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Sony A7s - New Low-Light Camera - Wow!

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#601 Don Rudny

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Posted 13 November 2014 - 01:01 AM

Even after following/contributing to this thread, owning two Mallincams, several DSLR's, and now both the A7R and A7S I'm still not quite sure what Electronically Assisted (Astronomy)(EAA) observing is?  

 

 

Hi Brian,

 

Not sure I can answer your question, but I can give you my view.  I follow this forum for one reason.  I like to observe DSO's.  I believe that EAA enhances the ability to observe them in far greater detail than purely visual observation through the eyepiece.  That means that near real time viewing is essential to defining what EAA is.  The near real time observing can be direct to a monitor or through a computer where the image is controlled with software designed for continuous on the fly observing.  Any imaging should only be captures of the image viewed in the observing session.  Stacking should only be done in camera or on the fly as the image is viewed.  Same with image control such as brightness, contrast and color correction.  If image data is saved and post processed in any way with separate applications to produce improvements, then it's imaging.

 

I realize that the intent of the forum may go beyond what I believe, but this is what I believe EAA is all about.



#602 ccs_hello

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Posted 13 November 2014 - 02:11 AM

I think what is allowed in EAA forum has been discussed and clarified by mods.

 

Can we refrain from again opening up that topic and beat that poor horse over and over?

 

Every new technologies which just came out have rough edges.

We should try to nurture the progress as oppose to "forming camps".

 

Clear Skies!

 

ccs_hello


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#603 Vondragonnoggin

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Posted 13 November 2014 - 07:38 AM

I think what is allowed in EAA forum has been discussed and clarified by mods.

 

Can we refrain from again opening up that topic and beat that poor horse over and over?

 

Every new technologies which just came out have rough edges.

We should try to nurture the progress as oppose to "forming camps".

 

Clear Skies!

 

ccs_hello

:applause:



#604 dvb

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Posted 13 November 2014 - 04:17 PM

Seems I did not make the point of my post clear.  It was not to address the TOS of this forum; there is no issue with moderation.

 

 

My point was to invite you to consider the revolutionary nature of the Sony A7s technology:  the apparent convergence of EAA and Imaging, and the breaking down of the "wall" separating the those two "boxes".   

 

Quite the opposite of  "forming camps", the effect of this technology is a unifcation of observers through a technology which is common to both EAA and imagers. 

 

I think what is allowed in EAA forum has been discussed and clarified by mods.

 

Can we refrain from again opening up that topic and beat that poor horse over and over?

 

Every new technologies which just came out have rough edges.

We should try to nurture the progress as oppose to "forming camps".

 

Clear Skies!

 

ccs_hello


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#605 ccs_hello

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Posted 13 November 2014 - 05:25 PM

dvb

 

My comments were generic and not to any specific individuals.  I saw the focus seemed to have drifted possibly to a direction that will dilute the value of the thread topic which is A7s.

That's my only reason.

Hope you don't mind.

 

Clear Skies!

 

ccs_hello


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#606 core

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Posted 13 November 2014 - 11:16 PM

Didn't see this posted (apologies if it's a repost), but here's a youtube video using A7S with 1/4sec videos of DSO's on a C14, everything from NGC6888, IC1318, to Helix, etc.  Very impressive for 1/4" seconds of exposure; the short duration of the star trails  as the mount slews around really does give you the sense of how real-time the 'live view' gets.

 

Also, Hutech just made an announcement that they are now authorized Sony dealers, and they will be offering 'no filter' modded  7, 7S, and 6000.  IDAS has a line of filter mounts as well.

 

http://www.youtube.c...zLJ-M2Z_I#t=140


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#607 Relativist

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Posted 14 November 2014 - 11:05 AM

That's very good news about Hutech, any word on price?

I know it's a lot to ask, but a scan of this thread should be done by anyone wondering why the A7s is here at EAA, wherein they would find the video you linked, among other nuggets. Since this camera has a cost that is not insignificant it's adoption will be tempered. For example, I'm looking at early next year given my current budgeting, but then will there be an A8s that I should wait for?

Edited by Relativist, 14 November 2014 - 11:06 AM.


#608 tim53

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Posted 18 November 2014 - 02:06 PM

For people who would like to latch on the term "video" (may mean analog SD video) as the hallmark for any iimager to "see" DSO,

the simple fact is that the so call "videocam that can go deep and it is in video!!" is just an illusion.

 

It is still doing long exposure (say, one shot every 8 second), but it is the presentation that masquerade the discontinuation/disjoint events of multiple shots in sequence.

 

Some other devices may not be built to make the same appearance out of the box, but if the market (hopefully a huge one) exists, there will be ways to make it happen.

 

Clear Skies!

 

ccs_hello 

We just need someone to write the software to save continuous images as video files.  Astro IIDC, for running firewire machine vision cameras on the Mac, can take video from Pt Grey cameras at frame rates as long as 60 minutes/frame and save them as video files.

 

-Tim.



#609 RandyC

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Posted 15 December 2014 - 09:55 AM

Hello, Are there any ideas as to the best filter for nebulae on a modded A7s. Last night, I tried the Kolarivision Hotmirror to get the right colors. But of course, it filters out most of the H-alpha. The IDAS HEUIB filter makes the nebulae very red. I was thinking of something like an Astronomike CLS. The filtering seems to be a good mix of blue and red. It would be great if the auto-white balance works using it. thanks

 

http://www.astropix....ROP/DSLR_HA.HTM



#610 bwallan

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Posted 15 December 2014 - 01:24 PM

I did respond to your post; however, realized after I'd posted that this is the "Electronically Assisted Astronomy" forum and I can't give stacked examples of the impact of using the HEUIB-II filter.

 

Sorry about that.  Post has been deleted!

 

bwa


Edited by bwallan, 15 December 2014 - 01:25 PM.


#611 RandyC

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Posted 15 December 2014 - 04:02 PM

Brian, thanks for responding. It seems the sensitivity of the A7s is so great that it gets too red with the HEUIBII filter. Something like the Astronomik CLS balances the red and blue more evenly. It might be better, have you ever tried one? I will try the custom white balance like daylight and see. 



#612 Dom543

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Posted Yesterday, 12:04 AM

Stacked images should be perfectly fine on this forum. Miloslick, AstroLive and LodestarLive all stack.

If we want to assess and compare different breeds of new equipment and technologies, then the same rules should apply to all.

--Dom



#613 David B in NM

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Posted Yesterday, 08:27 AM

Dom,

I believe the Forum Mods made the decision. All the programs you referenced in your post above do it live. Up to now, I don't believe there's any program that allows this to be performed in conjunction with the capture on the A7. Hence, at the present time it isn't EAA and it is Imaging because it's post processing.

David B in NM

#614 Relativist

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Posted Yesterday, 11:00 AM

At this point, there is the internal camera stacking, and there is the posibility that DSS will one day support A7 raw files, so that things like DSS live and Observer Toolbar for DSS could be used. So far no news on that end.

#615 RandyC

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Posted Yesterday, 11:24 AM

Here's 4mins on NGC7331 at iso2500. I find iso 6400 at @2mins to capture more detail than at iso2500 @3-4mins. But 2500 is smoother, so as long as the target is bright enough, it's fine.

Attached Files



#616 RandyC

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Posted Yesterday, 07:11 PM

For comparison, here's 2mins at iso6400. Enjoy.

Attached Files



#617 DonBoy

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Posted Yesterday, 09:35 PM

Randy,

 

I would think that the 6400 ISO image would have made a better comparison if it's exposure was more proportional to the ISOs:  2500/6400=.39;  thus .39x4 minutes = 1.56 minutes.   Two minutes was about 28% more exposure than 1.56 minutes.  Based on the stars the 6400 ISO image appears to be better focused or more sharpness was applied.

 

Keep the images coming and the comparisons using various settings.  This will help in getting an appreciation of the cameras personality and capability.  Thanks for sharing the A7S images.   Surprisingly we have not seen much of late since the initial release date from anyone.



#618 Relativist

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Posted Yesterday, 09:35 PM

Randy, those are great. Would it be possible to show us one at higher ISO, with the 30 sec exposure where the camera does the dark and noise reduction? Not sure what that setting is called.



#619 dvb

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Posted Today, 01:02 AM

Yes, great pictures Randy. 

 

But, there are lots of cameras that will do ISO 6400, no?  

 

So, shouldn't have to invest the big bucks in an A7s with its mega ISO to get such nice images?



#620 RandyC

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Posted Today, 09:28 AM

Randy,

 

I would think that the 6400 ISO image would have made a better comparison if it's exposure was more proportional to the ISOs:  2500/6400=.39;  thus .39x4 minutes = 1.56 minutes.   Two minutes was about 28% more exposure than 1.56 minutes.  Based on the stars the 6400 ISO image appears to be better focused or more sharpness was applied.

 

Keep the images coming and the comparisons using various settings.  This will help in getting an appreciation of the cameras personality and capability.  Thanks for sharing the A7S images.   Surprisingly we have not seen much of late since the initial release date from anyone.

Don, the exact time is not critical. Once you have the image from the camera, contrast can be adjusted. This usually compensates for an exposure being too long/short. Also, the exposure time is not linear. Typically, you would do 2 mins at 6400 and about 3.5mins at 2500. At about 4.5mins at 2500, skyglow would start to take over. It also seems like the sensor wells fill with data after a point. So for example, 6mins at iso1000 isn't that great. After about 4mins, the sensors don't seem to collect much more data. So whatever you got early in the exposure is the image. And being that the sensitivity was lowered to 1000, there is less detail in the object. I've found 2mins at iso6400 to be the best overall EAA setting.



#621 RandyC

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Posted Today, 09:34 AM

Randy, those are great. Would it be possible to show us one at higher ISO, with the 30 sec exposure where the camera does the dark and noise reduction? Not sure what that setting is called.

Hi Curtis, Here is an exposure of 3secs at iso65535. Typically, I will do a check to make sure the object is in the fov but raising the iso and exposing for a couple seconds. Then I lower the iso back down. I don't use darks, flats, stacking or any traditional imaging techniques. The image here has had no post processing. I used Fotor on the iso2500 and 6400 images to adjust contrast. The camera has great dynamic range to differentiate between the object and sky glow. Even if the object is way overexposed, the image is often usable by adjusting contrast.

Attached Files


Edited by RandyC, Today, 09:36 AM.


#622 RandyC

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Posted Today, 09:48 AM

Yes, great pictures Randy. 

 

But, there are lots of cameras that will do ISO 6400, no?  

 

So, shouldn't have to invest the big bucks in an A7s with its mega ISO to get such nice images?

Hi Doug, it's the A7s ability to get a usable astro image at iso6400 without too much noise. For an experiment, I tried the A7r and found it's smaller pixels at 36mp were not as good at getting details. So the A7r at iso6400 would have more noise and skyglow than the A7s. Also these image use the DRO processing built into the camera. After the image is done, the camera Bionz processor removes all the background pixelation noise. The Bionz processing takes about as long as the initial exposure time. On the iso65k image above, it didn't. But on an iso10k or less it will. Then all you have to do is adjust contrast. If you use the raw files straight off the camera, you have to use your own noise removal tool. I imagine less expensive cameras won't be as adept at low light situations.

 

All that said, the best single feature of the A7s is the fullframe sensor. Your go tos don't have to be exact. Think how much time you spent haggling around getting your object in view and centering it. With the FF sensor, it's pretty easy because of the wide fov. Subtract the time it takes you to center all your objects from your overall exposure and you have a really really fast camera.


Edited by RandyC, Today, 09:51 AM.

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#623 Relativist

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Posted Today, 01:01 PM

Very interesting Randy, what are the DRO limits in time/ISO range? Also, what other, if any, settings do you find useful for EAA?

 

BTW, I don't know if people are aware, Sony has announced/released the A7 II, which mainly adds a 5 degree of freedom image stabilization mechanism to the body. When they did so the regular A7 dropped down in price. I do not know if there was an update to the software or controller. Supposedly there will be an A7r II and an A7s II in the future.

 

http://www.sony.net/.../products/v6cd/



#624 RandyC

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Posted Today, 03:18 PM

Very interesting Randy, what are the DRO limits in time/ISO range? Also, what other, if any, settings do you find useful for EAA?

 

BTW, I don't know if people are aware, Sony has announced/released the A7 II, which mainly adds a 5 degree of freedom image stabilization mechanism to the body. When they did so the regular A7 dropped down in price. I do not know if there was an update to the software or controller. Supposedly there will be an A7r II and an A7s II in the future.

 

http://www.sony.net/.../products/v6cd/

I think there are 5 levels of DRO, but I just use Auto. I also use Picture Style Vivid which seems to bring out colors a little better. And you need a HEUIB-II filter for galaxies on a modded camera. I still haven't figured out the correct white balance for nebulae. Brian who has a camera here knows how to do nebulae.








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