Re: [Coronado_PST] Double stacked PST is very dim


Sep 5, 2013

 


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#11683 Sep 5, 2013

I just got my PST double stacked. However, what I see in the eyepiece is very dim. Its hard to make out anything. Is there any way to make it brighter? Thanks.

Jim



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#11684 Sep 5, 2013

Hi, Jim. If you look at the side of your doublestack filter, you should see the semi-circle of a wheel sticking out at right angles to the filter. If you turn this knob while looking through the scope, the image will brighten or dim. If you turn it to maximum brightness, you'll probably see another, reflected image of the sun appear. Turn the knob back the other way until that image disappears from your field of view and you'l have max brightness..

In my workflow, I tune the PST for max detail before I add the DS filter. After this tuning, I add the DS, adjust the brightness, and tune the DS for max detail.

I hope this helps.

Best,

Brian



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#11686 Sep 5, 2013

Thanks. It does help. However, it seems that I have to retune both etalons every time I observe. Is that right. Also, I am getting uneven illumination across the disk of the Sun. Is this normal.

Jim

--- In Coronado_PST@yahoogroups.com, Brian Straight brianstraight2010@...> wrote:

>

> Hi, Jim. If you look at the side of your doublestack filter, you should see

> the semi-circle of a wheel sticking out at right angles to the filter. If

> you turn this knob while looking through the scope, the image will brighten

> or dim. If you turn it to maximum brightness, you'll probably see another,

> reflected image of the sun appear. Turn the knob back the other way until

> that image disappears from your field of view and you'l have max

> brightness.

>

> In my workflow, I tune the PST for max detail before I add the DS filter.

> After this tuning, I add the DS, adjust the brightness, and tune the DS for

> max detail.

>

> I hope this helps.

>

> Best,

>

> Brian

>

>

> On Thu, Sep 5, 2013 at 6:35 AM, James vikelj@...> wrote:

>

> > **

> >

> >

> > I just got my PST double stacked. However, what I see in the eyepiece is

> > very dim. Its hard to make out anything. Is there any way to make it

> > brighter? Thanks.

> > Jim

> >

> >

> >

>



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#11688 Sep 5, 2013

Jim,

You are correct that you have to retune the etalons for every session. Lots of factors affect the tuning (you're dealing with a very narrow bandwidth of light), but you'll find with practice, it only takes a few seconds. The PST has a definite "sweet spot" where you get max detail and brightness. I still have this brighter area with the DS filter (a solarmax II), but the effect is less pronounced.

All the Best,

Brian



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#11690 Sep 5, 2013

A double stacked Ha etalon will result in a drop in transmission....the result is about 40% the brightness of a single stack. This is controlled by the laws of optics.....such is life!



On 5 September 2013 20:35, James vikelj@...> wrote:

.I just got my PST double stacked. However, what I see in the eyepiece is very dim. Its hard to make out anything. Is there any way to make it brighter? Thanks.

Jim


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