Photographing through a telescope with a (D)SLR

[Deleted member 93880]

I have three types of telescope, a couple of DSLRs and an adaptor for mounting an SLR to the viewfinder of the telescopes.

I can see some fantastic things through the telescopes (solar/astronomical/birding) with my eyes and eyepieces. The camera connects to the telescopes physically.

But I just can't see a usable image through the camera once it's mounted to the telescope.

Can anybody with some experience tell me what I might be doing wrong or what I need to do/avoid in order to see something I can photograph with my camera through the telescope(s)?

Please treat me like an idiot who know nothing because that's quite close to the truth in this situation.

 

[Jannyfox]

In what way is the image not usable? It's possible the scopes are not able to focus for the camera. Are you connecting camera lens to eyepiece or camera body direct to scope ie using the scope as a lens. More information required ...............

 

[john.margetts]

Does the camera need to be told that there will be no communication with the 'lens' (ie telescope)?

 

[moggi1964]

It is possible you need an extension tube to bring the camera further back in order to achieve infinity focus. Tell us more about the specifics of your setup.

 

[Petrochemist]

There are multiple ways to connect cameras & telescopes. With my mirrorless cameras I get best results using 'Prime Focus' where the camera body is linked directly to the telescope without either a camera lens or an eyepiece. However for infinity focus my Celestron Newtonian scope requires the camera to be closer than I can mount my DSLRs (connecting via a T2 adapter & ring - I connect my mirrorless cameras via c-mount instead) - this is not the case with all telescopes. It is apparently possible to move the primary mirror up the tube to get round the issue but that just sounds like hard work to me!
I have to admit I've never tried any of my other newtonians with a DSLR, it's just easier with a mirrorless.
Another popular approach is an 'Afocal' setup which makes use of both the cameras lens & the telescopes eyepiece. This is basically what you get if you hold a mobile phone to the eyepiece of your scope. Very high magnifications are possible with this set-up but the effective f-stop can get very small.
Connecting a camera without a lens to a telescope with an eyepiece is called positive projection. This is how my refracting telescope gets mounted as the eyepiece is fixed in place. It works OK with the eyepiece zoomed out where the scope works as a 1000mm f/16 lens, but zooming in to it's 4000mm f/64 position doesn't seem to add any detail. This zoom does help when used as a telescope.
Finally negative projection uses a barlow on the telescope but no eyepiece or camera lens. I can mount my DSLR on my Celestron this way (the barlow sits closer than the camera would).
The issues you are having could be similar to mine with the DSLR on the celestron in which case your system is focusing too close (I'd mine can focus at between 5m & 20m subject distance - not normal telescope distances but not too bad for birds in the garden.
Other setups might be focusing too far away needing the extension tubes suggested above.
Afocal set-ups might be easier to get started with. With the telescope focused for visual viewing light rays come out of the eyepiece close to parallel, the camera can then focus these on the sensor just as if they are coming from infinity. For best results use a low power eyepiece & don't use too long a focal length on your camera. Something close to normal on your camera will give a image similar to that you get directly from the eyepiece.

One of my eyepieces has a T2 thread hidden under the eyecup which makes it easy to use for positive projection or via a suitable stepping ring for a-focal use.

Back in 2014 I tried a set of comparison shots using different set-ups results can be seen here but would have been better if I chosen a static subject or a less windy day... the lifeboat was really rolling!
Sadly I missed the positive projection so perhaps I should go & have another try (taking a bit more time about it too).

Here's a quick effort done with a £25 Helios 1000mm f/8.7 telescope simply stuck under my arm:
Helios 1000 f/8.7 scope handheld 3 adj usm by Mike Kanssen, on Flickr
The scope badly needs collimation as can be seen by the left hand side!

 

[Deleted member 93880]

Thank you for all your replies. If I can answer them all here, in turn...

Jannyfox, Once I attach the camera and look through the camera eyepiece, I cannot see any images that look like anything I was viewing through the telescope. Maybe it's a focus issue or a light issue. I have no idea. I didn't think it would be this difficult to look through a camera just because it was connected to a telescope rater than a standard lens.

John.Margetts, The camera (Fuji S3 Pro) does not need to know what it's attached to. It can work in fully manual mode for focus and exposure with any lenses.

Moggi1964, I've attached a picture of how I've connected the camera to the telescope(s). The equipment is a Meade Basic Camera Adaptor(1.25") and I've tried it with one of the eyepieces inserted into the adaptor and without anything in there - so the adaptor is a bit like an extension ring but again I have no idea what I'm trying to achieve or how with whatever should go between the camera and the scope(s).

Petrochemist, Maybe I could be using the adaptor without what looks like the extension tube to get the camera closer to the telescope's focal plane?

 

[moggi1964]

Have you tried just the final pictured adapter as based on your setup I think you may be too far from the focal plane with the extended adaptor?

Also, the less you have to extend the focus tube the better as it isn't designed to have a DSLR hanging off it as full extension.

 

[Petrochemist]

The last image shows an adapter for use in Prime focus, but like my Celestron it might keep the camera too far away to focus to infinity.
T2 fittings like this are designed for the sensor to be 55mm from the flat face just to the right of the knurled bit.

Mounting your camera directly like this you should be able to focus on terrestrial objects like something within the typical garden. How far away focus is possible depends on the design of the telescope, the closer the camera is to the scope the further the system will focus.

With the central portion fitted it's designed to hold an eyepiece for positive projection, I'm not overly familiar with these but I suspect the eyepiece may again be sitting too far out. If you remove the nose piece (shinny tube) can the remainder fit over an eyepiece fitted to the scope for visual viewing?

 

[Jannyfox]

At a guess I'd say you only need an adaptor like that shown in your last image to connect the camera direct to the scope (without lens or eyepiece). Many years ago I bought a set of camera - scope mounts which included the T ring for prime focus (no lens or eyepiece) and another tube for eyepiece projection (lens and eyepiece both in place). It was very confusing trying to sort out what did what. Then I found that my camera wouldn't quite focus in the scope I was using at the time and I needed a low profile adaptor for the T ring. Now it's all I use as I've lost the other bits and pieces. That's a Canon on unbranded scopes. The problem with astrophotography is there are so many variables. It's great when standard off the shelf kit works but it doesn't always. I'd work with just one scope, connect with the adaptor in your last pic, wind the focus in and out and see what you get. And remember you need to play outside with something distant in view. The focus will be a long way from where the eyepiece focuses.
This is my T ring (apologies for the quality - for some reason I am incapable of taking a decent photo with a phone.)

 

[Petrochemist]

At a guess I'd say you only need an adaptor like that shown in your last image to connect the camera direct to the scope (without lens or eyepiece). Many years ago I bought a set of camera - scope mounts which included the T ring for prime focus (no lens or eyepiece) and another tube for eyepiece projection (lens and eyepiece both in place). It was very confusing trying to sort out what did what. Then I found that my camera wouldn't quite focus in the scope I was using at the time and I needed a low profile adaptor for the T ring. Now it's all I use as I've lost the other bits and pieces. That's a Canon on unbranded scopes. The problem with astrophotography is there are so many variables. It's great when standard off the shelf kit works but it doesn't always. I'd work with just one scope, connect with the adaptor in your last pic, wind the focus in and out and see what you get. And remember you need to play outside with something distant in view. The focus will be a long way from where the eyepiece focuses.
This is my T ring (apologies for the quality - for some reason I am incapable of taking a decent photo with a phone.)

View attachment 310552

I've never seen low profile T2 adapters - could be enough to get my DSLRs running in prime focus too.
Seems to be a very limited range e-bay can find one each for Nikon F, Canon EF & Pentax K. The price is enough to put my GAS on hold as my mirrorless options will do anything I can do with those.