96% : IrfanView.

Gallery Marseille by Night, shot with the Fujifilm GFX 100s
Maximum 3000*2250 pixels or 2,5 MB because ISP Speed's way Too Slow here,
DPR Time Stamps 80 min. Retries, Timouts, to Upload 6 JPGs, 12 MB !
So, a 100% Crop from the Fuji .JPG is inserted inside each.

Chassimages' story of 2 Testing Nights with the Fujifilm GFX 100s
Same Shooting, Editing, every detail is reported :
Chassimages' story of 2 Testing Nights : the next page

Fujifilm's White Balance presets Tests and Evaluation
For Cityscapes lit from 2200 up to 6600 Kelvin, is the best preset Fluorescent-2 ?

32-64/4 Zoom lens or 30/3.5, 45/2.8, 50/3.5, 63/2.8 Prime lenses ?
Instant, Silent Focusing, Very Good Optical Performance for the GF 32-64 f/4 !

Fuji GFX100,S,II MILCs' good to know Specs

Fuji Gfx100x cameras for Low-Light, Astro-Photography has moved here

17 Fuji GF lenses, 24*36 D,h,w equivalent FLs

All about Fuji GF Lenses for Fuji Gfx100x cameras has been moved here

Camera Jpegs' Low-Contrast Resolution ranking

I gathered datas about Cameras' Low-Contrast Resolution ranking from site
Low-Contrast-Resolution ranking from FF-DSLM/R datas - because Low-
Contrast measurements - in Line-Pairs per Image-Height - is very close to Real-Life
Results, opposed to somewhat optimistic High Contrast resolution values. Then I put
them in a sortable per column table in order you could easily compare these cameras.
This table also shows datas about Screen/Printed Visual Noise. It's searchable here :
* Calculation Method * : datas from + "Horizontale Tabelle Anzeigen"
- LCresXXX = Auflösung bei ISO-XXX * Detailtreue bei ISO-XXX / 100.
- Auflösung bei ISO-XXX = Max Resolution (in Line-Pairs per Image-Height)
measured at ISO-XXX setting according to ISO-12233.
- Detailtreue bei ISO-XXX = The level of detail is a measure of how well fine details
are retained in a subject with Low-Contrast ratio.
It sets the Low-Contrast Resolution measured according to ' Dead Leaves ' method
(in Line-Pairs per Image-Height) in relation to the number of Line-Pairs of the
' Normal ' Resolution measurement at the same ISO-XXX level.

I'll build the same table from datas for APSC Cameras as soon as possible.

~~~~~ tbc... ~~~~~

Camera's other Features to take into account

Is IBIS a Must-have Feature or... a Penalty ?

I am always very surprised to see so many photographers, even calling themself expert,
taking cityscapes at ISO 12800 and not seeing that in this way they lose more than half
of the sensor performance of their camera, often an Expensive High-End model ! High
ISO settings should of course be reserved for restless subjects, childrens, sports, etc...

If your camera does not include this IBIS feature, you are doomed to Zen still postures
to get sharp pics w/o tripod at very low speed Hand Held, depending on the lens used.

Sometimes it's successful, 2nd photo : Opera de Marseille shot from a giant flower pot
containing a palm tree, where I am climbed to avoid a row of parked cars in the frame :
Nikon D600 + Samyang 35mm F/1.4 Hand Held = 1/25 sec. at F/2.8 - ISO 200 :

Sometines you have no choice : Marseille, Chistmas 1984, my Bronica is loaded with
ISO 100 Fujichrome slide film and... No way to install the tripod in that crossroads :
Bronica GS1 + Zenzanon PG 100mm F/3.5 Hand Held = 1/8 sec. F/4 - ISO 100


The classic Big DSLR or the tiniest Mirrorless Camera ?

But, some reduced size ML cameras, stuffed with electronic cards and which sensor is
filled with Transistors to achieve On Sensor-PDAFC, PDAFS, EFCS, ES, NR, ADC,
Big Buffer, High Speed Transfer, etc... Plus the IBIS system that Thermally isolates the
sensor from the body, hence reduces the Heat Transmission from the electronics to the
outside via the camera body... All these drive to Over-Heating issues during Video, or
Self-Heating problems during Astro-Photography and/or Intervallometer usage !

~~~~~ tbc... ~~~~~

Sensors' Behavior in Long-Expos. / Low-Light

Canon was the first brand to promote CMos Image Sensors for its cameras since 2002,
so they're often cited as References for Low-Light, Long-Exposures, AstroPhotography.
That was true until 2007~2008 when Nikon then Sony came to CMos with Less Noisy
sensors than Canon and totally false since Sony's Revolutionary Exmor sensors in 2010.

A set of CMos-Cameras from site, sorted by their Conversion-Noise level :

Cameras sorted by Conversion-Noise level
Click Image to Enlarge

The highest Full-Well-Capacity, Q-E, ISO-Invariant values of the Nikon D5, a camera
optimized for High Quality pictures in very Low-Light or High-Speed conditions ! See
the Lowest Conversion-Noise values from the first cameras with Sony Exmor Sensors :
twenty times, 20x lower than the Eos 6d, best affordable Canon DSLR for this criteria,
the Pentax K-5 and the Nikon D7000 show a near to null Conversion-Noise value due
mainly to their On-Sensor Embedded ADC - Analog to Digital Converter that prevents
aSaP the Signal to be polluted by Weak Filtering Power Supply and/or Weak Shielding
that will totally ruin their potential Dynamic Range :
Pentax K-5 the Dynamic Range's Master compared to High-End 24x36 DSLRs

~~~~~ tbc... ~~~~~

Ten useful Tables full of Big Data on the web

DxoMark Sensors Tests Database

Photographic Dynamic Range, Low-Light ISO...
Camera + 3 Columns, computed from Datas collected by Bill Claff :

Max-PDR : Max. Photographic Dynamic Range (at Base ISO) as defined by bclaff :

Low-Light ISO :

... Compared to DxoMark measurements...

... Audited by Bill Claff :

Sensor Heatmaps...
Camera + 8 Columns, computed from Datas collected by Bill Claff himself :

... Plus this site about Camera Long Exposure Sensor Testing :
Camera + 5 Columns, ISO 3200 Test Shots collected by Brendan Davey himself :

Photon Transfer Curves :

Bill Claff, about Photon Transfer Curve
« The single most useful chart showing sensor performance is a pixel level chart... »
I think you should read the whole thread... and maybe more than once ?
Older threads :
Camera & 5 Columns, computed from Datas collected by Bill Claff :

ISO : Base ISO setting for the measurements.

Bits: useful to know at 1st because all ADU numbers Ranges depend on the bit.depth.
If bit-depth =12, then Max ADU(DN) value is 2^12 = 4096 else if bit-depth =14, then
Max ADU value is 2^14 = 16384 and Noise values vary Proportionally ! Clicking once
on 'bits' you get the 10 bit smartphones, click once more and you get 16 bit CCD cams
with high Read Noise Numbers. Older or Cheaper cameras are mostly 12 bit depth, the
higher the bit-depth, the stronger you can torture yer Raw files w/o getting Posterization.

σRead : Standard Deviation Read

DxoMark Derived Sensor Characteristics :
Camera + 7 columns computed from DxoMark sensor measurements :

Bits: useful to know at 1st because all ADU numbers Ranges depend on the bit-depth.
If bit-depth =12, then Max ADU(DN) value is 2^12 = 4096 else if bit-depth =14, then
Max ADU value is 2^14 = 16384 and Noise values vary Proportionally ! Clicking once
on 'bits' you get the 10 bit smartphones, click once more and you get 16 bit CCD cams
with high Read Noise Numbers. Older or Cheaper cameras are mostly 12 bit depth, the
higher the bit-depth, the stronger you can torture yer Raw files w/o getting Posterisation.

Unity ISO : the ISO setting where 1 electron e- is converted into 1 ADU = the numbers
in the Raw files = DN. MF CCD cameras have lower Unity ISO numbers.

FWC, Full Well Capacity e- = how much electrons e- stores One Pixel when clipping,
the Higher the number, the later Clipped High-Lights will occur. Clicking once on FWC,
you get tiny Pixels, CCD cameras, click once more and you get FF cameras with Fewer
Big Pixels : their Higher FWC value is fully expected = divide this by the 2 Noise values.
Don't be fooled by few High-FWC Big-Pixel, a High Good-Pixel Count is valuable too !
See explanations for DxoMark Per Pixel Screen Mode vs Normalized 8MP Print Mode,

Read Noise e- : all Noises produced at Pixel level. The lower, the better. Clicking once
on RN you get cameras with modern sensors, click once more and you get CCDs, older
CMos cameras with Huge Read Noise levels to avoid.

Conversion Noise e- : all the Noises produced by Surrounding Electronics : Analog to
Digital Converters, Amplifiers, Power Supplies, etc. The lower the better. Clicking once
on CN you get cameras with Modern Electronics, with On Sensor ADC, etc, click once
more and you get mainly Canon cameras with their ® Huge Electronic Noise ! 3 Recent
models, R5, R6/1Dx3 escape from this totally unbelievable disaster, 12 bit can't fool U !

QE % : Quantum Efficiency = how much incident Photons % are converted to electrons.
One Click you get lower QE sensor, CCDs, older CMos cameras with low Fill-Factor,
one more click you get the best QEs, iow FSI sensors w/ high Fill-Factor / BSI sensors.

ISO invariant at ISO : the ISO setting from which only Digital Amplification is applied,
iow the end of Analog Gain... but this is a Simple Theorical explanation, please read this : be continued...

  © Dima Lootvoet 2010-2024

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