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Post by Deleted on Oct 17, 2017 23:07:25 GMT
Ok, a quick update on what's happened to me with my VA following on from my thread asking for help with VA, cameras and light pollution. Yesterday arvo, a shiny, brand new red 224 camera arrived (stock photo below) I wasn't expecting it for another two weeks from China, but here it was. And wouldn't you believe it, the Sky Gods smiled upon me and gave me a clear night to!! WOOHOO! Thanks to Ken for putting up a few screenshots of the different camera control layouts provided by different suppliers. I actually did pay attention to the layouts and what they showed on how to control different parameters and functions. When I started playing around with my own machine, the whole process was not a horrendous learning curve, but a gentle gradient that I was able to very quickly expand upon and follow. Thanks mate! Oh, and a special thanks to Chris for challenging my views and encouraging me to ask HERE about a new camera! OMG! What a machine!!! Not only is it faster and more sensitive than my LN300, but so much easier to control, and the resolution! I was able to control contrast soo much better and the ills of light pollution so much easier to mitigate. I spent two hours last night throwing the 8" f/4 Newt from one side of the sky to the other, plundering it of its best treasures. Below are just a few screenshots of what I got with just a five second exposure. Good enough to convince me that this was a good camera choice. And now I have the outreach tool that I always wanted. Remember, these were all taken from my home in Sydney, not under the dark skies that Ken has... 47 Tuc Tarantula Neb NGC 253 I also had time to re-try the 1.25" 0.5X focal reducer with the 8" f/4 Newt. Below is an image of 47 Tuc taken with the reducer. You can see that there are major problems that stem from the optical mismatch between this reducer and a Newtonian. The image is not sharp but soft and there are ghostly bloated brighter stars around the edge of the FOV. See, I wasn't making up this stuff! And same with the Tarantula Many thanks again for everyone's suggestions and thought sharing. I am very happy with this new little camera, Now to get to learn a bit more about how to control it even more finely, a task that will so much easier than it was with my old LN300. Alex.
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Post by davy on Oct 18, 2017 2:43:57 GMT
I've bought the wrong camera,lol,😂 all it's done is rain and been cloudy since I got mine 😀 Great images,, your excitement is coming across load and clear Alex 😀 great to hear someone enjoying VA ,, hooked for life now mate
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Post by ChrisV on Oct 18, 2017 3:16:17 GMT
That's really nice Alex! The 224 (1/4") is a really great match with your f4 newt.
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Post by Deleted on Oct 18, 2017 4:01:35 GMT
Ken, I've been hooked and espousing the virtues of VA for many years now! Just that the cameras I had I quickly crashed into their limitations. This wee 224 item really gives me what I want, AND without killing the piggy bank. I know that there are more capable cameras, but VA for me is also about getting more without needing to spend the big bucks. Sure this new camera gives me the same FOV as my LN300, but I'm not concerned. Gives me some more mental exercises to try to pull more out of my gear and optics.
Alex
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Post by Deleted on Oct 18, 2017 7:17:53 GMT
I just spoke with a good friend about the artifacts I was seeing in the pics taken using the focal reducer. Nick is very experienced with optics, and his very first thought was internal reflections are at play. The camera has a clear filter that sits a few mm above the chip. Very likely it is not coated. As a result of the severe alteration of the light cone by the reducer, and because of the optical mismatch between the scope and the FR, the light coming off bright stars is reflected off this pre-chip filter, back off the FR, and because of the increased effective travel of these reflections, we now see the bloated rings around these bright stars. That this bloated circle around these bright stars is not perfectly co-centric also lends strength to these being internal reflections. This internal reflection is also the cause of the soft focus of the rest of the image.
Will be interesting now to see how this FR and refractor combo works with this camera.
Alex.
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Post by Dragon Man on Oct 18, 2017 10:13:27 GMT
Great to hear Alex. Yes, the little 224 is a miracle camera. The new 385 coming out will be as spectacular, just with a slightly wider FOV (it's a 1/2" version of the 224). I intend to get one as soon as they are released. On the subject of your strange results with the Focal Reducer. When I attach one of those cheapie 0.5x Focal Reducers to my 224 and plonk it in a dob I don't get any of the problems you get. Weird. I have tried it in a GSO 8" f6, GSO 12" f5, and a Skywatcher 16" f4.5 and none had the same artifacts. There must be something different about either the camera clear window or the focal reducer. But anyway, great to see you excited. Your results are great!
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Post by Deleted on Oct 18, 2017 22:27:33 GMT
Oops, sorry Davy, I got your name mixed up with Ken's, Ken, I'd like to try the camera/FR combo again but without the clear filter over the chip - I suspect it's this filter that's causing the bloating. I can't see any coatings on this filter. The problem I have is the thread that holds the filter is larger than the 1.25" filter thread. Real bummer. Might anyone know of an adapter thread that can fit between this camera and a 1.25" filter thread? Alex.
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Post by ChrisV on Oct 18, 2017 22:52:16 GMT
Maybe it's a c-mount thread?
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Post by Deleted on Oct 18, 2017 22:58:47 GMT
Hey Chris,
No, the thread between the filter and the camera body is not C-mount. The thread on the field side of the filter is a c-mount, but not the one on the camera body. C-mount thread is smaller than the 1.25". The thread on the camera body is larger again than the 1.25".
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Post by howie1 on Oct 19, 2017 3:31:43 GMT
Re reflections off the clear filter ... maybe you are correct, Alex.
Perhaps some daytime tests may help? So low gain and very, very fast (60+ fps) to allow you to instantly see focus or not, and do the tests below.
If you find that you still get blurry shots with the reducer screwed on, then slowly unscrew it and watch for focus ... even if you totally unscrew it still hold it as steady and close as you can to the centorid of the light path and my hand move it further away from the camera. Why might this achieve focus? See a section down below titled ****Why****!
If still blurry then can you take the nosepiece off that 224? Why ... so you have a large amount of freedom to place the reducer closer and closer to the sensor ... ie hold the reducer in your hand and slowly move it in and out in front of the sensor and watch the image to see if it ever reaches focus.
Do the same tests with your trusty old LN300 with the suspect 0.5x reducer on it. That'll point to your clear lens / reflections issues if that's whats happening.
If you never get sharp focus I'd be returning that reducer.
***** Why***** Some reducers are very pedantic about the distance from the sensor! It affects focus and vignetting ... and especially more problems with focus with small sensors (like your 224) and more problems with vignetting with large sesnors (like DSLR's). And ... when I measure the distances between the same stars on your Tarantula images I do not get 0.5x reduction which could either be (a) the capture software and images you posted are diff zoom's; or (b) as above, the reducer is not at the right distance to yield 0.5x reduction and sharp focus.
Cut and paste from my "tips" folder which I've collected from forum posts over the years ...
"the more distance between the reducer and image plane does give more reduction, but will vignette more also. Less distance gives less reduction." ... and ... "The real issue is related to something called design conjugates. When the designer figures out how to make this lens, he picks the object and image distances in order optimize not only how sharp the image is but how sharp it stays across the field of view. So when you start moving too far away from the correct conjugates, you will start to affect image sharpness and field performance as well as changing the amount of vignetting. Keep it close to the correct conjugates and you will get the best optical performance. Get it too far out of whack and you may not be happy with the images you produce."
Hope it helps you Alex as you must be pretty frustrated given the nice images using the new toy without the reducer. If you can get the reducer working not only will the FOV be bigger but you should find you can get the objects in even shorter times like 2 seconds.
cheers Howie
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Post by davy on Oct 19, 2017 4:57:58 GMT
Hi Alex, direct to camera should be c/C's and I think the other side is the the m48 and you can get a m48 to T mount adapter.
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Post by davy on Oct 19, 2017 5:05:39 GMT
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Post by Deleted on Oct 19, 2017 5:18:30 GMT
Thanks Davy, but the widest part of this camera is only 35mm. If you look at the camera photo in my first post, you will see a black ring on the front end. This ring is 1.25" in diameter. The thread that this ring winds into in the camera body is a little larger than that of a 1.25" filter, so the FR does not wind into the camera directly. Filter threads, and that of the FR, are roughly 28mm diameter. The thread in the camera body is 30mm. Crazy, huh...
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Post by Dragon Man on Oct 19, 2017 9:26:48 GMT
The inner reflection is certainly a real thing but could be solved with a spacer. The Mallincam MFR-5 Focal Reducer set is well known for creating inner reflections on the protective window. But by adding a 10mm spacer the problem vanishes (the Mallincam 5mm spacer makes the reflections even worse). So it may be worth trying a 10mm spacer on the focal reducer. Like this: Camera > 10mm Spacer > FR > Filters > Negative adaptor (if needed)
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Post by davy on Oct 19, 2017 10:02:31 GMT
Weird one,,I had to get a few adapters to link my DSLR to my Skywatcher focal reducer on the ed80,, even worse is the focuser on the sw explorer,,they use three different different ones,,,,
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Post by davy on Oct 19, 2017 10:03:13 GMT
Is it not a t thread
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Post by oldstash on Oct 22, 2017 15:41:22 GMT
Hi What camera is that? - so many look the same(and claim the same) - Nano,Touplek,Revolution ,Astro Altair,Rising what's it etc
Sorry if I missed the name in the text some where!
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Post by davy on Oct 22, 2017 16:45:11 GMT
Think it's the rising tech one,
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Post by oldstash on Oct 23, 2017 11:50:15 GMT
Think it's the rising tech one, Thanks Davy
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Post by Dragon Man on Oct 23, 2017 13:38:02 GMT
Hi What camera is that? - so many look the same(and claim the same) - Nano,Touplek,Revolution ,Astro Altair,Rising what's it etc Sorry if I missed the name in the text some where! Just to confuse things more, Alex's camera is an ISOLAB (which is still a Touptek. They are ALL Touptek cameras) SEE HEREAlex ,mentioned it back here: astrovideoforum.proboards.com/post/18611
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