Multiple aperture off axis mask with white light film on dob
Posted: Thu Jan 03, 2019 5:35 am
Hello and happy 2019!
I have purchased a Sumerian Alkaid 12" f/5 dob for a travel visual scope. For those not familiar, it packs down to a suitcase that is smaller than carry on dimensions.
The plan is to use this scope for night viewing, yes, but also have a white light filter for solar viewing.
I know the limiter is seeing when considering aperture for solar viewing. And I know that more aperture supports better resolution and higher magnification. So it's a balance to be struck. I would think that ideally, to have a means to increase or decrease aperture based on current seeing seems like a way to go.
The apertures allow sunlight through a white light filter, and film is my choice for this plan... Baader film.
Online, but not in person to gauge viability, I have seen off axis aperture masks with multiple apertures. I have seen the approach of three different sizes, where one uses one of the openings in the mask according to seeing and the other openings are covered. I have seen others where you have six openings and none are covered up.
My idea is to have an off axis aperture mask with four equally spaced holes (each hole the same size of either 70mm or 80mm) circling the spider vane center, and each opening placed between spider vanes. I would have four flags that could cover up any number of the openings to allow more or less light in, depending on the seeing. All flags covering all holes during transport, thus protecting the film. The hole size of around 70 or 80mm in diameter allows room for the unused flags to reside between holes.
So, in effect, I would have one, two, three or four openings. So, the aperture opening area of the 70 or 80mm hole x 1, 2, 3 or 4.
Is this a viable idea here? It would be homemade and I already put the design together using CAD. Is the transmission of sunlight through a variably set number of four same-size openings on an off axis mask a viable analogue for a set of four off-axis masks with a single opening whose aperture sizes vary from mask to mask?
As this is a travel scope for air travel, the goal is to figure how versatile this scope can be for visual use.
Any and all insight or input is appreciated and welcome!
Cheers, and sunny skies!
Bill
I have purchased a Sumerian Alkaid 12" f/5 dob for a travel visual scope. For those not familiar, it packs down to a suitcase that is smaller than carry on dimensions.
The plan is to use this scope for night viewing, yes, but also have a white light filter for solar viewing.
I know the limiter is seeing when considering aperture for solar viewing. And I know that more aperture supports better resolution and higher magnification. So it's a balance to be struck. I would think that ideally, to have a means to increase or decrease aperture based on current seeing seems like a way to go.
The apertures allow sunlight through a white light filter, and film is my choice for this plan... Baader film.
Online, but not in person to gauge viability, I have seen off axis aperture masks with multiple apertures. I have seen the approach of three different sizes, where one uses one of the openings in the mask according to seeing and the other openings are covered. I have seen others where you have six openings and none are covered up.
My idea is to have an off axis aperture mask with four equally spaced holes (each hole the same size of either 70mm or 80mm) circling the spider vane center, and each opening placed between spider vanes. I would have four flags that could cover up any number of the openings to allow more or less light in, depending on the seeing. All flags covering all holes during transport, thus protecting the film. The hole size of around 70 or 80mm in diameter allows room for the unused flags to reside between holes.
So, in effect, I would have one, two, three or four openings. So, the aperture opening area of the 70 or 80mm hole x 1, 2, 3 or 4.
Is this a viable idea here? It would be homemade and I already put the design together using CAD. Is the transmission of sunlight through a variably set number of four same-size openings on an off axis mask a viable analogue for a set of four off-axis masks with a single opening whose aperture sizes vary from mask to mask?
As this is a travel scope for air travel, the goal is to figure how versatile this scope can be for visual use.
Any and all insight or input is appreciated and welcome!
Cheers, and sunny skies!
Bill