Getting Focus

[Carole]

I managed to get out again last night first time since I got my flip mirror repaired which worked nicely last night.

I decided to have a go at the Moon this time.  I could not get any focus at all with the webcam with or without the Barlow x 2 lens (Telescope House were very reluctant to sell me a 3x Barlow even for Astrophotography).  Is it possible that I am pushing the telescope adapter on the Webcam too far into the socket?

Also, if I try to change the controls to reduce the brightness etc I have to take the auto off (there are two auto buttons, one is a tick in a square box (on K3 which you have to UNTICK) and one which gives a selection for auto, night sky, and two other choices which I can't remember).  I am assuming I should be unticking the auto in the square box.

Once I have de-selected auto I can change the controls but then sometimes lose the grey box which shows the image and I can only get it back by ticking auto again which then looses the setting changes.

So what's going wrong guys?

If I can't get this sorted out I think I will have to give up trying on my own and wait for either an imaging session (where we can actually image) or a DSC so one of you can have a look at what is happening/give advice etc.

Carole

[Ian]

Firstly, with the camera control, you need everything set to manual. None of the auto settings work particularly well for astro work, full auto won't work at all. So that's no ticks in auto boxes.

Getting focus is always the trickiest bit (apart from all the other tricky bits). If I remember the ETX focus mechanism is hidden from view which means you can do a rough focus by focusing using an eyepiece and then winding it in approxmately the difference in focus position for the camera. That sounds tricky because it's hard to explain, but much easier to demonstrate... Anyway, you can't do that.

Couple of tips, try and focus on the terminator. Unless the scope is massively out of focus you'll be able to recognise it. The contrast is highest there.

Wind the focusser all the way in (or out, doesn't matter) and then slowly wind the focusser out (at least slowly enough to recognise changes in the image) while watching the laptop screen, recentreing if necessary. You should see the focus improve. If you get the focusser all the way out achieving focus, try the same process with the barlow.

Bear in mind the barlow moves the focus out of the scope, a focal reducer moves it in.

I just googled and have found quite a few people imaging with an etx and a webcam, so focus is possible. You could also have a go during the day time, but again bear in mind that objects not at infinity will move the focus out a bit further. It's best to find something a very long way away to look at, that minimises the focus difference.

[JohnP]

Carole - Try in daytime first. Pick something a long way away - like telegraph pole or tree. I would leave settings in auto during daylight & try to focus. If you can't see anything from your garden why don't you pop across road to Norman park... Just take mount & scope etc. & setup at top end & then look at athletics track at bottom end - if I remember they have some suitable floodlight poles.. If you focus on these the position shouldn't be too far different for moon etc....

John

[mickw]

I also read somewhere about parfocal rings.
When you eventually get the webcam in focus, use a spare eyepiece (about 25mm) and attach a parfocal ring to it.
Remove the webcam, leaving barlows etc. attached to the scope, pop the eyepiece in and slide it up/down to bring into focus, do not use the focusser.  When it's in focus, tighten the ring.
Next time you set up, use the parfocal eyepiece to get into focus, then just swap it for the webcam - should be pretty close to being in focus.
This is all from memory....................

[Carole]

Hi Ian, John and Mick

I turned the focus knob slowly all the way both with and without the Barlow but all I got was a bright shape of the moon with at times something looking like white haze coming off of it.   I couldn't even get an out-of focus view of any craters. 
It could be perfectly focussed in the 25mm eyepiece using the flip mirror so it's not as if viewing conditions were bad.
What sort of magnification would the telescope adapter on the Webcam be do you know?  If I knew it's magnification it would give me some idea of where I was going.  Are these things standard?

Focusing in the daytime sounds a good idea, I'll give that a try.

Parfocal rings sounds a bit like what I was saying when I queried about maybe having pushed the webcam into the scope all the way.  I could have a try with various positions of insertion, then if that works I'll try something like the Parfocal idea. 

I'll also have a look at some ETX Astro-imaging users web sites.

Carole

[Mike]

Carle it sounds to me that your issue might not be focus but that the image of teh moon is far too bright and is beyond the well depth of the CCD. You may well have a perfectly focussed moon that is being viewed with too long a shutter time.

If you have been using auto settings that might be the case. As Ian says, ensure you control the exposure manually and keep the exposure times very short and the gain turned to minimum.

[Ian]

oh, and make sure the corrector isn't covered in dew. Not helpful to focussing, condensation ain't. See the C8n thread...

[Mike]

oh, and make sure the corrector isn't covered in dew. Not helpful to focussing, condensation ain't. See the C8n thread...

Ooh yeah good point. Shouldn't be any moistrue inside there if Carole has stored the unit correctly, but it would be a bugger to get out once it got in !!

[Ian]

Shouldn't be any moistrue inside

true, but I was think more along the lines of it being on the outside of the corrector... However, I don't believe the tube on an etx is particularly well sealed. Don't keep your scope in the bathroom folks!

[MarkS]

Carole, Mike,
I did EXACTLY the same thing last night with Mars.  I moved the focus in and out, in and out, in and out but Mars remained a featureless white blob on the screen. I then realised the image was totally saturated because the camera controls were in auto mode.

[Carole]

You're all giving me good input, but unfortunately I tried all this with auto on, auto off, brightness down, gain up AND down (as I was not sure which way it had to go), but it didn't make any difference either way.

I must say I was wondering along the same lines as Mike, whether the Moon was just too bright a subject for the CCD as it was still very bright even with brightness turned down to minimum.  should I have a Moon filter on to image the moon?

I don't know what bit of the telescope is the corrector, does it have another name?  There was a small amount of dew on the "glass aperture" end of the scope when I brought it in, but nothing to write home about, and that made no difference to normal viewing through the eyepiece.  I think the only sin I committed was not having the telescope in a cold room for more than about 1/2 hour before using it.

I never even got as far as taking an image as there seemed no point until I got something worth taking on the CCD screen. 

I am wondering whether it would be a good idea to try to focus the moon during the day time, as this will have the distance and not be as bright as night.

I normally keep my scope in it's padded carrier bag (having waited for any moisture from previous use to evaporate before putting the dustcap on and the scope away), and then keep this in my 3rd bedroom which is an office/Astronomy/sewing room, so no moisture in there.

I don't know whether I am being completely daft here, but is the telescope adapter on the webcam supposed to have any magnification in it at all as I've just had a look through it and it seems to just be a plain bit of glass to me.  I can't see how it can focus without something equivalent to an eyepiece or are we just relying on the Barlow for this at only 2 x magnifcation.  Or have I got a piece of kit missing that no-one has told me I need!!

Carole

[Ian]

the bit of glass in the adaptor is hopefully an IR filter, and you don't need any sort of lens to get an image on the ccd.

The moon isn't too bright, I have imaged the moon with a webcam on my 8" and that has a much brighter image than your ETX. Focussing on the moon during the day wouldn't be much different to during the night, it's just as bright (the sky's just caught up with it during the day). In fact, it's much lower contrast during the day which won't help.

If you can see the moon in the eyepiece you really aught to be able to get something, so I would suggest trying again, being methodical (which is a good habit have anyway when astroimaging) and adjust only one thing at a time.

Any dew on the corrector (the first bit of glass you see when you look down the business end of the scope) will affect focus. It's best to get rid. A hairdrier is the best for that.

Finally, there's a chance that you were trying to focus on an internal reflection in the scope, not the moon proper. It's easily done (I've done it) as they can be very bright. Might be worth double checking that the moon is in the middle of the eyepiece.

Once you get it, there'll be no stopping you...

[Mike]

Like Ian said, with teh gain at minimum and the shutter speed at its fastest (60fps?) you will get a nice DARK image of the moon if it is all set up correctly. If it is still too bright there is something seriously wrong somewhere.

[JohnP]

Carole - I know it's crap weather at the moment but you need to try it during the day - at least if you can focus on a distant object you know issue is with not having the right settings & not to do with the fact that you can't reach focus... it'll only take 5mins to test if we ever get a break in the clouds or you could even try pointiing the scope through an upstairs window if you have a reasonable horizon...

John.

[Carole]

John,

I certainly wasn't looking at an internal reflection of the Moon through the eye piece, and when I flipped the mirror over I could see the shape of the Moon against the dark sky on the CCD which was very bright, but other than that and the wisps of haze, nothing else whatever I did, focus and fiddling with controls gave any clearer picture.

I will check that what I am getting through the rear port is the same as the right angled eye piece (since the flip mirror has just been repaired) and also try to focus it during the day time.

Incidentally I did not bother to switch the motors on on the scope as really all I wanted to do on this occasion was find out how to get a good image on the screen(!!) using focus and controls, as Mike says - one thing at a time.

Since Ian has previously imaged without using drive I assumed it would not make any difference to the image on viewing, just on capture and I did not want to go through all the rigmarole of aligning the scope just to end up with nothing (once again!) at the end of it.  Had I managed to achieve this then I would have aligned the scope and taken an image.

Maybe this is what is wrong.

Carole

[JohnP]

Carole - Have you got the webcam connected directly to the scope or are you connecting via the flipped mirror... this may be causing you the problem - John

[Carole]

I am using the ETX rear port for the webcam and using the right angled eyepice to view the object.  Once I have the object in the eyepiece I flip over to the rear port to get the image via the webcam onto the laptop screen.

This method was suggested to me by the shop that sold me the webcam (as recommended by Mike) forgotten the name.  Obviously when I am looking through the eyepiece (on top) I get no image at all on the laptop.

Carole

[Carole]

Just remembered the name of the shop that sold me the kit - (Modern Astronomy).

As you can imagine I am getting rather frustrated having spent around £250 and lots of nervous energy (not to mention all your nervous energy) and still not made any headway except I think I understand the mechanics of it all now, thanks to all your help.  However I am not going to be beaten yet.

Plan:
a) Try the focus out during the day on a distance object.
b) Check the rear port is showing the same as the eyepiece.

If that fails - nervous breakdown.
Recover from that and then I think I have to get together with some-one and go through the procedure and kit etc etc.

I've done everything I have been told to do and still not getting any result from it.

Carole

[JohnP]

If you can't focus in daylight try taking the flip mirror off & putting the webcam directly in the focusser tube.. John

[Ian]

I can sense your frustration Carole, and it's something we've all felt. Ask Mike about imaging with his Bresser scope on it's blancmange tripod...

I would say you are probably doing everything right, except one thing. You've got your head around the software, you've got all the equipment you need to image the moon and maybe a planet or two.

Like John, I'm wondering about that flip mirror. Because the size of the webcam chip is very small, it can be a challenge to get the target onto it and it wouldn't take much for the alignment of the mirror to be off. That's not a critism of the scope or Telescope house who I know have recently repaired it, just a statement of fact.

I would try a couple of things. Firstly, as John says, try putting the camera in the eyepiece hole, see if that's any better (obviously leaving the mirror where it is). Obviously you can't take it off, it's integral...

Or, or and, I'd take a piece of tracing paper, ground glass or something, and try to locate the focus plane of the scope through the rear port. All you need to do is point the scope at the moon and then hold the paper over the hole. Move it back and forth until it looks to be in focus. If that's close to where the CCD would be great, otherwise adjust the focus (probably by quite alot) and try again. it will also give you a clue as to whether the moon is centred in the rear port when it's centred in an eyepiece.

Don't give up, there's always a logical explanation. Somewhere.

[Carole]

Thanks every-one I'll give all these suggestions a try (except removing the flip mirror) and report back - weather permitting!!!

I haven't tried using the eye piece for the webcam as Mike said this was not an option, but anything is worth a try just to try to eliminate the problem.

Carole

[Carole]

The Results:

Imaging during the day has been a good exercise. 

I did not go to Norman park for 3 reasons:
a) It was an awful lot of kit to take and set up.
b) I would have felt a right nana doing this on my own in the middle of the day with all this equipment amongst jo public.
c) As some of you know my laptop battery has had it and I would have had to have taken the leisure battery, all the leads and the invertor, none of which I have tried out yet and I am not quite sure how to wire up the invertor and thought I should get some advice before blowing every thing up.

I looked through the bedroom window as I could get a more distant land-object view than in the garden.  Only managed to look at something in the next parallel street. 

I did however manage to confirm that the flip mirror is looking at the same as the eyepiece but upside down (I had forgotten that would happen because of the right angled lens in the eye piece).  It doesn't seem quite so central (vertically) which is not a problem on land items but I hope that is not going to be a problem with vast distances, and the focus knob needs to turn about 120 degrees clockwise when switching to the rear port and the Webcam.

I was able to play around with the controls and got an image.  Yippee!!!!!

What I have learnt from this is that the image on the screen is more granular than I had expected and that I could really do with a remote controller to change the focus as it is jumping around all the time, and this might be the reason I got the haze artifact.  Do they do such a thing?

Now what I need to do is see whether Focus at a more distant object requires the same amount of turning.  Incidentally I did all this without the Barlow.

With the Barlow:  It seems to need to turn through 360 degrees clockwise.
Interestingly this 2nd subject (waving palm leaves) needs 1/3 gamma 90% brightness 1/50 shutter speed and Maximum Gain for the best picture.  I am sure this is because it is a daylight object.

So I will now try again and maybe try it out in some-one else's house who has a distant view.  though I can't think where at the moment.  If only I could take it to work, there is a fabulous view of the London Eye from the Gynae Ward at Lewisham Hospital!!!!!

So apart from having a better opportunity to play with the controls and actually being able to see on the screen what I am doing, and finding the focal point, I can't really seeing what I am doing wrong at night time.  But I guess it is just a question of doing excercises like this and experimenting.  At least I know it should all work now and I am not being thick.

Back to the night sky.

Thanks for all your help.

Carole

[Daniel]

Hi Carol, I've been having nightmares focusing too, partly because the live view display of my camera is much darker than what i see with the naked eye, and partly because of the horrible amount of shake as i turn the focus knob.

The latter i think i may have fixed by fitting an auto focuser (well a motorized focuser anyway) to my scope. The one i got was the skywatcher auto focuser and only cost me £49   http://www.widescreen-centre.co.uk/Catalogue/Focusers.html  it will fit most rack and pinion focusers and takes a couple of minutes to install.

I Haven't had the chance to test it in the field yet, but from what i've seen from it indoors, it seems to have an incredible amount of accuracy when you slow the speed of the focus down and i've been told it produces no scope movement at all.

Anyway, I'll be able to give you a better idea if this is any good as soon as this bloody cloud lifts and i get to try it out properly!

Daniel
:O)

[Carole]

Thanks for that Daniel, although it doesn't fit my scope, I thought there must be something out there. 

Thanks to the very useful daylight exercise yesterday (as suggested by the boys) I have come to the conclusion now that all the controls need fine tuning to get a good image and knowing where focus is is a big step forward as even if I had the controls in the correct position I still would not get anything without the focus and of course with me not doing any tracking on the last occasional I did not get enough time to fiddle with everything because it disappeared off the screen, so I've learnt another lesson there.  I am feeling much more positive about it all now.

Doug has kindly suggested I go to his house as he has a distant landscape view to try out focus on a more distant object which I will try to do as soon as we can both fit it in.

I believe you will be coming on Thursday as a new member.  Look forward to seeing you there.

Carole

[Daniel]

Hi Carole, which scope do you have? the auto focuser fits a lot more scopes than mentioned on that page (mine is a Celestron C8n) Might have to try the daylight focusing myself, though i too have the same problem, I used to be able to see the thames out my back window, now all i see is flats, might see if i can take the scope down to the waterfront some time and see if i can focus on the thames barrier a little way up.

I'd like to come along on thursday, but right now it's looking unlikely i'll be getting away from my computer till the 30th, have a deadline for a job im working on looming and im pulling some crazy hours (hence posting at all hours of the morning)

Anyway, here's hoping for some break in the clouds!

Daniel
:O)

[Carole]

I have an ETX105EC.  If it does others than the ones mentioned it might be worth an enquiry but the ETX has quite a different focus knob to most telescopes so I don't hold out much hope.

If you can't make the meeting, see if you can make Deep sky camp end of February/beginningof March if you have a tent and mate to bring you.  Nice dark skies there, lots of us viewing and imaging and lots of fun.

Carole

[Daniel]

Ahhh, February would be perfect for me, Im not due back at work till mid February and that's just some evening classes im teaching, so it's only a couple of nights a week which i can get someone to fill in for if it clashes, plus I'll finally be able to get some more use of my tent that i bought for glastonbury 05 (still looks a little worse for wear)

I'll be talking to the place i got my focuser from tommorrow, so i'll ask em about your scope aswell, I've just had an idea to sort out my focusing without a barlow woes, I've seen some slightly shorter T-adapters than the celestron one im using right now, im hoping that the extra half inch closer I can get the camera to the barrel  might just give me enough to focus with

Daniel
:O)

[Rocket Pooch]

I could have a try with various positions of insertion, then if that works I'll try something like

Would someone like to explain to me what's going on here? 

[Rocket Pooch]

[Shouldn't be any moistrue inside there if Carole has stored the unit correctly, but it would be a bugger to get out once it got in !!

Whats!

[Rocket Pooch]

I did EXACTLY the same thing last night with Mars.  I moved the focus in and out, in and out, in and out but Mars remained a featureless white blob on the screen. I then realised the image was totally saturated because

No!!!!!!!!!!!!!!!

[Rocket Pooch]

You're all giving me good input

Who what where?

[Carole]

Naughty naughty Chris, this is not pornography but me trying to ask how far to insert the webcam into the telescope.  But when you take it out of context, I agree it does look a bit risque. 

I think/hope I've got this sussed now, but still waiting for a clear night to confirm things.

Carole

[Ian]

Chris, write this down for when you're sober again.

I must not post when I'm p*ssed!

[Rocket Pooch]

I'm sober, I just scanned the thread and was shocked!!!!  You will never have me post anything like that, ever!

If I'm jolly it's because I'm at home more with my new job!