Quark advice

[Piero]

1 hour ago, newbie alert said:

So for Ha I'd only need the quark?

To observe the Sun in H-alpha, you can either get a dedicated solar telescope (e.g. Lunt telescopes - https://luntsolarsystems.com/telescopes ) or use a Quark. 

The advantages of the Quark are reduced cost, reuse of your telescopes for this kind of solar observation, and smaller image scale. The latter is due to the presence of a 4.2x tele-extender inside the Quark. A smaller image scale can be an advantage but also a disadvantage because it can prevent you from seeing the whole solar disk. It also means that you might need 1 or 2 eyepieces of longer focal lengths, in order to maintain a reasonable image brightness. Hopefully other members will comment on the eyepieces (exit pupils) they use the most during h-alpha observation.

As Mod Stu said, a full aperture ERF or a filter will help maintain the temperature in the Quark at reasonable levels, extending its lifespan. A full aperture ERF would be the best choice but it's also expensive. In smaller apertures one can use an internal filter. Typical choices are: 1) Baader UV/IR, 2) Astronomik UV/IR, 3) Baader h-alpha CCD 35nm. The Baader UV/IR has some leak in the IR (see Fig 1 below). This means that part of the heat will pass through the filter. The Astronomik UV/IR has been reported to filter the heat a bit more than the Baader. Unfortunately, in Fig 2, the plot does not show the function for values larger than 1100 nm. Finally, the Baader h-alpha CCD 35nm filters everything except for the ~35nm window where the hydrogen alpha bands is transmitted (see Fig 3). In my opinion the latter is a good solution for a small aperture telescope like your 80mm refractor.

It's worth remembering that these filters will reflect the light back through the tube. As this is done near the diagonal, the light concentration is rather high. As a consequence, one should be very careful not to point the telescope at things or people (e.g. do not pass your hand in front the tube), because it can be dangerous. As a reference, it was reported that Archimedes used a burning glass as a weapon in 212 BC, when Marcus Marcellus tried to attack Syracuse. Apparently, he incinerated the Roman fleet was supposedly incinerated. Eventually, the city was taken and Archimedes was killed. 

 

 

 

[jetstream]

I use an absorptive UV/IR cut filter using coated KG3 Schott glass.

https://beloptik.de/en/uv-ircut-on-kg3-filter/

[jetstream]

I forgot to say that the KG3 will cause tube thermals after a while, not bad though and they go away after a short break. Its a small price to pay however as the KG3 cannot fail (short of breakage) as it naturally absorbs IR.

Make sure all these in tube "pre filters" rattle in their cell......

[Pig]

Heat build up can be avoided by not leaving the scope pointed at the sun when you are not looking through it..... if I go for a coffee or some food etc.... I simply slew the scope toward the horizon, I am sure this is not a necessity but it doesn’t hurt ☀️

[skybadger]

I have used a baader 35mm filter in front of the quark and decided it reduced contrast unacceptably. That was on a st80.

 

[Merlin66]

Surprised to hear that....

The optical and transmission qualities of the Baader 35nm CCD filter should have no, or very minimal effect on the image.

Was this visual or imaging???

 

[Davey-T]

11 minutes ago, Merlin66 said:

Surprised to hear that....

The optical and transmission qualities of the Baader 35nm CCD filter should have no, or very minimal effect on the image.

Was this visual or imaging???

 

I use a 2" Badder 35nm HA filter in the 152mm refractor and can't see any difference in contrast without it, maybe it affects small apertures more ?

Dave

 

[Davey-T]

17 hours ago, Pig said:

Heat build up can be avoided by not leaving the scope pointed at the sun when you are not looking through it..... if I go for a coffee or some food etc.... I simply slew the scope toward the horizon, I am sure this is not a necessity but it doesn’t hurt ☀️

When I'm imaging I leave mine tracking the Sun all day, not that we've had many long sunny days recently, so passing cloud helps keep it cool

Dave