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Kenboy

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    Help with setup

    in Getting Started With Imaging

    Posted · Edited by Kenboy

    6 hours ago, rickwayne said:

    The very best way is to experiment. Fortunately this need only take a few minutes. Stop down the lens a bit, take a series of progressively-longer exposures, and examine each histogram as it appears. When the big peak of the histogram clears the left edge of the graph, stop -- that's long enough. You want your exposure to be long enough that you're not clipping any of the image to black (including the sky background), but otherwise as short as practical, to avoid problems with star trailing, satellites, airplanes, etc. Stacking integrates total exposure time, which is much more important than the length of a single sub-exposure.

    I've seen advice to put the top of the big histogram peak at 1/4 scale, 1/3, even 1/2, but all you really need is a little bit of flat no-signal space between its left edge and the edge of the graph. Too long a sub-exposure time (or too high an ISO) can give you the opposite problem, white clipping at the right side of the graph. Since stars are the brightest thing in astro images, that means your stars will lack color.

    Shorter sub-exposures means you need to shoot and stack more of them to achieve a given total integration time, which can place practical limits -- nobody wants to manage 3,600 sub-exposures if they can avoid it!

    As for total integration time, shoot as much as you can stand to image and process. For deep-sky objects, more is really better, although you hit diminishing returns pretty quickly. But think hours, not seconds or minutes.

    Likewise, as drjolo recommends, have a squint at the stars to determine if the f-stop suffices to your needs.

     

    Thanks all, very helpful 

     

    How do I improve from this, my histogram looks way off? 

     

    IMG_5553.thumb.jpg.fec217c75095f9c9f1534419da6f6023.jpg

    Help with setup

    in Getting Started With Imaging

    Posted

    Hi all! Happy weekend 

    I'm a beginner, hoping to get some good shots today 

    I have an astro modified Canon 550d on Sky-Watcher star adventurer tracker & Canon 50mm f/1.8 lens, Bortle 4 sky 

    Any suggestions for my camera ISO and exposure length? Would you suggest ISO 800, or higher? 

    Thanks ! 

    Advice needed

    in Getting Started With Imaging

    Posted

    7 hours ago, Carbon Brush said:

    No expert. So bear that in mind.
    A very nice image. I would be pleased to get something like this.

    Yes there are scratches, or line like greasy deposits on something glass.
    But I would not want to identify a specific part of the optical train.

    Why not try again using either a different camera lens, or without the CLS filter.

    As you are only looking for the flares on bright stars, you don't need so many images and you aren't worried about a brighter background.
    Maybe get some different combinations of glass on one evening?

    HTH, David.

    thanks :)

    i will next give it a go without the filter. and will give it a clean as well. 

    do you think I need longer exposures, if so how long? 

    Advice needed

    in Getting Started With Imaging

    Posted

    On 14/02/2021 at 15:52, Pixies said:

    I can't comment on the AP side of things. But those 'flares' on the brighter stars  look like scratches or smears across the filter surface in one direction.

    Is the filter new or secondhand? Have you tried to clean it?

     

     

    new filter, have cleaned it now, but waiting for next clear skies 😛 

    thx

    Advice needed

    in Getting Started With Imaging

    Posted

    Hello all,

    I took a wide field shot of Orion few nights ago. 

    My set up:

    Astro-modified Canon 550d, Canon 50mm F/18 STM lens, Svbony CLS clip filter in Bortle 5 skies.

    ISO 800, F/2.8, exposure 1 min x 40. 

    I'm not very happy with the result. Unsure why there is so much flare with the brighter stars and I didn't seem to get enough detail out of the nebula either  

    Any advice on how I can improve for next time? 

    I do understand I need to take longer exposures. Do I need a different filter? 

    thanks! :)

    orion.jpg

    Orion 11-02-21.TIF

    Re: Editing help

    in Getting Started With Imaging

    Posted

    5 hours ago, Aramcheck said:

    I think it's lens flare, but as I don't have any camera lenses I can't advise on that (so far I've only taken prime focus pictures with the DLSR attached to a 'scope). I've read that it can be reduced by more careful processing, i.e. creating & applying a mask of the flare when stretching... It may be worth trying to take some images without the filter, to check that isn't the problem & also with different lens if you have one.

    Colours are largely down to the the choices made in processing. You can alter the colour saturation, to help bring out the nebulous regions, but you'd benefit I think from a longer total exposure time. Here's a DLSR image of the same region but with 230mins total exposure:- https://britastro.org/observations/observation.php?id=20190204_195500_3b5f179fe8536100

    M42 - Orion Nebula, is quite bright in comparison to the Barnard's Loop, so it'll be difficult to bring out the loop without blowing-out the core of M42... (You can always process the image twice & then combine them)

    The amount of detail you can capture is down to the resolution of the equipment (focal length and camera pixel size) & sky conditions. The Canon 550d has a pixel size of 4.3 microns, so with a 50mm lens the resolution won't be better than 17.74 arcseconds/pixel. (See https://astronomy.tools/calculators/ccd) M42 is about 52 arcmins across (i.e 52 x 60 = 3120 arc seconds), so will only cover about 175 pixels on the camera. Longer focal length lens (or scope) will enable you to see more detail, but then you won't see as much of the sky...

    Hopefully somebody more knowledgeable will chime in & provide some better advice!

    Cheers
    Ivor

     

     

    Hey are you able to bring anything much out of this shot of Rosette I took? 

    Again I think maybe my exposure time was not long enough. it's 1.5min shots x 20

    Rosette 1.5 min.tif

    Re: Editing help

    in Getting Started With Imaging

    Posted

    39 minutes ago, Aramcheck said:

    I think it's lens flare, but as I don't have any camera lenses I can't advise on that (so far I've only taken prime focus pictures with the DLSR attached to a 'scope). I've read that it can be reduced by more careful processing, i.e. creating & applying a mask of the flare when stretching... It may be worth trying to take some images without the filter, to check that isn't the problem & also with different lens if you have one.

    Colours are largely down to the the choices made in processing. You can alter the colour saturation, to help bring out the nebulous regions, but you'd benefit I think from a longer total exposure time. Here's a DLSR image of the same region but with 230mins total exposure:- https://britastro.org/observations/observation.php?id=20190204_195500_3b5f179fe8536100

    M42 - Orion Nebula, is quite bright in comparison to the Barnard's Loop, so it'll be difficult to bring out the loop without blowing-out the core of M42... (You can always process the image twice & then combine them)

    The amount of detail you can capture is down to the resolution of the equipment (focal length and camera pixel size) & sky conditions. The Canon 550d has a pixel size of 4.3 microns, so with a 50mm lens the resolution won't be better than 17.74 arcseconds/pixel. (See https://astronomy.tools/calculators/ccd) M42 is about 52 arcmins across (i.e 52 x 60 = 3120 arc seconds), so will only cover about 175 pixels on the camera. Longer focal length lens (or scope) will enable you to see more detail, but then you won't see as much of the sky...

    Hopefully somebody more knowledgeable will chime in & provide some better advice!

    Cheers
    Ivor

     

    That's really sound advice 

    Thanks so much. 

    Yes I am planning on moving to a larger lens, but wanted to get bit better at taking wide field shots. 

    This flares hasn't happened on my previous images, so it might be my CLS filter...

     

    Re: Editing help

    in Getting Started With Imaging

    Posted

     

    3 hours ago, Aramcheck said:

    Thanks for sharing the data. I had a very quick go... but I think dealing with the flare on the bright stars will be a challenge!
    Cheers
    Ivor

    orion_rough_70.jpg

     

    Hey man, awesome thanks 

    What is causing these flares? was it a smudge on my lens? 

    Also this was my set-up: 

    Astro-modified Canon 550d, Svbony CLS filter, Canon 50mm lens f/1.8 STM, Bortle sky 5 

    ISO 800, f/2.8, 1 min exposures x 40

    Any suggestions on how I can improve to capture more detail and colour? 

    AP help

    in Getting Started With Imaging

    Posted

    1 hour ago, happy-kat said:

    Try f1.8 and f2, f2.8 etc and see what you prefer, star will be bloated and or towards the edges the stars won't be round if the aperture is too open for the lens being used. 

    You will need a remote trigger release for your camera, at the minimum use the onboard timer delay if you have no other way to trigger the shutter

    yup I've got a intervalometer. 

    ok I'm going to use ISO 800, f/2.8, 1 min exposure x 30. 

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