Infinity - Image Settings Help

[tweeb]

Hi all,

New member. 

Just borrowed an Infinity to try out to see how useful it would be for our astronomy society outreach - in sunny Eastbourne!

I have been doing imaging with a modified DSLR for a few years so i am used to long-exposure astro imaging. So when I tried with the Infinity yesterday I was bit flummoxed as to how to reduce the over-exposure in M42 even using 5sec exposures. Hopefully see attached screen print. With a DSLR I would normally reduce ISO and/or exposure time - is there an equivalent to ISO (or Gain) with the Infinity? Or is the only solution to reduce exposure time until you do not get the over-exposure?

For info I was using an old Vixen 102M and an EQ6 and MacBookPro running EQMac and Stellarium, with Infinity in a Windows 10 Virtual Box VM.

Thanks for any help.

Terry

[JimH123]

In your screen shot, I see you have the black and white sliders pulled in tight around the middle slider.  Spread them farther apart and allow the Infinity to use more of its 16-bit range.  The white slider, as it is moved left causes more and more of the light areas to go into saturation.  As it is moved right, you will recapture detail in the lighter areas.

[bwa]

...
So when I tried with the Infinity yesterday I was bit flummoxed as to how to reduce the over-exposure in M42 even using 5sec exposures. Hopefully see attached screen print. With a DSLR I would normally reduce ISO and/or exposure time - is there an equivalent to ISO (or Gain) with the Infinity? Or is the only solution to reduce exposure time until you do not get the over-exposure?
...

Set the Auto Range Type to FullRange and only adjust the Red (Median) slider.  That way you don't click the Black or White ends of the histogram.  Moving the White slider to the left will blow out bright areas of the image.

The Infinity can turn out gorgeous images with patience and a bit of experience, per attached.

bwa

[tweeb]

Thanks. Had been using Auto Range Medium - will try Full Range and will twiddle more with the black and white points. If I had thought about it I could have recorded the session and then had more of a play with the controls later.
Cheers
Terry

[Astrogate]

Like bwa states this Atik Infinity is a great camera for both live observing and imaging as long as you adjust the histogram correctly. Here is an image of M42 captured using only the Infinity software and my C9.25 at f5.6. This image was a real-time stack of 30 x 10 seconds capture as a jpeg with no post-processing.

Chris
Astrogate

[Starcloud]

Hi, very interesting topic as I too have the same problem with the stars in M42 blowing out. I am completely new to VA and any imaging and would like to be able to produce similar images to the amazing ones I see on this forum. 

Luckily I saved the session so can twiddle to my hearts content. I have tried the advice here and full range results in seeing the Trapezium stars but no nebula at all.  Max peak and mean SD work better but still blown out. Perhaps I need to take shorter exposures, or longer ones at full range?
Scope is a SW 250 PDS on NEQ6 in a lighted polluted area (Sheffield, UK).

Any further advice any one has would be very much appreciated.

Mark

[Starcloud]

Sorry forgot to attach an image (if this works!)

[Cliff Halliwell]

Ah, M42 is a testament to the huge dynamic range (difference between the brightest and darkest parts of the nebula) of the human eye and the limited dynamic range of even 16-bit cameras and the even more limited dynamic range of most monitors we would use to view our results.

With a big scope the naked eye can see lots of nebulosity in M42 and the stars of the Trapezium. 

The camera cannot capture both.  When you see a good astrophoto of M42 it is usually 2 photos blended together, with the Trapezum area shot with very short exposures and the nebulosity with much longer exposures.  Otherwise the whole Trapezium will just blow out (all the pixels r3cord at their highest level, which is pure white), and no amount of histogram manipulation can bring it back.

Moreover, when you see many astro photos on your PC, the image dynamic range is seriously compressed to brighten the shadows and darken the brightest areas.  That is because your typical monitor clips far too much of the dynamic range in an image.  That is why, even for daylight photography with a DSLR, you often have to brighten shadows to see what is in them.  It is in the image, just not on the screen.

So, as the old saying goes: you cannot get there from here, at least not with respect to M42.  M51 is a great target to see what you can capture, as it has no really bright bits.  M33 is a challenging target as, while large, it has only faint bits.  Even M31 (Andromeda) is a bit of a challenge as it is easy to blow out the bright core while trying to capture more of the arms and dust lanes.