Problems with Quark and Baader filters

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Problems with Quark and Baader filters

Post by krakatoa1883 » Mon Aug 22, 2016 6:14 pm

I purchased a 150 mm refractor to be used with my Daystar Quark. I am planning to mount a 110 or 135 mm front ERF but in the meantime I am using a simple Baader 2" UV/IR cut in front of the diagonal. Few days ago I tried (in the same position of the UV/IR cut) a Baader 35nm H-Alpha filter that someone recommends as internal ERF as it is more effective in preventing heat from reaching the Quark (I recently destroyed a red filter placed just behind the UV/IR cut). I immediately noted that with this filter the chromosphere became soft and many details disappeared. Comparing visually the 35nm Halpha to other filters I obtained the following results:

NO FILTERS: good contrast and details
ASTRONOMIK IR BLOCK: similar to no filter results
BAADER UV/IR CUT: a slight loss of contrast is evident, although tolerable
BAADER 35nm: contrast and details are washed out, the Sun becomes a red ball with only sunspots visibile plus few prominences in their brightest parts.

Initially I supposed the filter to be defective, however by placing it between the eye and the eyepiece the details of the chromosphere are fully visible, the poor results I am obtaining are clearly related to the filter position before the diagonal. The filter is threaded in the diagonal nose without inclinations and based on Baader specs it should be suitable down to f/2.8 (my scope is f/5). Rotating the Quark knob to different tuning positions has no effect at all.

Has anyone encountered similar problems ? Is there any specific position where this filter shall be placed ?

Thanks for attention !
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Re: Problems with Quark and Baader filters

Post by Merlin66 » Tue Aug 23, 2016 3:31 am

I've been using the Baader 35nm as an ITF replacement and as sub-diameter ERF on my SM60 and 100mm PST mod for the last few years.
I haven't experienced the issue you're having......
I can't think of any reason for the poor performance.
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Re: Problems with Quark and Baader filters

Post by mdwmark » Fri Oct 28, 2016 5:42 am

What you describe sounds like you just need to adjust the filter's set point. The set point is a balance between what temperature you need to move the etalon , plus the energy you are letting in from your ERF. The Baader filter has dropped the solar energy, so move the adjustment to get the filter back on band. I always start in the blue wing and increase the set point from there.
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Re: Problems with Quark and Baader filters

Post by marktownley » Fri Oct 28, 2016 5:50 pm

This is a very interesting slant you pose on this Mark - filters could be 'loaded' to a certain amount of 'heat' coming through to them. It is something i've certainly found with PST etalons in my past experiments, where a certain amount of pre blocking gives optimal results. Reflectively it would make sense with the Quarks too...
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Re: Problems with Quark and Baader filters

Post by Dewey » Wed Jan 04, 2017 6:17 pm

DayStar does not recommend using a UV/IR cut filter (or any other internal one) on any refractor over 120mm, as too much heat is involved to bounce back up the scope.
You really need the ERF for safe operation!

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Re: Problems with Quark and Baader filters

Post by krakatoa1883 » Tue Jan 10, 2017 3:28 pm

Yes, of course I agree. I forgot to mention that usually I stop down the scope to 110mm in order to have a better f/ratio for the Quark. What surprised me is that notwithstanding Baader filters are advertised for very fast ratios they seem not suitable if placed just in front of the diagonal in a f/6.8 light cone.

Thanks to all for your kind replies.
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Re: Problems with Quark and Baader filters

Post by ngwillym » Thu Apr 20, 2017 1:54 pm

Dewey wrote:
Wed Jan 04, 2017 6:17 pm
DayStar does not recommend using a UV/IR cut filter (or any other internal one) on any refractor over 120mm, as too much heat is involved to bounce back up the scope.
You really need the ERF for safe operation!
Not strictly true -
see https://www.cloudynights.com/topic/5278 ... with-uvir/ and
https://www.cloudynights.com/topic/5633 ... -aperture/

No problems with 127mm or maybe even 150mm with just a UV/IR cut - as long as they are air-spaced objectives and not esoteric designs such as Petzval or oil spaced objectives.

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Re: Problems with Quark and Baader filters

Post by Merlin66 » Thu Apr 20, 2017 11:05 pm

I'm disappointed to see the continuation of the "urban myth" that Petzval designs are not safe to use for solar observing (ie Herschel wedge etc.) without an added ERF.
This seems to be based on opinions and perpetuated by ill-informed amateurs who just don't know what they are talking about....
Al Nagler has gone on record (in S&T last year) saying all the TV Petzval designs are OK and 100% safe to use...
I obtained in writing last year similar assurances from WO and Takahashi that their Petzval designs were also 100% OK. So who is building and supplying the "unsafe" Petzval instruments??????
It annoys me!
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Re: Problems with Quark and Baader filters

Post by Merlin66 » Thu Apr 20, 2017 11:15 pm

I cancelled my order on Daystar for a Quark Chromo when they were unable to confirm that it would successfully operate (ie come on band) in ambient temperatures above 40 deg c.
It gets hot out here is Australia.......
They did suggest that it may be possible to get a "special" made up to function at these higher ambients....but no follow up.
The Quark relies on the heater to bring it up to the "design" temperature (28 deg????), above that it's out of band....there's obviously no provision to cool it back down..
Listening now to the discussion of using 150mm aperture telescopes with no ERF protection, I can't help but ask...what is the temperature reached by the Quark? That's a lot of incident energy just heating up the housing etc. I would be interesting to measure the actual temp.......
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Re: Problems with Quark and Baader filters

Post by PDB » Fri Apr 21, 2017 6:51 am

Good suggestion. Think the Quark is really sensitive to ambient temp an preload. Even if I put some insulation around it, can't get it to produce a decent image when ambiant temp drops below 12°C. Works best around 22-25 (we don't have 40 here) Also when sun is low on the horizon and less heat generated from incoming rays, quality seems to drop. (Maybe I should remove the UV/IR blocker in those cases). Even with the UV/IR in place, there is still a lot of heat falling on the Quark (from 80mm scope) Noticed that once when I forgot the plastic cap on the scope side. (started to melt fairly fast)

Rgrds,

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Re: Problems with Quark and Baader filters

Post by kornfeld » Sun Apr 30, 2017 4:30 pm

Merlin66 wrote:
Thu Apr 20, 2017 11:15 pm
I can't help but ask...what is the temperature reached by the Quark? That's a lot of incident energy just heating up the housing etc. I would be interesting to measure the actual temp.......

I can provide some info on this.....I had the exact same curiosity, so I measured the temps with an infrared gun-style thermometer. I have a Combo Quark Chromo (one of the newer/larger designs without an integrated barlow).

All measurements were made with the quark sitting on my kitchen counter, not connected in anyway to the telescope. I set the quark to the lowest temperature setting (-5 to the left on the dial), waited for the light to turn green, then basically held the measuring end of the gun against the eyepiece end of the quark such that the temperature sensor was aimed through the filter. This was repeated for all settings.

Three sources of error:

-It was difficult to get an exact measurement, because slight movements of the temperature gun would shift the temp a few tenths of a degree
-It was difficult to reproduce a single measurement--if I pulled the gun away and put it right back against the quark with no change to the dial, I would get a slightly different measurement (this is ultimately the same problem as above)
-I'm measuring the temp based on whatever IR light is emitted from the filter itself, or whatever is emitted by the housing around the filter (with light possibly reflecting off of the filter and into the temp gun), or both, or somewhere inside the housing, or......who knows :?:



However, this at least gives a general idea of the temps. I made four or five measurements per dial setting, and averaged them. All temperatures are in degrees Fahrenheit.

-5: 104.5
-4: 106.1
-3: 107.8
-2: 109.5
-1: 111.7
0: 112.5
1: 114.0
2: 117.0
3: 118.5
4: 120.3
5: 122.0

I'm *guessing* the heater is designed to adjust the temperature in 1.5 degree F increments. I should also redo all of the measurements again now that it's a different day. :)


On a very related side note--I have a piece of evidence that the heat from the Sun may indeed warm the assembly enough to affect functioning.

I use a battery pack that automatically turns itself off if it doesn't detect a current draw after a 30 second delay. This is important for the quark because if you adjust the dial too far down from whatever it was last set to, the battery will just turn off. For example, if I set it to +5 and let it come to temp, then rotate it to -5, the light will go reddish green (indicating that it is adjusting), then fully shut off after 30 seconds because it isn't drawing anything so the battery turns off.

Yesterday, external temps were about 65degreesF. I can sit myself under an overhang such that the telescope is fully in the sun, but the quark is fully in the shade. I had the Quark set to +4, which worked well for a 70mm telescope I have, but I was testing it out on an 80mm scope for the first time (I was not using an ERF or a UV//IR cut on the diagonal).

I decided to go all the way to -5, and just work my way up through the dial to see if a different setting worked on this scope. I adjusted to -5, and as expected, the light turned off after 30 seconds. I let it sit for 5 minutes to let it cool down on its own, turned the battery back on, and it shut off after 30 seconds again. Weird, because I would have expected it to drop in temperature in that time. I repeated this cycle for a good 15 minutes, and it never got to the point where I got a green light. I'm guessing this is because there was some additional heat just coming from the beam of sunlight that was keeping everything warmed up, but I don't know for sure. It did come to temp on -3, and I could start testing different settings. It might have come to temp on -5, but I got impatient and gave up because the Sun was getting lower and lower. :) All of this leads me to think that there is an additional heat load on everything from the beam of sunlight itself, and this was in relatively cool conditions with the quark pretty well shaded (definitely nowhere near 40degreesC external temps!).

Anyhow, I hope this info is helpful.

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Re: Problems with Quark and Baader filters

Post by Astrograph » Thu Jun 08, 2017 3:59 pm

Few things here

Did I read right that you tried the Quark on a 150mm scope with no ERF? I doubt it liked that!
Daystar are not consistent with their suggestions for max size of scope using a UV/IR cut. We don't recommend it beyond 100mm. Put your hand where the Quark sits on a 100mm scope with a UV/IR cut in place and you will understand why. Using a 35nm Ha the light is cold even on a 152mm.
When Baader etc quote compatibility of filters with different F ratios they are assuming the filter is behind a flattener because these are imaging filters. If you put a filter upstream as a solar ERF (which no filter company will say there filters are designed for) then you have converging light hitting the filter. That causes some spherical aberration and reduces the filters efficiency around its edge. Having said this they still visually work better than a bit of coloured glass on the objective but not nearly as well a proper dielectric coated polished ERF.
Internal filters should be as far up the light path as possible so they encounter the least focused light. They will work better.
The argument about Petzvals and also oiled optics is as much about liability as anything else. Yuri from TEC says using an internal filter (which is reflecting a converging beam of UV/IR back toward the objective) should be OK. If you do it and damage the lens cell then 'not for solar use' arguments are likely to start. As a minimum you would have a large shipping bill. As for Petzvals, the rear element/elements do encounter a more focused light cone which will cause some local heating. This might not be enough to cause expansion in its cell and make it crack but its better not to take the chance.
Quarks are passively cooled. They can refuse to reach operating temp if its too hot or even cold. Even a Quantum we once had would not reach the standard CWL temp on a 30 degree day. The other thing with a Quark is they seem to have oven and temp sensor faults. We have given up with them and now only offer Solar Spectrum which are actively cooled.

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Re: Problems with Quark and Baader filters

Post by Merlin66 » Thu Jun 08, 2017 4:20 pm

Televue, Takahashi and William Optics have gone on record as confirming their telescopes are all 100% safe to use for solar observing.
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Re: Problems with Quark and Baader filters

Post by Astrograph » Thu Jun 08, 2017 4:39 pm

Speaking as a retailer, I would not advise use of any type of scope for solar use which is potentially problematic unless the brand involved had issued a statement to dealers on the subject. If you have correspondence from these three, can you post it or send me it?

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Re: Problems with Quark and Baader filters

Post by Merlin66 » Thu Jun 08, 2017 8:03 pm

Al Nagler published his response in Sky&Telescope, I think Jan 2016.
I can send you copies of the confirmation emails from Takahashi and Williams Optics.
You just have to ask them and they will confirm to you.
Have to asked them????
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Re: Problems with Quark and Baader filters

Post by Astrograph » Fri Jun 09, 2017 12:00 am

I have not asked them Ken because traditionally converting a refractor for solar use dictates a front mounted ERF. Internal ERF's have only become more popular since the arrival of Quark to convert them for Ha

To convert a Refractor for solar use with a rear filter dictates use of a telecentric. Those assume a converging beam. A Petzval is not presenting the right light path to get the best from a Telecentric. Plus they are normally low native focal ratio making them hard to get up to F30. Basically they are not a great starting point for a solar scope. Oilled scopes are more relevant to the argument.

The other factor is internal ERF's are not as good a quality as a good front mounted one so if you want the best performance the question ceases to exist.

For White light of course there is still the question if using a wedge. For me the question won't exist. My refractor brands that are affected are TEC and for that Yuri gave a verbal answer, and Some Tecnosky Quads which are, like WO, badged scopes. Out of interest I will ask United Optics who are the major badge manufacturer.

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Re: Problems with Quark and Baader filters

Post by Merlin66 » Fri Jun 09, 2017 12:05 am

My comments were based on using those refractors in white light with a Herschel Wedge.
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Re: Problems with Quark and Baader filters

Post by krakatoa1883 » Fri Jun 16, 2017 6:31 pm

kornfeld wrote:
Sun Apr 30, 2017 4:30 pm
I decided to go all the way to -5, and just work my way up through the dial to see if a different setting worked on this scope. I adjusted to -5, and as expected, the light turned off after 30 seconds. I let it sit for 5 minutes to let it cool down on its own, turned the battery back on, and it shut off after 30 seconds again. Weird, because I would have expected it to drop in temperature in that time. I repeated this cycle for a good 15 minutes, and it never got to the point where I got a green light.
May I suggest you to repeat this experiment without actually observing the Sun, just with your Quark on a table indoor. This will tell you if the described behavior depends on heating by the sun or is due to a defective tuning.
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