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Old 04-08-2015, 02:16 PM
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graham.hobart (Graham stevens)
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OSC cameras

I'm thinking of getting another OSC as an alternative to DSLR and or mono LRGB which the latter seems a struggle to string consecutive hours let alone nights together at the moment.
I have owned a QHY 8 and QHY10- both of which I quite liked.
I had an SX H14C but the chip was too small for me.
Having read the article on this IIS about OSC I would be trying to oversample to make up for the loss of sensitivity with OSC. At between 800-1000fl that would mean quite small pixels.
I wondered about the Sony ICX sensor -3.69um pixels with 1000 fl would give me 0.76 which would be ridiculously over sampling for my seeing on average.
The 814C Trius crossed my mind, as did the QHY 12
or even getting another QHY 8 and using it with a TV powermate on my 925mm refractor?!!
I aim to have a choice of 925mm frac, and 800 & 1000mm fl newts (8 inch and 10inch f4).
Comments, thoughts, invited as no firm plans yet.
Graham
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Old 04-08-2015, 02:54 PM
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Shiraz (Ray)
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hi Graham. undersampling will give you increased sensitivity, so you need to aim for bigger pixels and accept that the image scale will be small and that you will get wide field of view at the expense of less resolved detail.

A QHY8 or even a QHY10 on your scopes would be fine without a Barlow (especially the 250f4). The QHY12 would give more resolution and larger scale, but it will probably be somewhere round 1/2 as sensitive as the 8. I would stay away from cameras with small pixels if you are seeking high sensitivity. It is a good idea to have a camera with adjustable focal plane tilt with your f4s - I think that all of the latest QHYs have that option.

I can relate to your desire to go OSC - I have quite a few datasets waiting around where I just need maybe 1/2 the green and all of the blue to complete, but the weather will just not cooperate.

Last edited by Shiraz; 04-08-2015 at 05:07 PM.
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Old 04-08-2015, 04:25 PM
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strongmanmike (Michael)
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Ray makes sense here...of course

Quote:
Originally Posted by Shiraz View Post
I can relate to your desire to go OSC - I have quite a few datasets waiting around where I just need maybe 1/2 the green and all of the blue to complete, but the weather will just not cooperate.
So can I. I too regularly think I should go OSC for the same reason but somehow the probably overly fearful thought of lower res dominates my frustration in not having complete data sets...

Mike
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Old 04-08-2015, 06:55 PM
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graham.hobart (Graham stevens)
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Osc

Sterling advice as always folks.
Another reason to get an Osc in my mind is that I have a cooled 60 da and it must be at least 1.5-2kgs, which is fine for the refractor but it does worry me in the newts- changing focuser would be an option. A nice 500gm Osc would help things. Another thing is the length of the imaging train on my mono FLI- I have camera, filter wheel, OAG and focuser which sticks out the back of the refractor a country mile!!!
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Old 04-08-2015, 08:05 PM
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Atmos (Colin)
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I am pleading ignorance here but wouldn't it, in that case, just be better to take all of your filters at once? By that I mean, LRGB LRGB LRGB and so forth so that at the end of the nights imaging you have a whole set of data to play with instead of just one filter at a time?
Or is it simply so that time isn't lost between constant filter changes?
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Old 04-08-2015, 09:49 PM
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hello dr graz!, before i got my qhy10 from some nice gent, i was looking at the FLI 8300 unit that was a good price second hand, it is more expensive but an amazing cam from the reviews
pat
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Old 05-08-2015, 07:12 AM
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Starlight Express H26C might be a good one. The SX25 has been a popular one shot CCD for a long time. The 26 seems interesting. The Trius has 3 usb port in the back which is very handy plus tilt tip front adapter plate. Low noise.

There are also a number of cameras using those True Sense faster that have a clear rgb colour matrix and claim to be twice as sensitive. KAI8050 is one. FLI and Apogee have one of those and now I see SBIG offers one in 3 types, mono, Bayer and Sparse Colour which is the LRGB colour filter array over the sensor with higher QE (supposed to be twice as sensitive as straight Bayer).

It would be hard to beat the SX26C though, 55% QE Sony sensor is more sensitive on paper at least than KAI11002! And it would be lower noise. 6.05 micron pixels would be a good match to 250 F4. US$3350 at Optcorp so that's about AUD$5600 landed. A 2nd hand SX25C may be around as they were popular. That would be a lot cheaper.

Greg.

Last edited by gregbradley; 07-08-2015 at 04:13 PM.
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Old 05-08-2015, 08:03 AM
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I too often think that collecting RGB data would be far easier using a cooled colour CCD, but, like Mike stated, the thought of giving up the resolution inhibits the move to do so.

However, perhaps old school a bit, many used to (and probably still do) bin 2x2 for RGB but combine this with unbinned luminance. So what about using two cameras? One camera does luminance at full resolution and camera #2 does RGB in one go. Would that not save a lot of time (but not money!) and perhaps give the best of both options?

As far as doing LRGB, LRGB, etc. It's a fine idea as long as the filters are really parfocal. Mine are not good enough to get away without a zillion focus routines. It's probably my refractor optics rather than the filters so this option might work fine on a newtonian perhaps.

Peter
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Old 05-08-2015, 08:51 AM
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The other option would be buying a mono 8300 camera for Ha and L data and an osc 8300 for rapid collection of colour data. If you had two cameras running and two scopes on the mount you could build LRGB/HaRGB datasets really fast. Just put the colour camera on a cheaper scope with a comparable focal length. 8"f/4 sucking down lum with something like an 80mm refractor on colour duties...
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Old 05-08-2015, 01:26 PM
loc46south (Geoffrey)
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Quote:
Originally Posted by AlexN View Post
The other option would be buying a mono 8300 camera for Ha and L data and an osc 8300 for rapid collection of colour data. If you had two cameras running and two scopes on the mount you could build LRGB/HaRGB datasets really fast. Just put the colour camera on a cheaper scope with a comparable focal length. 8"f/4 sucking down lum with something like an 80mm refractor on colour duties...

There is often a misconception that it is quicker to take colour data with a OSC - it is not. If you take 2 hours each of R - G - B with a mono then you need 6 hours data to get equivalent with a OSC.

I have used a dual setup for some time now - using a SBIG ST4000 XCM for RGB and a ST10XME for mono and narrowband - the system works very well - especially if you get limited imaging time.

Cheers
Geof Wingham
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Old 05-08-2015, 01:43 PM
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Started CCD with an SXVR M25C. Fantastic camera.

Moved to mono, large mistake given my circumstances like yours Graham.

Went back to OSC with the sublime FLI ML8300C. ...but stupidly had to sell it. Got an SBIG ST8300C now and whilst not an FLI I am VERY happy with it.

And yes I do narrowband with the OSCs too. Very easy.

My minimum exposure is 10 minutes at f/5 but my usual is 20 minutes per exposure (Tak FSQ106ED at f/5). When I use the reducer (f/3.65) I use 20 min still.
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Old 05-08-2015, 01:51 PM
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Thomas Davis uses an STL 11 mono and STL 11 colour to good effect with 2 scopes.

I used an STL11000C for a while. It was a great camera.

Greg.
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Old 05-08-2015, 03:14 PM
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Geof, indeed you need 6hrs osc to match 2hrs each or rgb, the difference would come into play if that 6hrs of osc data was being captured at the same time as your second scope was capturing 6hrs of lum.

Lewis. I used to use a Qhy8 and an orion pro for both osc and narrowband. It did work well but it required masses of data to match what I could get from my st8300 mono. The st10xme was by far the most efficient way to collect photons that I ever owned.
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Old 06-08-2015, 08:31 AM
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Totally agree that no time is saved using a colour camera vs a mono + filters. But, the nice bonus would be that every shot with the colour CCD is "complete" so at the end of the night you have something and would not be missing one filter change. On the down side would be the loss in sensitivity and resolution. Is the trade off worth the convenience?

Peter
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Old 06-08-2015, 10:05 AM
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Yes, it is worth the trade off when you have such a hectic lifestyle that even some clear nights you just can't be bothered! So, making colour in EVERY shot is a HUGE bonus. As the old saying goes, Make every shot count.

Take a usual high-end image - circa 20 hours with an LRGB mono. 20 hours of OSC data might only be half that "value" wise, but to some of us, 10 hours relative is amazing IF we can achieve that.

Frankly, astronomy is just a VERY distant last - a MAYBE - in my list of priorities. It is just a hobby after all Whatever keeps ourselves happy - there is no need to satisfy the whims of the greater populace (unless you need that narcissistic requirement in your life)
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Old 07-08-2015, 06:41 PM
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Another option could be bicolour narrowband imaging with a sensitive mono camera, only 2 filters are needed instead of 4 for LRGB...not all objects are suitable, but bicolour imaging is particularly effective when imaging nebulae form suburbs or with the moon up.
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Old 07-08-2015, 07:18 PM
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Quote:
Originally Posted by AlexN View Post
The other option would be buying a mono 8300 camera for Ha and L data and an osc 8300 for rapid collection of colour data. If you had two cameras running and two scopes on the mount you could build LRGB/HaRGB datasets really fast. Just put the colour camera on a cheaper scope with a comparable focal length. 8"f/4 sucking down lum with something like an 80mm refractor on colour duties...
Interesting concept. I just purchased a Celestron Nightscape 8300 which is an OSC and also have an ST-8300M. How would you suggest the setup if the following were the scopes available: FSQ-106ED, FS-78, TEC160FL
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Old 07-08-2015, 08:18 PM
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Quote:
Originally Posted by Hans Tucker View Post
Interesting concept. I just purchased a Celestron Nightscape 8300 which is an OSC and also have an ST-8300M. How would you suggest the setup if the following were the scopes available: FSQ-106ED, FS-78, TEC160FL
You'd have to use the 160FL for luminance and the 106ED for colour. Colour could be a lower rez and still be useful. F5 would also offset some of the lack of QE of the one shot colour cam.

The luminance gives the detail of the image.

Greg.
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Old 08-08-2015, 05:02 PM
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Quote:
Originally Posted by Hans Tucker View Post
Interesting concept. I just purchased a Celestron Nightscape 8300 which is an OSC and also have an ST-8300M. How would you suggest the setup if the following were the scopes available: FSQ-106ED, FS-78, TEC160FL
I've been working on my dual scope system now for quite a while. It's a good concept but doing so on one mount can get rather tricky, especially if you want to use one computer, dither, or go automated. All the automation programs will only control one camera...so, I had a special program written that will trigger images from TSX to CCDSoft (camera #2) (or a 2nd instance of TSX). Another consideration is the FOV with cameras for the 2 scopes. I get a rather similar resolution and FOV by using a KAF8300 CCD on my TEC180 and a H694 CCD on the TEC140. Then there is the problem of aiming both scopes which can be quite difficult without something like the Optec Libra. But, I had to modify the device to eliminate flexure. Then there is the problem of focusing both scopes. FocusMax will do 2 focusers with Acquire Star but the process is a little slow. CCDAP5 will run FM and the Acquire Star script. Anyway, it's a nice thought to do this and it does work. But, you will spend many many months getting it all to play nice together. Often I wonder if I'll ever actually realize any time saving.

Anyway, I'd start by using the Ron Wodaski tool to compare FOVs with the two cameras. I think yours will be very different. Perhaps a mild application of a barlow (Maybe the TAK 1.6?) on the small scope would better equalize the FOVs and resolutions. I'd recommend that you do luminance with the TEC160, colour with the smaller scope.

Peter

Last edited by PRejto; 09-08-2015 at 07:09 AM.
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Old 08-08-2015, 06:04 PM
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Has anyone seen any reports of the Sparse Colour chips being offered by SBIG in the STF-4070SC cameras??

Not the standard RGGB Bayer array, but some clear pixels to gather luminance data amongst the RGB pixels.

I emailed SBIG - there are some in the hands of astronomers, but I couldn't find any images on the forums.

DT
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