RASC Hamilton Transit of Venus

Roger Hill Roger.Hill at hiteach.net
Sat May 12 16:12:49 EDT 2012 

No problem...try it out ahead of time...go looking for first contact at the solar eclipse on May 21st.

Roger


-----Original Message-----
From: astronomers-bounces at hamiltonrasc.ca on behalf of Ed Mizzi
Sent: Sat 12/05/2012 4:08 PM
To: astronomers at hamiltonrasc.ca
Subject: Re: RASC Hamilton Transit of Venus
 
Thanks a million.


On 2012-05-12, at 4:01 PM, Roger Hill wrote:

> I put a hole in the bottom of a coffee can, put the eyepiece through it and then inserted the eyepiece into the focusser.  
> 
> The wax paper was held in place using an elastic band.
> 
> To change the eyepiece, I removed the wax paper, changed the eyepiece, grabbed a new piece of wax paper and put it back in place.
> 
> Simple.
> 
> Roger 
> 
> 
> -----Original Message-----
> From: astronomers-bounces at hamiltonrasc.ca on behalf of Ed Mizzi
> Sent: Sat 12/05/2012 3:20 PM
> To: astronomers at hamiltonrasc.ca
> Subject: Re: RASC Hamilton Transit of Venus
> 
> Thanks Roger, but how did you connect the coffee can to the eyepiece and keep it mounted properly? I cannot attend on that Sunday in May because I'll already be in Algonquin, but a great idea.
> 
> Ed
> 
> 
> On 2012-05-12, at 1:04 PM, Roger Hill wrote:
> 
>> Ed...
>> 
>> I used a coffee can, with black construction paper taped inside to cut
>> down internal reflections.
>> 
>> There are a number of variables you can play with to adjust the size of
>> the image.
>> 
>> 1) The longer the distance from the eyepiece to the screen, the larger
>> the image.
>> 2) The shorter the focal length of the eyepiece used to project, the
>> larger the image.
>> 3) The longer the focal length of the telescope, the larger the image
>> (think Barlow Lens).
>> 
>> Adjust the various parameters you can to give the best sized image.
>> 
>> 
>> May I make a suggestion?  How about we gather at the observatory on the
>> last Sunday afternoon in May before the transit and test out filters,
>> projection systems, etc.? 
>> 
>> Get there for about 4pm and be set up for 6pm.  The Sun will be at
>> (roughly) the same altitude and as the evening passes and the Sun sets
>> you'll get a good feel for how the geometry of your equipment will
>> change.  You may also be able to get some help with photography, too!
>> 
>> 
>> Some of the people who will NOT be at Saltfleet (like myself) might be
>> able to make the "dry run" and offer any assistance we can.
>> 
>> Just a thought.
>> 
>> Roger
>> 
>> 
>> 
>> -----Original Message-----
>> From: astronomers-bounces at hamiltonrasc.ca
>> [mailto:astronomers-bounces at hamiltonrasc.ca] On Behalf Of Ed Mizzi
>> Sent: Saturday, May 12, 2012 12:34 PM
>> To: astronomers at hamiltonrasc.ca
>> Subject: Re: RASC Hamilton Transit of Venus
>> 
>> Roger, I am planning to do this as well. I received an 8" x8" piece of
>> rear proj. material free (a sample from the manufacturer) but I'm having
>> trouble finding the size of funnel used on that website??
>> 
>> Ed
>> 
>> 
>> On 2012-05-12, at 12:26 PM, Roger Hill wrote:
>> 
>>> There's a great resource at
>>> http://www.transitofvenus.org/june2012/eye-safety .  
>>> 
>>> You can find out how to make a "Sun-Funnel" at the above site, too.  I
>> 
>>> made something similar to view the 1970 March 7th solar eclipse, but 
>>> since hi-performance rear projection screen material was not 
>>> available, I sued a piece of wax paper, instead.  It worked quite
>> well.
>>> 
>>> Roger
>>> 
>>> -----Original Message-----
>>> From: astronomers-bounces at hamiltonrasc.ca
>>> [mailto:astronomers-bounces at hamiltonrasc.ca] On Behalf Of Roger Hill
>>> Sent: Saturday, May 12, 2012 12:08 PM
>>> To: astronomers at hamiltonrasc.ca
>>> Subject: Re: RASC Hamilton Transit of Venus
>>> 
>>> What were the issues?  #14 (no less...#12 is NOT dark enough) stops 
>>> sufficient ultra-violet, visible and infra-red.  The only danger might
>> 
>>> be securely fastening them to the front of a binocular.
>>> 
>>> Roger
>>> 
>>> -----Original Message-----
>>> From: astronomers-bounces at hamiltonrasc.ca
>>> [mailto:astronomers-bounces at hamiltonrasc.ca] On Behalf Of Andy 
>>> Blanchard
>>> Sent: Saturday, May 12, 2012 11:48 AM
>>> To: astronomers at hamiltonrasc.ca
>>> Subject: Re: RASC Hamilton Transit of Venus
>>> 
>>> London just did whole thing on welders glasses and they are clearly 
>>> too dangerous.
>>> 
>>> Andy Blanchard
>>> 905-465-2031H
>>> 905-847-7777B
>>> 
>>> On 2012-05-12, at 10:34 AM, "Ed Mizzi" <emizzi at cogeco.ca> wrote:
>>> 
>>>> Roger,
>>>> 
>>>> With the welder's glass, if I secured it to both sides of a pair of
>>> binoculars would that be safe?
>>>> 
>>>> Thanks
>>>> Ed
>>>> 
>>>> 
>>>> On 2012-05-12, at 9:32 AM, Roger Hill wrote:
>>>> 
>>>>> Sorry, Al...I won't be there.  I have my own spot chosen.
>>>>> 
>>>>> In 2004, I saw the Sun rise out of Lake Ontario with a big round 
>>>>> black spot on it.  It was very impressive, and remains one of my 
>>>>> favourite events (and I've seen three total solar eclipses).
>>>>> 
>>>>> I'm going to watch the sun sink down into a lake
>>>>> 
>>>>> The Saltfleet site is very good, and will allow some great 
>>>>> photographs with Venus and tree branches silhouetted against the
>>> setting sun.
>>>>> 
>>>>> One person mentioned solar projection as being safe.  You want to be
>> 
>>>>> careful what sort of telescope and eyepiece you use for this, 
>>>>> particularly the eyepiece.  Make sure that the eyepiece is one that 
>>>>> you don't care about, because the heat build up inside it can ruin 
>>>>> the glues which hold some lenses together.  Apart from that, it is a
>>> safe method.
>>>>> 
>>>>> What is very definitely NOT (and I cannot stress this enough), is 
>>>>> the
>>> 
>>>>> use of eyepiece filters.  You used to find them all the time with 
>>>>> little 60mm refractors sold in the '60's and '70's.  A friend of 
>>>>> mine
>>> 
>>>>> had one, and we'd used it every now and then for a quick glimpse at 
>>>>> the sun.  One time, though, we decided to use it to try our hand at 
>>>>> sketching sunspots. It took less than three minutes to crack.
>>>>> Fortunately, it did just as Wayne looked away to start sketching and
>> 
>>>>> before I got to have a look.
>>>>> 
>>>>> What you have is 60mm (or more) of sunlight compressed down into a 
>>>>> tiny disk, and then compressed even more by the eyepiece.  All of a 
>>>>> sudden, at the speed of light, all that energy will hit the back of 
>>>>> your eyeball as the filter cracks...you cannot get out of the way 
>>>>> fast enough.  There are no pain receptors in the back of your eye, 
>>>>> so
>>> 
>>>>> it won't be the pain that makes you move out of the way.  There is 
>>>>> an
>>> 
>>>>> excellent chance that the back of your eye will be permanently 
>>>>> burned, and you'll see the transit for the rest of your life, 
>>>>> forever
>>> etched in negative.
>>>>> 
>>>>> When I do public courses or classes in Astronomy and we get to solar
>> 
>>>>> observing, I always ask if anyone has one.  I offer to buy it from 
>>>>> them if they'll bring it to the next class.  It has been quite a few
>> 
>>>>> years since I saw one, and I'd really hoped that these nasty pieces 
>>>>> equipment were gone for good.
>>>>> 
>>>>> 
>>>>> Another alternative is #14 welders glass.  This works very well, and
>> 
>>>>> a
>>>>> 2x2 piece of it makes an excellent filter for a finder-scope.  
>>>>> Please
>>> 
>>>>> make sure that it is secured to the finder, though.  Back in the 
>>>>> '70's, Johnny Carson show had John Davidson as guest on his show.
>>>>> Davidson was also an amateur astronomers (Carson had a C14), and 
>>>>> mentioned that he'd bought a hydrogen-alpha filter for observing the
>> 
>>>>> sun.  The views were fantastic, but something didn't smell right, 
>>>>> and
>>> 
>>>>> he realized that his hair was smouldering, lit by the finder-scope.
>> 
>>>>> He'd used the projection method to find the Sun (minimize the size 
>>>>> of
>>> 
>>>>> the shadow of the findersope, and then project the image on to a 
>>>>> piece of paper to centre it).  He'd forgotten to put a cap on the
>>> finder-scope.
>>>>> 
>>>>> 
>>>>> Hope this helps,
>>>>> 
>>>>> Roger
>>>>> 
>>>>> 
>>>>> -----Original Message-----
>>>>> From: astronomers-bounces at hamiltonrasc.ca
>>>>> [mailto:astronomers-bounces at hamiltonrasc.ca] On Behalf Of Al Jones
>>>>> Sent: Saturday, May 12, 2012 6:00 AM
>>>>> To: astronomers at hamiltonrasc.ca
>>>>> Subject: Re: RASC Hamilton Transit of Venus
>>>>> 
>>>>> ROGER
>>>>> Thanks for that advice. I did not realize the mylar was a sharper
>>> image.
>>>>> See u at the transit perhaps.
>>>>> AL
>>>>> 
>>>>> On 2012-05-11, at 23:58, "Roger Hill" <Roger.Hill at hiteach.net>
>> wrote:
>>>>> 
>>>>>> Al...
>>>>>> 
>>>>>> Mylar gives a better image.  I've used both, and while I like the 
>>>>>> colour that is produced by InCoNel filters, the image is sharper 
>>>>>> using
>>>>> mylar.
>>>>>> 
>>>>>> Further, since mylar is coated on both sides (the good filters are,
>> 
>>>>>> anyway), if there is a pinhole or a scratch, it's less likely to go
>> 
>>>>>> right through.
>>>>>> 
>>>>>> Lastly, if you drop the mylar filter, it is far more likely to
>>>>> survive.
>>>>>> 
>>>>>> Roger
>>>>>> 
>>>>>> -----Original Message-----
>>>>>> From: astronomers-bounces at hamiltonrasc.ca
>>>>>> [mailto:astronomers-bounces at hamiltonrasc.ca] On Behalf Of Al Jones
>>>>>> Sent: Friday, May 11, 2012 7:41 PM
>>>>>> To: astronomers at hamiltonrasc.ca
>>>>>> Subject: RASC Hamilton Transit of Venus
>>>>>> 
>>>>>> Hi Gary
>>>>>> 
>>>>>> I have a CPC 1100 but no solar filter. I've tried to a get a glass 
>>>>>> one
>>>>> 
>>>>>> from Efston Science but no stock. They said mylar possible but much
>> 
>>>>>> less durable.
>>>>>> 
>>>>>> Suggestions?
>>>>>> 
>>>>>> Thx
>>>>>> 
>>>>>> Al
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