RASC Hamilton Transit of Venus

Sat May 12 17:19:36 EDT 2012

I was out to Durham Skies (Pickering) today to pick up a Dioptrx.  The 
owner, Gary Wilkinson, said he has 3 solar filters left in stock ( 1 x 5", 
and 2 x 80 mm), and that he expects more in before ToV.

Suggest you give him a call if interested (sorry, but I don't have any 
details other than above).  FYI - He closes at 4pm on Saturdays and reopens 
Tuesdays at 1100h.

http://durhamskies.com/index.html

-David MacMillan
Milton

-----Original Message----- 
From: Andy Blanchard
Sent: Saturday, May 12, 2012 4:16 PM
To: astronomers at hamiltonrasc.ca
Subject: Re: RASC Hamilton Transit of Venus

I really don't know squat about it. Your eyes your choice. London centre has 
some pretty smart guys too.

Sent from my iPhone

On 2012-05-12, at 4:12 PM, "Roger Hill" <Roger.Hill at hiteach.net> wrote:

> Odd...Ralph Chou (MSc, OD, Associate Professor, School of Optometry, 
> University of Waterloo and current President of the Toronto Centre) says 
> it's perfectly safe.
>
> http://www.transitofvenus.org/june2012/eye-safety/280-viewing-the-transit-eye-safety
>
> Roger
>
>
> -----Original Message-----
> From: astronomers-bounces at hamiltonrasc.ca on behalf of Andy Blanchard
> Sent: Sat 12/05/2012 3:10 PM
> To: astronomers at hamiltonrasc.ca
> Subject: Re: RASC Hamilton Transit of Venus
>
> There carried on the conversation for a couple of days. The consensus was 
> that the harmfully rays are not blocked by a welders helmet and will cause 
> permanent damage.  The buz was more about the web sites selling its use 
> during the TofV then the question of it's safety. Bottom line don't use 
> it.
>
> Andy Blanchard
> 905-465-2031H
> 905-847-7777B
>
> On 2012-05-12, at 12:08 PM, "Roger Hill" <Roger.Hill at hiteach.net> wrote:
>
>> 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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