<p>The problem you have with many newtonian reflectors - especially smaller ones - is that to use them for prime focus photography (where you're effectively using the telescope like a big telephoto lens) , you need to set things up so that the camera sensor ends up at the focal plane of the telescope. And in a DSLR, the sensor is some way inside the camera body (behind the shutter, which is behind the mirror.</p>

<p>With a newtonian scope, the focal plane is usually somewhere inside the focuser tube, and many newts don't have enough focuser inwards travel to let you get the focal plane the 40mm or so beyond the end of the focuser that you need to get it to reach a DSLR sensor.</p>

<p>(With other types of scope that use a separate star diagonal, things are usually easier - you can leave the star diagonal off, which has the same effect as a big chunk of inward focus).</p>

<p>With a newtonian, if you can't reach prime focus, there are three basic options - either take photos through the eyepiece (afocal photography) as you already tried,</p>

<p>or move the main mirror further up the tube (which moves the focal plane further out, giving you more in focus). It also means the light cone is fatter when it reaches the secondary mirror, so you may lose some light as the outer part of the light cone misses the secondary.</p>

<p>or you can try using a barlow lens - that replaces the last bit of the light cone with a longer, narrower angle version (which increases the magnification and moves the focal plane further out). That MAY or MAY NOT let you reach infinity focus; it's not guarenteed, but may help. You can get barlows that have a T-Thread on the output end, so you can attach a T ring directly to the barlow (yours doesn't look like one of this type) and then hook the camera up that way. (as an added benefit, since you end up with a closed tube setup (the barlow lens closes off the access to the camera, it also keeps spiders and dust out of the camera :) ).</p>

<p>If you have a look at the bottom bit of the barlow (with the lens) you may find that you can unscrew it. You might be able to make a short top section with a T thread for the T ring at the back, and a suitable thread for the lens at the front; you'd probably need to make it the same diameter as the eyepiece barrel (to fit in the focuser) with a fatter bit at the back for the T thread and to stop it sliding all the way into the focuser.
I've used a commercial 1.25" barrel T threaded barlow (somewhat shorter than yours) for lunar and solar (WITH A SUITABLE FRONT OF SCOPE FILTER - DON'T TRY LOOKING AT THE SUN WITHOUT ONE) imaging with an APS sensor camera.</p>

<p>(You may need to check your scope - older ones often used a .965" barrel rather than the current 1.25" (or 2") barrel size used by most modern astro scopes.)</p>

CC BY-SA 3.0
2017-08-24T16:13:56.290Z
Great information, thank you.  I like the idea of moving the main mirror inwards to get access to the primary focus point.  My tube is a 1.25" type.  My Nikon D40 has a marking on the exterior indicating the position of the sensor plane it coincides with the tripod socket screw (as with most SLR cameras).
Wossname
CC BY-SA 3.0
2017-08-24T23:28:41.727Z
One side note - looking at the parts list, you may have one of the eyepiece style solar filters. These are NOT SAFE. The problem is that you have unfiltered sunlight focused on the filter - and that includes heat as well as light, which means the filter is prone to split due to the heat buildup, which then lets unfiltered sunlight through, damaging your eyesight.  They're especially dangerous if you try to use them with the full aperture of the scope rather than the small hole in the front scope cover.
JerryTheC
CC BY-SA 3.0
2017-08-24T23:34:19.183Z
One possible trick for moving the mirror forward that would avoid having to drill new holes in the tube for the primary mirror mount - depending on how the primary mirror collimation works (if it's adjustable) - if the mirror holder is attached to the base part only with bolts and springs, you may be able to replace the bolts with longer ones (and longer springs, or sleeves around the bolts to support the existing springs), thus moving the mirror up inside the tube,
JerryTheC
CC BY-SA 3.0
2017-08-24T23:40:58.460Z
It's also worth checking to see if the black bit on the outer end of the focuser unscrews, On some newtonians, this may reveal a T thread. If it does, you can attach the T ring and camera direct to the end of the focuser, which gets the camera a bit closer in (with a separate T-adapter, many also have a T thread on the front nosepiece section, which unscrews - so you can attach the T ring just to the nosepiece bit, which again lets you get the camera closer in.)
JerryTheC
CC BY-SA 3.0
2017-08-25T06:55:29.537Z
Thanks for the safety info Jerry.  Actually I'm only interested in night-time astronomy, but it's good to know anyway.  Yes there is a thread on the focusing tube, I've already ordered a T2 adaptor for my SLR :)
Wossname
CC BY-SA 3.0
2017-08-28T17:43:47.817Z
Partial success! I have managed to build a device that lets me firmly attach my DSLR to my adjustable focusing tube.  I have even managed to take a couple of photos that demonstrate that a coherent image is possible.  I was able to take a picture of a building (several hundred metres away) and it fills the entire sensor area, which is great news.  however it is (as expected) horribly out of focus.  I think I will either have to move the primary mirror inwards, OR move the camera outwards.  But I don't know how far I have to move them.  Will it be 1mm or 100mm?  Any ideas?
Wossname
CC BY-SA 3.0
2017-08-28T18:01:18.880Z
With a T ring, the T ring to film/sensor distance is standardised at 55mm, I think (cameras with shorter flange to film distances have deeper T rings to compensate, longer flange to film distances have shorter T rings to keep the total the same.  So if you can figure out where infinity focus is, you want it to end up at least 55mm pas the end of the fully racked in focuser.
JerryTheC
CC BY-SA 3.0
2017-08-28T18:10:19.437Z
Note that the formula for where the focal point is 1/u + 1/v = 1/f, where u is the lens/mirror to subject distance, v is the lens to focal point distance, and f is the focal length. At infinity, 1/u is zero, so v = f, but as you focus closer, the focal point moves further out (so a nearby building will focus further out than something at infinity (though if I've done the sums correctly only by around 1mm for a building 500 metres away with a 700mm scope).
JerryTheC
CC BY-SA 3.0
2017-08-28T18:14:23.733Z
Okay, that seems like something I can test.  If I can get a clear sky tonight I can try to photograph a star which should serve as a subject at infinite distance.  I do have a luxury of being able to use the camera's viewfinder to get a rough aim.  This might just work! :)  I can take a few pictures, winding out the focus tube a quarter turn per shot and viewing the results.
Wossname
CC BY-SA 3.0
2017-08-28T18:19:41.053Z
Weather reports look OK for this evening.  I'll go put my tripod together  :)
Wossname
CC BY-SA 3.0
2017-12-07T00:10:19.107Z
I had the exact same telescope some years ago and found that the easiest way (for me) to reach focus was to shave a few millimetres from the plastic to let the focusing tube travel in a little farther.
Mick
CC BY-SA 3.0
2017-08-23T23:43:47.180Z
2017-08-23T23:43:47.180Z
JerryTheC
<p>Another problem I found, is that the tasco rack and pinion focus system, was not robust enough to deal with the weight of a DSLR, as you try to obtain focus, the tube would get stuck! You may need to replace it with one that can handle the weight!</p>

CC BY-SA 4.0
2020-10-18T18:23:59.730Z
2020-10-18T18:23:59.730Z
Nemo
<p>I was given a 1995 vintage Tasco "302003" <a href="https://en.wikipedia.org/wiki/Newtonian_telescope" rel="nofollow noreferrer">Newtonian</a> telescope recently and have had some exciting success with it.  I have managed to view the Moon in beautiful detail and also had my first glimpse of Jupiter (with <s>Enceladus</s> Ganymede &amp; Europa in the same shot!).</p>

<p>I was able (with very considerable difficulty) to photograph both Moon and Jupiter scenes by holding my camera up to the eyepiece.  Far from ideal but it has really fired my imagination about doing more astronomical photography.</p>

<p>Here's a picture of my telescope and it's accessories.  Despite spending the last 15 years in the back room of a charity shop, it's in brand new condition and all the parts are present including the tripod and all fixings!...</p>

<p><a href="https://i.sstatic.net/Tvrjg.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/Tvrjg.jpg" alt="enter image description here"></a>
(Blue arrows indicate places where eyepiece lenses can be inserted).</p>

<p>My camera is a Nikon D40 (APS-C format, DX lens ring system).</p>

<p>Is it possible to modify this telescope's eyepiece (a rack-and-pinion tube-length adjustable type) so that I can attach my camera in order to take photographs of astronomical subjects?  Photographs of the Moon would be my primary goal.</p>

<p>I am happy to make severe modifications to the telescope if necessary.  But I realise that certain measurements would be absolutely critical to making good photographs possible.  I think I can make an adaptor that goes between the eyepiece socket and the camera.  But I don't know all of the parameters I will have to know to design such an adaptor.</p>

<p>Problems I believe I need to solve...</p>

<ul>
<li>I think that holding the camera's central axis perfectly concentric with the eyepiece's axis is critical.</li>
<li>I need some sort of <a href="https://en.wikipedia.org/wiki/Relay_lens" rel="nofollow noreferrer">Relay Lens</a> between the secondary mirror and the camera body.</li>
<li>Keeping the rack-and-pinion tube adjustment (actually a fairly sturdy mechanism) is important and would allow better focusing of the picture as the camera is not likely to have enough auto-focus range to cope with the 700mm F length.</li>
</ul>

<p>I do have a small Milling machine and most of the basic machine tools.  I have a ready supply of aluminium stock and industrial plastic stock (RG1000) that I can build an adaptor from.</p>

<h2>Is this project feasible?</h2>

<p>I'm not looking for perfect photos, but rather something that is better and more convenient than holding my cellphone camera close to the eyepiece and holding my breath! :)</p>

<p>My astronomy/optics knowledge is practically zero but I'm a fairly savvy mechanical engineer and can build things to a specification.</p>

<p>Thank you for reading, I look forward to your responses.</p>

CC BY-SA 3.0
2017-08-22T15:31:22.797Z
What you need is called a T2 adapter. There are adapters for the standard 1.25" and 2" eyepiece tubes behind the focuser. They attach to your dslr (where you would usually attach the lense). The T2 adapters are brand specific though. If you have a Canon camera you need a Canon T2 adapter.
Also, you won't need any "Relay lense". Just put the camera at the correct distance behind the focuser tube to get it into focus on the cameras sensor and you are good to go
RononDex
CC BY-SA 3.0
2017-08-22T18:12:20.170Z
I didn't realise it was that simple.  I've ordered a cheap T2 / Nikon DX adaptor.  My only concern now is that I've got nothing but thin air between the sensor and the infinite void.  Knowing my luck within an hour of using this I'll have a spider building a nest behind the mirror mechanism!  Perhaps I can rig up one of my UV filters over the small "dust cover hole" to keep out some of the atmosphere.
Wossname
CC BY-SA 3.0
2017-08-24T14:37:42.353Z
If the T2 adapter is not adequate, you can make a custom adapter with a metal lathe and an aluminum cylinder. Mine works nicely, and since I had the lathe and spare aluminum, was a lot cheaper than storebought.
Wayfaring Stranger
CC BY-SA 3.0
2017-08-25T07:46:45.217Z
@Wossname most astrophotographers only use "air" between sensor and the void xD. Unless you do planetary photography where you usually need barlow lenses to increase zoom
RononDex
CC BY-SA 3.0
2017-08-25T09:12:11.310Z
@RononDex, so it seems.  However, DSLR sensors will electrostatically attract dust and other airborne particles.  These will cause shadows to form on any (normal) photographs taken in daylight unless the sensor is cleaned.    It's not a good idea to leave a DSLR body open to the atmosphere for prolonged periods.
Wossname
CC BY-SA 3.0
2017-08-25T11:18:42.890Z
@Wossname thats what DSLR cleaning sets are for. Also once its mounted you should not really get any dust on it.
RononDex
CC BY-SA 3.0
2017-08-25T16:25:22.903Z
Dang, the T2 ring I bought is the wrong one.  It's got a 1-5/8" thread on it. https://www.amazon.co.uk/dp/B00U80SZ90/
Wossname
CC BY-SA 3.0
2017-08-27T15:23:53.893Z
Um, Enceladus is one of Saturn's moons. Not Jupiter's
toniedzwiedz
CC BY-SA 3.0
2017-08-28T14:58:01.920Z
@toniedzwiedz, which makes the achievement all the more remarkable :)
Wossname
CC BY-SA 3.0
2017-09-02T19:02:03.383Z
Usually Eyepieces and T2-adapters have mounting threads to attach filters. So buy a cheap IR-filter in addition.
Grimaldi
<photography><newtonian-telescope>
Retrofitting a DSLR camera to a super-cheap Tasco reflector telescope
Wossname
# Retrofitting a DSLR camera to a super-cheap Tasco reflector telescope

(Asked by: username_0 on 2017-08-21)

I was given a 1995 vintage Tasco "302003" [Newtonian](https://en.wikipedia.org/wiki/Newtonian_telescope) telescope recently and have had some exciting success with it. I have managed to view the Moon in beautiful detail and also had my first glimpse of Jupiter (with ~~Enceladus~~ Ganymede & Europa in the same shot!).

I was able (with very considerable difficulty) to photograph both Moon and Jupiter scenes by holding my camera up to the eyepiece. Far from ideal but it has really fired my imagination about doing more astronomical photography.

Here's a picture of my telescope and it's accessories. Despite spending the last 15 years in the back room of a charity shop, it's in brand new condition and all the parts are present including the tripod and all fixings!...

[![enter image description here](https://i.sstatic.net/Tvrjg.jpg)](https://i.sstatic.net/Tvrjg.jpg)
(Blue arrows indicate places where eyepiece lenses can be inserted).

My camera is a Nikon D40 (APS-C format, DX lens ring system).

Is it possible to modify this telescope's eyepiece (a rack-and-pinion tube-length adjustable type) so that I can attach my camera in order to take photographs of astronomical subjects? Photographs of the Moon would be my primary goal.

I am happy to make severe modifications to the telescope if necessary. But I realise that certain measurements would be absolutely critical to making good photographs possible. I think I can make an adaptor that goes between the eyepiece socket and the camera. But I don't know all of the parameters I will have to know to design such an adaptor.

Problems I believe I need to solve...

* I think that holding the camera's central axis perfectly concentric with the eyepiece's axis is critical.
* I need some sort of [Relay Lens](https://en.wikipedia.org/wiki/Relay_lens) between the secondary mirror and the camera body.
* Keeping the rack-and-pinion tube adjustment (actually a fairly sturdy mechanism) is important and would allow better focusing of the picture as the camera is not likely to have enough auto-focus range to cope with the 700mm F length.

I do have a small Milling machine and most of the basic machine tools. I have a ready supply of aluminium stock and industrial plastic stock (RG1000) that I can build an adaptor from.

## Is this project feasible?

I'm not looking for perfect photos, but rather something that is better and more convenient than holding my cellphone camera close to the eyepiece and holding my breath! :)

My astronomy/optics knowledge is practically zero but I'm a fairly savvy mechanical engineer and can build things to a specification.

Thank you for reading, I look forward to your responses.

**Tags:** photography, newtonian-telescope

> **Comments:**
> **username_1**: What you need is called a T2 adapter. There are adapters for the standard 1.25" and 2" eyepiece tubes behind the focuser. They attach to your dslr (where you would usually attach the lense). The T2 adapters are brand specific though. If you have a Canon camera you need a Canon T2 adapter. Also, you won't need any "Relay lense". Just put the camera at the correct distance behind the focuser tube to get it into focus on the cameras sensor and you are good to go  
> **username_0**: I didn't realise it was that simple.  I've ordered a cheap T2 / Nikon DX adaptor.  My only concern now is that I've got nothing but thin air between the sensor and the infinite void.  Knowing my luck within an hour of using this I'll have a spider building a nest behind the mirror mechanism!  Perhaps I can rig up one of my UV filters over the small "dust cover hole" to keep out some of the atmosphere.  
> **username_2**: If the T2 adapter is not adequate, you can make a custom adapter with a metal lathe and an aluminum cylinder. Mine works nicely, and since I had the lathe and spare aluminum, was a lot cheaper than storebought.  
> **username_1**: @username_0 most astrophotographers only use "air" between sensor and the void xD. Unless you do planetary photography where you usually need barlow lenses to increase zoom  
> **username_0**: @username_1, so it seems.  However, DSLR sensors will electrostatically attract dust and other airborne particles.  These will cause shadows to form on any (normal) photographs taken in daylight unless the sensor is cleaned.    It's not a good idea to leave a DSLR body open to the atmosphere for prolonged periods.  
> **username_1**: @username_0 thats what DSLR cleaning sets are for. Also once its mounted you should not really get any dust on it.  
> **username_0**: Dang, the T2 ring I bought is the wrong one.  It's got a 1-5/8" thread on it. https://www.amazon.co.uk/dp/B00U80SZ90/  
> **username_3**: Um, Enceladus is one of Saturn's moons. Not Jupiter's  
> **username_0**: @username_3, which makes the achievement all the more remarkable :)  
> **username_4**: Usually Eyepieces and T2-adapters have mounting threads to attach filters. So buy a cheap IR-filter in addition.  

---

## 2 answers

### Answer by username_5 on 2017-08-23. Score: 2 | Accepted answer

The problem you have with many newtonian reflectors - especially smaller ones - is that to use them for prime focus photography (where you're effectively using the telescope like a big telephoto lens) , you need to set things up so that the camera sensor ends up at the focal plane of the telescope. And in a DSLR, the sensor is some way inside the camera body (behind the shutter, which is behind the mirror.

With a newtonian scope, the focal plane is usually somewhere inside the focuser tube, and many newts don't have enough focuser inwards travel to let you get the focal plane the 40mm or so beyond the end of the focuser that you need to get it to reach a DSLR sensor.

(With other types of scope that use a separate star diagonal, things are usually easier - you can leave the star diagonal off, which has the same effect as a big chunk of inward focus).

With a newtonian, if you can't reach prime focus, there are three basic options - either take photos through the eyepiece (afocal photography) as you already tried,

or move the main mirror further up the tube (which moves the focal plane further out, giving you more in focus). It also means the light cone is fatter when it reaches the secondary mirror, so you may lose some light as the outer part of the light cone misses the secondary.

or you can try using a barlow lens - that replaces the last bit of the light cone with a longer, narrower angle version (which increases the magnification and moves the focal plane further out). That MAY or MAY NOT let you reach infinity focus; it's not guarenteed, but may help. You can get barlows that have a T-Thread on the output end, so you can attach a T ring directly to the barlow (yours doesn't look like one of this type) and then hook the camera up that way. (as an added benefit, since you end up with a closed tube setup (the barlow lens closes off the access to the camera, it also keeps spiders and dust out of the camera :) ).

If you have a look at the bottom bit of the barlow (with the lens) you may find that you can unscrew it. You might be able to make a short top section with a T thread for the T ring at the back, and a suitable thread for the lens at the front; you'd probably need to make it the same diameter as the eyepiece barrel (to fit in the focuser) with a fatter bit at the back for the T thread and to stop it sliding all the way into the focuser.
I've used a commercial 1.25" barrel T threaded barlow (somewhat shorter than yours) for lunar and solar (WITH A SUITABLE FRONT OF SCOPE FILTER - DON'T TRY LOOKING AT THE SUN WITHOUT ONE) imaging with an APS sensor camera.

(You may need to check your scope - older ones often used a .965" barrel rather than the current 1.25" (or 2") barrel size used by most modern astro scopes.)

> **Comments:**
> **username_0**: Great information, thank you.  I like the idea of moving the main mirror inwards to get access to the primary focus point.  My tube is a 1.25" type.  My Nikon D40 has a marking on the exterior indicating the position of the sensor plane it coincides with the tripod socket screw (as with most SLR cameras).  
> **username_5**: One side note - looking at the parts list, you may have one of the eyepiece style solar filters. These are NOT SAFE. The problem is that you have unfiltered sunlight focused on the filter - and that includes heat as well as light, which means the filter is prone to split due to the heat buildup, which then lets unfiltered sunlight through, damaging your eyesight.  They're especially dangerous if you try to use them with the full aperture of the scope rather than the small hole in the front scope cover.  
> **username_5**: One possible trick for moving the mirror forward that would avoid having to drill new holes in the tube for the primary mirror mount - depending on how the primary mirror collimation works (if it's adjustable) - if the mirror holder is attached to the base part only with bolts and springs, you may be able to replace the bolts with longer ones (and longer springs, or sleeves around the bolts to support the existing springs), thus moving the mirror up inside the tube,  
> **username_5**: It's also worth checking to see if the black bit on the outer end of the focuser unscrews, On some newtonians, this may reveal a T thread. If it does, you can attach the T ring and camera direct to the end of the focuser, which gets the camera a bit closer in (with a separate T-adapter, many also have a T thread on the front nosepiece section, which unscrews - so you can attach the T ring just to the nosepiece bit, which again lets you get the camera closer in.)  
> **username_0**: Thanks for the safety info Jerry.  Actually I'm only interested in night-time astronomy, but it's good to know anyway.  Yes there is a thread on the focusing tube, I've already ordered a T2 adaptor for my SLR :)  
> **username_0**: Partial success! I have managed to build a device that lets me firmly attach my DSLR to my adjustable focusing tube.  I have even managed to take a couple of photos that demonstrate that a coherent image is possible.  I was able to take a picture of a building (several hundred metres away) and it fills the entire sensor area, which is great news.  however it is (as expected) horribly out of focus.  I think I will either have to move the primary mirror inwards, OR move the camera outwards.  But I don't know how far I have to move them.  Will it be 1mm or 100mm?  Any ideas?  
> **username_5**: With a T ring, the T ring to film/sensor distance is standardised at 55mm, I think (cameras with shorter flange to film distances have deeper T rings to compensate, longer flange to film distances have shorter T rings to keep the total the same.  So if you can figure out where infinity focus is, you want it to end up at least 55mm pas the end of the fully racked in focuser.  
> **username_5**: Note that the formula for where the focal point is 1/u + 1/v = 1/f, where u is the lens/mirror to subject distance, v is the lens to focal point distance, and f is the focal length. At infinity, 1/u is zero, so v = f, but as you focus closer, the focal point moves further out (so a nearby building will focus further out than something at infinity (though if I've done the sums correctly only by around 1mm for a building 500 metres away with a 700mm scope).  
> **username_0**: Okay, that seems like something I can test.  If I can get a clear sky tonight I can try to photograph a star which should serve as a subject at infinite distance.  I do have a luxury of being able to use the camera's viewfinder to get a rough aim.  This might just work! :)  I can take a few pictures, winding out the focus tube a quarter turn per shot and viewing the results.  
> **username_0**: Weather reports look OK for this evening.  I'll go put my tripod together  :)  
> **username_6**: I had the exact same telescope some years ago and found that the easiest way (for me) to reach focus was to shave a few millimetres from the plastic to let the focusing tube travel in a little farther.  

---

### Answer by username_7 on 2020-10-18. Score: 1

Another problem I found, is that the tasco rack and pinion focus system, was not robust enough to deal with the weight of a DSLR, as you try to obtain focus, the tube would get stuck! You may need to replace it with one that can handle the weight!


---

