Image By Request

Ive posted one of my images (Jupiter), taken earlier on this year at the request IceinSpace members and readers of Australian Sky and Telescope.
Image taken with a 205mm F5 Newtonian with EPP at an effective F/32.
Enjoy.

[asimov (John)]

Nice image.

[matt]

Bert

Great pic. I'm new to imaging. Can you explain how you achieve F/32?

I keep seeing people refering to the effective f number of their scope for a pic, but don't know how they achieve it or calculate it?

I'm keen to hear from you since I'm working with exactly the same aperture and f ratio.

Thanks mate.

[davidpretorius]

welcome bert.

nice intro, you are more than welcome here. That is really great imaging!!!

Come on Saturn!!!

[davidpretorius]

hi matt,

you have a 200mm aperture (8") f5, so i would calculate your focal length to be 1000mm ie 200 x 5

if you start using a 2x barlow, that now is 2000mm or the ratio that was f5 (1000/200) is now (2000/200) = f10

a 5x powermate would give you 5000mm focal length of ratio of f25.

hope this helps

Originally Posted by matt

Bert

Great pic. I'm new to imaging. Can you explain how you achieve F/32?

I keep seeing people refering to the effective f number of their scope for a pic, but don't know how they achieve it or calculate it?

I'm keen to hear from you since I'm working with exactly the same aperture and f ratio.

Thanks mate.

[matt]

cheers Dave...

The learning never ends. I love it!!!!

Matt

[rumples riot]

Matt, if you have an f8 scope and put a 2x barlow in you will have and effective ratio of f16, or with a 5x f40. The Barlow does the multiplying to your scopes focal length.

Bert nice shot, and welcome to the Mad house.

[acropolite (Phil)]

Welcome Bert, nice shot...

[matt]

Thanks rumples.

So how did Bert achieve f32 out of an f5 scope, which is the same as mine??

[davidpretorius]

it could be a combo of barlows,ie 2 x and 2.4x etc.

i am not sure where the 50mm of a say a camera at prime focus comes into the calcs.

also coma correctors like the televue parracor, have aprox 1.16 x adjustment as well.

so they may be a few ways to end up at f32 mathematically.

[ving (David)]

32 divied by 5 will give the barlow you require matt.

great shot of joop there!