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BrendanC

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Posts posted by BrendanC

  1. I've recently realised why my DSLR sometimes does portrait and sometimes landscape.

    It's nothing to do with how I attach it to the scope. It's to do with whether the scope is pointing more upright or more horizontal. It switches automatically because of, from what I've read, sensors that tell it when to do portrait or landscape, depending on which way it's facing. Or something.

    It's really irritating. I've just noticed it's even switched from one to the other midway through a shooting session. This will probably affect my framing and stacking, and cause all my bright stars to have weirdly spaced, multiple diffraction spikes.

    One fix is to rotate the whole OTA so that the DSLR is always pointing up. I'd rather not do this because I'd like to keep the option of using the eyepiece, which would be rotated to a weird angle. Also it will be harder to access the camera for battery changes etc.

    A much better fix would be simply to tell the darned thing always to shoot in landscape, or always to shoot in portrait. But I cannot seem to find any way to do this.

    There are 'landscape' and 'portrait' modes, but they also enhance the image in strange ways that I don't want them enhancing.

    Or do I need to create a custom mode? 

    Does anyone have a fix for this? It's a Canon EOS1000D but I expect this issue (and, hopefully, fix) applies to similar models.

  2. This is probably heresy, but what do people think of using the Google Photos filters on their astro photos?

    I tend to find that, after spending ages on a photo, and then uploading it to Google Photos, if I apply a filter it almost invariably looks better!

    This annoys me. I don't want my photos to look better after being put through a poxy filter, I want them to look worse. I want them to be fine after I've diligently spend hours on them. Humans good, algorithms bad.

    Or, if I just think it looks better, is that ok? Should I stop worrying and learn to love Google Photos?

    • Haha 1
  3. Thanks everyone for the helpful suggestions!

    As luck would have it, I did actually find an entire leg for sale on Astroboot, for 16 quid, so that's not too bad (even if delivery costs £13!)

    Totally get what you're saying about the clamp being riveted, so it looks like maybe replacing the whole leg is in fact the best (and perhaps only) solution to this. I just wanted to have it as pristine as possible, and I won't be overtightening them any time in future...

    • Like 1
  4. So, I overtightened one of the all-too-flimsy height adjustment clamps on the tripod legs and fractured it (see photo).

    I've tried gluing it but it didn't take. 

    The photo makes it look a lot worse than it is - in reality you can barely notice it and it doesn't really affect the operation because it still holds the leg in place - but I'd rather either fix it or replace it.

    For fixing it, does anyone have a recommendation for glue that will definitely work? I guess I could just strap it with duck tape.

    For replacing it (my preferred option, in case I ever want to sell this), I've looked around and can't seem to find this as something that can be bought separately. Any recommendations on that score?

    IMG_20200214_144956.jpg

  5. I know, I know, lots of this one taken before and I've already submitted mine, but after seeing what StarTools can do I gave it another go, properly this time, by actually following an actual tutorial. I have to say, I'm very impressed and have bought a license. So much detail revealed that I didn't know existed. This is with my setup as per my signature, bringing together frames from two separate shoots which total around 250, plus 50 darks and biases, no flats. I had to crop out more than I wanted because of stacking artefacts but managed to keep the Running Man nebula in (one lot of frames was portrait, the other landscape, hence the double diffraction spikes on some stars) and I added a luminosity layer in Photoshop just to finish it off (which might have pushed it over the edge, not decided yet), but I'm pleased with this one. I wanted to get M42 as good as possible as it's really my first proper stab at a DSO, and now I feel a bit more confident moving ahead to others. Total inspiration from this forum I have to say. :)

    startools plus photoshop.jpg

    Post-edit: And now, having watched the StarTools demo by Ivo Jager who developed it, I can already see that I've overdone the deconvolution because I have those dark rings around my stars... https://www.youtube.com/watch?v=hqm4mB2TKN0&t=6s  Oh well, I'll try again and do it better! (but don't worry, I won't repost here)

     

    • Like 5
  6. Brilliant, thanks all. It's very much clearer now. I actually tried using darks in DSS and it really didn't work out. I think this could be why - it's just not suitable for my situation. I might try again sometime, but I'll also experiment with just flats.

    Nice to know that I can do the flats after the shoot too rather than sticking around in the cold and dark, Gollum-like.

    I'll also think about whether or not to use AV focus. I just did it because I read somewhere that you should, but I can see it introduces something random into the process that should be under control.

    Finally, @Pompey Monkey I'm not guiding, but when you say I should be dithering, do you mean I should be whether or not I'm guiding? In which case, is this something I should be looking at my camera to control (Canon EOS1000D), or software? I thought DSS could handle this sort of thing? I realise this isn't strictly related to calibration but I'd like to tie this final one off, now I'm a bit clearer on the other stuff.

  7. Thanks for this, really appreciate the feedback - and here we go again...

    When you say "Otoh, darks don't always work with non-cooled dslrs, and you replace them with bias frames."

    Does this mean that, given I'm using a non-cooled DSLR, I should forget about darks and use bias frames instead?

    "You can also replace flat darks with bias frames."

    Does this mean I can, or I should? And if I replace dark flats with bias too, then does this mean I don't need to bother with darks at all?

    In which case 'the recipe' becomes:

    ANY TIME
    Bias - 50 frames, optics covered, exposure time=shortest

    DURING SHOOT
    Flats - 25 with the cap off, diffuse white frames eg t-shirt with light behind it or morning sun, exposure=AV mode

    Yes? No? Somewhere in between?

     

  8. There are lots of links out there, all of which claim to be 'the definitive guide' but every time I read one, I notice that they've said something that makes no sense, or they're unclear about a certain specific part of it, or there's a huge debate that ensues around very obscure technicalities.

    I just want to know whether this extraordinarily basic 'recipe' I've come up with, for my specific situation of having a DSLR, could work, as very, very, very, very basic starting point, as a general rule. without going into any specifics whatsoever.

  9. I know, I know, this has been discussed endlessly here and elsewhere, but I've read lots and watched lots and some of it I understood and some of it I didn't. A lot of it I didn't, actually, mainly because every time I think I get it, someone else contradicts what I think I've 'got'.

    I've reduced it all to this, regardless of the number of lights I take, assuming I'm using a DSLR, with all the below steps at the same ISO value as the shoot:

    ANY TIME
    Bias - 50 frames with the cap on, exposure time=shortest

    DURING SHOOT
    Darks - 50 with the cap on, exposure=as per shoot
    Dark Flats - 25 with the cap on, exposure=AV mode
    Flats - 25 with the cap off, diffuse white frames eg t-shirt with light behind it or morning sun, exposure=AV mode

    I know everyone has their own take on this (which is kind of my problem understanding it) but, reducing this to the very, very, very basics, as a starting point for a total noob with calibration... would this work?

    • Like 1
  10. ... and this seems to be where I can buy it! https://www.teleskop-express.de/shop/product_info.php/language/en/info/p7628_Shoestring-FCUSB-Focus-Motor-Controller.html

    Costs a bit more than I expected, but I can see that, if this is attached to my little, ancient Windows notebook PC, which isn't being used for anything and has great battery life, then that's my wireless, remote, manual focusser sorted.

    Hmmm. I wonder if I can get away with buying yet another bit of kit... (strokes chin...)

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