New with DSLR Astrophotography

[MichAstronomer]

I have a Meade 4420 reflector telescope (D=114mm, F=900mm) that I previously used with a Canon A-1 35mm for astrophotography many years ago.

I now have an Olympus E-510 DSLR for which I do have a T-ring that fits the same T-adapter I used with the Canon.  While I have gotten the moon in focus using the 25mm eyepiece, I am unable to bring into focus using the 15mm or 6.4mm eyepieces.

Some suggestions that I've come across is that perhaps the T-adapter is too long for the DSLR.  The T-adapter is approximately 2.5" long not including the barrel piece.

I did get a 1.25" 2x barlow lens a few years ago, but it doesn't seem to resolve the issue.

If anyone could offer help, it be appreciated.

[wxsatuser]

Most likely difference in flange focal distance.

The Canon A-1 is FD mount with a flange focal distance of 42mm.
The Olympus is Micro 4/3 with a flange focal distance of 38.67mm.

You will need a spacer/adapter that matches the difference between the two, in this case 3.33mm
 

[ronin]

Slight confusion here: Initially it reads that you have he attachments and are doing Puime Focus imaging, then you mention getting focus with the 25mm but not the 15mm or 6.4mm which means A-Focal imaging.

If it is Prime Focus then it will be as Mike says the mechanical distances that require setting/altering and they can be a problem - moving out is easy, moving in is not.

If it is A-Focal then  best I can think of it that the output from the eyepiece, it should be collimated, is too divergent for the camera to achieve a focus, maybe the "image" is too "far" from the camera. Optically it is possible for the light delivered to be coming from beyond infinity and the DSLR is going to really dislike that idea.

In either case the DSLR needs to be set to fully manual, well the auto focus has to be off and I cannot see it doing everything with the any of the "auto" features being on. Just too much conflict between what the scope does and what the DSLR does. Can that DSLR be set to a fully Manual state? Some cannopt.

Do you still have the A-1 ?

[The Admiral]

I'm a little confused too. If you used appropriate T-mounts with both cameras for prime focus imaging, then that should equalise the mount to sensor distance to 55mm, so there shouldn't be any difference. Your post reads as though you're using two T-adapters together? If you are, indeed, if it's possible, you shouldn't be. Or are you using a 4/3rds to Canon converter?

By the way, strictly the Oly 510 is standard 4/3, not micro 4/3, though the distance Mike gives is the correct one. That name  difference is important though as the flange to sensor distance on micro 4/3 is only 19.25mm.

Ian

[MarsG76]

To add to the above, when projecting onto you DSLR using the 15mm or the 6.4mm EPs it MIGHT be that due to seeing/turbulance and it might look like it was out of focus, but stacking will reveal more detail.... of course can also be back focus.

 

[MichAstronomer]

To answer some questions.

Sorry for any confusion regarding Prime Focus, even with the Canon, I did not use Prime Focus.  An eyepiece was always inserted into the T-adapter and then attached to the camera with the T-ring.

I am attempting the same with the E-510 and for the smaller eyepieces, seem unable to bring the image into focus.  I am not using two different T-adapters, I am using the same T-adapter that I previously used with the Canon, which I still have, use swapped out the T-ring so it attaches to the E-510.

It should be clear tomorrow night and the Moon will be out, I will set things up and double check, but I seem to recall that I could not bring the E-510 closer enough to focus the image with the 15mm or 6.4mm eyepieces.  Partially why I am wondering if I should get a shorter T-adapter.

[wxsatuser]

Confusion sorted, I think.

With no lens attached to the camera you are doing eyepiece projection.
If the camera lens was attached you are doing afocal imaging.

With eyepiece projection you may find that your focuser tube does'nt come out enough.
You may have to add some extension to the focuser tube first then your eyepiece adapter.

The distance between the eyepiece and camera sensor is not critical, adding more space between the two
increases image scale but does reduce the amount of light, adjust exposure to compensate.

Here is an eyepiece projection of the Double Double.
Canon 60Da mounted directly on top of a Hyperion zoom, 80ED Pro scope, cannot remember the extension but
think it was more than 40mm between eyepiece and camera.

[Astrosurf]

8 hours ago, wxsatuser said:

With no lens attached to the camera you are doing eyepiece projection.
If the camera lens was attached you are doing afocal imaging.

 

 

That should be the other way around? DSLR attached directly to the scope is afocal and to an eyepiece is eyepiece projection.

Alexxx

[Astrosurf]

OP, can you not attach the camera directly to the focuser??

[MichAstronomer]

55 minutes ago, Astrosurf said:

OP, can you not attach the camera directly to the focuser??

I don't believe so, never attempted that with the Canon.

The T-adapter held the eyepiece, the T-ring attaches the camera (camera lens removed) then the barrel from the T-adapter is inserted into the focuser.

9 hours ago, wxsatuser said:

Confusion sorted, I think.

With no lens attached to the camera you are doing eyepiece projection.
If the camera lens was attached you are doing afocal imaging.

With eyepiece projection you may find that your focuser tube does'nt come out enough.
You may have to add some extension to the focuser tube first then your eyepiece adapter.

The distance between the eyepiece and camera sensor is not critical, adding more space between the two
increases image scale but does reduce the amount of light, adjust exposure to compensate.

Here is an eyepiece projection of the Double Double.
Canon 60Da mounted directly on top of a Hyperion zoom, 80ED Pro scope, cannot remember the extension but
think it was more than 40mm between eyepiece and camera.

I seem to recall it perhaps being too long, but I also haven't had the opportunity to setup it since.  I hope to do so tonight.

If it is just that I need a focuser tube extension, how long should it be?

[wxsatuser]

5 hours ago, Astrosurf said:

That should be the other way around? DSLR attached directly to the scope is afocal and to an eyepiece is eyepiece projection.

Alexxx

Directly attached to scope is prime focus.

With eyepiece and without a lens its eyepiece projection, with a lens afocal.

 

[wxsatuser]

5 hours ago, MichAstronomer said:

I don't believe so, never attempted that with the Canon.

The T-adapter held the eyepiece, the T-ring attaches the camera (camera lens removed) then the barrel from the T-adapter is inserted into the focuser.

I seem to recall it perhaps being too long, but I also haven't had the opportunity to setup it since.  I hope to do so tonight.

If it is just that I need a focuser tube extension, how long should it be?

Think you will need to do a bit of trial an error.

[Astrosurf]

15 hours ago, wxsatuser said:

Directly attached to scope is prime focus.

With eyepiece and without a lens its eyepiece projection, with a lens afocal.

 

Grrr, I always get mixed up!