2336 replies to this topic

[mmalik]

Simplicity and agility of the design: Contrast the plastic sensor-mount skeleton and spring-loaded (calibration "required") sensors of Canon...

 

 

Source: Own rendering

 

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[mmalik]

...with magnesium alloy sensor-mount and solidly-mounted (NO calibration required) sensors of Sony (a7S)

 

 

Note: Full-frame sensor 'is' mounted in the picture.

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Edited by mmalik, 20 January 2015 - 04:09 PM.

[mmalik]

A somewhat non-correlated size perspective...

 

 

Note: ONLY sensor-mount/lens-mount module of a7S is shown; full-frame sensor 'is' mounted in the picture.

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Edited by mmalik, 20 January 2015 - 04:22 PM.

[Jon Rista]

 

 

...they all need a 5Dmk 4 with Sony sensors!

 

Canon + Sony = Cany A5D mk IV

 

We all want the best, but what sensor do you find in many cooled CCD cameras? yes a very old 11002 or the 8300! both sensors have limitations, (poor ha sensitivity, small pixels), and yet 90 % (I guess) of the best astronomical images are made with these sensors.

You don't need 70% QE for a fine astronomical image, you need clear sky and no moon.

 

Garrett van der Veen

 

 

Totally agree with the bolded statement. And, further...you need dark skies. Driving 35 minutes from my house to a dark site to do my RGB imaging has improved my work 100x, and it's 100x more efficient (at least).

 

One thing I will say about the 8300, 11002 or 16803, though, is even though they don't have as good of Ha sensitivity as the new Sony CCDs (which are 65% @ Ha), the KAF sensors DO have pretty high Ha sensitivity at just shy of 50%. That is a 5-6% difference in Ha sensitivity between a KAF and a Sony, which isn't nearly as big as the difference between a KAF an most DSLRs, which start out at around 10% Ha sensitivity (unmodded.) The other benefit of a CCD is the cooling...being able to regulate the temperature and keep it low, so that DC accumulates very slowly, is a big bonus. With a DSLR, even the newer ones that have very low dark current at very low temperatures, have lower doubling temperatures (i.e. 4.7C, vs. ~6C or so with most CCDs), so dark current fluctuates more and faster as temperatures change, and can get extremely high at warmer temperatures. One of the main reasons I want to go to CCD is the ease of generating darks that can be reused.

[Jon Rista]

 

I'd LOVE to see a detailed review of how the Samsung NX1 performs for astrophotography. 

 

No detailed review yet partly because I'm stuck in a white zone but I did run a couple of quick tests w/Comet Lovejoy.

http://www.slrlounge...ull-frame-cmos/

 

Read noise is definitely very low.   Sony like rather than Canon like.  No posterization in the RAW.

 

NX1
ISO100 3.14 e-/pixel (SD 7.9 e-)
ISO1600 1.68 e-/pixel (SD 4.0 e-)

 

I don't know the full well capacity of the NX1 since I only know how to measure it to the nearest 1/3 stop and that doesn't seem to be entirely accurate.  Thermal noise is also pretty good.  

 

ISO 1600 NX1
Two 1/8000 bias frames: StdDev 11.4 ADUs
Two 30 second dark frames: StdDev of 22.3 ADUs

The median difference is 0 or 1.

 

So for 3.6 micron pixels, that's pretty impressive I think.

Attached: M42 10 second subs, ~30 minutes of integration.  Polar alignment through compass+inclinometer. 180mm lens.  No flats/darks.  Taken indoors.  On a 50mm lens, the left side of the frame would show the window sill and the right would have the window frame.  This gives you a sense of the Ha sensitivity for unmodified.

 

 

Thanks, Alan! Does sound impressive. Looking forward to hearing more. 

[alan.dang]

 

 

 

Hopefully we'll get other reviewers checking this out the hardware in greater detail.  I image with small telephoto lenses (open aperture 72-77mm only) in the middle of San Francisco where I never get >3 min subs and usually can only get 30 second subs.

 

I do have an ear to the PR people for Samsung so I've given them three "not too difficult, but will make astrophotographers happy" suggestions

 

1 - allow the on-board intervalometer to do >30 second exposures

2 - add FWHM to the live-view tethering mode to help us with focusing

3 - AC power adapter

[cherokawa]

 

 

 

...they all need a 5Dmk 4 with Sony sensors!

 

Canon + Sony = Cany A5D mk IV

 

We all want the best, but what sensor do you find in many cooled CCD cameras? yes a very old 11002 or the 8300! both sensors have limitations, (poor ha sensitivity, small pixels), and yet 90 % (I guess) of the best astronomical images are made with these sensors.

You don't need 70% QE for a fine astronomical image, you need clear sky and no moon.

 

Garrett van der Veen

 

 

Totally agree with the bolded statement. And, further...you need dark skies. Driving 35 minutes from my house to a dark site to do my RGB imaging has improved my work 100x, and it's 100x more efficient (at least).

 

One thing I will say about the 8300, 11002 or 16803, though, is even though they don't have as good of Ha sensitivity as the new Sony CCDs (which are 65% @ Ha), the KAF sensors DO have pretty high Ha sensitivity at just shy of 50%. That is a 5-6% difference in Ha sensitivity between a KAF and a Sony, which isn't nearly as big as the difference between a KAF an most DSLRs, which start out at around 10% Ha sensitivity (unmodded.) The other benefit of a CCD is the cooling...being able to regulate the temperature and keep it low, so that DC accumulates very slowly, is a big bonus. With a DSLR, even the newer ones that have very low dark current at very low temperatures, have lower doubling temperatures (i.e. 4.7C, vs. ~6C or so with most CCDs), so dark current fluctuates more and faster as temperatures change, and can get extremely high at warmer temperatures. One of the main reasons I want to go to CCD is the ease of generating darks that can be reused.

 

 

If you ask me, the biggest advantage an astro cameras has over DSLRs is the mono sensor. Even if a DSLR (or mirrorless) sensor has 80% QE and is modded, it will still lag behind mono CCDs in terms of photon gathering efficiency in luminance or narrowband. Give me a mono DSLR with microlens and I won't mind a 3 gen old sensor and lack of cooling. Even better if it comes in the form of a mirrorless with short backfocus requirement.

 

 

 

 

 

 

Hopefully we'll get other reviewers checking this out the hardware in greater detail.  I image with small telephoto lenses (open aperture 72-77mm only) in the middle of San Francisco where I never get >3 min subs and usually can only get 30 second subs.

 

I do have an ear to the PR people for Samsung so I've given them three "not too difficult, but will make astrophotographers happy" suggestions

 

1 - allow the on-board intervalometer to do >30 second exposures

2 - add FWHM to the live-view tethering mode to help us with focusing

3 - AC power adapter

 

 

An SDK with access to bulb exposures and uncooked RAW would make the camera astro-friendly. 

Edited by cherokawa, 20 January 2015 - 08:38 PM.

[whwang]

 

 

If you ask me, the biggest advantage an astro cameras has over DSLRs is the mono sensor. Even if a DSLR (or mirrorless) sensor has 80% QE and is modded, it will still lag behind mono CCDs in terms of photon gathering efficiency in luminance or narrowband. Give me a mono DSLR with microlens and I won't mind a 3 gen old sensor and lack of cooling. Even better if it comes in the form of a mirrorless with short backfocus requirement.

 

 

I totally agree with you.  The real advantage of astro-CCDs is the light gathering power in L (of LRGB) and narrowband mode.  The ability of stabilize sensor temperature is a plus, but cooling is not.  The ironic fact is that if those Kodak CCDs are not cooled, they totally cannot compete with CMOS in terms of thermal noise.  Cooling is to hide the weakness of those CCDs, not an advantage.

 

Cheers,

Wei-Hao

[fetoma]

I found this as a way around programming "bulb" exposures.

 

http://www.terrastro...ny-nex-5-timer/

 

And there is a NEX hack project.

 

http://www.nex-hack.info/

Edited by fetoma, 21 January 2015 - 01:26 PM.

[Jon Rista]

Oh sure, mono CCDs have a much higher fill factor, and gather more light. No doubt. Much lower noise, much cleaner images. That is probably the biggest benefit. 

 

I also agree that KAF sensors have higher dark current than current CMOS sensors...however outside of some warranty-voiding mods to add coldfinger cooling to a DSLR, REGULATING the temperature, so that you can easily take effective darks, is another big bonus of CCD, IMO. Plus, Sony CCD sensors have extremely dark current as well, about as good as a modern CMOS sensor.

[fetoma]

Someone is doing something here to shoot images over a wifi connection using a PC. Maybe it could be used for long exposures?

 

https://www.youtube....h?v=2400atQO8Ng

 

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[ccs_hello]

RE:   I found this as a way around programming "bulb" exposures.

 

         http://www.terrastro...ny-nex-5-timer/

 

The above link's implementation (on BULB)  is incorrect (actually already commented by another person in that link.)

 

Using wired remote will only trigger IR pulse as the SNAP (say 10" exp), at the beginning of the exposure.  Camera will have to terminate the exposure through its setting setting.

BULB will require two trigger signals: one is BULB_start and the other BULB_end, which the wired remote cannot supply.

 

Also a minor comments, some IR remote, due to its internal design, cannot be triggered by the wired remote.

 

Clear Skies!

 

ccs_hello

[ccs_hello]

Someone is doing something here to shoot images over a wifi connection using a PC. Maybe it could be used for long exposures?

 

https://www.youtube....h?v=2400atQO8Ng

That link is also for intervalometer on a preset exposure time, not multiple exposures of timed BULB.

 

Clear Skies!

 

ccs_hello

[fetoma]

Thanks ccs_hello. Just trying to find something that works.

[ccs_hello]

For A7s and a5000, etc. which can be USB tethered.  Using SONY's PC software "Remote Camera Control", BULB can be simulated by holding the SHOT button down (mouse click down) for the entire duration.

Then there is a small add-on program "RemoteCtrlTool" which will run on top of the "Remote Camera Control" which will accomplish the hold the mouse click down method to accomplish BULB (and multi-shot BULB).

 

Clear Skies!

 

ccs_hello

[ccs_hello]

In summary,

 

1) using WiFi tether method, there is no BULB support,  <-- this is also the (Wifi-)SDK method

2) when using USB tether, there is a way to simulated the BULB effect,

3) when using wired shutter cord (muti-terminal connector), BULB can be accomplished (multiple ways to control that cable, including using a PC software thru a USB serial-RTS dongle),

4) when using IR remote control (multiple ways to control the IR remote fob), need two pulses for BULB (one at the beginning and one at the end of BULB time.)

 

Clear Skies!

 

ccs_hello

[mmalik]

This... works well with a7S for any length of long exposures in bulb (M in a7S) mode via USB. Regards

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Edited by mmalik, 21 January 2015 - 10:33 PM.

[ccs_hello]

Yep, I used this "standalone corded":

http://www.cloudynig...hutter-control/

 

PC based USB control to multi-terminal connector: http://www.cloudynig...n/#entry5943935

 

 

Clear Skies!

 

ccs_hello

Edited by ccs_hello, 21 January 2015 - 11:25 PM.

[Greenbbs]

This is the wireless/IR trigger I use

http://www.bhphotovi...s=REG&A=details

[mmalik]

In addition to Sony, I think Samsung's new Backside Illuminated APS-C sensor that they have used in the NX1 mirrorless is something we should keep an eye on. That sensor has already tested very well, and technologically it is one of the most advanced sensor's out there. With 65nm transistors and the BSI design, it is putting far more light-sensitive space into the path of the light, so it's fill factor, and thus overall Q.E., should be higher than any other APS-C sensor on the market (including Sony's).

 

Few questions; do we know exactly what is the QE of NX1? While we are at it what is the QE of a7II? I see www.sensorgen.info doesn't yet have data on any of these. Regards

Edited by mmalik, 22 January 2015 - 08:56 PM.

[ZeroID]

LOVE to see a BYSony system. Had them for years from early Konica Minolta SLR days. Currently using a SLT A77v and love it's feel in the hand. And it takes brilliant pix too. Movie mode can go for 30 mins non stop, then it has to store it, then back to movie mode no problem. I use a remote with interval timer for long exposures. Nikon get SONYs last years chip so never far behind.

 

I've picked up a cheap 450D Canon to see how BYEos works, very good system. I'll mod the 450D for IR soon but otherwise the SONY just does it all.

 

If we all keep mentioning it SONY might crack and release an SDK.

[Jon Rista]

Not sure about Q.E. on the NX1 sensor yet...someone on DPR forums mentioned it was in the 65% range, but it seemed anecdotal. The NX1 sensor is a BSI (backside illuminated) sensor design, with "shallow" pixels...i.e. the photodiodes sit very close to the surface, almost directly below the microlens layer. This greatly increases the pixels sensitivity to off-axis light, and light in general as it doesn't have to penetrate as deeply into the SiO2 layer. A friend who tests cameras sent me some test samples a while back, of both the 7D II and the NX1. They weren't the greatest samples, and he didn't quite understand how to properly use a step wedge, but the difference between the 7D II (Canon's most advanced sensor to date) and the NX1 was astonishing...the NX1 exposures were significantly deeper, far better color balanced, with significantly lower noise, by about two orders of magnitude as far as I could tell (although since the test images were produced incorrectly, I believe the total difference was closer to 2 2/3rds orders magnitude). 

 

So, I expect the Q.E. of the NX1 sensor to be quite high. Even if it is not, though, I still expect it to perform phenomenally well compared to other common astro cameras. The only thing I do not know about is the dark current...I never saw any long exposures, nor any bias exposures (I did ask for them, though.) I hope DC is low...but, who knows.

 

I did just find this:

 

http://www.eoshd.com...ding-log-gamma/

 

The real power of the NX1 is it's dynamic hardware. The NX1 is paired with an on-camera processing chip that can be reconfigured at the hardware level for high speed processing. Samsung does have an SDK, and apparently (based on the above) they are quite serious about it. Programmable firmware is one thing, but to be able to take full advantage of the speed of the hardware is entirely another. I really wonder how the NX1 could perform for astro...or what kind of astro-centric things we could do with hardware level programming right in the camera...

Edited by Jon Rista, 23 January 2015 - 04:17 AM.

[mmalik]

Don't you think a7II is going to steal NX1 thunder; how do you compare these two, 24.3MP/FF/$1,698 and 28.2MP/APS-C/$1,499, respectively? Do we have any data on a7II? Regards

[Jon Rista]

Technologically speaking, I think the NX1 is far superior to the A7 II...despite the latter having a full frame. Having used the A7r myself, the A7 II is going to need to be a massive improvement to interest me, where as from what I've seen of the NX1 so far, it's designed well (ergonomoically) and technologically (primarily the DRIMeV DSP with it's programmable hardware and BSI APS-C sensor running an open OS) has the potential to run circles around anything Sony has put out so far. Plus, Samsung seems dedicated to putting together an awesome SDK, which as we all know is essential to a camera's success in the astrophotography arena. 

 

At the moment, at least from my perspective, it's no contest: The NX1 is the top dog. For astro. 

 

The A7 II will probably be more popular in general simply because it's from the Sony Alpha line, which already has a growing reputation. The NX1 is quite new, and Samsung is a newer player in the digital camera arena...so just from a reputation standpoint they have some work to do. I don't really care about which camera garners more overall popularity, though....I care about which one will perform best for astro. A BSI sensor in an APS-C form factor, especially with the design innovations Samsung has put into it, paired with a well rounded SDK should trounce anything Sony has right now. I'll happily give up sensor size for those things.

Edited by Jon Rista, 23 January 2015 - 05:29 AM.

[mmalik]

For those wondering what is backside illumination or back-illuminated sensor (BI or BSI)...

 

 

Source: Own rendering

 

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Edited by mmalik, 23 January 2015 - 06:11 AM.