Main camera focus

[bosun21]

I have been out in the  freezing cold for hours trying to get my main camera focused. I am using an asiair plus and a ASI585 MC camera. Everything is connected and settings etc but when I try to focus the main camera all i get is a gray screen like a bayer matrix 

 
I have racked the focuser to each extreme and tried changing the gain on the main camera. Still nothing. I set it on 2 second exposures and looped them while focusing, or trying to. This first try at EEVA has been a disaster. Any help folks? Thanks 🙏🏻

[LaurenceT]

Try it in Preview mode.

[Gary Clayton]

As the moon is out tonight try focusing on that first, if you don't have any luck it could be that the camera is not at your scopes focal plane and more spacers could be required to get there.

[Gfamily]

What are you trying to focus on?  Start with something bright - the Moon if it's visible, or Jupiter (or even a distant streetlight). If you know you have something bright properly centred in the field of view, then you can start adjusting the gain and the exposure to get the image on the screen.  

[tomato]

+1 for pointing it at the moon right now. You’ll know it’s in the field of view no matter how far out the focus is and as the previous posters have stated, then you have something to start making your camera and focuser adjustments on.

[bosun21]

Thanks for advice. I was just pointing at the dark sky. My fingers are like bananas now going to pop inside for a bit and let them heat up a bit. Total brain freeze. I didn’t even think of the moon or Jupiter despite them being in my face!  I’ll try this next. Thanks  

   Ian 

[bosun21]

36 minutes ago, LaurenceT said:

Try it in Preview mode.

It’s in preview mode 

[LaurenceT]

34 minutes ago, bosun21 said:

It’s in preview mode 

Looked to me like it was in Focus mode.

[Elp]

What is your imaging train setup (scope, flatteners/coma corrector, filter drawer manufacturer/models) and what distance of backspacing have you set from the rear of all that to the camera?

[Gfamily]

For the Moon, you shouldn't have any problem getting it in the field of view, but for planets, it'l be worth boosting the exposure or the gain right up high.

The focus is likely to be way out, so the image of the target will be bigger (and more diffuse) than you might expect, so boosting the gain should allow you to see the out of focus image - even if it's slightly outside the field of view of your sensor.

ETA - once you know roughly where the focus point is, it'll be time to switch to a nearby bright star and use a Bahtinov mask to refine and lock down the focuser.

Edited December 7, 2022 by Gfamily

[bosun21]

55mm from my reducer/flattener to the camera sensor. Reducer/flattener - 15.5mm spacer- 17mm filter drawer- 5mm spacer to ASI585 MC = 55mm

[bosun21]

1 hour ago, Elp said:

What is your imaging train setup (scope, flatteners/coma corrector, filter drawer manufacturer/models) and what distance of backspacing have you set from the rear of all that to the camera?

55mm from my reducer/flattener to the camera sensor. Reducer/flattener - 15.5mm spacer- 17mm filter drawer- 5mm spacer to ASI585 MC = 55mm

[bosun21]

1 hour ago, LaurenceT said:

Looked to me like it was in Focus mode.

I’ve had it in preview mode most of the night 

[bosun21]

I’m calling it quits tonight. 3.5 hours of banana fingers and no image has broken my resolve for the night. It’s supposed to be a clear night tomorrow so I’ll resume then. I was thinking of removing the reducer/flattener and spacers etc and just fitting my vixen flip mirror. That way I can see the target centered in my eyepiece then flip it to camera. Thoughts anyone.

[PeterC65]

My advice is to try the kit in daylight first, especially if you're using a reducer as they can move the focus point in unexpected ways.

I test all of my camera setups (camera alone, with Reducer, with Barlow) in the daylight pointing the scope at a distant object and recording the focuser position needed to achieve focus, and whether any extension tube is needed. Then on the night I set the focuser to the appropriate setting so that I can be confident that whatever I point at will be approximately in focus.

Dark empty sky and clouds can be very confusing with EEVA. They can look like masses of noise which is what your image seems to be. Being inside doing EEVA I'm often unaware of cloud rolling in and then wonder why there is so much noise in the image🥴.

I usually point the scope manually at something obvious (Jupiter at the moment) using the RDF and go from there. Jupiter is not a great target for focussing so I find some bright stars nearby and focus on them with a Bahtinov mask.

[PeterC65]

7 minutes ago, bosun21 said:

I’m calling it quits tonight. 3.5 hours of banana fingers and no image has broken my resolve for the night. It’s supposed to be a clear night tomorrow so I’ll resume then. I was thinking of removing the reducer/flattener and spacers etc and just fitting my vixen flip mirror. That way I can see the target centered in my eyepiece then flip it to camera. Thoughts anyone.

My first EEVA session was VERY frustrating and I came away thinking I had wasted my cash, but keep persevering and you will find it a useful tool.

I would start without the reducer / flattener, and check the kit in the daylight tomorrow before having another go at night. You need to be confident that you have the right configuration to achieve focus, and preferably that you are already close to focus. The nighttime camera image can look pretty weird when you are far from the focus point. The flip mirror may be a good idea, in the same way as I use the RDF. 

[Elp]

Seems okay as long as it's correct to your flattener, to confirm that's 15.5+17+5+11 (zwo camera ring)+6.5 (cam front to sensor distance) = 55mm.

In your screenshot above the preview looks white (like a detuned TV white noise pattern), is that correct? Even if you're not in focus the preview should be mostly black unless there's local light pollution, and if you decouple the camera and point it to a light it should be an almost solid white colour in the preview.

[bosun21]

16 minutes ago, Elp said:

Seems okay as long as it's correct to your flattener, to confirm that's 15.5+17+5+11 (zwo camera ring)+6.5 (cam front to sensor distance) = 55mm.

In your screenshot above the preview looks white (like a detuned TV white noise pattern), is that correct? Even if you're not in focus the preview should be mostly black unless there's local light pollution, and if you decouple the camera and point it to a light it should be an almost solid white colour in the preview.

The only way I can get it all black is by moving the histogram slider. I brought it all back indoors as I was numb to the bone. I set it all up indoors and pointed it to a streetlight through my window and by selecting auto on the histogram I managed to get a picture of the streetlight with a ton of aberrations, Probably due to my window glass. Should I be moving the histogram to achieve a picture? Thanks

      Ian 

[Elp]

4 minutes ago, bosun21 said:

Should I be moving the histogram to achieve a picture?

It's just for preview purposes. If you leave it on auto it will give you a general idea of what each sub will look like. Sometimes it's useful to adjust if you're imaging something very dim.

[bosun21]

42 minutes ago, PeterC65 said:

My first EEVA session was VERY frustrating and I came away thinking I had wasted my cash, but keep persevering and you will find it a useful tool.

I would start without the reducer / flattener, and check the kit in the daylight tomorrow before having another go at night. You need to be confident that you have the right configuration to achieve focus, and preferably that you are already close to focus. The nighttime camera image can look pretty weird when you are far from the focus point. The flip mirror may be a good idea, in the same way as I use the RDF. 

Thanks Peter, this was my exact thoughts as well. I spent a ton of money and I was thinking " What a total waste of time and money". I brought it all back indoors and tried it on a streetlight. By moving the slider on the histogram I got a badly focused streetlight with a load of aberrations due to the window glass. I will not throw the towel in, and I'll be back out tomorrow night plus I will try it in daylight as well. 

[bosun21]

56 minutes ago, Elp said:

Seems okay as long as it's correct to your flattener, to confirm that's 15.5+17+5+11 (zwo camera ring)+6.5 (cam front to sensor distance) = 55mm.

In your screenshot above the preview looks white (like a detuned TV white noise pattern), is that correct? Even if you're not in focus the preview should be mostly black unless there's local light pollution, and if you decouple the camera and point it to a light it should be an almost solid white colour in the preview.

Here it is 👇

[PeterC65]

10 hours ago, bosun21 said:

The only way I can get it all black is by moving the histogram slider. I brought it all back indoors as I was numb to the bone. I set it all up indoors and pointed it to a streetlight through my window and by selecting auto on the histogram I managed to get a picture of the streetlight with a ton of aberrations, Probably due to my window glass. Should I be moving the histogram to achieve a picture? Thanks

      Ian 

Looking at the image you first posted, you seem to have too much gain and / or too much histogram stretch, both while pointing at dark sky / cloud or while very out of focus.

It took me a while to figure out how to use the camera controls when I started EEVA and I struggled to find any advice online, so here is what I do ...

I use SharpCap and with my Player One version of the IMX585 that gives me a gain range of 0 to 800, so you may need to adjust the gain settings I mention if the range available to you is different.

I use a gain of 400 for most DSOs. Sometimes I go down to 250 for brighter objects, maybe a little less for planets. I use a gain of 650 only when finding objects. Anything more than 650 and there is too much noise in the image.

With an F6 scope, I use an exposure of 4s for most DSOs, 0.5s for focusing and around 10ms for planets and the Moon. For these brighter objects I adjust the exposure so that the image is just below the clipping level (SharpCap has a tool that tells me when the image is clipped). I only go above 4s when I have the Barlow fitted (>F6) as I like the image to be close to real time. When focusing 0.5s gives me a sufficiently frequent update.

Histogram stretch can be useful for revealing faint detail but use it with great care. SharpCap has two histograms, one which operates on each frame and affects just the display (the Display Histogram) and one which operates on the live stack, again affecting just the display (the Stack Histogram). I almost never use Display Histogram stretch these days. Instead I wind up the gain (to 650) and point at bright stars when focusing. I always use the Stack Histogram stretch, but that's not used for focussing or framing the image.

My advice for focussing next time you're out in the evening is to set the gain to 650, the exposure to 0.5s, the histogram to no stretch, and point the scope manually at a bright star, something that is obvious with the naked eye.

Take a bit of time getting used to the camera controls. I tried out gains in steps of 50 before settling on my prefered settings.

 

[PeterC65]

Just another thought about focus ...

The StellaMira x0.6 reducer that I use with the Photoline 72 when set to the correct 55mm of back focus will not achieve focus. It needs 2mm of additional in focus. You may have a similar problem. I resolved this temporarily by setting the back focus to 53mm which meant I could achieve focus at 2mm. I've now resolved it permanently by replacing the clamp on the Photoline 72 with a shorter one that gives me 21mm of additional back focus, and the reducer is back to it's required 55mm of back focus (actually 55.5mm as it should be 55mm + 1/3 of the thickness of any bits of glass in between, like filters and the camera window).

 

[bosun21]

Thanks Peter, I don’t have Sharpcap as the asiair plus is a stand alone unit. There was no clouds in the sky at the time. The gain recommended by ZWO is 250 for the ASI585 MC and I think the maximum i can adjust it to is 400. Can I set it up in daylight and try to focus on a distant target or other? I don’t want to be wasting any more clear nights. Thanks  

   Ian 

[bosun21]

Cracked it! I have set it up in daytime and just dropped the gain and exposure times to achieve focus on a distant berry tree. I achieved almost perfect focus on my main color camera and decent with my asi120mm guide camera. I am now looking forward to freezing again tonight. Thanks all  

   Ian