Coupling a Nikon DSLR to a newtonian

[Diver99]

Hi

I know this is a really basic question but couldn't immediately find the answer.

I have a skywatcher 130 newtonian and want to try and photograph with either my Nikon DSLR (D500) or Olympus micro4/3. I have T adaptors for both. I hit the immediate problem of not being able to get either to focus and a quick search has shown this is not an unusual problem. 

I have no idea how to resolve this and am looking for advise please. I have read about 'flatteners' and such like but no idea what they are!

Any help greatly appreciated. 

[Cornelius Varley]

1 minute ago, Diver99 said:

Hi

I know this is a really basic question but couldn't immediately find the answer.

I have a skywatcher 130 newtonian and want to try and photograph with either my Nikon DSLR (D500) or Olympus micro4/3. I have T adaptors for both. I hit the immediate problem of not being able to get either to focus and a quick search has shown this is not an unusual problem. 

I have no idea how to resolve this and am looking for advise please. I have read about 'flatteners' and such like but no idea what they are!

Any help greatly appreciated. 

Hello and welcome to SGL. The standard Skywatcher 130 newtonians, like many other reflectors, don't have the ability to reach focus with a camera, Skywatcher actually introduced the 130PDS to fix this. The problem can be solved by either using a barlow lens to move the point of focus outwards, or, more drastically, by reducing the distance between the primary and secondary mirrors (not recommended)

[Diver99]

Hi Peter

Thanks for the reply. I tried a 2x barlow but that didn't appear to fix the problem. Do I need something higher? 

Cheers

Steve 

[Cornelius Varley]

13 minutes ago, Diver99 said:

Hi Peter

Thanks for the reply. I tried a 2x barlow but that didn't appear to fix the problem. Do I need something higher? 

Cheers

Steve 

A 2x Barlow should be sufficient. Can you upload a few photos of the camera/telescope connection ? 

[Mr Spock]

I use a x2 Barlow with my 12" Newtonian, D500 and Nikon to 2" push fit adaptor. Works perfectly 

 

 

 

[Diver99]

Photos attached -  Adaptor on camera, barlow, barlow on scope, camera on scope with barlow between camera and scope. 

Lovely shot - I can't seem to get mine to focus at all.  I have a skywatcher 130 

[Cornelius Varley]

Quick question. The focuser drawtube seems to have a threaded end (m42x0.75?). Can the T2 adaptor attach directly to that, keeping the distance between the camera and focuser as short as possible.

[Diver99]

You mean without the barlow in between? Yes it will, never though of connecting that way. 

We have a couple of days of cloud here so it will be Wednesday probably before I can try it

[Diver99]

I may try tonight but as the moon doesn't rise until silly o'clock, not sure if I'll have anything to focus on !

[alacant]

On 05/06/2023 at 11:06, Diver99 said:

Nikon DSLR

Hi

- lose the Barlow, t-adapter and nosepiece.

- screw this adapter onto the telescope focuser:

 https://www.opticstar.com/Opticstar-Nikon-style-Low-Profile-T-Ring.html

- attach the camera to the exposed bayonet.

HTH

 

Edited June 7, 2023 by alacant

[Diver99]

Hi, Alacant, thats basically what I did last night, my adaptor ring comes off the T adaptor and screws straight on to the focuser tube. I'm clearly doing something very wrong. I tried to image a planet last night and could only see the primary mirror.....I need some serious help...

 

[alacant]

1 hour ago, Diver99 said:

T adaptor and screws straight on to the focuser tube

So you're still ~10mm too far out. If you don't want to use the low profile adapter, you'll have to go to:

Camera > t-ring > barlow, leaving out the nosepiece.

Your Barlow should have a t-thread, enabling it to be screwed into the t-ring camera side and clamped into the focuser, telescope side:

Why not post a shot of your focuser from last night with the camera attached? We can then maybe help further.

Cheers and HTH.

Edited June 9, 2023 by alacant

[Mr Spock]

From what I can see, without a low profile focuser and a reduction in the tubes you are using, you are never going to get there.

You can see here how much closer my camera is to the scope.

 

[Diver99]

I'll try with the barlow tonight. Unfortunately the barlow doesn't have a thread so I have to use the full T adaptor. 

I've attached photos of the camera without barlow and just T adaptor thread section  screwed straight on the focusser and with barlow with full T adaptor push cylinder into the focusser. My focusser seems to possibly be longer than the one shown above., but not sure it's by much Can the focusser on the skywatcher newtonian be replaced?

I'll also try my micro 4/3 camera. The adaptor for that doesn't disassemble to just a thread section, but the focal plane to front of camera distance is a bit shorter.

Any help appreciated. .

[alacant]

The 4/3 gives you an extra 20mm or so, so that may just do it. Otherwise you're going to need a threaded Barlow and/or a low profile t- adapter.

This may be a good point to go along to your local astro club who armed with a box full of adapters, will get you focussed within a few moments of arriving;)

HTH

[wulfrun]

Different scopes but I can get my Panny G9 (m4/3) to focus using a t-adapter/nosepiece and a 2.25x barlow. I can also reach focus with the barlow elements screwed into the nosepiece directly (1.3x??), since mine has the removeable ones.

Scopes that I've tried it in are a 114mm, 500mm FL, f4 and 150mm, 1200mm FL, f8. Yes, I know it's spectacularly useless with the f8 but it can reach focus. Your Olympus should do likewise.

HTH

[Diver99]

Thanks, I'll see how I get on with the barlow with both cameras tonight

Good suggestion for the local Astro club. I think I have one fairly close. I'll get in touch with them

[Diver99]

Good news, I managed to get both cameras to reach focus on venus last night with the 2x barlow. Actually achieving sharp focus is way more tricky than I imagined, especially with the planet shaking all over the place (live view), but that is a different skill I have to learn. Also, the image had massive chromatic aberration but that could be collimation, the scope mirror quality or the barlow itself. 

Thanks very much for the help

[wulfrun]

2 hours ago, Diver99 said:

Also, the image had massive chromatic aberration but that could be collimation, the scope mirror quality or the barlow itself.

Barlow is a candidate, as is wobbly atmospherics. Mirrors, afaik, can't cause it.

[Diver99]

That's good to know. Now I know that a 2x barlow works I'll look at better ones. Mine is "Celestron 2x Barlow lens". No idea if that's 'good' or not. 

[Diver99]

I was thinking about the skywatcher 2x deluxe Achromatic barlow as that has a camera screw adaptor fitting as well as thumbscrew, so Ideal for my Nikon thread mount. 

Would this be any good (seems rather cheap!)

[wulfrun]

Can't offer any opinion on that one, others will have to advise. Mine's the Baader Classic Q, which seems pretty good. Saying that, I've only used it for visual and casual-snap type things and not for serious AP.

My only criticism of it is that the removeable elements are threaded on the "wrong" end, in my opinion. Means it's limited to eyepieces that have a recess, when used directly on them. Not relevant here though and might even be advantageous for it to sink into the nosepiece.