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  #101  
Old 15-02-2017, 03:58 PM
mmalik (Mike)
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Here is how noise in RAWs crescendo-es overnight in an actual imaging session in an UN-Cooled scenario...
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  #102  
Old 15-02-2017, 04:09 PM
mmalik (Mike)
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Here is how noise in RAWs stabilizes in an actual imaging session in a 'Cooler @ the Base' scenario...

Note: Comparison with un-cooled sessions shown
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  #103  
Old 15-02-2017, 04:55 PM
mmalik (Mike)
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Following is a7S 'Cooler @ the Base' sample for the data presented...
  • 36x3min, ISO2000
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  #104  
Old 15-02-2017, 05:23 PM
mmalik (Mike)
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Quote:
Originally Posted by luka View Post
...I can see that in one of your tests you used ISO2000. You should probably stick to full-step ISO numbers (200, 400, 800, 1600, 3200 etc) as lots of DSLRs still take exposures at full-step ISOs and then use multiplication to get the ISO values in between.
Luka, a7S is not a typical camera, and old rules don't apply. Here is why ISO2000 is recommended for a7S. There is ton of data out there to support this. Regards
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  #105  
Old 17-02-2017, 04:10 PM
mmalik (Mike)
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Quote:
Originally Posted by mmalik View Post
Here is how noise in RAWs stabilizes in an actual imaging session in a 'Cooler @ the Base' scenario...

Note: Comparison with un-cooled sessions shown
http://www.iceinspace.com.au/forum/a...1&d=1487138987
Here is how subs look at stages pointed out in the graph...

Note: Click the image below to look closer
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  #106  
Old 18-02-2017, 03:04 PM
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rcheshire (Rowland)
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Mike. Not sure how I am categorised an expert. All of the material in my publication is available to anyone with an inquisitive nature. It just so happens I decided to put it in one place.

It makes sense that consistent temperature across a data set is beneficial. CCDs demonstrate that clearly. My point is, that very low temperatures, while reducing dark current significantly, can be problematic technically, in DIY systems. Go for consistency and take darks. Temperature regulation makes it easier to compile libraries for long term use.

The biggest issue is the camera getting wet. Sort out the protection requirements and then work out the cooling system details. As yet no one has come up with a really efficient cooler box. But Glen's argon bag is a clue.
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  #107  
Old 18-02-2017, 04:47 PM
mmalik (Mike)
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Originally Posted by rcheshire View Post
The biggest issue is the camera getting wet. Sort out the protection requirements and then work out the cooling system details.
Thanks Rowland; this is exactly the mastery that goes in 'Cold finger Inside' mods. Each camera is unique so I design internal insulation (electrical & moisture) accordingly.

To give you one example, look at the base of a7RII. First off it is all metal, no circuits. Second, I put in a thin layer of neoprene rubber insulation at this level to prevent any wetting.

Note: Neoprene goes in between the two layers shown; each image being a layer

This pretty much thermally isolates the whole bottom to prevent any inside wetting.

In short, each camera would have similar measures in place to prevent internal condensation. Regards
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  #108  
Old 15-04-2017, 01:35 PM
mmalik (Mike)
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Here is the neoprene at the base of a7RII which serves as thermal, as well as moisture insulation. Regards
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  #109  
Old 15-04-2017, 01:46 PM
mmalik (Mike)
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While one has camera open for 'Cold finger Inside' mod, it can be an opportune time to perform an astro mod as well.


Performing a 2-in-1 cooling and astro modification on a7RII next...
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  #110  
Old 15-04-2017, 01:48 PM
mmalik (Mike)
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a7RII LPF stack...
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  #111  
Old 15-04-2017, 01:50 PM
mmalik (Mike)
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Once LPF stack is removed, a full-spectrum look of a7RII...
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  #112  
Old 15-04-2017, 01:52 PM
mmalik (Mike)
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Houston, we have a problem...


IMPORTANT: A post Full-Spectrum a7RII dark shows severe light pollution from an internal light source. After much investigation, this has now been "confirmed" to be a 'known' problem with a7RII. There is a light source in/around the shutter mechanism that gets exposed after a full-spectrum mod. Stay turned for its remediation!
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  #113  
Old 15-04-2017, 01:54 PM
mmalik (Mike)
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a7R and a7RII are completely different animals; people have done a7R full-spectrum mods without such issues and the reason is that a7R had no LPFs; no LPFs meant there weren't IR sources inside to begin with, no IR sources meant full-spectrum had no issues. Sony had their head attached while they designed a7R.


a7RII 'has' LPFs as I show above; removing them in a full-spectrum mod exposes the internal light pollution which otherwise would have been blocked by the LPFs. This is a Sony design flaw [I am sure intentional] but I would call it a blunder; but we have some choices which I'll get into next. Regards
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  #114  
Old 15-04-2017, 01:56 PM
mmalik (Mike)
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This kind of leak (like the one in a7RII) is not amenable to any kind of external filtering since light source lies within or close to the shutter; so any blocking of such an IR source has to be on the sensor itself. So here is the solution I came up with...
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  #115  
Old 15-04-2017, 01:57 PM
mmalik (Mike)
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How Baader fits in a7RII's native bracket...


Note: Adequate insulation is needed to block light getting in from the edges of the Baader and the sides of the bracket; a job only a professional should attempt!
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  #116  
Old 15-04-2017, 01:58 PM
mmalik (Mike)
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a7RII dark with Baader installed...
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  #117  
Old 15-04-2017, 02:02 PM
mmalik (Mike)
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An actual image taken with a7RII Baader modified above...


Note: Image courtesy of a professional astro-photographer (DL); taken after 40min of astronomical darkness
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  #118  
Old 19-04-2017, 06:07 AM
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rcheshire (Rowland)
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Mike. I see what you are doing with the base of the camera. How have you addressed internal components. Anything within proximity of the conductor strip? Exclusion rather than insulation is going to protect in humid conditions.
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  #119  
Old 19-04-2017, 07:08 AM
glend (Glen)
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Quote:
Originally Posted by mmalik View Post
How Baader fits in a7RII's native bracket...


Note: Adequate insulation is needed to block light getting in from the edges of the Baader and the sides of the bracket; a job only a professional should attempt!
Haha, yeah, a professional like you, eh? Free advertising through forums. There are hundreds of filter mods that have been conducted by camera owners, its not hard to do and the step by step instructions for some cameras are available online for free. Folks in Australia, who may not wish to try it themselves, can usually get a camera repair shop to do the work for them at reasonable cost. I seem to recall a Sydney camera store was charging $150 for a full spectrum mod.
Don't get sucked into this guys web, if your considering DSLR mods ask about it on the IIS forum first.
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  #120  
Old 19-04-2017, 09:37 AM
mmalik (Mike)
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Originally Posted by rcheshire View Post
Mike. I see what you are doing with the base of the camera. How have you addressed internal components. Anything within proximity of the conductor strip? Exclusion rather than insulation is going to protect in humid conditions.
Rowland, you are correct and I have accounted for the exclusion. Not sure if you paid attention how I have excluded besides insulation in my older posts. Will see if I can elaborate the exclusion concept further but it is there and accounted for. Regards
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