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Mercury May 22

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#1 Isaac

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Posted 23 May 2020 - 09:50 AM

Hi guys, 

 

I show you another image of Mercury I captured yesterday from my house. 

 

I'm waiting a ZWO ADC I bought on Thursday, and I guess results will become a little sharper. Also, I'll miss Venus, since this was my perfect alignment object in the afternoon. 

 

XmErbsn.jpg

 

See you. 


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#2 John Boudreau

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Posted 23 May 2020 - 10:43 AM

Hi Isaac,

 

Somehow I missed that you were using a UV/IR cut filter with yout ASI120MM, and to me that makes your images even more impressive! While an ADC will certainly keep the atmospheric dispersion under control, your best overall bet is to image Mercury in the deep red to the near-IR. While there is a resolution penalty in the longer wavelengths, the seeing is noticeably steadier and can allow better results than with the entire 'visible' spectrum. I have filters such as the Baader 610 longpass, the Baader 685 IR longpass, and the Astronomik 642 IR (which is actually a bandpass filter ranging from 642 to 842nm). The 610 LP  has given me fine results in very good seeing, and the 685 IR LP has been a workhorse in average to good conditions. A few years ago I stopped imaging Mercury, but with a thought about getting back into Mercury imaging I purchased the Astronomik 642 as I see it as having strong potential--- as a 200nm wide bandpass filter it should work well without use of an ADC in all but the lower target altitudes. Atmospheric dispersion is weaker in these longer wavelenghths so a 200nm deep red/near-IR bandpass should keep it under control even without an ADC in the 25 to 40 degree altitude range. I did find that I preferred an ADC with the longpass filters though. 


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#3 Isaac

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Posted 23 May 2020 - 02:54 PM

Hi John, 

 

Thanks for taking your time giving me such a great information! bow.gif

 

The filter I've used for that image is the only one I have, and I've had it for two and a half weeks. I've read your post a few times and looked for these filters to see the transmission curves, so that I know how they work. 

 

I'll take my time analyzing the images people are posting on this and other forums to see their/your results. Clearly there are a lot of filters and they often work for such specific purposes. 

 

Besides the ZWO ADC, which is already coming home, I plan to upgrade my camera, just to switch to the color side, which will benefit the three next planets (Jupiter, Saturn and Mars). There are a lot of things to be considered in all of these things lol.gif



#4 Isaac

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Posted 24 May 2020 - 01:37 AM

Oops, I don't know the performance of these kind of filters in telescopes like mine. Is it a good idea to use a 685nm filter on a 200mm telescope? Maybe for Mercury the reduction on brightness is really important.

#5 John Boudreau

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Posted 24 May 2020 - 08:57 AM

Oops, I don't know the performance of these kind of filters in telescopes like mine. Is it a good idea to use a 685nm filter on a 200mm telescope? Maybe for Mercury the reduction on brightness is really important.

Well, my avatar was taken with a C11 using an Astronomik 742 LP. I would have achieved  somewhat better resolution with a Baader 685 LP and collected more light.  On a 200mm scope I'd expect a 685 LP to result in roughly the same brightness, or at least not too far behind the brightness as the 742 was on my C11.

 

My best Mercury images were taken with the Baader 610 LP which is actually their red planetary filter--- it's a popular filter with many of us here on CN. Only issue with it is that while it gets good resolution and brightness by collecting a good amount of visible light, it's limited in that you'll need good seeing as it won't control fair seeing as well as the 685 or longer cut-on wavelength longpass filters. But since your location is likely one of the better places in the world for seeing, it may be just the filter for you. It'll certainly give you better results than you've had so far as it will cutoff the shorter and mid-range visible wavelengths. It's usually one of the least expensive high quality LP filters out there. You'll probably want to use your ADC with it for best results. 

 

An ADC can be accurately adjusted using a color cam in FireCapture's ADC adjustment tool. Or you can adjust it visually. Just be sure that either the color cam or your eyepiece is set to be parfocal with your mono imaging cam, as ADCs create a counteracting dispersion that increases in width with projection distance. 


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#6 sunnyday

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Posted 24 May 2020 - 09:00 AM

nice work 

thanks 


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