DSLR to Telescope - Prime vs Afocal? etc...

[cwalrus]

Help me stop spending money!  My father in law donated his Celestron NexStar 8i to my family, and I've gone nuts spending money on gear, without researching it first... 

I just want to connect my Nikon DSLR 5100 to the telescope, to take pictures and be able to see better...
 
First I bought the t-ring for my my Nikon, and the Universal T-adapter. This works, but the objects in the view are TINY. 
 
So I read about a Nikon DSLR - Deluxe Telescope Camera Adapter Kit which costs $90 on ebay, and then I realized that my 8 -24 zoom eyepiece won't fit into it... so I bought an 8MM fixed lens. 

But then I read about afocal photography, and it seems that i could simply buy this: Celestron Universal Digiscoping Adapter 

and return everything else! 

On the other hand, I realize that the less Rubbish in between your camera and the telescope mirror the better, so is it possible I just need to get the camera closer (or farther) from the mirros, buy extending the Universal T-Adapter? 

and then to confuse things further I came across this:Celestron Deluxe Tele-Extender on B and H photo. 

-cameron

[MarsG76]

I experimented with various methods of taking pictures with a similar scope to yours.. the NexStar 8SE.

I found that prime focus, raw F10 or through a f6.3 focal reducer is the best quality when it comes to using your DSLR for astrophotography. Generally I image using a OAG, Filterwheel and a DSLR, and depending on the size of the object I image, I might add a f6.3 FR before all of that.. I have no problem in attaining focus, but with the reducer it is quite close to one mirror position focus limit.

When you say that everything is small, are you talking about imaging planets? If you are then the DSLR is not the best for it, you would have to crop it down to 640x480, and for best results you need a minute or two of UNCOMPRESSED video. DSLRs have big sensors, hence small planet discs on the frame and the ones that record video generally compress in mpeg4 format, losing a lot of detail. This is why web cams or dedicated planetary CCDs will run ring around a DSLR in planetary imaging quality. Here to magnify you should only use a barlow before the sensor, no eyepiece projection which I found to be a lot softer than just a bare barlow, so don't worry about the deluxe tele-extender. ( have one and never use it)

If imaging nebulae then they size of most of them will be quite sizeable in the frame.

The other thing to think about is the alt-az mount for photography. It will have field rotation and you will be limited to 60-90 second subs before the rotation becomes visible, of course that too is depending on what you're imaging and where it is in the sky.

So to summarize the gear you need to get started is a T-Ring for your Nikon, a T-adapter and a f6.3 focal reducer, this will enable you to start to do basic DSO images.. use a program to de-rotate the subs when stacking, like Nebulosity (not sure is DeepSky Stacker de-rotates I'd think it would, never used it, but its free.)

For Planetary imaging, get a web cam or planetary CCD, like NexImage, Imaging Source DBK/DMK 21au618 or Skyris cams and a 2X or 3X barlow (celectron ultima 2X barlow or TeleVue 3X Barlows are great and sharp). Stack your captures in Registax.

[baggywrinkle]

Warning! The universal adapter for digiscoping will not work. It is designed for compact cameras not DSLR's. The max mounting distance between the 1/4'' thread and the plate it sits on an the EP of the scope is too small. Only about 50-60mm.

The focal reducer and T adapter will be OK, but as said above planet images will be small. The Moon and Sun will be better.

The alternative to to use a T ring adapter to mount the camera onto an EP. I use a Baader Zoom, some Celestron EP's have a suitable thread under the rubber protector. This would be better for Lunar shots but the planets will still be small.

The 8SE is a very good OTA. I had a 6SE and nout have the 9.25 SCT. The 6SE was sold to fund the bigger beasty.

[jambouk]

Prime focus.

[Tinker1947]

Just be aware your never get the Hubble Space telescope imagines, Prime Focus is the way to go, as this appears to be you first scope you have a lot to learn, buy a book and read it then read it again....this book is highly recommended....

http://www.firstlightoptics.com/books/making-every-photon-count-steve-richards.html

[jambouk]

This is a great book:

https://www.amazon.co.uk/gp/aw/d/0521700817/ref=mp_s_a_1_2?qid=1439226108&sr=8-2π=AC_SY200_QL40&keywords=dslr+astrophotography&dpPl=1&dpID=41ZEVrnfPNL&ref=plSrch

A new book by Mark Thompson is also not bad:

https://www.amazon.co.uk/gp/aw/d/1849073147/ref=mp_s_a_1_1?qid=1439226172&sr=8-1π=AC_SY200_QL40&keywords=mark+thompson+astronomy&dpPl=1&dpID=51tVDK0j1xL&ref=plSrch

James

[cwalrus]

Thanks everyone- let me digest this...

[cwalrus]

Ok so i've read this carefully now - one thing I've realized is there are a bunch of acronyms I'm going to have to figure out.   I'm going to start googling like mad.

thanks for help peeps

I experimented with various methods of taking pictures with a similar scope to yours.. the NexStar 8SE.

I found that prime focus, raw F10 or through a f6.3 focal reducer is the best quality when it comes to using your DSLR for astrophotography. Generally I image using a OAG, Filterwheel and a DSLR, and depending on the size of the object I image, I might add a f6.3 FR before all of that.. I have no problem in attaining focus, but with the reducer it is quite close to one mirror position focus limit.

When you say that everything is small, are you talking about imaging planets? If you are then the DSLR is not the best for it, you would have to crop it down to 640x480, and for best results you need a minute or two of UNCOMPRESSED video. DSLRs have big sensors, hence small planet discs on the frame and the ones that record video generally compress in mpeg4 format, losing a lot of detail. This is why web cams or dedicated planetary CCDs will run ring around a DSLR in planetary imaging quality. Here to magnify you should only use a barlow before the sensor, no eyepiece projection which I found to be a lot softer than just a bare barlow, so don't worry about the deluxe tele-extender. ( have one and never use it)

If imaging nebulae then they size of most of them will be quite sizeable in the frame.

The other thing to think about is the alt-az mount for photography. It will have field rotation and you will be limited to 60-90 second subs before the rotation becomes visible, of course that too is depending on what you're imaging and where it is in the sky.

So to summarize the gear you need to get started is a T-Ring for your Nikon, a T-adapter and a f6.3 focal reducer, this will enable you to start to do basic DSO images.. use a program to de-rotate the subs when stacking, like Nebulosity (not sure is DeepSky Stacker de-rotates I'd think it would, never used it, but its free.)

For Planetary imaging, get a web cam or planetary CCD, like NexImage, Imaging Source DBK/DMK 21au618 or Skyris cams and a 2X or 3X barlow (celectron ultima 2X barlow or TeleVue 3X Barlows are great and sharp). Stack your captures in Registax.

[MarsG76]

Ok so i've read this carefully now - one thing I've realized is there are a bunch of acronyms I'm going to have to figure out.   I'm going to start googling like mad.

thanks for help peeps

Sorry, second nature... The acronyms I used are:

OAG: Off Axis Guider

DSLR: Digital Single Lens Reflex

CCD: Charged Coupled Device (camera sensor)

CMOS: Complex Metal Oxide Semiconductor (camera sensor)

FR: Focal Reducer

DMK/DBK: Digital Mono/Bayer (color) Kamera (models in German Imaging Source CCD cameras)

T ring/adapter: Telescope adapter and bayonet for attaching DSLR to telescope.

Alt-Az: Altitude & Azumuth mount/direction

MPEG4: High compression lossy method for video - Motion Picture Experts Group version 4

SE: as in 8SE... Second edition...

:-D

There are a lot more...