From: Milton Aupperle <milton@outcastsoft.com>

Date: March 22, 2012 4:33:29 PM MDT

To: Astro_IIDC@yahoogroups.com

Subject: Re: [Astro_IIDC] Re: Help needed with some newbie questions

Hi Vince;

You can't transgress if you don't know what the rules are, so not a problem at all.

If you have questions on Astro IIDC, ask either me directly via the milton@outcastsoft.com address or to the list.

HTH..

Milton Aupperle

On 22-Mar-12, at 4:04 PM, vbertus wrote:

Thanks for your detailed response Milton. Sorry about my transgression of discussing other software.

--- In Astro_IIDC@yahoogroups.com, Milton Aupperle <milton@...> wrote:

Dear Vince, George and others;

On 22-Mar-12, at 1:51 PM, vbertus wrote:

Hi folks, Astro IIDC newbie here. I read through most of the

manual and it explains the software very well, but I have some even

more basic operational questions so go easy on me. :-)

I am using the software for lunar and planetary imaging with a Mono

PGR Flea3.

1. Camera Settings: Exposure time, gamma, and gain. Previously,

with cheap webcams, I have only worked with exposure time and gain

(called brightness in IIDC?) The gamma setting is new to me, so

what should be my basic thought process in these adjustments prior

to capture? I was thinking adjusting exposure time and gamma first,

then adjust the gain to the minimum amount necessary to get an image

of acceptable brightness on the screen. Would this be correct?

Also, what effects do different amounts of gamma have on the final

image wrt detail, noise, etc?

Gain always increases noise levels, so your choices in order of least

noise effect are exposure, Gamma, Binning and Brightness for noise.

Gamma will generally not affect noise levels - except if you crank it

way up or way down. Generally I would leave it to 1.00 except for

narrowband Solar imaging where your tying to get faint prominences and

the bright disk visible at the same time.

If your shooting LRGB or IRGB (even for planetary), have a look at

using 2x2 binning for your R G B filters. Your Blue and to some extent

Green channels don't carry much detail for planets like Mars and

usually get blurred badly by atmosphere. That's why lots of people

shoot the moon using an IR cut filter, to reduce atmospheric loss.

Here is an example of Saturn I shot L 1x1 RGB 2x2 to keep the

exposure times reasonable:

http://www.outcastsoft.com/AstroImages/Saturn20090502MJA.jpg

Also my software Binning algorithm preserves image scale, so binning

1x1 or 2x2 or 4x4 has the exact same image scale and size.

File size: Man, the 16 bit files are huge, about 1 gb per min @

60fps.

Depending on your target, you can reduce the size by restricting

capture dimensions using Hardware ROI (see page 31 of the Astro IIDC

manual). So if you have a big (i.e. 1300x1300) pixel Flea3 camera and

are capturing Mars, then use Hardware ROI to isolate it and capture a

smaller (say 400x400) pixel area which saves file space.

I was wondering about using a 500 gb external firewire drive for

the capture of the files. Would this preclude me from be able to

get 60 fps in 16 bit mode? I'm running a late 2008 MBP, 2.8 ghz

Intel Core 2 Duo, OSX Lion, so not exactly a cutting edge machine.

That will not work if your expecting to Capture to an external hard

drive. The data is moved into the Mac from the camera over FireWire

800 and then moved out of the Mac over FireWire to the External Drive.

That cuts your available bandwidth in half or less, so you will max

out at about 35 to 40 megabytes per second and reduce the frame rate.

If you use USB 3 or E-Sata or a Thunderbolt Hard drive then you could

do it, but not via FireWire on the same FireWire bus at the same time.

If you have an expandable Mac with an Express or PCI slots, then

adding a second FireWire card will work as long as you keep them on

separate FireWire busses (Camera to the internal FW port - FW 800 Hard

Drive to the Express Card FW port).

Avoid USB 2 as Apple's USB 2 drive support is abysmal and you get

about 2/3 to 1/2 the rate you get with Windows or Linux (using all the

same hardware). It would never keep up with a FireWire 400 camera,

let alone a FireWire 800 camera.

Apple's built in giga ethernet throughput is also mediocre and doesn't

even come close to FireWire 800 speeds either.

2. Guiding: I'm clear on calibration etc. However the manual

seems to imply that I can actually guide on a centroid or limb while

simultaneously using the same camera to capture the image? Would

this be correct? If so, would this lower the useable frame rate for

the image capture?

Yes that's correct. You can guide and capture an object at the same

time. You need to control the Capture (to frames or movies) via an

ApplsScript, which are supplied in the "Other" folder of the .dmg.

Unless your using a really old < 1 gighz single Core Mac, doing both

at the same time it will not have any effect as our Centroid and other

code is all done in SIMD (hand written Altivec and SSE3).

3. Registration and stacking: I have only ever used Registax, but

it of course requires you to convert to an .avi file which I would

rather not do.

You lose 16 bit support too. Apple doesn't support 16 bit Avis

conversions.

How do you find the frame sharpness filters, registration and

stacking algorithms in Astro IIDC as compared to Registax?

I don't use Registax, so I don't know how it compares. I do know that

they still have problems doing MAP, where as we don't. Also Astro IIDC

4.08.00 Alpha is now massively multi threaded for 8 or 16 bit stacking

and has even more SIMD (Altivec and SSE3) optimizations, so the more

CPUs you have the faster it runs - well until the hard drive access

becomes the next bottleneck.

For final sharpening, is there anything on the Mac platform that is

similar and at least as effective as the wavelets function in

Registax? The sharpening algorithms in Pixinsight perhaps?

Astro IIDC does multi spatial Wavelet sharpening in the Image

Processing part and has done so for at least 4+ years now (see page 60

and 73 of the Astro IIDC manual).

4. Further Post Processing: I have migrated completely to

Pixinsight for processing my deep sky astro images and now only use

Photoshop for some final tweaks. Do any of you use Pixinsight for

processing your planetary and lunar stacks, and how do you find the

results?

Just so you know, it's not considered appropriate to discuss other

software on this list. If this was a generic Astronomy list that

would be fine. But this is an Application Specific list to promote and

support Astro IIDC, not other products. I don't want to be an ogre

about it, but that is one of the few rules I do enforce here rather

strictly.

HTH..

Milton Aupperle

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