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First Venus of the year

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#1 Vinny1980

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Posted 19 January 2020 - 03:46 AM

Dear all

 

attached it is my very first result with Venus, taken in full daylight with planet close to meridian.

On ALPO Japan you can find a more scientific version of the same image, I mean that I did not attach the disc on black background and I was much more careful with UM. Here there's a cosmetical version, so to say, more pleasant to the eye smile.png The typical venusian V cloud pattern is visible.

Pure reflective telescopes are definitely better suited for this kind of work, but, with some effort, something can be obtained with small SCT's as well.

 

Clear skies,

Vincenzo

Attached Thumbnails

  • 20200111_1324_Vdel_cosmetic.jpg

Edited by Vinny1980, 19 January 2020 - 04:30 AM.

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#2 james7ca

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Posted 19 January 2020 - 04:38 AM

That's an impressively detailed image for Venus. What Astrodon UV filter did you use (is there more than one, I can only find their Photometrics UV).



#3 Vinny1980

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Posted 19 January 2020 - 04:51 AM

James,

 

mine is this one:

 

https://optcorp.com/...-25inch-mounted



#4 james7ca

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Posted 19 January 2020 - 05:07 AM

James,

 

mine is this one:

 

https://optcorp.com/...-25inch-mounted

Thanks, I'm surprised that you were able to get that much contrast during the day given the blue sky. But, maybe that is what you mean by "cosmetical version" and the "black background." I've used fairly deep IR filters to image Jupiter and Saturn during the day and even then the sky turns out fairly bright with pretty low surface contrast on the planets.



#5 Vinny1980

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Posted 19 January 2020 - 06:20 AM

No need to be surprised really. As you can see from the raw image attached, the originary contrast is much lower. Obtaining the final image is all in regulating levels or in careful using of contrast enhancement functions, without of course creating artifacts. In the case of my image, I enhanced the clouds furtherly with soft zonal Unsharp masking (many imagers do this, of course, even though this is rarely declared). Im confident about details because, luckily, I could use for comparison an image by Tiziano Olivetti taken in the same hours, where clouds show similar patterns (it is on ALPO Japan as well).

To conclude, better results than this are definitely possible. Small Newtonians (<8") are capable of unexpectedly good performances on Venus UV imaging.

Attached Thumbnails

  • 2020-01-11-1324_1_UV_raw.jpg

Edited by Vinny1980, 19 January 2020 - 06:34 AM.

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#6 Michael Barbieri

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Posted 19 January 2020 - 08:18 AM

Good job Vincezo! Recently i acquired a W47 filter to link at BG40 filter. I hope to do some photo soon.



#7 Vinny1980

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Posted 19 January 2020 - 10:05 AM

Thanks.

By the way, where did you buy your BG40? It should be a good choice, together with BG39.


Edited by Vinny1980, 19 January 2020 - 11:11 AM.


#8 Michael Barbieri

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Posted 19 January 2020 - 04:44 PM

on newport.com waytogo.gif


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#9 John Boudreau

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Posted 19 January 2020 - 08:38 PM

Thanks.

By the way, where did you buy your BG40? It should be a good choice, together with BG39.

In addition to Newport, Thorlabs should have BG39 and BG40. I made a stack of BG3 and BG39 2mm thick filters from Thorlabs in 2018 that work nicely, although I found that my Astrodon UVenus had an edge in better overall transmission for the camera (but the BG3/39 stack is a very nice visual filter while the Astrodon is almost unusable visually) . Perhaps if I had used BG40 the stack would have had a bit better transmission (it was nearly 2x the cost of the BG39 though).



#10 sunnyday

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Posted 19 January 2020 - 08:46 PM

very very nice, amazing detail.



#11 Vinny1980

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Posted 20 January 2020 - 03:08 AM

Thanks for you input John, well appreciated waytogo.gif

Since the argument could be interesting for some readers, and Venus maximum elongation is in sight, I think we can stress it a little. 

About BG40, I ve found a Ebay vendor (google it) selling them just mounted in 1.25" cell. Effective availability should be checked because the supplier (Adriano Lolli) declares them out of stock in his website. 

I placed an order for 25,4 mm BG39 from Edmund, the only concern would be the filter mount accepting that glass. There's a supplier from USA  I am aware of (Omega Optical), maybe someone can indicate some european seller?

A last word about IR-cut  filters (maybe John could be of futher help here), their reliability in time. I recall Emil (Kraaikamp) complaining about his BG39, whose performance quickly fell in couple of years. 


Edited by Vinny1980, 21 January 2020 - 01:57 AM.


#12 John Boudreau

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Posted 20 January 2020 - 09:47 AM

Thanks for you input John, well appreciated waytogo.gif

Since the argument could be interesting for some readers, and Venus maximum elongation is in sight, I think we can stress it a little. 

About BG40, I ve found a Ebay vendor (google it) selling them just mounted in 1.25" cell. Effective availability should be checked because the supplier (Adriano Lolli) declares them out of stock in his website. 

I placed an order for 25,4 mm BG39 from Edmund, the only concern would be the filter mount accepting that glass. There's a supplier from USA  I am aware of, maybe someone can indicate some european seller?

A last word about IR-cut  filters (maybe John could be of futher help here), their reliability in time. I recall Emil (Kraaikamp) complaining about his BG39, whose performance quickly fell in couple of years. 

I recall seeing comments about humidity issues with BG39--- and yes I believe you are correct, I'm sure one of the comments came from Emil. The other was on a general UV photography forum and had recommended AR coated versions and for long term storage recommended a desiccant. I don't recall the finer details of those BG39 humidity comments. My BG39 was purchased in the 1st quarter of 2018 and still looks perfect--- but I haven't actually used it since Dec of 2018! It has been stored in a fairly dry environment indoors as much of my home heating is done with a wood pellet stove.  Maybe I'll use it visually soon with Venus so well placed now.

 

As for the BG3/BG39 stack I made--- if done now I probably would go with the BG40 instead of the BG39 in part because of BG40's better transmission on the shorter wavelength side of the BG3 bandpass. I haven't heard of any humidity issues with BG40, but that's certainly no guarantee that an issue couldn't occur given enough time.

 

BTW--- The Edmund BG39 is 3mm thick--- to a point, the thinner you can get these filters the better. Largely because 3mm thick colored glass filters have a noticeably lower transmission than 2mm thick filters, but also because it's easier to stack thinner filters in a cell. The Thorlab versions are 2mm thick and they do have BG40 available. I don't see any thickness spec on  Adriano Lolli's website for that mounted BG40 you mentioned, although it looks like a thin one in that photo of it.



#13 TareqPhoto

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Posted 21 January 2020 - 01:20 AM

That is amazing, i must give it a try then.



#14 Vinny1980

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Posted 27 January 2020 - 04:07 AM

As I suspected, Lolli wrote his BG40 mounted filters are not available. Futhermore, he said this is due to the glass he had which got ruined, confirming somehow also on this glass the fragility we were talking about regarding BG39. 


Edited by Vinny1980, 27 January 2020 - 05:14 AM.


#15 John Boudreau

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Posted 27 January 2020 - 09:41 AM

As I suspected, Lolli wrote his BG40 mounted filters are not available. Futhermore, he said this is due to the glass he had which got ruined, confirming somehow also on this glass the fragility we were talking about regarding BG39. 

Ouch. That's too bad. My first Schott colored filter was an RG780 longpass that I used for Mars back in 2003. Eventually I collected other near-IR longpass filters with higher transmission that took it's place in my arsenal, and by 2010 or so I revisited the RG780 just to try it again--- but it's surface was crazed, rendering the filter unusable. Most likely because it wasn't stored as well as my current filters for years, but this and the BG39/40 problem shows that any of these uncoated colored glass filters may be prone to degrading over time. Best to store them in a box with a desiccant pack that can be recharged periodically, which is what I do now in my observatory.  Some of my filters are stored in my house which tends to be dry enough itself, but I probably should be even more careful with their storage.

 

Here's the type of desiccant pack I'm referring to: 

 

https://www.bhphotov..._desiccant.html


Edited by John Boudreau, 27 January 2020 - 11:49 AM.


#16 Vinny1980

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Posted 27 January 2020 - 10:07 AM

Good points John waytogo.gif

I normally use a dessiccant too: 

 

https://www.highpoin...l-orange-silgel

 

I ve just checked out the Schott catalog, it rates the BG39 as "very sensitive" to moisture (2 umbrellas) while the BG40 as "sensitive" (one umbrella). See attachment.  

Attached Thumbnails

  • 1.JPG

Edited by Vinny1980, 27 January 2020 - 02:20 PM.

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