ASL 224 MC disappointed help p!ease

[Neil H]

Hi all can you help please I have the Orion Optics VX8l  and the ASL224mc camera  first outing this morning and did not go well

So I lined up on Jupiter put in camera and can't focus not enough back focus so put the case of a Barlow no lens still can't focus , so then I put Barlow with lens in and it will focus but not a sharp image ( it's nice and sharp with an eyepiece in ) I have a better image on my mobile phone camera ,so gutted at the moment 

The image on my laptop in sharpcap is steady it was windy so a little movement , if I try the focus aid like the bahtinvo mask the image goes mad  jumps all over the the screen so i can't focus or tell if focus is right 

The image looks like I am looking through thick fog , if I take the camera back out and fit an 15mm eyepiece the image to your eye is sharp , so put camera back in no matter what I change in sharpcap the image never gets good , I also tried Saturn same thing it's a blur 

I know it's more than likely some thing I am doing wrong , I am New this this so be gentle lol

[PeterCPC]

When I use that camera I use a Bahtinov mask to focus on a star first. I always use an IR block filter as the camera does not have one, otherwise I would get a fuzzy image. I can't answer to the VX81 because I use a C9.25 but I suspect that you need an extension tube.

Peter

[Neil H]

Hi Peter I have a IR cut filter coming today I hope , but if I used Barlow without lens as extension tube still don't focus  it may be better with IR cut filter

[fireballxl5]

It was a long time ago,  but when I first tried imaging using my OO GX250 with my SLR (in late 90's) I didn't have enough back-focus. I overcame this by using the full range of the primary mirror holder to move the mirror further up,  into the tube.  This pushed the focus point further out at the focuser. If you can do this it should avoid the need of the Barlow. 

[Neil H]

I had to move the mirror forward for visual focus after fitting new focuser , if I move it again will it mess up visual focus if an extension is needed  and would work I would go this route as I can just fit this when using the camera 

Edited June 6, 2020 by Neil H

[Neil H]

The only thing I did not try this morning was seeing the Barlow helped with focus would fitting the lens part of the Barlow to the camera this will bring camera down the focuser a little ?

Edited June 6, 2020 by Neil H

[andrew s]

When you focus with a eyepiece where is it aperture stop ? It will normally be inside the focus tube. That's where the ccd needs to be for focus. If you take the eyepiece out and just add the camera you should  move the focus in towards the main mirror.

Regards Andrew 

Re read your posts maybe that's what you are doing. Got confused by the barlow.tube.

tuse 

Edited June 6, 2020 by andrew s

[Neil H]

Just now, andrew s said:

When you focus with a eyepiece where is it aperture stop ? It will normally be inside the focus tube. That's where the ccd needs to be for focus. If you take the eyepiece out and just add the camera you should  move the focus in towards the main mirror.

Regards Andrew 

Hi Andrew if I remove eyepiece then fit camera I do moved focuser in towards secondary mirror but can't go in enough to focus so I removed one of my extensions I had to fit for visual use , but the camera still won't focus ?

Is this due to no IR cut filter  I am still waiting for it to come ?

I am using the 1.25 nose plate but it's a 2 inch camera so could fit direct to focuser but will need a 2 inch to 125 filter adapter

[andrew s]

An IR cut filter may make 1mm difference to focus. If you can identify the aperture stop it

 will tell you where the focal plane is.

Post a photo of both.set ups that might help.

Regards Andrew 

[Neil H]

Andrew what is ment by aperture stop ? Sorry very new to this 

[andrew s]

If you look in to the bottom of you eyepiece you should see a ring of metal that defines the edge of the field of view of the eyepiece.  This assume is it a simple non zoom eyepiece. This is where the telescope  focuses the light. Estimate where that is in the focuser when it is visually focused and that tell you where the ccd of the camera needs to get to.

Regards Andrew 

[Neil H]

Andrew will that change from what the mag of the eyepiece is ?

 

[andrew s]

27 minutes ago, Neil H said:

Andrew will that change from what the mag of the eyepiece is ?

 

What changes is where the aperture stop is in the body of eyepieces.  You have to refocus because they are in different places. Parfocal eyepieces have them at the same physical location in the eyepiece barrel.

The focal plane of the telescope is fixed in a Newtonian. 

Regards Andrew 

[Neil H]

Hi Andrew I hope I have it sorted now working on what you said , I am going to try this I will remove the self centering eyepiece holder and the 1.25 nose piece adapter  this will move the camera towards the mirror by about 17mm , which I think may sort it as it nearly focused but I run out of back focus this will give me more if not I will get a shorter extension

Edited June 6, 2020 by Neil H

[Neil H]

Hi Andrew I tried again last night seeing was not very good , but the camera did focus on a star with a little change in software  and no Barlow , when I tried the moon due to it being

low down it was not that clear 

How do you reduce the size of it ? What I mean is it's like using a high mag eyepiece could only get a 1/4 in the FOV 

Trying to get my head round sharpcap lol

[andrew s]

High magnification is what you want for planets but the only way to increase the field would be to use a focal reducer but I have no experience of them with a Newtonian. 

.Regards Andrew

[Tomatobro]

Whenever I get a new setup I always do a daylight test first. I am fortunate that I can see a top of a tree which is about a kilometre away so I point the scope at this and then play with the focus position etc. Also it allows for experimentation with the camera and software. If insufficient back focus is available you can even pull the camera out and by hand move it to when rough focus is achieved. I then wind in the focuser half way, measure this distance and search the suppliers for a suitable spacer.

Its not at infinity but near enough for a first look. When the spacer arrives I redo the test and make a note of the focuser wind out measurement ready for the next clear night.

[Neil H]

It seems to focus before the end of the back focus , I cant do focus test in the day time stuck at home can't see anything more than 30 feet once I can get out I will be able , the seeing was to bad last night for planets so I will carry on playing with software etc  till things change 

This is arcturus just as a focus test 

Edited June 7, 2020 by Neil H

[Tomatobro]

see how those diffraction spikes are split into two on two spikes. That's a hint that your mirrors need collimating.

[Adam J]

20 minutes ago, Tomatobro said:

see how those diffraction spikes are split into two on two spikes. That's a hint that your mirrors need collimating.

It can be about three different things, colimation would have to be very far out and you would not expect it to effect all four at the same time.

So this is more likely twisted spider vanes.

Adam

[Tomatobro]

I agree. Vane checking is part of collimation so I just used it as a reference. My guess was that Neil did not know that there was some extra information in the picture of the star that might help with his problems.

[Neil H]

Hi guys I do normally check Collimation after the scope has cooled down it may be a little out but I think it's the vanes I get it even if Collimation is 100% other than changing mirror mount to a single vane what else can we do to stop it 

[Tomatobro]

I think I am guilty of confusing you a bit. The diffraction is (usually) because when you look down the tube you will see that one or two of the secondary mirror support vanes is not parallel with the light path and it is twisted slightly. If the vane support screw is slackened off a bit the vane can be twisted back and the screw re tightened.  When that is done it may (read probably will) push the collimation out a bit. 

So what I mean is that just straightening the vane is a bit of a bodge if done in isolation without going through all the collimation steps.

[knobby]

All I can add is that planets are low so you're shooting through a lot of murky atmosphere and heat haze. You'll be very lucky to get much more than a blurry image till the planets are higher in the sky again. The whole idea of video / lucky imaging is that amongst the 2 or 3 minutes of video you collect , some of the frames will be during the moments of good seeing. When you stack the frames and select the better ones you end up with an image that you can sharpen. Don't give up and good luck.

[Neil H]

I did 3 x 300 frame videos of the moon in raw but autostacker3 does not want to stack them, I  can't work out what I am doing wrong  I select points for it to align to but no joy 😂

Edited June 7, 2020 by Neil H