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Venus from the 28.01.2020 with Baader UV filter.


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Venus from 28.01.2020, captured with Celestron C9.25, baader UV filter and Asi 290mm camera.

Stacked 10% of 25,000 frames captured Fair seeing conditions, the phase and clouds showing very nicely.

The baader UV filter delivers again on Venus. I would love get a sharper image sometime, but not its the easiest of targets.

715992398_2019_01_2817.08UVfilter.png.cf02c4bf4a73553b86ba6a987a7b294d.png

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Excellent image @Pete Presland!. The filter may be the trick but it also takes to really master the scope just to make focus with Venus. At what time did you make the capture, please?.

Yesterday I got the chance to try my wratten #47 plus the UV/IR cut filters and the captures I made at about 16:30 came out pretty bad, probably due to too much daylight, maybe... That is why I'm asking. I also made a few more at about 18:00, right before I had to finish my session, but I haven't got the time to preocess them yet.

Regards,

NV

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11 hours ago, NenoVento said:

Excellent image @Pete Presland!. The filter may be the trick but it also takes to really master the scope just to make focus with Venus. At what time did you make the capture, please?.

Yesterday I got the chance to try my wratten #47 plus the UV/IR cut filters and the captures I made at about 16:30 came out pretty bad, probably due to too much daylight, maybe... That is why I'm asking. I also made a few more at about 18:00, right before I had to finish my session, but I haven't got the time to preocess them yet.

Regards,

NV

This particular image was at around 4:50pm, so still light. My best images have nearly all been in daylight, one of them was the middle of summer in the afternoon.

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Yay, so it was not that... I don't lose all hope yet, I still have to try imaging at a higher altitude, but it may be wise for me to start saving for one of those filters because they don't seem to pop up at the second hand market.

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Pete, what exposure times are you managing with Venus and the Baader filter?

As I've mentioned in my post here, this filter lets through so little light that I can't capture anything with an exposure faster than 1/4 second. So I can't manage to freeze the seeing. I managed a reasonable effort with that image last night, but this evening I couldn't capture it anywhere near as sharp. I noticed someone on Cloudy Nights had managed to capture it at 1/100 sec. I wonder what I'm doing wrong?

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1 hour ago, lukebl said:

Pete, what exposure times are you managing with Venus and the Baader filter?

As I've mentioned in my post here, this filter lets through so little light that I can't capture anything with an exposure faster than 1/4 second. So I can't manage to freeze the seeing. I managed a reasonable effort with that image last night, but this evening I couldn't capture it anywhere near as sharp. I noticed someone on Cloudy Nights had managed to capture it at 1/100 sec. I wonder what I'm doing wrong?

Its around 14ms. The image from the 18th was 13.25ms at 3.30 in the afternoon (daylight), the image on the 28th was captured later, but still only 14.84ms. 

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On 03/02/2020 at 20:43, Pete Presland said:

Venus from 28.01.2020, captured with Celestron C9.25, baader UV filter and Asi 290mm camera.

Stacked 10% of 25,000 frames captured Fair seeing conditions, the phase and clouds showing very nicely.

The baader UV filter delivers again on Venus. I would love get a sharper image sometime, but not its the easiest of targets.

715992398_2019_01_2817.08UVfilter.png.cf02c4bf4a73553b86ba6a987a7b294d.png

Excellent, beats my recent attempt with a UV filter, but the seeing was terrible, I was surprised to get this , certainly no cloud detail...

 

 

 

18_22_32_pipp_l4_ap4.png

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9 hours ago, Pete Presland said:

Its around 14ms. The image from the 18th was 13.25ms at 3.30 in the afternoon (daylight), the image on the 28th was captured later, but still only 14.84ms. 

Thanks Pete. It's a complete mystery to me how you can capture it at 14ms and I can only manage 250. I'd welcome any suggestions! I didn't  think my camera was that unsuitable for the job. I note that you use Firecapture. Perhaps you can crank up the gain better in Fircapture than Sharpcap? Perhaps the filters are different?

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On 07/02/2020 at 07:51, lukebl said:

Thanks Pete. It's a complete mystery to me how you can capture it at 14ms and I can only manage 250. I'd welcome any suggestions! I didn't  think my camera was that unsuitable for the job. I note that you use Firecapture. Perhaps you can crank up the gain better in Fircapture than Sharpcap? Perhaps the filters are different?

I have been thinking about why your exposure is so different from mine. 

Looking at the QE graphs for both cameras and reading about it, i think mine might be a little more sensitive at the UV end of the spectrum.

I copied this off their website, it mentions a UV-IR blocking filter?

ALTAIRGP130M-FULL Package:

  • CS-Mount adapter with built-in Clear Optical Window, AR coatings. (Attached at factory but removable).
  • CS-Mount adapter with built-in UV-IR Blocking Filter, AR coated. (Removable)

I also wonder whether your scope has some sort coating on the mirror perhaps, not been able to find any info despite a long look online. 

Not sure i have helped, but i was interesting reading about the subject anyway.

891573632_AltairGPCAMv2130MonocameraQEcopy.jpg.47cfada32e5f168a33158ca948a1e32e.jpg

2145384993_zwoptical-asi290mm-mini-ac-camera-sensitivity-1000copy.jpg.8f1a879480d2f826e0b423deb8c38454.jpg

 

baader-u-venus-filter-2-350nm-26a.jpg

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39 minutes ago, Pete Presland said:

I copied this off their website, it mentions a UV-IR blocking filter?

ALTAIRGP130M-FULL Package:

  • CS-Mount adapter with built-in Clear Optical Window, AR coatings. (Attached at factory but removable).
  • CS-Mount adapter with built-in UV-IR Blocking Filter, AR coated. (Removable)

 

That's very interesting. I wonder if I've just been blocking all of the UV light by having the UV blocking filter in place.

There are two seemingly identical CS-mounts in the box, which have no identification marks on either, apart from the letters 'CS'. However, one of them has a pink bloom at certain light angles as you can see below, so I assume that's the UV-IR blocking one. I have been using the other one, which I therefore assume is the clear one and thus not the cause of the problem?

49512304662_405557d680_b.jpg

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7 minutes ago, lukebl said:

That's very interesting. I wonder if I've just been blocking all of the UV light by having the UV blocking filter in place.

There are two seemingly identical CS-mounts in the box, which have no identification marks on either, apart from the letters 'CS'. However, one of them has a pink bloom at certain light angles as you can see below, so I assume that's the UV-IR blocking one. I have been using the other one, which I therefore assume is the clear one and thus not the cause of the problem?

49512304662_405557d680_b.jpg

I think i would leave them both off when imaging in UV, if that is an option.

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On 09/02/2020 at 19:04, Pete Presland said:

I think i would leave them both off when imaging in UV, if that is an option.

I just had a go with neither CS mount in place, and I still require lengthy exposures.

I guess, then, that it must be down to the UV sensitivity of the sensor.

Edited by lukebl
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