Jump to content

740427863_Terminatorchallenge.jpg.2f4cb93182b2ce715fac5aa75b0503c8.jpg

Monocular binocular, seriously!


ollypenrice
 Share

Recommended Posts

Okay, this arises from the 'Binoculars and the eye' thread and why doubling aperture in binos doesn't increase perceived brightness.

Here's the idea; Take two identical refractors and combine their light into a single beam directed onto the chip. Double the light grasp so come down one full f-stop equivalent. You pay for two objectives and the mirrors but could have just one focusser and one ff/fr lens at the back.

Better still, take two Petzval doublet objectives, combine their beams and send them through a single Petzval rear doublet and out through a single focusser. Yo!! Result! The f3 refractor is born.

Something to remember; you cannot at any fixed point in technological develpment make a refractor faster than 'x' for a given level of colour correction at a given aperture. So for imaging purposes you cannot increase the aperture for a given focal length. The TOT (Twin Objective Telescope!!) is the only way to get faster.

Marketing would be a dream for Takahashi; after the Baby Q they could produce a twin objective version called - of course - the Tiny TOT... icon10.gif

At the moment I'm working on a primitive equivalent of this wonderful new way of spending even more money; I am setting up our WO ZS66 to shoot Ha into the mono camera while our Baby Q collects colour in the OSC version. Two Baby Qs would be nice but ho-hum. The idea is to make large HaRGB mosaics far more viable in terms of time. I have this little 72 hour project in mind that could be knocked off in a trifling 36 with the double barrel device.

Olly

Link to comment
Share on other sites

Olly, I think the issue here is that in order to combine the signals the alignment has to be perfect & maintained to an accuracy of 1/4 wave or better ... the gubbins to do this (mirrors & precision mechanics) would use up the space between fast objectives and the focal plane as well as adding hugely to the complexity & therefore cost.

I have a different idea ... much simpler ... take a load of identical imaging scopes, pointed in the same direction & on the same mount (so only one guider needed) & sum the outputs from the sensors. This could be done in software, no need to do anything at exposure time. An array of 16 f/4 scopes effectively acts as f/1 ... but with 16 times the saturation well depth ...

Link to comment
Share on other sites

An array of 16 f/4 scopes effectively acts as f/1

Just as well the EQ7 is coming out :)

I was thinking the same as Brian, would this not be really really hard to line up right

In binos, your eyes do all the hard work, but for this you would need amazing accuracy to pull it off

I wonder if there are any scope and CCD combos that would give you effectively the same FOV so you could use a big CCD for high detail luminance and a smaller chip for the colour detail

Even then then would have to have really similar flat fields, two astrographs perhaps?

Edited by Euan
Link to comment
Share on other sites

Even then then would have to have really similar flat fields

Not really, if you're doing the combination in software you can correct distortions / changes of scale etc. ... if you're doing optical combination then the objectives would have to be identical in all respects, that's why optical interferometry has generally used flat mirrors cobining small aperture beams onto a single large objective rather than seperate objectives. When you get to radio wavelengths the engineering becomes easy enough to use seperate objectives, but you still need to control the signal timing very very accurately.

Link to comment
Share on other sites

Hi Olly

Sounds like an interesting idea but if your after a short focus fast refractor for your project why stop at F3, Canon make a very nice 107mm F2.8 with built in camera mount and even has auto focus..... just wish I could afford one :icon_salut:

Mel

"Here's the idea; Take two identical refractors and combine their light into a single beam directed onto the chip. Double the light grasp so come down one full f-stop equivalent. You pay for two objectives and the mirrors but could have just one focusser and one ff/fr lens at the back.

Better still, take two Petzval doublet objectives, combine their beams and send them through a single Petzval rear doublet and out through a single focusser. Yo!! Result! The f3 refractor is born."

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.