Jump to content

SkySurveyBanner.jpg.21855908fce40597655603b6c9af720d.jpg

Uranus with ASI224MC August 14th...

Kokatha man

By Kokatha man
in Imaging - Planetary

Recommended Posts

Kokatha man

Kokatha man

Posted
Posted

Hi all - the ASI224MC is proving to be a very good iR camera for Uranus with an iR610nm filter...we used it the other morning screwing it onto the rear of the EFW which with the 42.5mm spacing from the rear of the Antares 1.6X barlow to the camera sensor meant f22. (2X)

We had not used it at that image scale/focal length before on Saturn but it turned out fine here...clouds kept on making the onscreen image fluctuate in brightness & although the seeing was reasonable this poor transparency meant we could only find 803 frames out of more than 20,000 captured to stack with - & this was going down to a cut-off value of 50% quality...!

However this did not seem to worry the outcome too much & it was very easy to bring out the cloud bands/belts despite the poorish conditions - a real testament to this camera's capabilities: given decent conditions it would seem that picking up storms/bright spots shouldn't be too difficult this apparition..! :)

Here it is at capture scale (100%) plus larger scales...I made up the "false colour" images for this composite using the colour image values from another capture where we used the camera for a "normal" colour capture of Uranus...purely for interest's sake. ;)

post-3551-0-82807000-1439733491_thumb.pn

Link to comment
Share on other sites
Kokatha man

Kokatha man

Posted
  • Author
Posted

Thanks to everyone - there really isn't any choice in planetary cameras atm if you are specifically looking for a planetary cam as opposed to ones with bigger sensors etc for Lunar et al...the ASI224MC is quite literally head & shoulders above the rest: there are some restrictions if you want to image in uV where it isn't responsive & iR in & around the 742nM bandwidths but just about everywhere else...colour, iR610 for Uranus & Neptune, CH4 it trumps the field..! ;)

Of course I want to see a mono camera with these sorts of specifications, but I'll wait! :grin:

Link to comment
Share on other sites
Kokatha man

Kokatha man

Posted
  • Author
Posted

Thanks to everyone - there really isn't any choice in planetary cameras atm if you are specifically looking for a planetary cam as opposed to ones with bigger sensors etc for Lunar et al...the ASI224MC is quite literally head & shoulders above the rest: there are some restrictions if you want to image in uV where it isn't responsive & iR in & around the 742nM bandwidths but just about everywhere else...colour, iR610 for Uranus & Neptune, CH4 it trumps the field..! ;)

Of course I want to see a mono camera with these sorts of specifications, but I'll wait! :grin:

Thanks once again fellas - just want to correct what I said above. (in the quote here)

My mind went into a bit of senile drivel in the above but it doesn't devalue my comments re the ASI224MC, in fact it reinforces them!...blue & especially uV are the really weak points for this colour camera, the R-iR is in fact a very good aspect right up to the methane band just below 900nm: here is a graph I made up converting the ASI174MM (mono) camera's QE to a rough equivalent of the ASI224MC's "Relative response" figures - you can see that at just below 750nm the response of the green pixels in the colour camera are identical to the mono cam's response whilst the red pixels' response is much higher...in the methane band area all of the colour camera's pixels are responding much better than the ASI174's pixels.

The ASI120MM/S has a very similar response curve to the ASI174MM, although a whisker better... ;)

post-3551-0-42927300-1440166264_thumb.jp

Link to comment
Share on other sites
neil phillips

neil phillips

Posted
Posted

Thanks to everyone - there really isn't any choice in planetary cameras atm if you are specifically looking for a planetary cam as opposed to ones with bigger sensors etc for Lunar et al...the ASI224MC is quite literally head & shoulders above the rest: there are some restrictions if you want to image in uV where it isn't responsive & iR in & around the 742nM bandwidths but just about everywhere else...colour, iR610 for Uranus & Neptune, CH4 it trumps the field..! ;)

Of course I want to see a mono camera with these sorts of specifications, but I'll wait! :grin:

Lovely Work Darryl. I wonder if a mono version will be forth coming ?

Link to comment
Share on other sites
JamesF

JamesF

Posted
Posted

I think a mono version of the 224 sensor would be interesting, but right now Sony only appear to make a colour model and I've not seen that they have any plans to do otherwise.  I'd guess that the mass market isn't really that interested in mono sensors and these aren't really being developed for astro use in the first place.  It's just fortunate when they happen to suit what we want to do with them.

James

Link to comment
Share on other sites
neil phillips

neil phillips

Posted
Posted

I think a mono version of the 224 sensor would be interesting, but right now Sony only appear to make a colour model and I've not seen that they have any plans to do otherwise.  I'd guess that the mass market isn't really that interested in mono sensors and these aren't really being developed for astro use in the first place.  It's just fortunate when they happen to suit what we want to do with them.

James

Yeah that's pretty much what I had read James.

This colour model seems so good. Its really a good time to go back to a single shot camera though I think. A easier life. Colour animations which I enjoy creating. Really will benefit from this one. In time, effort, and consistency.

I can see me using this when Jupiter returns for our final, if somewhat lower fling in the new year. Will be interesting to see if snatching those rare moments of calm seeing in the UK

will produce better images overall from the UK. Using this camera

If I do get it. Might be time to sell the Filters and wheel

Time for a easier life. If no mono version is on the horizon. And even if one did appear. Everything mentioned still applies. I guess we are suckers for that last ounce of performance though.

Thanks to Darryl and others for showing what it can do

Link to comment
Share on other sites
JamesF

JamesF

Posted
Posted

A return to OSC does seem very alluring.  Personally I'd just like to get my head around how (for example) only having one red pixel in four affects the resolution and what, if any, other artefacts we might expect.  I've seen a fair bit of hand-waving about this and appeals to intuition or common sense, but intuition and common sense are notoriously fallible.  (And the same issues apply to using the camera with narrowband filters.)

Certainly I'm not going to deny that the results are excellent, because some are utterly jaw-dropping.  It's just part of my nature to want to understand the whys and hows.

For instance, it may be that the dithering effect of a planet not being absolutely still on the sensor means that the resolution could be as good as a mono camera as long as you capture enough frames.  But how many might be enough?  And if, say, "enough" meant that you had to capture four times as many frames as for a single colour for an RGB image using a comparable mono sensor, might that affect your decision about which camera would be a better choice?  Or might you look at the sensitivity of this camera and decide that it's sufficiently better than any mono camera that you could afford that it's worth sticking with?

I'm sure there will be lots of people who just say "Never mind the theory!  Just shut up and get out there and do some pigging imaging with it!" and that's fair enough really.  I'm just not made that way :D

James

Link to comment
Share on other sites
  • 2 weeks later...

Archived

This topic is now archived and is closed to further replies.

Go to topic listing

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.