Crook moon picture.

Snibs · #1 12-06-2006, 09:07 AM

Hi all.
Can anyone tell me what the halo is around the moon? on some shots its only on 1 side. Looks fine through viewfinder

. tried all sorts of settings and different focuses but similar results.
Thanks again.

Rigel003 (Graeme) · #2 12-06-2006, 09:29 AM

The blue fringing looks like chromatic aberration and because it flares out on one side, it your focusser or camera might not be square on to the focal plane. What kind of telescope was it and what did you have in the imaging train?

Graeme

Snibs · #3 12-06-2006, 10:34 AM

used a gso 10in dob with D50 and andrews camera adaptor with 25mm ep (its the only one that works). Had same problem with sun but not as bad, without camera it looks great...
Thanks.

asimov (John) · #4 12-06-2006, 11:02 AM

Yes, certainly looks like something in the optical train is not square on.

Have you checked your collimation by way of star testing or a cheshire lately?

Lester · #5 12-06-2006, 11:37 AM

Hi Mick,

Try shot at prime focus, and then with 2x barlow. The 2x barlow should give the same magnification as the 25mm eyepiece.

If results are still the same= collimation problem

If results are better=eyepiece problem

Snibs · #6 12-06-2006, 04:03 PM

Will give that a go, I'm thinking I might be doing it wrong anyhow, this is a quote from Mike's article:

They can be connected at prime focus using the appropriate T-rings and T-adapters, with the lens off the camera and the eyepiece out of the focuser.

Does that mean useing the eyepiece from the focuser IN the adaptor (I assumed because the adaptor was made to take an eyepiece you would use one) or leave it out all together? will try out all together and see if thats where I stuffed up. Anything's possible with me....I did think sunspots were a problem with my mirror the first time I saw one. Will post how I go later.
Thanks again all.

[1ponders] (Paul) · #7 12-06-2006, 04:14 PM

Hi Snibs
Prime focus means connecting your DSLR direct to the scope focuser. To do that you need a couple of adapters (different to the one you have). If you are shooting through an eyepiece with your camera with the lense inplace (afocal) then you will probably find the Chromatic aberation is in the camera lense.

Even though these are images of prime focua on an SCT and a Refractor you should get the idea. The third shot is of the various adapters. You won't need a focal reducer or the AC adapter but you will need the T mount adapter and the T adapter specific for a newt

Rigel003 (Graeme) · #8 12-06-2006, 04:18 PM

Quote:

Originally Posted by Snibs

Does that mean useing the eyepiece from the focuser IN the adaptor (I assumed because the adaptor was made to take an eyepiece you would use one) or leave it out all together?

The simplest technique is prime focus photography with the eyepiece out and the camera lens out - the telescope mirror replaces the camera lens. This will give you a smaller image scale but a much sharper image.

Graeme

Volans · #9 12-06-2006, 08:25 PM

Dear oh dear oh dear [1ponders],

Look at those pictures of your set up that you submitted! You are trying to give poor old Snibs the correct advice but you have FAILED to do so!!

You forgot to open up the flash on your camera.

How else will a good image of the Moon or especially any DSO be acheived? These things are faint and need all the illumination they can get!!

Snibs · #10 13-06-2006, 08:58 PM

Thanks again for the replys, it's been overcast so not done anything as yet. I am useing the T adaptor setup as in your pictures 1ponders but I had a 25mm eyepiece in the adaptor tube so that is where I went wrong I would say. No other ep's or barlow would work. Will post a pic tomorrow of the setup so you can see.
I realise the flash would be non affective in this situation...it was pointing in the wrong direction...thats why I pointed the spotty's on the front of my car at the moon.

Thanks again everyone.

Snibs · #11 14-06-2006, 01:29 PM

here's the pics of my setup, and one of the sun with the camera just pointed down focuser with normal lens on, tried ep in and out but could not focus anything with it out. The pic of the sun is much better than it looks here.
Thanks again all.

Rigel003 (Graeme) · #12 14-06-2006, 01:47 PM

Hi Mick
You need to get your camera closer the focal plane of the telescope lens. Can't you take out the middle section of your adapter and screw the camera T ring directly to the end bit that goes in the focuser? I have a similar one that works like this.

Graeme

[1ponders] (Paul) · #13 14-06-2006, 02:32 PM

Ok with the eyepiece in your are using Positive Eyepiece Projection. Try taking the eyepiece out and see how you go. You will get vignetting by using that Tele-extender. As Graeme says you really need to get the camera right down onto the focuser.

Snibs · #14 19-06-2006, 11:33 AM

Sorry for the delay in reply, I get gouty arthritis which puts me off my feet.
Didn't think of taking out the middle part but still no sign of focusing, I even butted the camera body alone up the the focuser but still nothing focus wise. short of taking the focuser off completely from the ota which defeats the purpose of a camera adaptor I can see no way to get the camera closer to the secondary mirror. The pic below is how I tried it this time, no ep can be used like this with this adaptor. Now I have another problem with mirror, I store the scope with open end pointing down and pillow cases on each end but there is some stain on it 2 to 3 inchs across so will have to clean it up before the days finished.
Thankyou all again and cheers from Mick.