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ollypenrice

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Posts posted by ollypenrice

    Giving up dso astrophotography

    in The Astro Lounge

    Posted

    3 minutes ago, saac said:

    From the moment the camera was invented it was mated to a telescope. Photographing the cosmos and the stuff in it is as part of astronomy as nighttime is.   There is no divide, there is no one or other.

    Jim 

    The last great eyepiece professional and the first great astrophotography professional were one and the same person, the incomparable E.E.Barnard.

    Olly

    • Like 2

    Giving up dso astrophotography

    in The Astro Lounge

    Posted

    16 minutes ago, Elp said:

     

    I always put it like so, a camera sees over time whereas visual you see at the time. The camera will always reveal more than you can see visually, 

    Six stars in the Trapezium? But yes, in terms of faint stuff, the camera is a hands down winner.

    Olly

    • Like 1

    Giving up dso astrophotography

    in The Astro Lounge

    Posted

    14 minutes ago, Mr H in Yorkshire said:

    My ignorance. What about a 12" in somewhere nice - your neck of the woods for instance.

    We've used 14 inch, 8 inch, 5.5 inch, 4 inch, 3.5 inch and lenses of 200, 135 and 80mm here. They do what they do. We did find that a good 5.5 inch apo could resolve at the limit of the seeing, pretty much, and that more aperture did not really produce more resolution. If the aperture were used to produce more light grasp (at fast F ratios) then it would, in principle, be great - but you'd need to find optics as good as the TEC140 and, though possible, that would not be easy.

    Olly

    Giving up dso astrophotography

    in The Astro Lounge

    Posted

    1 hour ago, Mr H in Yorkshire said:

    Disclaimer: I am visual only, and I enjoy making stuff, that is my area of interest, might be tempted one day to EEA but never AP. 

    Although there are so many people agonising over their difficulties in simply getting results these past many months, it seems to me that most posts are about processing - so much so that it also seems to me that processing is the major interest for very many observers. Given that, I don't know why simply buying the best data from worldwide, best site telescopes isn't way more popular. A metre-class scope in say Namibia is always going to outdo a 5" objective in soggy UK and still cost a packet with a decent camera/mount/computing. What am I missing?

    Several answers:

    1) Part of astrophotography is deciding what data to capture. What wavelengths, what field of view, what framing? If you just buy data you don't have much control of any of these important factors.

    2) A metre class scope in Namibia is certainly going to out perform a metre class scope in the UK but it is not necessarily going to out-perform a 5 inch in the UK or anywhere else. With aperture comes focal length and a metre class telescope, even at F3 (which is optimistic) would have a 3 metre focal length. That will give a tiny field of view. Giant optics can do what they do very well. Tiny optics can also do what they do very well. In the real world, nobody is going to take the image below with a 3 metre focal length. It took 42 panels to shoot it with 135mm focal length.

    ORION%20MONOCEROS%2010K%20web2-X3.jpg

    Much of the fun of making this image came in the form of 'Can we do it?'  A hell of a lot of obstacles stand in its way.

    That said, I don't know whether or not I would do deep sky AP if I lived in the UK.

    Olly

     

     

    • Like 4

    "First light" with Touptek IMX571 - what is going wrong - cont'd ...

    in Getting Started With Imaging

    Posted

    12 minutes ago, AstroRookie said:

    I've checked, and I think my error is that I did not take into account the 17mm sensor to flange distance; so I had 17+55 = 72mm. Corrected that, now it's a matter of waiting till it gets dark, because it will be ab excellent night: clearoutside's opinion

    Thanks for your help!

    17mm is huge so you've probably cracked it. If using a filter, add 1/3 of the filter thickness to the backfocus. Filters are often 3mm thick so add 1mm.

    Olly

    Meade ACF 0.68x Focal Reducer

    in Sponsor Announcements and Offers

    Posted

    3 hours ago, Xsubmariner said:

    I’m intrigued the same reducer works with both the f8 & f10 OTA’s across the ACF range. The initial documentation released with this product lacks any performance metrics a user can expect across the Meade ACF range. 

     Owner of a 12” f8 OTA I am very interested in a reducer that is dedicated/designed for my OTA. Already the owner of both the AP 0.67x and Lepus 0.62x reducers, I have struggled with either one when using an APS-C camera.  Regrettably I am reluctant to invest in any new reducer until I have read some positive user/independent feedback. Keen but watching.

    I take this view with all reducers!

    Olly

    • Thanks 1

    Dual rig with different focal lengths (?)

    in Imaging - Discussion

    Posted

    11 hours ago, WolfieGlos said:

    Thanks Olly, and that was my thinking for the faint stuff.

    I would have stacked the images from the two setups separately (with their own calibrations) and then “stacked the stacks”. Assume this is what you mean by co-registering? Using Siril I think this is the only way I could do it.

    However. Right now, with 4 different forecasts showing it as clear until midnight, of course….its cloudy.

    So I might not get to try it tonight anyway 🙄  Hopefully the forecast is correct for later this week.

    Yes, I think making 2 images is the only way. I would then co-register the larger FOV to the smaller in Registar and crop it to fit. As for how to combine them, I think you'd want to give each one a test stretch of its own to assess noise and resolution. I'd probably give each a basic stretch, not too hard, put one over the other in Photoshop layers, set the opacity to 50% at first and then move the opacity slider each way to see where I got the best result. I'd flatten and then stretch harder. There are lots of ways to kill this particular cat, depending on software.

    Olly

    • Thanks 1

    Dual rig with different focal lengths (?)

    in Imaging - Discussion

    Posted · Edited by ollypenrice

    Do it-.More data beat less data. You may not really reach a true resolution of I.3"PP anyway, and 2.49 is perfectly respectable. There are some very fine little details in M78 but the bulk of the image is about faint stuff, so signal is the key.

    Olly

    Edit: when you co-register the data, register the lens to the scope - but I'm sure you would anyway.

    • Like 1

    New to imaging after a few years lay off

    in Getting Started With Imaging

    Posted

    https://www.teleskop-express.de/shop/product_info.php/info/p14967_TS-Optics-ToupTek-Color-Astro-Camera-2600CP-Sony-IMX571-Sensor-D-28-3-mm.html

    In the great tradition of SGL this is over budget but not excessively so. I use one of these and also the ZWO equivalent. I'm happy with it. We use it with a Samyang 135, viz

    I think it is all but certain that, if you buy a small chip, you will crave a bigger one and buy twice.

    Olly

    • Like 2

    RASA 6???

    in Discussions - Scopes / Whole setups

    Posted · Edited by ollypenrice

    What the RASA needs, based on two years and hundreds of hours use, are the following:

    - A system of collimation which leaves the camera in place.

    - A system of tilt adjustment which leaves the camera in place.

    If these could be managed remotely, or even automated into the system, the RASA would be perfect.

    - A built-in slide drawer.

    Olly

    • Like 1

    RASA 6???

    in Discussions - Scopes / Whole setups

    Posted

    330mm focal length. Nice, assuming it can cover an APSc chip. Pity the F ratio is so slow, though.:grin: 

    (More seriously, 2.2 squared is 4.84. The 2 squared of the RASA 8 is 4. The difference is not totally insignificant at these speeds. Still, not a big deal!)

    Olly

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