Venus with a ZWB1 and a #47 stacked (24th of March)

[NenoVento]

Hi all,

Here you have the best image I managed to get today by stacking a ZWB1 filter with a wratten #47 filter:

The stacked filter have a maximum transmitance of about 72% at 338 nm (but also leaks a little bit of IR, that is, a 2% at 746 nm), as you can see in the graph below:

Although the weather conditions were pretty bad (a rather cloudy afternoon , with seeing of 1.5-2" and a transparency of 0.5-0.6), to be honest, after looking at this graph I was hoping I would get better results... Ah well, maybe next time I'll get better weather!.

The gear:

Celestron CPC 800 GPS XLT
ZWB1 filter stacked with a wratten #47 filter
GSO 1.25" 2.5x Apochromatic Barlow Lens
Risingcam GPCMOSS02000KMA (mono camera)

The software:

ToupSky (I made two minute movies with 14,23 gain and 95 ms which, at about 10fps, gave me 1200 frames to work with)
Autostakkert (40%)
RegiStax
Fitswork
The Gimp

Regards,

NV

Edited March 24, 2020 by NenoVento

[NenoVento]

Hi,

Just in case @Merlin66 comes along this thread, I'll answer the questions he made me when I comented the amazing pictures @CraigT82 has published here, and said that I wasn't able to capture at a higher rate thatn 10 fps with my setup.

which scope?

Celestron CPC 800

which camera?
Risingcam GPCMOSS02000KM (a rebranded Touptek camera that carries a Sony IMX290 mono sensor)

fast computer with USB3 and SSD drive?

A Samsung R540 laptop which carries an Intel Pentium CPU P6100 @ 2 GHz and 4 GB of RAM, so not really fast... Also, the laptop is rather old, which means that it has no USB3, but I did upgrade its HD with a SSD unit (mainly because the stock HD died on me a year ago or so).

Regards,

NV

Edited March 25, 2020 by NenoVento

[Merlin66]

NV,

Thanks for the information.

Not familiar with that camera, need to investigate it's capabilities.

[NenoVento]

The probem seems to be the exposition time I used (95 ms). After a few dry test, I do get the 16 fps that the producer indicates in its website (here) at @1920x1080 as long as I don't go higher than 60 ms (and a bit higher if I do ROI). However, I assume this will mean to crank up the gain and, therefore, add way too much noise to the video feed.

[Merlin66]

NV,

That makes sense....

1/16 (fps) = 62.5ms, any exposure longer than that will take precedence over the frame rate......