FS-60Q and Herschel Wedge

[heliumstar]

A quick question if someone can chime in. FS-60Q and Herschel Wedge. I don't have enough knowledge to properly understand but it looks to me that it should work and be ok. The extender lenses are not close enough to concentrate as much heat as to be an issue. Is my thinking sound?

[fireballxl5]

Interested as I have similar equipment (FS60CB with 1.7x extender + HW). I usually use a solar filter film at the front of this scope but would like to try the wedge if safe.

[RT65CB-SWL]

Hi guys.

I use the Lunt solar wedge with a TeleVue Ranger, (image below), which is a 70mm semi-achromat. The reason I opted for the Lunt was the pre-installed/built-in ND3.0 filter. I find it is a lot safer than using a full aperture or off-axis solar filter.

I used it with a variety of eyepieces with and without a 1.6x screw-on lens or a 2.8x Barlow lens without any issues. Though I am not sure though about the use of extender lenses. Hopefully someone can answer this.

[heliumstar]

To update the thread. I collected information from multiple sources and all agree that considering the extender lens is further inside the tube and not close to focuser/focal plane it's okay to use Herschel Wedge plus I found one person actually using Herschel wedge with FS-60Q.

Now the question is which one? Lunt 1.25", Lacerta Brewster-angle. Want to keep everything 1.25" although Baader and Altair Astro ones look good with built-in solar finder. The other thing is you can get Lunt and SW Solar mount for the price of Baader...

[JeremyS]

On 20/10/2019 at 15:44, heliumstar said:

To update the thread. I collected information from multiple sources and all agree that considering the extender lens is further inside the tube and not close to focuser/focal plane it's okay to use Herschel Wedge plus I found one person actually using Herschel wedge with FS-60Q.

Now the question is which one? Lunt 1.25", Lacerta Brewster-angle. Want to keep everything 1.25" although Baader and Altair Astro ones look good with built-in solar finder. The other thing is you can get Lunt and SW Solar mount for the price of Baader...

Did you ever get to the bottom of this and try it out, @heliumstar? I am interested to know if I can use the Tak Extender CQ x1.7 with the Tak FC 76 DCU and a Lunt Herschel wedge...

[heliumstar]

7 minutes ago, JeremyS said:

Did you ever get to the bottom of this and try it out, @heliumstar? I am interested to know if I can use the Tak Extender CQ x1.7 with the Tak FC 76 DCU and a Lunt Herschel wedge...

I used it in FS-60Q configuration without any issues 👍 The longest I used it pointing straight to the Sun was 1.5hrs during Mercury transit last year.

I would assume the same for 76 since the configuration is identical. Extender is quite down the tube.

[JeremyS]

12 minutes ago, heliumstar said:

I used it in FS-60Q configuration without any issues 👍 The longest I used it pointing straight to the Sun was 1.5hrs during Mercury transit last year.

I would assume the same for 76 since the configuration is identical. Extender is quite down the tube.

Brill: thanks  👍 

[andrew s]

40 minutes ago, JeremyS said:

Brill: thanks  👍 

If it were me I would use it with a full aperture  UV IR cut filter.

Regards Andrew 

[JeremyS]

7 minutes ago, andrew s said:

If it were me I would use it with a full aperture  UV IR cut filter.

Regards Andrew 

Any particular reason, Andrew? 

[andrew s]

20 minutes ago, JeremyS said:

Any particular reason, Andrew? 

Safety,  and to keep out wavelength you can't see reducing heating. It's common to do this on h alpha solar scopes.

Regards Andrew 

[andrew s]

38 minutes ago, JeremyS said:

Any particular reason, Andrew? 

Just a thought. If you use it with a manual mount don't leave it pointing at the Sun and go away.  The Sun will quickly go off axis and melt all the plastic inside your Takahashi! 

Seriously I nearly set my observatory  on fire with a 16" mirror which was nowhere near pointing at the Sun. It could vaporise the black coating etc.

Regards Andrew 

Edited July 5, 2020 by andrew s