help with magnification .

[hemihaggis]

hi folks , i have been dabbleing with photography , but how do i get mag on subjects such as the ring nebula , i can resolve it really well with my scope using my 26 mm and my 10mm ep , but if i was to attatch my dslr to scope and take pics the ring nebula is a tiny dot ? i have seen several images on here where the ring neb fills the pic .. help

do i just crop ?

[pvaz]

You can use barlow lenses. A 2x will double the image size. You can find them up to 5x, maybe more.

Another (expensive) alternative is to have a few scopes with different focal lengths for different magnifications.

[Shibby]

Hi,

M57 is a very small planetary nebula, so you won't see too many close-ups of it. A DSLR has a large sensor, meaning that the light from the nebula will only take up a small space in the centre of your image. The images with best scale will be taken through long focal length telescopes using CCDs with small sensors (and pixels). Magnifying is not easy, you could use a barlow to increase focal length but this will result in a higher focal ratio ("speed") meaning you would need use longer exposures.

In short, yes, I would just crop! You could also try using drizzle in DeepSkyStacker.

[steppenwolf]

This is all down to focal length, the longer the focal length, the larger the image in the field of view. The Ring Nebula is a tiny object roughly 1' X 1.4' in size. Although with a telescope and an eyepiece you can calculate the actual magnification by dividing the focal length of the telescope by the focal length of the eyepiece (for your SN10 the magnification with your 10mm EP would be 1016/10 = 101.6 times and with your 25mm EP it would be 1016/25 = 40.6 times), with a camera, magnification is a little meaningless as it depends on how you display the final image. For example, you could display it on the camera's built in LCD screen or print it out to poster size!!

To put this into some kind of context, if you attach a 50mm lens to a normal DSLR camera and look through the camera's viewfinder, you see a pretty much life-like view so the camera and lens are giving a 1 times magnification. If the lens if 50mm then visually, the camera must be acting as a 50mm eyepiece to achieve a magnification of 1 times. So, if you were to look at the Ring Nebula though your camera's viewfinder whilst it is attached to your SN10, it would be acting as a 50mm EP so the magnification through the camera/telescope combination would visually be 1016/50 = 20.32 times. In other words, not a great amount of magnification.

This is why the image looks pretty small in your images but cropping and displaying on your computer screen will go some way to getting a larger image.

[LukeSkywatcher]

The ring nebula is tiny in many scopes. I would also say use a barlow lens and then you can always still crop the image afterward.

[Shibby]

Here is the documentation on drizzle. This *can* get you higher resolution.

DeepSkyStacker - Technical Info

[hemihaggis]

cheers for that guys , i kinda figured as much but was just checking i had not missed somthing silly , anyway heres to clear skies and a few pics soon

[king-jaffethehutt]

Hi Guys,

on the topic of photography, I have been trying to use my digital camera (canon Sx200) A-focally but I am finding it almost impossible to get a image lined up.

My scope is a Skymax 127mm and trying to steady the images has been nearly

impossible.

I used to have an ETX 90 and used to use an old Nikon 5200 and got some great hand held results!

Also my scope seems to have got some ghosting under the rear mirror (only noticeable at certain angles)

only started after the last few nights viewing is this normal? it's as if dew has stained the mirror?

Any suggestions or advice would be greatly appreciated.

Cheers Scott