Jove Nov 4th ASI120MM 742nm-807nm comparison

[Quark (Trevor)]

Hi All,

Imaged Jove this morning in reasonable seeing for the alt.
Over the last several years all of my IR data has been captured at 807nm with a Astronomik Planet Pro IR filter with either my Flea3 FW or Flea3 GigE cameras. More recently I also purchased the Astronomik Planet Pro 742nm IR filter, mainly for Saturn to get higher frame rates.

This morning the seeing was quite stable so I captured successive IR data sets, 742nm, 807nm, 742nm, 807nm with my new ASI 120MM camera which, according to the spec's would seem to suffer into the IR compared to my Flea3. I have attached the the final two data sets. Regardless of the filter I am using I always like to go with a histo of approx 90%. In this instance the 742nm had a histo of 89%, Gain=78 at 60 FPS. The 807nm had a histo of 91%, Gain=100 at 47 FPS. The processing for each data set was identical.

Disregarding the brightness of the images and concentrating on the actual detail, it seems that most of the detail in the 742nm image is also visible in the 807nm image, that said, with this particular camera I am inclined to go forward with the 742nm filter.

Regards
Trevor

[Dennis]

An excellent series Trevor, the detail on Io is wonderful. Thanks for the report and analysis re the filters and the ASI120 – interesting reading.

Cheers

Dennis

[renormalised (Carl)]

I would agree with you on that one, Trevor. The 742nm filter shows pretty much all you're going to get, but the the good thing is the frame rate seems to be higher for very similar values in histogram and gain. Plus, you do have a brighter image.

Nice shots, BTW

How well do you think the ZWO goes head to head with the Flea3? It would be interesting to see the same pics done with the Flea under the same conditions.

[Solar (Ralph Smith)]

Lovely work as usual Trevor.
Can't get a go here due weather and work.

[Quark (Trevor)]

Thanks very much Dennis, these cameras are becoming quite popular so I guess it's good to compare some real world comparisons to the spec's.

Thanks very much Carl, the Flea3 is an excellent camera and I have produced some very hi res images with both the FW & GigE versions over the last few years. The higher resolution of the ASI120MM is attractive 1280x960 along with it's ability to run at very high frame rates on USB 2. It is more sensitive in B & G but falls away in IR and struggles in CH4. I know that some are producing CH4 data with it but many prefer the Flea3 for the longer wavelengths. I expect the greater sensitivity in B will extend nicely into UV, something I will be playing with shortly. At the end of the day I think the seeing is key, any competent camera will shine in good seeing.

Thanks very much Ralph, the weather seems to remain unsuitable for imaging Jup at low alt with only the very occasional break in it. Still, we have so much to look forward to here in OZ over the next several years.

[Larryp (Laurie)]

Very nice, Trevor-love the detail on Io