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mercury transit and 8x42 binos question

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#1 opticsguy

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Posted 10 September 2019 - 11:32 AM

I will traveling overseas during the upcoming Mercury transit and will be located in Turkey on transit day. I try to travel light but wanting to see this event and thinking to take my Bushnell 8x42 binos.  Any recommendations for easy on and off solar filters?  Mercury will be a very tiny black dot, I am assuming visible in these binos?

 

Thank you.



#2 sg6

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Posted 10 September 2019 - 11:42 AM

Will have to be a homemade set up that covers both lens with ND5 solar film.

Suppose individual filters for each is easier.

May have a bit of a problem finding the sun. I tend to look at the target then lift the binoculars up but that is a definite No-No.

 

I would suggest (if you do) making seperate filters and then taping each on more then a little securely.

 

Will 8x be sufficent? Mercury will be small and 8x is not a lot. Equally I will be using just 44x I guess. Suppose all you/we/I want is a black dot.

 

You will I expect have to make something before to have test and development time.



#3 Grimnir

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Posted 10 September 2019 - 12:04 PM

I will traveling overseas during the upcoming Mercury transit and will be located in Turkey on transit day. I try to travel light but wanting to see this event and thinking to take my Bushnell 8x42 binos.  Any recommendations for easy on and off solar filters?  Mercury will be a very tiny black dot, I am assuming visible in these binos?

 

Thank you.

 

As sg6 above, make your own filters with Baader solar film. Clouds permitting you will be able to see Mercury transit at 8x but only as a small black dot. Still worth the effort though.

 

Graham



#4 TOMDEY

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Posted 10 September 2019 - 12:58 PM

I will traveling overseas during the upcoming Mercury transit and will be located in Turkey on transit day. I try to travel light but wanting to see this event and thinking to take my Bushnell 8x42 binos.  Any recommendations for easy on and off solar filters?  Mercury will be a very tiny black dot, I am assuming visible in these binos?

 

Thank you.

Hi, opticsguy! Actually, that should be almost easy --- I'm basing that on my experience that a sunspot that is 8x bigger can readily be seen just looking at the sun thru a plain hand-held welder's glass filter (the dark kind, not the feeble brazing goggles... the dark arc-welding mask!) The most important part will be holding your binos steady enough... like a tripod or something.   Tom



#5 Nicole Sharp

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Posted 10 September 2019 - 12:59 PM

It's possible but going to be really tough.  Baader AstroSolar film is also pretty fragile to be carrying around when traveling overseas unless you can have it shipped from Germany to Turkey.

 

If you have a DSLR camera, I would recommend a telephoto lens with a screw-in Hoya Solar filter.  Something like a 250-mm f/6 for an APS-C camera would be just about the bare minimum.  With a 27-mm sensor at 250 mm of focal length and f/6, you would have about the equivalent view of a 9X45 binocular, but with much greater resolution due to the small pixels on the sensor.  But Mercury would still only occupy a handful of pixels.  It's really small.

 

Something like this on a photo tripod is likely going to be a much better and safer option for you:

 

https://www.telescop...60/p/118193.uts

 

You can use that visually or with a camera.  It has a built-in permanent nonremovable Solar filter so is very safe for travel.

 

Something from the Celestron EclipSmart series may also be a good option for portability and safety when traveling for Solar events.  But Celestron EclipSmart uses yellow-light filters instead of white-light filters.


Edited by Nicole Sharp, 10 September 2019 - 01:06 PM.


#6 Jon Isaacs

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Posted 11 September 2019 - 01:36 PM

It's possible but going to be really tough.

 

I agree. Mercury is small and not easily seen...  Even in a small telescope, it can be an issue because of seeing during a bright sunny day is rarely stable.  A stable mount is a big help.  This is an image of Mercury I took during a transit about 15 years ago using a C-5.  It should have been more apparent but it wasn't.

 

4624525-transit of mercury.jpg

 

Jon


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#7 paulsky

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Posted 11 September 2019 - 02:51 PM

nice picture Jon!

Paul


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#8 danielgolite

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Posted 11 September 2019 - 08:06 PM

     I checked my notes on my Televue Ranger that I used to view the transit of Mercury in 2016. I used two Plossl eyepieces, a 26 mm and a 17mm which produced magnifications of 18x and 28x. Mercury was a very small dot but recognizable instantly. Remember that the scope was completely still on a tripod though. With binoculars, even at 8x, the view will shake some of you plan to hand hold them. That will make spotting tiny Mercury more difficult.



#9 Boki

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Posted 13 September 2019 - 02:28 AM

I have those EclipSmart 10x42 binoculars on a tripod, is there any chance i will be able to see Mercury at that magnification? I would like to do a simple outreach, where visitors would point and look and see a small dot on a solar disc. Would this work? 

Cs, boki



#10 Grimnir

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Posted 13 September 2019 - 02:37 AM

I have those EclipSmart 10x42 binoculars on a tripod, is there any chance i will be able to see Mercury at that magnification? I would like to do a simple outreach, where visitors would point and look and see a small dot on a solar disc. Would this work? 

Cs, boki

I don't know anything about the quality of the solar filters on this binocular but if you can see small sunspots through it I think you should be able to see Mercury as a minute black dot.

 

Alternatively, you could make some Baader solar film filters for your Fuji 10x50 FMTR-SX.

 

Graham



#11 Jon Isaacs

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Posted 13 September 2019 - 06:14 AM

I have those EclipSmart 10x42 binoculars on a tripod, is there any chance i will be able to see Mercury at that magnification? I would like to do a simple outreach, where visitors would point and look and see a small dot on a solar disc. Would this work? 

Cs, boki

During the transit, Mercury will be 10 arc-seconds in diameter.  In 10x binoculars that will be about 1.6 arc-minutes, very close to the limit of the eye's resolving power.  It's very small and would take perfect focusing to see it.  I am skeptical that even a skilled observer could see it in 10x binoculars but I could be wrong on that. Looking at my photo taken with a C-5, it is certainly a tiny, surprisingly low contrast shadow.  

 

For outreach, some sort of solar projection scheme seems like the best plan. 

 

Jon



#12 Grimnir

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Posted 13 September 2019 - 10:41 AM

Jon

 

As you well know, Mercury is visible with the unaided eye (not during transit obviously!) so I think the question is not one of resolving an object with a tiny angular diameter but one of contrast. For example, stars have a minute angular diameter but are extremely high contrast. During transit, Mercury will also have good contrast - although not the extremely high contrast of stars against a black background of course). It is this which will render Mercury visible in low magnification optics providing they are of good quality.

 

I am well aware that this argument opens a can of worms about contrast and primary vs secondary light sources etc.

 

Graham



#13 Rich V.

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Posted 13 September 2019 - 11:02 AM

 

For outreach, some sort of solar projection scheme seems like the best plan. 

 

IMO, for comfortable viewing by several people at a time, projection would seem best to me.

 

Venus projected onto a shaded white paper plate with one side of a 10x50 bino; Mercury should be easy to see though much smaller, of course.

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#14 stargazer193857

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Posted 13 September 2019 - 11:34 AM

Mercury will look smaller than Jupiter. About 1/4 the size. But if you have sharp eyes or just want to see a black speck that hopefully is not amoungst other sun sports, then 8x should work.

#15 Jon Isaacs

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Posted 13 September 2019 - 12:18 PM

Jon

 

As you well know, Mercury is visible with the unaided eye (not during transit obviously!) so I think the question is not one of resolving an object with a tiny angular diameter but one of contrast. For example, stars have a minute angular diameter but are extremely high contrast. During transit, Mercury will also have good contrast - although not the extremely high contrast of stars against a black background of course). It is this which will render Mercury visible in low magnification optics providing they are of good quality.

 

I am well aware that this argument opens a can of worms about contrast and primary vs secondary light sources etc.

 

Graham

 

Mercury is not a bright point of light, it's extended shadow on a bright surface in bad seeing.

 

Look again below at the photo I took of Mercury with my C-5, my comments are based on experience, the small angular size is only mentioned as an explaination for Mercury being a small, faint dark spot. Visually It was difficult in the C-5.

 

This first photo shows a partial eclipsed sun taken with the C-5.

 

2226713-eclipse with sunspots.jpg
 
This is the transit of Mercury taken with the same exact setup.
4624525-transit of mercury.jpg
 
Have you observed a transit of Mercury with 8 or 10x binoculars? 
 
Jon

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#16 harbinjer

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Posted 13 September 2019 - 12:30 PM

During the last transit, it was smaller than the largest sunspot.Unmounted, it takes me a while to find sunspots at 10x. Contrast is the issue; if you wear glasses, it will be even harder because of daytime reflections.  I would recommend 12x or more and a small mount.  I think Jon Isaacs' picture is very illustrative. Try scrolling past it up and down and see if you can see Mercury easily to simulate hand holding.


Edited by harbinjer, 13 September 2019 - 12:30 PM.


#17 Erik Bakker

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Posted 14 September 2019 - 02:18 AM

I think where a Venus transit is an easy object for binoculars in the 7-10x range, a Mercury transit is very challenging. But could be fun and rewarding too, with the best being a 10x binocular solidly mounted and properly filtered for the sun's intense rays. I use Baader Astro solar filter for that and regularly observe the sun with my 10x56 with that combination.

 

Incidentally, in my avatar you can see me using my 10x56 with a Baader Solar filter while traveling to the Alps, to catch a glimpse of a solar eclipse on a parking lot near the Autobahn. The filter I made for the FL102 S perfectly fits these big binoculars with my IPD. Secure it with a tape and you're good to go. You may have something similar from a 4" refractor or so that might fit the smaller 8x42's. Or you make/buy a pair for your 42mm binoculars. Colorwise, I prefer the Thousand Oaks and Questar solar filters with their orange colored sun though.

 

When seeing is good enough, I suspect you might be able to catch a glimpse of the Mercury transit. But then again, you might not. But it is always fun to make the best of what you have, so get those 8x42's out with a decent solar filter and give it a try. 


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#18 Jon Isaacs

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Posted 14 September 2019 - 02:27 AM

I think where a Venus transit is an easy object for binoculars in the 7-10x range, a Mercury transit is very challenging. But could be fun and rewarding too, with the best being a 10x binocular solidly mounted and properly filtered for the sun's intense rays. I use Baader Astro solar filter for that and regularly observe the sun with my 10x56 with that combination.

 

waytogo.gif

 

Well said.  My wife and I were in the Bighorn mountains of Wyoming for the 2012 Transit of Venus.  I hadn't really thought about the size issue and since Mercury had been so difficult, I naively assumed the Venus transit would also be a difficult.  How wrong I was.  This is a photo of the Venus transit for comparison.

 

5789855-Venus transit Cloudy Nights 1.jpg
 
Jon

 


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#19 Erik Bakker

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Posted 14 September 2019 - 02:28 AM

You can find more info on my observations with my 7x42, 8x25 and 10x56 binoculars and a 4" telescope of the 2016 Mercury transit with some pictures on CN here. Just had it slumbering in a distant corner of my mind, but remembered it after typing my post above and found it on CN wink.gif

 

An 8x42 will definitely be enough to observe it. The filter and support of the binoculars are big factors you can influence in how easy you can see this transition.


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#20 Grimnir

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Posted 14 September 2019 - 11:49 AM

 

 
Have you observed a transit of Mercury with 8 or 10x binoculars? 
 
Jon

 

 

See (e.g.) posts # 2, 7, 9 and 19 in this thread:

 

https://www.cloudyni...ercury-transit/

 

Graham



#21 Boki

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Posted 14 September 2019 - 02:52 PM

Thank you for all ideas, i will have a solar projection telescope, that i built myself and a 10x42 eclipse binoculars. 

 

https://www.cloudyni...on#entry8564419

 

I just hope we'll be able to see Mercury.




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