ED66 First Light - the Good, the Bad and the Ugly

[Stub Mandrel]

I got my first light with the ED 66 last night.

Colours and definition are great, in fact hardly any colour correction needed. Nebulas don't show well, presumably because of the poor seeing really unstarry sky even through bins (through bins Andromeda was a pallid averted vision object), and high background level also I stuck with short subs - as you can see from the heart nebula ?

 I'm sure my focus was off as well, as I forgot to print a suitable bahtinov mask. I think this is why some stars look a bit doughnutty and not too tight.

I can't see any CA, which is great!

I forgot to take flats before splitting the kit and a couple of dust specks moved, luckily the resulting patches were round and easily masked and darkened/lightened

The big issue is the stretched stars at top right.

I'm using a field flattener that has been reported to work well with the ED 66, my guess is that this is tilt as it is just the one corner.

It could be that my sensor isn't level in the camera as it's been apart many times.

What's the best way to address the issue?

Ah... the pictures, still works in progress:

First up the Veil, very affected by poor transparency, mostly bits of cloud passing through. which also hit guiding. 38 usable 2 minute subs. Disappointed by teh near total lack of detail in the nebula, probably my bad focusing:

Next off to Andromeda, 33 2-minute subs, probably the best of the bunch, a decent number of subs and less cloud. Every time I've imaged Andromeda I've battled with colour. This one just sorted itself!:

The Heart Nebula, barely visible despite being 15 5-minute subs. I finally get the framing right and the nebula hardly shows!:

Back to 2-minute subs for 11 quick snaps of the Pleiades (I wanted to go to bed, but decided to give it another 20  minutes...):

[Demonperformer]

Very promising start for the new setup, Neil.

[Allinthehead]

Nice first light. As for the elongated stars, well that could be down to focus as i see it in more than one corner, but yes check for tilt and double check spacing. I often find bad focus has an impact on my corner stars among multiple other causes.

[Stub Mandrel]

32 minutes ago, Allinthehead said:

Nice first light. As for the elongated stars, well that could be down to focus as i see it in more than one corner, but yes check for tilt and double check spacing. I often find bad focus has an impact on my corner stars among multiple other causes.

Thanks, I've printed a bahtinov mask and it's 2mm too small to fit on the dewshield!

I'll have another go tomorrow. It shows promise for good conditions and the framing complements the 130P-DS and 150PL very well.

The lack of CA compares to even a really good camera lens is striking.

[happy-kat]

Great to read you're enjoying the use of your baby ED project.

[Adam J]

9 hours ago, Stub Mandrel said:

The big issue is the stretched stars at top right.

I'm using a field flattener that has been reported to work well with the ED 66, my guess is that this is tilt as it is just the one corner.

It could be that my sensor isn't level in the camera as it's been apart many times.

What's the best way to address the issue?

You need a laser collimator, a 2 inch nose piece and a 2 inch eyepiece extension tube.

Attach the nose piece to the camera t-ring, then the extension then place the laser collimator into the other end of the extension pointing at the camera sensor.

You need to have the camera disassembled so that you can access the three sensor tilt adjusters. Also you need to manually trigger the mirror.

You will see the reflection of the laser from the sensor on the collimator. Adjust the sensor until the brightest reflection is exactly in the center.

I place some sticky tape over the laser aperture to you can see the dot.

The longer your eyepiece extension the better the accuracy you can achieve.

I did this with my 550D

Make sure its not the scope first be rotating the camera and seeing if the distortion pattern is fixed relative to the scope or to the camera.

Adam

[Stub Mandrel]

10 hours ago, Adam J said:

You need a laser collimator, a 2 inch nose piece and a 2 inch eyepiece extension tube.

Thanks Adam,

I have the bits so I'll do the check.

This is a pic using the same camera with my 130P-DS, which is only 590mm effective FL (compared to 400) and it doesn't show the effect so I'm starting to think it's either focus or maybe some tilt in the imaging train.