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Author Topic: Is it the camera or me?  (Read 541 times)

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Offline denagirl

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Is it the camera or me?
« on: 16:16:55, 14 October, 2017 »
Hi there I am very new to this group so be gentle with me. I have a Lunt 50ha scope and have tried unsuccessfully to take pics of the Sun but could not get focus using a DMK 21 so yesterday at the IAS I bought an Altair Astro gh 130 mm and today, between the clouds, I gave it a go, but much to my dismay I could not get focus. I tried it with and without my Barlow (x2)  I moved the blocking filter (b600) in and out, adjusted the exposure and gamma Etc. but all I got was a white blob with absolutely no detail. I took off and replaced the tuner still nothing so I finally gave up. I put in an eyepiece and although no sun spots I could see promencies and some surface detail. Any ideas. :(

Offline chris.bailey

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Re: Is it the camera or me?
« Reply #1 on: 16:39:57, 14 October, 2017 »
Hi

If you are seeing a white blob you are probably fairly close. Do you keep the diagonal in place with the camera i.e. just drop the camera in where the eyepiece goes? The zone of focus is actually fairly narrow so you need to find how far the blocking filter needs to be out (on mine its about halfway) and then rack the focuser in and out until you see it snap into focus.

The other thing is that the exposure needs to be pretty darned short so if the white blob is very bright, shorten the exposures a bit until it dims down.

HTH

Chris
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Offline Carole

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Re: Is it the camera or me?
« Reply #2 on: 20:11:41, 14 October, 2017 »
Are you looking at the white blob on a computer?  If so, what capture software are you using?  It might well be that the sliders need adjusting and it's just over exposed.

How many frames per second are you choosing to focus with? 

It can all make a difference.

Carole
Mount: NEQ6 (on pier), HEQ5 (for astrocamps),  Telescopes: SW ED120 Pro and SW Evostar ED80 pro, WO ZS71 APO, Cameras: Modified Canon EOS 450D, Atik 460EX, Atik314, DMK21, DBK, Dual rig options. Observatory: SkyPOD & PZT
https://sites.google.com/site/caroleastroimaging/home

Offline denagirl

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Re: Is it the camera or me?
« Reply #3 on: 22:07:33, 14 October, 2017 »
Hi Carole, the software is Sharpcap, the latest version that I downloaded from the Altair Astro site. The frames I set at 15 per second.

Offline Carole

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Re: Is it the camera or me?
« Reply #4 on: 10:41:20, 15 October, 2017 »
OK well next time try adjusting all the sliders, it might well be that  one of them is too high when you are trying to focus and you are simply overexposing.

When you capture use something like 30fps.

Carole
Mount: NEQ6 (on pier), HEQ5 (for astrocamps),  Telescopes: SW ED120 Pro and SW Evostar ED80 pro, WO ZS71 APO, Cameras: Modified Canon EOS 450D, Atik 460EX, Atik314, DMK21, DBK, Dual rig options. Observatory: SkyPOD & PZT
https://sites.google.com/site/caroleastroimaging/home

Offline denagirl

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Re: Is it the camera or me?
« Reply #5 on: 11:03:58, 15 October, 2017 »
Hi Carole thanks for the tip. Next clear day I will try as you suggest. Cheers.

Offline Nomis Elfactem

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Re: Is it the camera or me?
« Reply #6 on: 21:19:57, 15 October, 2017 »
Firstly, ignore the frame rate, that's just how many frames are being thrown down to the computer from the camera... you can have very different exposure settings but still have the same frame rate... the exposure and gain are the important ones....

First thing to do it to turn the gain down to 0 (we'll look to changing it later but not until we get a clear focused image). 

Leave the Gamma at 1. 

Then if you look under the exposure you will see a "quick picks"... click on that and select 1/250.  As you are imaging the surface it is quite bright so you need to use a high shutter speed.

Next (assuming you are aligned on the sun) move it till you can see that you are leaving the edge of the disk (it will start to get dark over the field of view as you move the mount).... when it appears to start to go dark stop and start to try and achieve focus.  As Chris says you try it half way out and move the focuser in... if you reach the end pull back out. 

If you are on the edge of the sun you should be able to if the disk is getting bigger or smaller as you move the focuser which will hopefully give you an idea which way focus exists.

Its worth noting that if you can see surface detail with an eye piece then the pressure tuning is nearly there which won't effect focus.

Give it a go and see how you get on.... if you are able to record a short video of what you're getting and post it somewhere for us to look we may be able to help a bit more too ;-)

S.
Simon

Scopes: Astro-Tech AT-111EDT Triplet, TS65ED Quad, Orion ST80, Modded PST-90 Solar Scope, PST Cak (on loan)
Cameras: SXVF H694, Atik 16ic, Canon EOS 600d, DMK41, DMK21, QHY 5L-II (mono & colour)
Accessories: SX USB Filter Wheel, SX OAG, Baader LRGB Ha SI OII Filters, SharpSky Focuser
Mount: EQ6 (EQMOD), SW Star Adventurer, plus a lot (and I mean a lot) of other bits and pieces

Offline denagirl

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Re: Is it the camera or me?
« Reply #7 on: 10:24:26, 16 October, 2017 »
Thanks for that I will try those settings once the Sun comes out to play. With the help I'm getting on here I feel I'm getting somewhere. Thanks to everyone. As I say once the Sun shows I am going to try again. I will keep you posted and let you know my final settings.

Offline denagirl

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Re: Is it the camera or me?
« Reply #8 on: 13:28:44, 17 October, 2017 »
I have taken a pic of my laptop which shows the best I can achieve. I have even tried putting two Barlow in both with and without the lenses, it was not this hard studying for my Masters Degree.

Offline Nomis Elfactem

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Re: Is it the camera or me?
« Reply #9 on: 20:44:00, 17 October, 2017 »
Great stuff.... that looks pretty good from a focus point of view which is half the battle.

Looking at the all white area at the top it's clear you're still over exposed, quite a bit.  Now increase the exposure until the whole area goes grey (i.e. no white bits).  To help you, if you look at the top menu bar, next to the Zoom bit (where it says "100%) you can see a button with a graph on it... if you click on that you will see what's called the Histogram.... you need to change the exposure now so that it looks like the graph image on the button itself (i.e. the line is up at the right hand side but drops down and hits the zero line about two thirds of the way along).

Once you've got the exposure right you can start to play with the tuning to get the surface detail to jump out.

Finally, looking at the picture it looks like you've got some Newton's Rings (a form of light interference due to internal reflections of internal optical surfaces).... you may need to consider a "tilt adapter" or  different/higher quality barlow, if one was used, that has a better transmission coating (like a Powermate) which should remove them but that's the last thing to worry about. 

Finally, I think I can also make out your frame rate is set to 30... change this to "maximum" and you don't need to worry about it again ;-)

You've nearly got it so hang on in there.... if it helps the solar surface is a little barren at the moment so a good to time to work things out for when hopefully some spots will develop/come into view ;-)

S.

Simon

Scopes: Astro-Tech AT-111EDT Triplet, TS65ED Quad, Orion ST80, Modded PST-90 Solar Scope, PST Cak (on loan)
Cameras: SXVF H694, Atik 16ic, Canon EOS 600d, DMK41, DMK21, QHY 5L-II (mono & colour)
Accessories: SX USB Filter Wheel, SX OAG, Baader LRGB Ha SI OII Filters, SharpSky Focuser
Mount: EQ6 (EQMOD), SW Star Adventurer, plus a lot (and I mean a lot) of other bits and pieces

Offline denagirl

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Re: Is it the camera or me?
« Reply #10 on: 21:49:35, 17 October, 2017 »
Thanks again, if I move the exposure then the Sun goes really fuzzy at the edge, having the exposure where it is gives me the sharpest edge I can get. I moved,very slowly, gamma, gain Etc. I put in two Barlows they were both x2 I tried with a combination of one lens no lens and both lenses in. I think I may end up saving for a Powermate.

Offline Einari

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Re: Is it the camera or me?
« Reply #11 on: 06:03:15, 18 October, 2017 »
If you lower the exposure and edge goes fuzzy I think you then have to tweak focus some more.
Tapio

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Offline Nomis Elfactem

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Re: Is it the camera or me?
« Reply #12 on: 12:14:42, 18 October, 2017 »
Yeap, exactly as Tapio says.... get the exposure right then (re)adjust the focus !!  The fact you can see a defined edge means you're nearly there so it's just a case of getting each part of the equation right.  The fact that it (appears) to go out of focus when you adjust the exposure is a good indication you're actually technically not focused.  :no: :D

I'd also leave Gamma and Gain set to default... we can talk through those when focus and exposure are correct, as they will just make things worse / confuse things until true focus is achieved and the exposure is in the correct ballpark.  As I mentioned above, the best way to know when exposure is right is to use the histogram  ;) :thumbup:

Finally, I would recommend only using 1 barlow max and it might actually be simpler to not use one at all until you get the settings right.  Using x4 on that scope / camera combination is always going to be pushing things unless atmospheric conditions are near perfect.... I would never recommend going above x2 for solar work unless you have top of the range optics and camera and live is a hot country with nice clear and transparent skies  ;)

If you can post up a picture of your set-up that might also help us point you in the right direction  ;) :thumbup:

S.
Simon

Scopes: Astro-Tech AT-111EDT Triplet, TS65ED Quad, Orion ST80, Modded PST-90 Solar Scope, PST Cak (on loan)
Cameras: SXVF H694, Atik 16ic, Canon EOS 600d, DMK41, DMK21, QHY 5L-II (mono & colour)
Accessories: SX USB Filter Wheel, SX OAG, Baader LRGB Ha SI OII Filters, SharpSky Focuser
Mount: EQ6 (EQMOD), SW Star Adventurer, plus a lot (and I mean a lot) of other bits and pieces

Offline denagirl

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Re: Is it the camera or me?
« Reply #13 on: 14:31:55, 19 October, 2017 »
Hi guys thanks for the input, once the Sun comes out to play I will try again and keep you posted as to any or not progress. That's the trouble with this lark, we have to wait for things, that are not in our control, to get better.

 

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