Solar Imaging

Full Disk

I take full disk images using my LS60MT double stacked with the LS50C. To connect the LS50C front mounted etalon to my LS60MT I use a 3D printed adapter.

Instead of the Lunt B600 that came with the Lunt LS60MT I use a Coronado BF10. Originally I bought the BF10 for it's bigger size, but it turns out that it also blocks less of the Halpha wavelength making it brighter than my Lunt B600. This might not be true for every BF10!

For a camera I use the ZWO ASI 462MM, which gives good enough sampling when used with an F8.4 scope. F10 would be better according to wilmslowastro planetary Sampling calculator.

The camera chip is not big enough to capture the solar disk all at once, I usually combine two images to get a full disk image.

Image train parts from right to left

1. Lunt LS50C
2. LS50C to LS60MT Adapter.
3. Lunt LS60MT
4. Adapter from 2'' to 1.25''
5. Coronado BF10
6. ZWO ASI 432MM

Closeup

The base of my closeup imaging setup is a Bresser Messier AR150L-1200 that I shortened to get the Lunt LS60MT etalon in in the correct position for it's collimating lens. You can take a look at Marty's thread on solarchatforum for information on how to do this. In contrast to Marty's setup mine uses a 3D printed adapter. If you want to do something like this MEASURE THE BACK FOCUS YOURSELF like Marty says in his post. Cutting the scope to short is not fun! (PS. I didn't do that, but I had to cut it 3 times because I didn't take off enough at first)

It's important that you use an Energy Rejection Filter like the Baader D-ERF or Antlia Solar Discover with apertures of this size to protect the rest of the optics from overheating. This could lead to damage to your etalons and more importantly your eyes. You might be able to use a smaller D-ERF inside the optical path, but this comes with some compromises.

! DO NOT TRY THIS MOD IF YOU ARE NOT 100% SURE THAT YOU KNOW WHAT YOU ARE DOING !

! I DON'T GRANTEE THAT ANY OF THIS WORKS OR IS SAFE !

! I Hope this is clear enough !

I use a Baader D-ERF 160mm but it might be better to use one of those tri-band ERFs if you ever want to take CaK images.

The image below shows the way I have set up my Bresser Messier AR150L-1200 using an adapter for connecting the LS60MT etalon housing and the Baader D-ERF with it's holding cell up front. Depending on if I'm only imaging prominences and the solar surface on their own or if I'm imaging "over" the solar limb to get surface details in combination with prominences I connect different optical trains to the scope.

Double Stack

When imaging "over" the solar limb the optical train I use consists of two etalons. The LS60MT etalon is in a collimated light beam by default and only requires the correct back focus. My LS50C on the other hand is designed to go on the front of a scope where it normally sees almost perfectly parallel light rays from the sun. To get the LS50C working at the back of the telescope I use a Baader Sundancer TZ-4S telecentric lens.

As christian viladrich shows on his website, the FWHM of an air spaced etalon in a telecentric system depends on the F ratio of that system. My scope is 1200mm/150 = F8 with the TZ-4S it comes out to F32 which might not be enough in a single stack but in a double stack helps suppress the photosphere leading better contrast especially when imaging at the solar limb.

I decided to change my BF10 from diagonal to straight using an adapter you can find on the 3D-Models page. And to be a bit saver I use an IR/UV cut filter on KG3 glass to block the high wavelength IR.

The following images and lists show my double stacked closeup optical trains which can be connected to the Bresser Messier AR150L/1200 using the adapter I mentioned before. I use multiple configurations because I'm still figuring out which one gives me the least reflections and the best final image.

LS50C without housing

Image train parts from right to left

1. LS60MT Etalon Housing
2. 2'' extension
3. 3D printed 2'' extension 80mm
4. Coronado BF10 converted to straight using a 3D printed adapter
5. Baader Sundancer TZ-4S
6. Adapter from LS50C without its red housing to T2 thread
7. LS50C without its red housing
8. Adapter from LS50C back thread to T2
9. 3D printed T2 extension
10. ZWO ASI 432MM

LS50C tiltable using 3D printed extension

Image train parts from right to left

1. LS60MT Etalon Housing
2. 2'' extension
3. 3D printed 2'' extension 80mm
4. Coronado BF10 converted to straight using a 3D printed adapter
5. Baader Sundancer TZ-4S
6. LS50C housing side telescope side
7. LS50C
8. LS50C housing camera side
9. Adapter from LS50C back thread to T2
10. 3D printed camera tilter
11. ZWO ASI 432MM

LS50C tiltable using 2'' to 1.25'' adapter

This setup has some flexure problems but still works okisch. I used this before i designed the 2'' extension.

Image train parts from right to left

1. LS60MT Etalon Housing
2. 2'' extension
3. 2'' to 1.25'' adapter
4. Coronado BF10 converted to straight using a 3D printed adapter
5. Baader Sundancer TZ-4S
6. LS50C housing side telescope side
7. LS50C
8. LS50C housing camera side
9. Adapter from LS50C back thread to T2
10. 3D printed camera tilter
11. ZWO ASI 432MM

Single Stack

My single stack setups don't suffer from reflections and are more easy to use.

ZWO ASI 462MM

The 2x Teleextender is used to get better sampling and to "zoom in" enough to get within the sweet-spot of the LS60MT etalon.

Image train parts from right to left

1. LS60MT Etalon Housing
2. 2'' to 1.25'' adapter
3. Coronado BF10
4. Lacerta 2x Teleextender 1.25''
5. ZWO ASI 462MM

ZWO ASI 432MM

Here the 4x Baader Sundancer TZ-4S is used to get within the sweet-spot and sample "correctly" using the ZWO ASI 432MM

Image train parts from right to left

1. LS60MT Etalon Housing
2. 2'' extension
3. 2'' to 1.25'' adapter
4. Coronado BF10 converted to straight using a 3D printed adapter
5. Baader Sundancer TZ-4S
6. 3D printed T2 extension
7. ZWO ASI 432MM