Heat through Quark

[Davey-T]

Just noticed the end cap of the quark is melted, accidentally left it on the other day when I swopped it for an eyepiece, I have a Baader UV/IR filter in the diagonal but this is obviously not keeping the heat out, is this OK ? seriously thinking of getting a front mounted ERF.

Excuse picture taken with wifes point and shoot camera but the autofocus doesn't work. you get the idea though.

Dave

[Luke]

I'm not surprised the cap melted. The UV/IR cut filter is going to reflect some of the energy, but a lot will still be making it through. I don't know about the innards of the Quark, but a snippet from the Company7 webpage:

"Looking inside the QUARK (don't ask how Company Seven found out) reveals there are optical blocking components, that are separated from the rest of the assembly, which take the heat."

The full Daystar page is here:

http://www.company7.com/daystar/products.html

[Pig]

How long did it take to melt like that ? and what size was the refractor ?

[Davey-T]

How long did it take to melt like that ? and what size was the refractor ?

100mm refractor, not sure how long it took to melt, probably only a few minutes as I was packing up.

Dave

[101nut]

I would find that incredibly worrying for visual use ... Some form of reassuring comment from Daystar would be good.

AndyG 

[Moonshane]

I presume it is the end cap scope side?

There is bound to be heat. You are looking at the sun and concentrating the light at a point.

On the basis you follow Daystar's spec I would be surprised if you have any problems

[Luke]

Folks, Dave is I believe talking about the cap that goes scope side, not the cap where the eyepiece goes, which is a different shape and colour. There is as Shane says bound to be heat scope side, one or two others have also melted this scope-side cap, forgetting to remove it before putting the Quark in the diagonal (can be done as the Quark's cap is on its 1.25 inch barrel, but you can also use the Quark in 2 inch mode...)

I use the Quark for visual with an ED100 and UV/IR cut, never felt any warmth on the diagonal, during or immediately after use.

Of course, you always need to take care with solar.

Bottom cap, scope-side = black!

[Pig]

If its on the scope diagonal then I am surprised any of the cap survived

[101nut]

I hadn't considered that it was a scope-side cap, assuming that to be the case I'm no longer surprised at the results. The Baader uv/ir cut filter appears to have about 2% pass at 740nm and simply takes most of the load off the main filter (the Quark). 

Perhaps this sort of thing should be 'take care' advice for people doing solar mods? 

AndyG

[Davey-T]

I think a warning would be appropriate as it was only exposed to the Sun for a short while, could have melted completely and made a mess of the diagonal

May already be a warning in the info as I haven't read it all but a warning sticker on the cap would be good for dummies like me.

Dave

[Luke]

When looking at UV/IR cut as an option I checked out what percentage of energy is visible, I can't remember the original link, but Wikipedia has it like this:

"In terms of energy, sunlight at the earth's surface is around 52 or 55 percent infrared (above 700 nm), 43 or 42 percent visible (400 to 700 nm), and 5 or 3 percent ultraviolet (below 400 nm)."

http://en.wikipedia.org/wiki/Sunlight

[michael.h.f.wilkinson]

Whatever Daystar says, I am going for an internal or front mounted ERF, just to be sure.

[allcart]

There is no safety issue here, its just a case of removing the end cap from the Quark before inserting it in the scope. Maybe Daystar should just change the cap colour to red so that its more obvious.

[Moonshane]

I think some kind of ERF might be prudent. Although I am very new to Ha solar (thanks Allan!) I note that even the tiny PST's 40mm aperture warrants a mini ERF after the etalon and before the blocking filter.

[michael.h.f.wilkinson]

There is no safety issue here, its just a case of removing the end cap from the Quark before inserting it in the scope. Maybe Daystar should just change the cap colour to red so that its more obvious.

I agree, with the culture of litigation prevalent in the USA, no US company would risk putting out any advice that may cause harm. Using an ERF (which I already have) instead of a UV/IR block filter just is an extra layer of protection.

[allcart]

I'm pretty sure there is an erf built into the quark, and I'm not sure of the qualities of the UV/IR, but the literature does state that an additional erf should be used on any scope over 80mm.

[Stu]

Somebody correct me if I'm wrong, but I believe that D-ERF's basically perform the same function as a UV/IR filter is reject the energy by reflecting it. So a D-ERF is nothing more than a big UV/IR filter. Is that correct????

If so then the same thing would happen in either instance...

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[Moonshane]

LOL - maybe I should shut up until I know what I am talking about. 

[Stu]

Shane, I'm just splashing about in the same pool of ignorance, hoping someone out there really knows!!

Peter D, Michael, Ken? Anyone? ;-)

Stu

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[Moonshane]

LOL - for me it's 'edging towards the cliff of ignorance'

I suppose the main thing is follow the advice of the provider.

[Luke]

Until a resident expert turns up, there's a review on the Baader D-ERF on Mark Townley's brill site:

"ERFs or Energy Rejection Filters like this are used in Hydrogen Alpha solar scopes to reject all but a narrow band of energy centred on the Ha line at 656.28nm, this can be seen in the graph above."

Review here:

http://brierleyhillsolar.blogspot.co.uk/2012/12/baader-d-erf-review.html

And transmission graph for the Astronomik L filter:

Page for the Astronomik L filter here:

http://www.astronomik.com/en/photographic-filters/l-filter.html

[michael.h.f.wilkinson]

An ERF has a narrower passband than the UV-IR filter, which essentially blocks IR and UV, and lets through all of the visible wavelengths. ERFs can differ in the exact passbands. As I understand it, many pass only the H-alpha (and sometimes Ca-K) band (quite broad-band), and therefore cut more of the energy passing through the system. Some of these rely on an interference (reflecting) part to block IR, and use some dye to block unwanted parts of the visible spectrum. These can still run pretty warm used internally. I have a tri-band ERF which passes a band arround H-alpha, Ca-K and the "solar continuum" band in the green, so it can stay put when I switch between white light and a (future) quark. It is a pure dielectric filter, so the unwanted part is (for the most part) reflected.

[michael.h.f.wilkinson]

Here is the plot for the tri-band from Beloptic

[Stu]

Very interesting Luke. I guess that us simpletons might be able to work it out from here.

The visible spectrum is like this:

The UV/IR cut is obviously designed to allow 'all' visible light through whilst cutting out most of the UV/IR

The D-ERF seems much more focussed on the Ha frequency so will ensure that virtually no UV/IR gets through. So although they work in similar ways, the D-ERF will certainly prevent more heat getting into the OTA and hitting the diagonal/Quark

Does that sound plausible?

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[Stu]

My post crossed with Michael's but I think I was pretty much there! Phew :-)

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