Ad Astra Observatory

Art Morton wrote:
> J,
>
> This is a 12 Bit system for color conversion so it has to use a Bayer
> Matrix so the colors have to be
>

> RGB color filter array. The color spacing has to be Ia, II, or IIIA.
> 2/3 resolution of the Sony B/W only chip with an affective size ~ 30.4
> microns.
15.2mu square instead of 7.6mu square. Each 2×2 square has 1 red, 1
blue, and 2 green pixels. These are all interpolated together and
produce 4 full RGB pixels.
> This kind of explains the incredible sensitivity and the 2×2 binning

> thing in MaxDL/FocusMax
Yes, I believe that I am effectively binned 2×2 at all times. Kills my
fine detail, but boosts the sensitivity through the roof. OTOH, if you
want to see some fine detail, let me send you a photo of a dove that was
hanging out on my roof a couple months ago. You can basically see
individual barbs on the feathers.
> Did you ever shoot thing thing at JPG fine 1:4 in the large mode?

Large mode = 3008×2000 (you can also shoot at a variety of other modes
all the way down to 640×480 I think). Fine compression means largest
files but least compressed, which is how I usually run.

BTW, for some reason, Max has figured out how to squeeze a couple of
extra pixels out of the camera; Max photos are like 3019×2008 or
something like that. Haven’t figured that out yet.

> 12 bit lossless should make the ear wax run out on your shoulder.
If I had a nice way of dealing with RAW files, yes, I think you’re
right. Max shoots RAW and then converts to FITS, which I guess is good
enough. I have the choice of shooting RAW Color, RAW Mono, JPEG Color,
JPEG Mono, or “Raw to Disk” in Max. All of these shoot at max resolution
unless binning is on, in which case they shoot at 1500×1000 or so.

> by the time you throw out all the Sony Chip stuff I think you have got
> about 6.1 megapixels to work with.
Yes, it’s a 6.1Mpx camera. Or 6.3. I can’t remember. Either way, it’s
decently big. The next step up would actually be a full-35mm sized chip
(which has just come out in the last year or so); all the 8Mpx and 10Mpx
(and some 12Mpx) still use the same APS-sized chip, which means the

pixels start getting *small*. As it is, I think I’m hitting the Airy
Disk/Rayleigh/whatever limit at ~1.6”/px. I can’t imagine what would
happen if all of a sudden there were more pixels crammed into the same
space.
> AIP4WIN puts the camera out at RAW 3008×2000 5MB, 3008 x or
> 2000 – 5.8 MB fine JPG

Yep, that’s the one. Like I said, Max squeezes out a handful more px,
but 3008×2000 is what the camera shoots out of the box.
> In B/W mode the resolution must be breath taking.
Yes, I mean, it’s tough to find an astronomical object that covers
enough pixels to really showcase the chip, which is one reason that I
decided to try out the 8” SCT (0.8”/px ouch). But nicely-framed objects

cover a lot of pixels, and for instance, I often have so much extra room
around an object that I can really choose how to frame it.

M51, for instance, was a 90� rotated 1500×1000 crop (the 1500 went in
the 2000px direction). I resized the photo down a little to tighten up
the fine detail (I think that this is my way of getting around the Bayer
Matrix, although I’ve never really thought of it that way before). With
my webcam, I’m forever resizing the frames *up* to get a bigger photo of

Jupiter; with the D70 it’s the other way around.

It’s a really nice camera, and I’m glad I’m getting used to it.

> I can understand running out of space now easily.
(: The JPGs and NEFs are ~5mb. For some reason, the FITS that Max
produces are like 35mb.

> Still raining and confused.
Come down for some sunshine in March or April or both!

J