How far with a DSLR

[Brian28]

Hi all . As you can see I'm new to this site and about as new to Astro photography.. I've only taken pics with my Nikon 810 and a 300 2.8 with a x2 converter  so 600 f5.6 ..   if I used a Nikon d2x with a crop sensor , I would get 900 @ 5.6 . 

Would I be able to get any images of nebulas with this set up ? .. I have brought a Canon 650 which I will be getting modified , I have an adapter to connect this to the Nikon lens . I can then connect this to Backyard Canon for a live view ..  but has anyone had any experience with this sort of set up ? .. 

thanks Brian ?

[ollypenrice]

Expunge this 'crop sensor' malarky from your brain and don't ever let it back in again. It is best in astronomy to deal in the correct and real values. You have a focal length, you have a chip size, you have a pixel size. These will allow you to model everything you need to model to find what field of view you'll have and at what resolution (meaning 'resolution' in the useful units of arcseconds per pixel.)

Many planetarium software packages will allow you to input focal length and chip size so as to get a virtual frame superimposed on a star map. I use SkyMap Pro, which isn't free, but I bet some kind soul appears in this thread and identifies a free one. There are endless targets for your chip size at 300mm without the converter. Many nebulae are huge and would need a mosaic even at that.

Using a smaller chip gives a smaller field of view and that is all. It does not 'get you closer,' it does not increase your focal length, it does not mimic a longer focal length because, for a given pixel size, it does not increase your resloution in (arcseconds per pixel). Looking down an empty cardboard tube reduces your field of view but it does not replicate a telescope view.

Olly

 

[Brian28]

Lol .. received and understood !  I had a mind melt , I should have known TBH .. 

yes it crops your FOV to the equivalent of a 900mm. IT's NOT 900mm ..  .

so now that's sorted out ..

 

would I actually see anything on the computer screen , or is it a matter of accurately pointing in the right place and focusing on something near ? .. 

And would you see anything through a dedicated scope ? 

 

 

 

[RayD]

54 minutes ago, ollypenrice said:

Looking down an empty cardboard tube reduces your field of view but it does not replicate a telescope view

WHAT??????  You mean my parents were lying to me for all those years!! ?

[kendg]

1 hour ago, ollypenrice said:

Many planetarium software packages will allow you to input focal length and chip size so as to get a virtual frame superimposed on a star map. I use SkyMap Pro, which isn't free, but I bet some kind soul appears in this thread and identifies a free one. There are endless targets for your chip size at 300mm without the converter. Many nebulae are huge and would need a mosaic even at that.

Olly

 

Stellarium will do exactly what Olly says.

[Stargazer33]

At the top of this page under the Resources tab you will find Astronomy Tools within this you have FOV calculator. Does exactly the same thing that Ollie is talking about but instantly for various selectable targets DSOs and Solar System objects.

[Stargazer33]

This would be your view of the Andromeda Galaxy: Nikon 810a @ 300mm

[Brian28]

Ok that's great thank you .. .. 

 

 

[happy-kat]

And given the true expanding width of Andromeda you could use a 200mm and still be ok.

[ollypenrice]

1 hour ago, happy-kat said:

And given the true expanding width of Andromeda you could use a 200mm and still be ok.

Yes, go deep enough and Andromeda will amaze you with its size.

Olly

[Alien 13]

7 minutes ago, ollypenrice said:

Yes, go deep enough and Andromeda will amaze you with its size.

Olly

Its certainly big, I wonder if the outer edges of the Andromeda galaxy and our own actually touch already..

Alan

[Alien 13]

2 hours ago, Stargazer33 said:

At the top of this page under the Resources tab you will find Astronomy Tools within this you have FOV calculator. Does exactly the same thing that Ollie is talking about but instantly for various selectable targets DSOs and Solar System objects.

I like this one best of all the FOV simulations because you can add most commercially available scopes, camera lenses and cameras available.

Alan

[Owmuchonomy]

21 minutes ago, Alien 13 said:

Its certainly big, I wonder if the outer edges of the Andromeda galaxy and our own actually touch already..

Alan

It has certainly been postulated by those in the know! Galactic haloes and all that.

[david_taurus83]

1 hour ago, Alien 13 said:

Its certainly big, I wonder if the outer edges of the Andromeda galaxy and our own actually touch already..

Alan

Interesting, I seen a documentary or read it, can't remember lol. But the point being made was that even though both galaxies are on a collision course that the chances of 2 stars actually colliding were very remote due to the actual distances between stars. The galaxies could effectively pass through each other and eventually form an elliptical galaxy. Even though we can see them in our own images I still think we can't comprehend the sheer scale of these things!