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brsseb

How to photograph what I actually see through the various eye pieces

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Im just getting started with astronomy. Been doing some simple observations of the moon and Jupiter with my Celestron AstroMaster 114EQ with various oculars. Ive also got a Barlow and a T-ring, and have attached my DSLR (Nikon D5300 DX) to it and taken som simple shots. My (silly) question is: how can I take photographs using the same maginfication levels that I am seeing through the various eye pieces? I got a 2x Barlow, which only allows me to take shots in either 2x magnification, or 1x (when I screw the end bit off the Barlow). But how can I take photos of what I am seeing when I use the various eye pieces that I got , like my 16mm, (which allows for way more detailed closeups of, say the craters on the moon, than my 2x Barlow does). 

Ive attached two photos taken with my Barlow, one with the 2x magnification and one without it.  

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Simplest and cheapest way (free) is to get your camera phone out. If you have a half decent camera on your phone simply position the lens of that over your eyepiece (it can take a bit of playing to get right, especially in the dark). I have taken some really good pictures using my smartphone.

This pic was taken with my smartphone through the eyepiece. its nothing special but gives you an idea of what you can expect:

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Edited by Colsey
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On ‎16‎/‎03‎/‎2016 at 22:11, brsseb said:

how can I take photographs using the same maginfication levels that I am seeing through the various eye pieces?

A common misconception is that a telescope magnifies images. In truth it is a light gathering device that concentrates light and projects an image circle at the other end of the tube.

Without getting into too much detail, the size and characteristics of that image circle are determined by the focal length and the aperture of the telescope.

In visual observation, magnification itself is a product of the eyepiece you fit on the telescope. Conversely, in imaging, the characteristics of the light recording device (cmos or ccd) determine the perceived level of magnification of the resulting images (field of view). Fundamental factors are the size of the pixels on the chip and the number of them (resolution).

Many people on this forum will be able to give you a much more robust version of the theory behind this. But, as we know, images are worth a 1000 words :) so if you go to http://astronomy.tools/calculators/field_of_view/ you can use the FOV calculator in both Visual and Imaging mode to see what sort of combination of scope/sensor you need to get images having a FOV the same of your eyepieces. Don't be swayed into thinking you can just add some barlow lenses before the imaging chip. These devices significantly degrade the quality of the imaging circle and can be suitable only for certain targets (planetary imaging is one of them). 

Without discouraging you it all gets downhill from there :)  because other factors will influence the ancillary equipment you need (not to mention atmospherical transparency and light pollution) to achieve the most demanding results.

As mentioned in the previous post, you can take a shortcut trying 'Afocal Astrophotography' which essentially is aiming a camera at the eyepiece and try to frame what it shows. In this way the camera itself plays the role of your eye.

I hope this helps!

G.

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+1 for camera phone photography through the eyepiece... With a bit of practice and maybe an app that lets you manually focus/expose you can get some decent results... Some of my best below:

(and photoshop express is a great app to process and get the best out of your phone pics)

 

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Edited by CraigT82
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Those are some really nice pics Craig! I feel embarrassed by mine as a camera phone example :embarrassed: I am letting the side down!

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Thats some awesome shots you got there. Thats what I am looking for. I have already ordered a used eye piece adapter online, but I will try to get some photos with my iPhone 6S also, and compare the results that I get. I have a feeling the iPhone 6S is gonna do the job nicely.  

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9 hours ago, Colsey said:

Those are some really nice pics Craig! I feel embarrassed by mine as a camera phone example :embarrassed: I am letting the side down!

Not at all!! Your pic is a good shot of the full moon which I find really difficult to photograph nicely... I only really bother taking pics of stuff along the terminator as it looks much nicer with all the shadows :thumbsup:

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9 hours ago, brsseb said:

Thats some awesome shots you got there. Thats what I am looking for. I have already ordered a used eye piece adapter online, but I will try to get some photos with my iPhone 6S also, and compare the results that I get. I have a feeling the iPhone 6S is gonna do the job nicely.  

Yeah give it a go, I bet the camera in the 6 will take some great looking shots. I downloaded an app called 'manual' which lets me control the camera settings, but to be honest I find that the standard camera app does a good job with much less faffing about (turn your flash off or we'll get some really nice pics of your eyepiece!).

I just hold the phone with both hands about 3 inches away from the eyelens so I can see the exit pupil (which will be a white dot in the centre of the eyelens) then slowly move the phone closer whilst keeping the white dot in the centre. Then when I've got the image on the screen i just gently tap the shoot button as many times as I can until I inevitably move too much and lose the view. Chances are one on the shots will be nice :)

I've never used an adaptor for the phone, I think it might get annoying to keep having to move it out the way to look through the EP.

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We don't use the term 'magnification' in imaging because there is no standard image size to multiply by up by 10x or 100x etc. In visual observing the starting point which is multiplied up is the apparent size naked eye.

What we talk about is image scale, so a certain size on the sky (normally measured in arcseconds) is transformed into a certain size of projected image on the chip (normally measure in mm.) The professionals call this Plate Scale.

This is controlled by one single factor, the focal length of the optical system. The scope has a focal length. This can be turned into a longer effective focal length by adding Barlows, Powermates or eyepieces which will put fewer arcseconds of object onto more mm of image on the chip. This is what you're after.

Some people get hold of the idea that a smaller chip, which only just lets the object fit, somehow gives you a more 'zoomed in' image. It doesn't. It just crops the edges from what you'd get on a larger chip.

The longer the effective focal length the better everything has to be - the visual stability of the air ('the seeing'), the focus, the stability of the mount, etc. In other words longer focal lengths make it harder.

Olly

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Hi , I am surprised that nobody has mentioned buying a ZOOM eye piece. I have invested in a hyperzoom . It is an amazing piece of kit. It will zoom from 24 /20 /16/12/8 . you can buy masses of bits to fit it and play around. I have a ring that you fit after you have unscrewed the eye relief and that then allows me to screw it to my cannon camera. This in turn means that I can photo what the eye piece is seeing. With another small attachment I can fit my small guide camera to it to image planets. I enclose a few images of the item and in my setup in which you can use it with a diagonal or straight in the back. It has a 2" or 1.25 fitting. Jay

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