Re: Eclipse photography

[Mark Roberts]

I finally found a well-written and thorough discussion of solar
photography and filters. It's on Canon's web site but is very much
brand agnostic for the most part:
http://learn.usa.canon.com/resources/articles/2017/solar-eclipse/solar-filters-eclipse-photography.shtml


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Re: Eclipse photography

[james]

What i have done in the past is to use 2 polarizing filters and cross 
polarize them. 1st one (closest to sun) must be a non circular type.

Done it this way as i am cheap and is all that i have.
Also good results can be had with a welding glass. How you mount it 
however is entirely up to you.


James

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Re: Eclipse photography

[Gonz]

Thanks John.


On Thu, Jul 13, 2017 at 10:14 PM, John  wrote:
> Mine is a Sigma 300mm F2.8 EX APO in Pentax KAF mount. It's the last of
> their film lenses in that focal length, before they reformulated for
> digital. It has a detachable lens hood that reverses when it's in its
> case. Measuring across the outside of the lens hood it's 129mm.
>
> The Astrozap 124mm-130mm fits snugly over the end of the lens hood. I
> barely need to tighten the three thumb screws to keep it in place.
>
> Measuring outside to outside of the front element is 115 mm, so it looks
> like the hood adds 14 mm. I was able to buy from a local camera dealer
> & actually verify it fit when I purchased it.
>
> The Pentax Forums specs for the SMC Pentax-FA* 300mm F2.8 ED[IF] says it
> can take 112mm screw on filters on the front and gives a Diam x Length =
> 123 x 247 mm. So, I'm thinking the outside of the lens hood is 123mm.
>
> The AZ-1514 I bought might fit loosely or you might need to go with the
> next size smaller - AZ-1513 117mm-124mm (4-5/8 to 4-7/8) diameter to get
> a snug fit.
>
> The page I linked before has the full line of Astrozap filters.
>
>
> On 7/13/2017 16:34, Gonz wrote:
>>
>> John, I'm thinking of getting this too.  Is yours for the A *300/2.8?
>> Thats what I'm going to use and haven't had a chance to measure the
>> outside diameter of the lens end.
>>
>>
>>
>> On Tue, Jul 11, 2017 at 11:02 PM, John  wrote:
>>>
>>> On 7/11/2017 21:54, Mark Roberts wrote:


 I expect there will be more than a few of us attempting to photograph
 the eclipse next month. I've just started a little research into it
 and I'm closing in on a decision as to what filter to use. My longest
 lens is my FA*300/2.8 and it's happily configured with an in-lens 43mm
 filter capability. Here's what I've found that looks most promising:
 https://www.optcorp.com/spectrum-threaded-camera-solar-filter-43mm.html

 Anyone have any experience or other recommendations?

>>>
>>> I've talked to several people who photographed previous eclipses and was
>>> told not to use the internal filters because the lens will concentrate
>>> enough light to melt them & besides messing up the filter it can damage
>>> the lens & the sensor. One of my sources stated he had found out the
>>> hard way.
>>>
>>> I got an Astrozap AZ-1514 Full Aperture Glass Solar filter that fits
>>> over the lens hood on my 300/2.8 - "Full Aperture Glass Solar Filter
>>> 124mm-130mm (4-7/8 to 5-1/8) diameter."
>>>
>>> https://www.astrozap.com/scripts/prodList.asp?idCategory=36
>>>
>>> I tried it out at GFM. It worked just fine, but I'm still learning how
>>> to aim the camera. I should measure the lens hood diameter on my
>>> 80-200/2.8 Tokina ATX-Pro and order a filter for it.
>>>
>>> --
>>> Science - Questions we may never find answers for.
>>> Religion - Answers we must never question.
>>>
>>>
>>> --
>>> PDML Pentax-Discuss Mail List
>>> PDML@pdml.net
>>> http://pdml.net/mailman/listinfo/pdml_pdml.net
>>> to UNSUBSCRIBE from the PDML, please visit the link directly above and
>>> follow the directions.
>>
>>
>>
>>
>
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> Religion - Answers we must never question.
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Re: Eclipse photography

[John]

Mine is a Sigma 300mm F2.8 EX APO in Pentax KAF mount. It's the last of
their film lenses in that focal length, before they reformulated for
digital. It has a detachable lens hood that reverses when it's in its
case. Measuring across the outside of the lens hood it's 129mm.

The Astrozap 124mm-130mm fits snugly over the end of the lens hood. I
barely need to tighten the three thumb screws to keep it in place.

Measuring outside to outside of the front element is 115 mm, so it looks
like the hood adds 14 mm. I was able to buy from a local camera dealer
& actually verify it fit when I purchased it.

The Pentax Forums specs for the SMC Pentax-FA* 300mm F2.8 ED[IF] says it
can take 112mm screw on filters on the front and gives a Diam x Length =
123 x 247 mm. So, I'm thinking the outside of the lens hood is 123mm.

The AZ-1514 I bought might fit loosely or you might need to go with the
next size smaller - AZ-1513 117mm-124mm (4-5/8 to 4-7/8) diameter to get
a snug fit.

The page I linked before has the full line of Astrozap filters.

On 7/13/2017 16:34, Gonz wrote:

John, I'm thinking of getting this too.  Is yours for the A *300/2.8?
Thats what I'm going to use and haven't had a chance to measure the
outside diameter of the lens end.



On Tue, Jul 11, 2017 at 11:02 PM, John  wrote:

On 7/11/2017 21:54, Mark Roberts wrote:


I expect there will be more than a few of us attempting to photograph
the eclipse next month. I've just started a little research into it
and I'm closing in on a decision as to what filter to use. My longest
lens is my FA*300/2.8 and it's happily configured with an in-lens 43mm
filter capability. Here's what I've found that looks most promising:
https://www.optcorp.com/spectrum-threaded-camera-solar-filter-43mm.html

Anyone have any experience or other recommendations?



I've talked to several people who photographed previous eclipses and was
told not to use the internal filters because the lens will concentrate
enough light to melt them & besides messing up the filter it can damage
the lens & the sensor. One of my sources stated he had found out the
hard way.

I got an Astrozap AZ-1514 Full Aperture Glass Solar filter that fits
over the lens hood on my 300/2.8 - "Full Aperture Glass Solar Filter
124mm-130mm (4-7/8 to 5-1/8) diameter."

https://www.astrozap.com/scripts/prodList.asp?idCategory=36

I tried it out at GFM. It worked just fine, but I'm still learning how
to aim the camera. I should measure the lens hood diameter on my
80-200/2.8 Tokina ATX-Pro and order a filter for it.

--
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Religion - Answers we must never question.


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Re: Eclipse photography

[Gonz]

John, I'm thinking of getting this too.  Is yours for the A *300/2.8?
Thats what I'm going to use and haven't had a chance to measure the
outside diameter of the lens end.



On Tue, Jul 11, 2017 at 11:02 PM, John  wrote:
> On 7/11/2017 21:54, Mark Roberts wrote:
>>
>> I expect there will be more than a few of us attempting to photograph
>> the eclipse next month. I've just started a little research into it
>> and I'm closing in on a decision as to what filter to use. My longest
>> lens is my FA*300/2.8 and it's happily configured with an in-lens 43mm
>> filter capability. Here's what I've found that looks most promising:
>> https://www.optcorp.com/spectrum-threaded-camera-solar-filter-43mm.html
>>
>> Anyone have any experience or other recommendations?
>>
>
> I've talked to several people who photographed previous eclipses and was
> told not to use the internal filters because the lens will concentrate
> enough light to melt them & besides messing up the filter it can damage
> the lens & the sensor. One of my sources stated he had found out the
> hard way.
>
> I got an Astrozap AZ-1514 Full Aperture Glass Solar filter that fits
> over the lens hood on my 300/2.8 - "Full Aperture Glass Solar Filter
> 124mm-130mm (4-7/8 to 5-1/8) diameter."
>
> https://www.astrozap.com/scripts/prodList.asp?idCategory=36
>
> I tried it out at GFM. It worked just fine, but I'm still learning how
> to aim the camera. I should measure the lens hood diameter on my
> 80-200/2.8 Tokina ATX-Pro and order a filter for it.
>
> --
> Science - Questions we may never find answers for.
> Religion - Answers we must never question.
>
>
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> http://pdml.net/mailman/listinfo/pdml_pdml.net
> to UNSUBSCRIBE from the PDML, please visit the link directly above and
> follow the directions.



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Re: Eclipse photography

[Paul Stenquist]

Hmmm, let me think. Scores of highly skilled photographers from all over the 
world will be shooting the eclipse, and their work will be displayed 
everywhere. Should I drive 8 hours to add my undoubtedly less than stellar 
image to the huge pile? Uh, no.

Paul via phone

> On Jul 11, 2017, at 9:54 PM, Mark Roberts  wrote:
> 
> I expect there will be more than a few of us attempting to photograph
> the eclipse next month. I've just started a little research into it
> and I'm closing in on a decision as to what filter to use. My longest
> lens is my FA*300/2.8 and it's happily configured with an in-lens 43mm
> filter capability. Here's what I've found that looks most promising:
> https://www.optcorp.com/spectrum-threaded-camera-solar-filter-43mm.html
> 
> Anyone have any experience or other recommendations? 
> 
> 
> -- 
> Mark Roberts - Photography & Multimedia
> www.robertstech.com
> 
> 
> 
> 
> 
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Re: Eclipse photography

[Mark Roberts]

John wrote:

>On 7/11/2017 21:54, Mark Roberts wrote:
>> I expect there will be more than a few of us attempting to photograph
>> the eclipse next month. I've just started a little research into it
>> and I'm closing in on a decision as to what filter to use. My longest
>> lens is my FA*300/2.8 and it's happily configured with an in-lens 43mm
>> filter capability. Here's what I've found that looks most promising:
>> https://www.optcorp.com/spectrum-threaded-camera-solar-filter-43mm.html
>>
>> Anyone have any experience or other recommendations?
>
>I've talked to several people who photographed previous eclipses and was
>told not to use the internal filters because the lens will concentrate
>enough light to melt them & besides messing up the filter it can damage
>the lens & the sensor. One of my sources stated he had found out the
>hard way.

Funny, I've read just the opposite — of success using a DIY filter
inserted between a teleconverter and the lens it's attached to.

I'll have to do some more digging.
 
-- 
Mark Roberts - Photography & Multimedia
www.robertstech.com





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Re: Eclipse photography

[John]

Ran across this map on Twisted Sifter. It gives average drive times from
locations in the U.S., Canada & Mexico to the center-line of the eclipse
path.

http://tinyurl.com/Aug21-Drive-Time

On 7/11/2017 21:54, Mark Roberts wrote:

I expect there will be more than a few of us attempting to photograph
the eclipse next month. I've just started a little research into it
and I'm closing in on a decision as to what filter to use. My longest
lens is my FA*300/2.8 and it's happily configured with an in-lens 43mm
filter capability. Here's what I've found that looks most promising:
https://www.optcorp.com/spectrum-threaded-camera-solar-filter-43mm.html

Anyone have any experience or other recommendations?





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Re: Eclipse photography

[J.C. O'Connell]

On Tue, 11 Jul 2017 21:54:43 -0400, Mark Roberts  
 wrote:



I expect there will be more than a few of us attempting to photograph
the eclipse next month. I've just started a little research into it
and I'm closing in on a decision as to what filter to use. My longest
lens is my FA*300/2.8 and it's happily configured with an in-lens 43mm
filter capability. Here's what I've found that looks most promising:
https://www.optcorp.com/spectrum-threaded-camera-solar-filter-43mm.html

Anyone have any experience or other recommendations?




try to use a longer lens, like a 500 or 600mm
--
J.C. O'Connell
hifis...@gate.net
-
Using Opera's mail client: http://www.opera.com/mail/

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Re: Eclipse photography

[Larry Colen]

Just as I was heading out on my road trip B sent out an eclipse mailer:
https://www.bhphotovideo.com/c/solar-observing/ci/33818/N/3583558376/sba

When I was in Portland I was talking to my rocket scientist friend Phil 
about watching the eclipse, he wants to make a camera obscura to project 
the image of the sun.  It turns out that if you take a long lens 
(500mm), and place it back to back with a wide angle lens (samyang 8mm?) 
you can then focus a projected image a reasonable distance away.


We did some quick proof of concept with my bigma and my sigma 20/1.8.

Philip just ordered himself an inexpensive Celestron.  Here are his 
notes from when he was waiting for it:


From the intarwebz:

D = 0.0093P(FLtelescope/FLeyepiece)

D = image diameter, m
P = Projection distance, m
object - sun

And, if your telescope has an all metal and glass eyepiece, you can just
use that for projecting.  Even back projection, through a funnel stuck
into the objective tube, to a screen strapped on the end of it.
Reflectors can melt their secondary mirror's mounting if it's plastic.
If so, you can stop it down with a 1-2" aperture on the inlet end.
So 1 1/4" eyepieces may make the best second lens for this.  The
Celestron AStroMASTER 114 comes with 10mm and 20mm ones, so it'll
project nice images using those if they don't melt.

I then got this update from him yesterday:
Hey,

The ASStroBlaster 114 arrived.  Some things I've learned.
The tripod/mount is acceptable, though the solar image wiggles pretty 
easily, that's pretty good mag, so more solid would be better.


Its 20mm eyepiece has just enough FOV to project the sun and maybe the 
moon, but the spare on the edges is so slim that you have to constantly 
be tracking to keep up with that sucker.
A motor drive is definitely in order.  There's one for this beast, I'll 
have to track it down.


This situation should improve with wider FOV eyepieces (in theory), but 
will get worse with shorter FL ones.  The projected image size is nice 
but not as wide as I dream of for the Camera Obscura.

So, looking for very wide FOV eyepieces of 10-15mm now.

The 'scope is "A Jones-Bird Newtonian telescope ... is a mirror-lens 
(catadioptric) variation on the traditional design sold in the amateur 
telescope market. The design uses a spherical primary mirror in place of 
a parabolic one, with spherical aberrations corrected by sub-aperture 
corrector lens usually mounted inside the focusser tube or in front of 
the secondary mirror. This design reduces the size and cost of the 
telescope with a shorter overall telescope tube length (with the 
corrector extending the focal length in a "telephoto" type layout) 
combined with a less costly spherical mirror. Commercially produced 
versions of this design have been noted to be optically compromised due 
to the difficulty of producing a correctly shaped sub-aperture corrector 
in a telescope targeted at the inexpensive end of the telescope market." 
(Wikipedia)


So far, the solar image is not sharp like it clearly could be.  Have to 
see how much of that is the eyepiece.  Cool set of big sunspots today, 
though.


Projecting through the eyepiece gets you a screen that is naturally at 
90 degrees to the sunlight.  A small sized screen (1'?) and a simple 
up-sun shade could be built onto the 'scope, and you'd have a decent 
setup without much trouble.


The cover that comes with it has a hole that makes it a perfect aperture 
for not roasting plastic optics.  I may have prematurely let some of the 
smoke out of it, but it's still alive.  Turns out as the sun drifts off 
to the side, it wants to melt any black plastic mounting the secondary 
optics.  Like around that cursed corrector lens mounted at the deep end 
of the focuser tube.  Or the focuser tube itself.  Or the eyepiece. 
Motor drive!  Maybe a fan for the secondary mirror.


-Phil


=

In any case, it seems that one critical aspect is some rough 
approximation of an equatorial mount, not to keep the image from 
blurring but to just keep it relatively centered.



Mark Roberts wrote:

I expect there will be more than a few of us attempting to photograph
the eclipse next month. I've just started a little research into it
and I'm closing in on a decision as to what filter to use. My longest
lens is my FA*300/2.8 and it's happily configured with an in-lens 43mm
filter capability. Here's what I've found that looks most promising:
https://www.optcorp.com/spectrum-threaded-camera-solar-filter-43mm.html

Anyone have any experience or other recommendations?




--
Larry Colen  l...@red4est.com (postbox on min4est) http://red4est.com/lrc


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Re: Eclipse photography

[John]

On 7/11/2017 21:54, Mark Roberts wrote:

I expect there will be more than a few of us attempting to photograph
the eclipse next month. I've just started a little research into it
and I'm closing in on a decision as to what filter to use. My longest
lens is my FA*300/2.8 and it's happily configured with an in-lens 43mm
filter capability. Here's what I've found that looks most promising:
https://www.optcorp.com/spectrum-threaded-camera-solar-filter-43mm.html

Anyone have any experience or other recommendations?



I've talked to several people who photographed previous eclipses and was
told not to use the internal filters because the lens will concentrate
enough light to melt them & besides messing up the filter it can damage
the lens & the sensor. One of my sources stated he had found out the
hard way.

I got an Astrozap AZ-1514 Full Aperture Glass Solar filter that fits
over the lens hood on my 300/2.8 - "Full Aperture Glass Solar Filter
124mm-130mm (4-7/8 to 5-1/8) diameter."

https://www.astrozap.com/scripts/prodList.asp?idCategory=36

I tried it out at GFM. It worked just fine, but I'm still learning how
to aim the camera. I should measure the lens hood diameter on my
80-200/2.8 Tokina ATX-Pro and order a filter for it.

--
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Religion - Answers we must never question.

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Re: Eclipse photography resource

[John Sessoms]

Thanks. I took a look at it & it has some information I can use even if
it is a Canon site.

On 4/20/2017 10:09, Stanley Halpin wrote:

John, others gearing up (pun intended) for the eclipse this August: I
just noticed a reference to a Canon site that has tips on preparation
for the event. Including a discussion of focal length, disc image
size, corona size, etc. You may find this useful…

http://learn.usa.canon.com/resources/articles/2017/solar-eclipse/choosing-lenses-for-eclipse-photography.shtml

stan



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