SolarChat!

Solar Spectrum filters, normally made from unobtanium, which usually take somewhere between many, many months or even years so I hear are available from stock!

Currently available are

46mm Research Grade 0.5A
32mm Research Grade 0.3A, 0.5A, 0.65A
25mm Advanced Observer 0.5A
19mm Observer 0.65A
25mm Sundancer 0.7A
19mm Sundancer 0.7A

More on the way. See details at astrograph.net.

Apart from being real quality, these filters come ready to let you use the 0.7x and 0.4x (which can also be used at 0.3x by adding a 15mm extension) Baader telecompressors. This gives you huge flexibility with image size and combating seeing.

By the way, were having a Summer SALE, we must be mad, but alas, SS filters are not in it as we are not deranged!

It will be useful for potential buyers if they will see:

1. Prices for these products

2. Correspodence between SS quality types (Sundancer, Observer, Advanced observer, Reserch grade) and DayStar SE and PE.

3. What really these different types Sundancer, Observer, Advanced observer, Reserch grade mean uniformity wise in badnwidth and CWL shift.

4. Any passport mapping (uniformity of bandwidth and CWL shift within filter aperture) available for SS filters?

Thanks.

Valery.

Hi Valery,

Prices. These are all on my website and include VAT @ 20% (/1.2 to remove). Subject to change as rates move but stable for the moment.

Types. Basically 'Observer' models and Research Grade have Active heating and cooling. The Sundancer is heated only but also features tilt tuning. Daystars Quantum is heated only.

All models feature an SC female thread front and rear and come with an SC/T2 thread insert for both sides. This allows easy connection to telecentrics and also use with the telecompressors.

Quality. Research Grade is equivalent to PE, and non Research Grade is SE.

CWL Adjustment. SS filters work a bit differently. Each filter has an operational temperature at which point it is at 656.28nm. The temperature is indicated on a standalone controller. You then have a set point for temperature. A 9°C change is equivalent to 1A shift. It is suggested that when you turn on the filter you start with it around 5°C under the CWL temp and increase until the view is optimum. This is to allow for the suns energy also heating the filter.

I have no specifics about the uniformity over the etalon. However I never got that with Daystar either including the PE we used to have on demonstration. I can say that so far they look good. Solar Spectrum has been around 20+ years and is run by Mark Wagner who worked with Del Woods. I hope to get this sort of info over time.

Hi Rupert,

Thanks a lot for your info about SS filters immediately available. From what I saw in the net, SS filters have excellent homegeneity. But I don't know which procedures in postprocessing were applied to the raw stacked images.

Valery.

Valery, I have looked through Luca's Solarspectrum and it was completely uniform, I don't remember doing flat fields with him. At the time I had never heard of a Quark so I didn't expect anything less than perfect. His is detailed here http://www.amun-ra.org/equipment.asp

Alexandra

Luca's Solar Spectrum is an RG46 and therefore equivalent to a 'PE'. It should therefore be completely uniform. Any non RG / PE type from anyone might be uniform but could also have some non-uniformity.

This is completely normal and to be expected from any 'normal grade' solar filter, because Mica is a variable organic material. This and the coating can affect the illumination level across the surface. Information I had from Daystar after a whole delivery of bad Quarks, said that a 0.2A variation in coating thickness on a 0.5A filter would affect illumination by 8%. The same variation on a 0.15A filter would affect it by 25%. Based on that I would assume that the more narrow the bandpass, the more likely you are to see non-uniformity in a standard filter. Apart from 2 Quark Prominences, I have never seen any obvious non-uniformity in any filters in the 0.7A + range when used on their own. When stacked or you drop to 0.5A and below, non-uniformity becomes more obvious. Sometimes it is not obvious or in an area that is not going to be an issue. If its going to be fixable with a flat then I would tend to let it pass. If it has dark patches, lines, spots etc then that's going back from me.

As yet I have not had long term experience with Solar Spectrum. However Baader help with elements of production. Having chatted with Thomas Baader about the evils of solar filters, and dealing with Mark directly about the custom filter for the Sunbyte project, it is clear that the ethos of Solar Spectrum is about quality, not shifting boxes surrounded by BS.

I don't expect every filter will be perfect, but I get the feeling I won't be throwing my toys.

Astrograph wrote: ↑Fri Aug 04, 2017 10:00 am Luca's Solar Spectrum is an RG46 and therefore equivalent to a 'PE'. It should therefore be completely uniform.

Jen Winter wrote me that PE grade filters warrant +/- 0.05A CWL shift and +/- 0.05A bandwidth variations.
This is obvously not as good as RG by SS where Mark warrants +/-0.03A variations. Still I am curious about RG grade filters from SS does this +/-0.03A mean only bandwidth variations or only CWL shifts or both.

I also curious about mapped passports for SS filters (are they available?) and does DayStar offers same +/-0.03A for their best filters?

Valery.

Good info Rupert thanks!

Now, i need a winning lottery ticket!

Valery

I will ask about the measured uniformity. May take some time to get an answer though.

Mark

Don't we all? £10 would be nice.....

Hi Group,
I make a point not to advertize when I am on the site. But I will explain my filters systems and how I check the etalon for uniformity.
Questions about uniformity and how I judged the filters.
I scan the etalons across the silt of a .5 meter spectrograph. I have a camera on the spectrograph to a monitor. I can see any change in wavelength as I move the etalon across the slit. This way I can move anywhere to check for wavelength shifts. This is how I have done it for years and it gives you a clearer view of the etalon then mapping small areas. But that is only the first test. Where I live the sun is out most of the year. I check every filter on a scope to make sure it is working. So the final test is when you really look through the filter. You can have etalons that look good on the spectrometer. But when you look through them is where you really see how good they are or not. And all mica is not the same. Mica comes in different shades of color. The mica that is a little darker has a lower index of refraction. So it may read .3Ang on the spectrometer but when you test the filter, it doesn't have the contrast as it should. I take this into consideration and will mark this as a broader filter.
For the HW, I only have 3 steps. There is really no reason for more. .65Ang+.1/-.05ang is not that much difference in contrast. .5Ang +.1/-.05Ang are about the same, and .3Ang +.1/-.05Ang looks pretty much the same at F/30.
OK, so what is my line of filters for Ha?
The Research Grade series, RG46 and RG32 will be uniform (wavelength +/-.05Ang) for the central 90% of CA. The RG46 has a 46mm CA. the RG32 has a 32mm CA.
The ASO is a 32mm CA filter. The minimum uniformity (wavelength +/-.1Ang) for these is the central 80% of the CA.
The SO1.5 has a 25mm CA, where the SO-1 has a 19mm CA. They will have the same spec as the ASO for uniformity. All these models are TEC temperature controlled. Using a TEC to control the wavelength is far superior then a resistor heating control. It has the advantage of being able to heat or cool to hold the wavelength.
The SD25 (SunDancer) has the same specs as the SO-1.5. This filter uses a resistor heater and is tilt able.
I hope this is what you needed for an answer to your questions.
Mark W.

Great information Mark, thanks!

So there you have it folks, all the info you need about SS filters straight from the horses mouth.

Thanks for that Mark

Hello guys,
This year I will do an upgrade in my solar equipment, I would like to buy a SS RG32, but the 0.2A version... But seems that version don't longer fabricated , right?
Ronnie

A 0.2A can probably be done to special order. I happen to know that there are two 'really good' 0.25A Solar Observer 1's available (19mm Standard Grade). These would be advertised as 0.3A. If you want a 0.2 RG32 then this can be put on order but you may have to wait a long time. Happy to find out for you. Just PM me.

Astrograph wrote: ↑Fri Aug 25, 2017 3:12 pm I happen to know that there are two 'really good' 0.25A Solar Observer 1's available (19mm Standard Grade). These would be advertised as 0.3A.

Hi Rupert,

Always nice when a dealer can answer most of special technical questions!

May I ask what does it mean "really good" unifomity wise?

Hi group,
All of the SO-1's will be uniform. They where designed for imaging . When it comes to 19mm etalons if they are not inform I toss them.
Mark W.