Is a diagonal necessary for solar imaging?

[CharlesS]

I am not clear on this point. Please let me know.

Thanks,

-Charles

 

 

[vlaiv]

No. In general, diagonals are redundant for any type of imaging.

There is however one special case and special type of "diagonal" that you might have seen for solar imaging.

This is not regular diagonal, although it looks just like diagonal. It is Hershel wedge - which is acting like a solar filter (it must be combined with other filters) and is used on refractor telescopes.

this image shows such a setup for imaging.

This piece of kit is used for white light solar imaging.

Another place where you are likely to see diagonal used for solar imaging is with Ha scopes. This is not because the diagonal is needed - but because Ha scopes have special filter (again it's about filters with Solar) - that is placed in diagonal for convenience. It is there mainly for visual - and there are straight through filters that can be purchased for imaging, but most people use their Ha scopes for visual and don't want to pay for additional piece just for imaging - and then image with diagonal.

Here is image of such setup:

Diagonal here is true diagonal - but with addition of blocking filter (you must use one with Solar Ha scope). There is version of blocking that is straight through, that is suitable for imaging

Here it is Lunt B3400 - but it's very expensive and only dedicated Solar Ha imagers usually get one.

[RT65CB-SWL]

Hi @CharlesS and welcome to SGL. 

Question: What 'scope are you using?

During August 1999, I was fortunate to go to Bulgaria for the solar eclipse.

The 'scope I used was my TeleVue Ranger plus a full aperture glass solar filter. To achieve focus on terrestrial and celestial targets it requires the use of a star diagonal. To cut a long story short, I did not use a star diagonal and attached my eyepiece projection unit [aka EPU] and placed a TeleVue 8mm Plossl e/p inside and a Pentax ME Super 35mm SLR directly to the drawtube. It was a bit uncomfortable looking up and crouching and kneeling on Bulgarian ground/soil, but I did get some photo's.

<--- the EPU is shown in the centre.<--- my TeleVue Ranger [1].<--- my TeleVue Ranger [2].

For solar viewing now [imaging with an iPhone] I use a Lunt Herschel/solar wedge and at the time of posting, I have not tried any solar imaging with a 35mm camera as I have gone digital compact camera and/or DSLR.

image above of my TeleVue Ranger and Lunt Herschel solar wedge.  

Edited April 13, 2023 by Philip R

[Cornelius Varley]

21 hours ago, vlaiv said:

This is not regular diagonal, although it looks just like diagonal. It is Hershel wedge - which is acting like a solar filter (it must be combined with other filters) and is used on refractor telescopes.

And can only be used with refractors and then only certain types of refractor (not refractors with plastic components or Petzval refractors). Herschel wedges cannot be used either with reflectors or cassegrain type telescopes ie SCT or MCT types.