TV Powermates For DSLR Planetary Imaging

[Startrek]

Has anyone had any experience using Televue Powermates, in particular the 2.5x and 4x for DSLR planetary and Lunar imaging

I am currently using a Canon 600D , 150mm F6 reflector on a HEQ5 mount and a 2" 2 x Barlow for Jupiter, Saturn and the Moon in average seeing conditions in Sydney night skies ( I also observe from a good dark site down the south coast at my holiday house but I use Sydney as a test base for any new equipment due to the poorer seeing conditions )

Reports from various other forums say that the Powermates have an advantage over Barlows for imaging

My 2" 2 x Barlow works extremely well for Lunar and Planetary visual observation and Lunar imaging, however not so good with Planetary imaging

I welcome any advice and comments in regard to using Powermates for Planetary imaging

Thanks in advance

[Merlin66]

I use TV powermates for solar imaging and spectroscopy.

They, as you probably know, have excellent optics and can be used at different back focus with minimal change to the amplification.

I use the 1.25" x2.5 with the T thread adaptor to give f18.75 on the ED80 for close up solar images, and the 2" x4 sometimes on the Genesis f5 to push it to f20.

(Rule of thumb - the imaging focal ratio should be around x4 or x5 the pixel size (in micron) This means with a 5 micron camera using around f20 to f25.

Hope that helps.

[Startrek]

Thanks for the reply Ken and expert comments

I read an interesting article just a short time ago from Jerry Lodriguss on planetary imaging with a DSLR

He suggests to use the following formula for estimating the ( general rule of thumb ) focal length for detailed planetary imaging

FL = 8/ (P/S)

where P=image scale per pixel in arc sec ( use 1/3 arc sec or 0.33 )
S=size of pixel in microns

My Canon 600D is 4.3 micron

FL= 8/(0.33/4.3)
FL =104 inches or 2700mm

My scope has a FL = 900mm

2700/900 = 3 x mag required ( therefore F18 )

So therefore a 2.5x Powermate or 4x Powermate with my DSLR should provide good planetary detail

Of course atmospheric seeing conditions and location of planet ( > 50deg Alt ) are huge factors as well

Whats your thoughts on the above method and calcs ??

[Merlin66]

I think Jerry has more experience than me....
I'd certainly take his recommendations on board.

[astro744]

Don't forget the T-Ring adapters to get the design amplification factor.

See http://www.televue.com/engine/TV3b_page.asp?id=123&Tab=_con and

http://www.televue.com/engine/TV3b_page.asp?id=123&Tab=_app and

http://www.televue.com/engine/TV3b_page.asp?id=123&Tab=_acc

The top eyepiece housing unscrews and the T-Ring adaptor replaces it. One available for 2" 2x, one for 2" 4x and one that does both 1.25" 2.5x and 1.25" 5x.

[Startrek]

Thanks for the heads up Astro744

Yeh I checked uncle Al's website on Powermates and he shows you the set up of a 2.5x and 4x with T ring adapters etc..

Makes life easier when an Astro accessory is designed ready to fit to your scope or camera

Welcome any other comments/advice from DSLR / Powermate astrophotographers

[Merlin66]

For solar with the ASI 174 I also need to add a T2 tilter between the PM and the camera.....