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Ouroboros

Recommendations please for CCD/CMOS for non-permanent set up.

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For a while I've been contemplating upgrading from my trusty unmodded Canon 450D to a cooled CCD or CMOS detector for imaging. 

I don't have an observatory. So I've got to be able to set up and get everything working on the afternoon of the evening I plan to image.

I am pretty much convinced (by reading the posts of knowledgable people here :) ) that mono is the best way to go, which will require a filter wheel, filters etc. I guide with a finder guider at present, but would consider moving over to OAG if this is feasible on a non-permanent set up.  

I have a warm room next to my set up area, so I can operate and control the mount/imaging from my MacBook in there. 

So the questions are: is it practicable to use a CCD/CMOs detector, filter wheel and OAG etc in a non-permanent set up?  What are the technical issues? 

Secondly what CCD and accessories would you recommend?   My main interest is in deep sky objects, and I want a field of view similar to my 450D (or more). I will use the camera with my current telescopes: SW 80ED pro and SW 200p.

Thanks in advance for any advice/comments offered. :)

 

 

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Personally I'd look out for a secondhand Atik 314L+ and filter wheel and not worry about achieving the same FOV as a DSLR.

Large CCDs produce large files and take an age to download, the Atik 314 files are much smaller and download pretty well instantaneously.

No reason it can't be a portable setup, loads of people use similar at star parties.

Use the 80ED and finder guider, you may need a flattener / reducer

Dave

Edited by Davey-T

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I'm using the ZWO 1600mm-c with filter wheel and OAG on a non-permanent set up. I leave the image train permanently connected and just screw it onto the scope when I set up. I have all the cables tied together so it's relatively quick to get it all plugged in a operations. As I set up at dusk, setup time is less of an issue but it takes less than 5 minutes to tear it down and back indoors at the end on the night. 

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46 minutes ago, Davey-T said:

Personally I'd look out for a secondhand Atik 314L+ and filter wheel and not worry about achieving the same FOV as a DSLR.

Large CCDs produce large files and take an age to download, the Atik 314 files are much smaller and download pretty well instantaneously.

No reason it can't be a portable setup, loads of people use similar at star parties.

Use the 80ED and finder guider, you may need a flattener / reducer

Dave

How long do large CCD files take? 

The Atik 314L really is quite a bit smaller than the 450D isn't it. Less than half the size in both axes. 

Good point about the flattener. I use the recommended 0.85 reducer/flattener now when imaging with the 80ED.  I need to think carefully about the spacing. 

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44 minutes ago, Filroden said:

I'm using the ZWO 1600mm-c with filter wheel and OAG on a non-permanent set up. I leave the image train permanently connected and just screw it onto the scope when I set up. I have all the cables tied together so it's relatively quick to get it all plugged in a operations. As I set up at dusk, setup time is less of an issue but it takes less than 5 minutes to tear it down and back indoors at the end on the night. 

That's encouraging to read. Of course by doing that you keep the relative positions of the CCD and guide cameras at the correct distances without have to adjust them. This must speed set up considerably. 

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28 minutes ago, Ouroboros said:

How long do large CCD files take? 

The Atik 314L really is quite a bit smaller than the 450D isn't it. Less than half the size in both axes. 

Good point about the flattener. I use the recommended 0.85 reducer/flattener now when imaging with the 80ED.  I need to think carefully about the spacing. 

Atik 314 files are 2827kb or 709kb binned 2x2, and download pretty much instantly, 8300 files are 15.8 mb unbinned and take 5 secs to download using QSI683 and Win 10 with SSD drive.

 8300 files obviously take up loads more disc space as well.

Does the ZWO1600 also capture lots of large short exposure files ?

Dave

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I put everything up every night and tear it down every morning. As mentioned, you really have to leave everything attached to the scope. Putting it all together each evening would mean most of the evening getting spacing, focus, all manner of frustrations right. This means the setup involves physically moving  everything outside, polar alignment and then a slew/plate solve and off you go, with a possible PHD calibration thrown in for good measure. As for camera choice, a smaller chip makes sense to begin with as it makes all the post processing so much easier, and there are a lot of targets that fit. I went from a 450d to an Atik 414ex and while some targets were too big, most are not and it was a great camera for me to cut teeth on the whole mono aspect of astroimaging.

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1 hour ago, MattJenko said:

I put everything up every night and tear it down every morning. As mentioned, you really have to leave everything attached to the scope. Putting it all together each evening would mean most of the evening getting spacing, focus, all manner of frustrations right. This means the setup involves physically moving  everything outside, polar alignment and then a slew/plate solve and off you go, with a possible PHD calibration thrown in for good measure. As for camera choice, a smaller chip makes sense to begin with as it makes all the post processing so much easier, and there are a lot of targets that fit. I went from a 450d to an Atik 414ex and while some targets were too big, most are not and it was a great camera for me to cut teeth on the whole mono aspect of astroimaging.

Would you not make the recommendation to go straight to the ASI1600? You've taken some lovely images with that as I recall. 

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I am also wondering whether I shall need remote focusing. Are these truly confocal or is focusing required on each filter change? Presumably CCDs are focused using a PC's screen. My PC is 5m away in the shed. So not having remote focusing I'm a bit snookered.  With a DSLR I simply focus at the scope using live image mode on the 450D's screen.   

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4 minutes ago, Ouroboros said:

Would you not make the recommendation to go straight to the ASI1600? You've taken some lovely images with that as I recall. 

Using the ASI1600 needs careful consideration of your setup to keep filters close to the sensor to avoid paying out for larger more expensive filters, it also produces masses of data to store and process.

I think an Atik 314 or newer equivalent would be a more sensible place to start CCD imaging using your 80ED and EQ6 you'd have a trouble free undemanding setup.

Dave

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7 minutes ago, Ouroboros said:

I am also wondering whether I shall need remote focusing. Are these truly confocal or is focusing required on each filter change? Presumably CCDs are focused using a PC's screen. My PC is 5m away in the shed. So not having remote focusing I'm a bit snookered.  With a DSLR I simply focus at the scope using live image mode on the 450D's screen.   

Careful or you'll have an empty bank account before know it.

There is the cheap option of the SW motor focuser but I don't know if this works over a remote connection otherwise you're into the realms of dedicated motor focusers for a few hundred pounds, plus some compatible software to work it.

Always best to refocus on filter change whether they claim to be parfocal or not.

Dave

Edited by Davey-T

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19 minutes ago, Davey-T said:

Careful or you'll have an empty bank account before know it.

There is the cheap option of the SW motor focuser but I don't know if this works over a remote connection otherwise you're into the realms of dedicated motor focusers for a few hundred pounds, plus some compatible software to work it.

Always best to refocus on filter change whether they claim to be parfocal or not.

Dave

Well, you can't take it with yer can you! ;).  

I thought a refocus on changing filter might be required.  I might get away with using the cheap focuser and a long lead I guess. 

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33 minutes ago, Davey-T said:

Using the ASI1600 needs careful consideration of your setup to keep filters close to the sensor to avoid paying out for larger more expensive filters, it also produces masses of data to store and process.

I think an Atik 314 or newer equivalent would be a more sensible place to start CCD imaging using your 80ED and EQ6 you'd have a trouble free undemanding setup.

Dave

Noted. :)

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I use the ASI1600 now, but it would have been a beast of a camera to start with and I was very glad of the head start I had with my 414. Needs USB3 really and the files are vast, even bigger than the Atik 11000, as there are more pixels, and given the tendency for shorter exposure times, it means even more subs to process, which without a decent spec machine is challenging, and not conducive to experimentation, which is what learning is all about. It also makes a lot more demands on getting spacing right, tilt fixed and all that mechanical stuff as the sensor is large and more unforgiving. Not to say don't get it, as it is a very flexible camera as it can do planetary as well and I think mine is amazing, just a steep and cpu intensive learning curve and more challenging than the smaller chip.

As for focusing, I found that adding an autofocuser turned a corner for my imaging, as I could set up all night runs without needing to be present for it all. Slewing away to a bright star for bhatinov manual focusing on filter change and then back to target again was painful. Olly had a good tip though to get good focus on L and then not worry about the focus for RGB as the detail comes from L anyway, so you could get good L focus and then set up a L,R,G,B,L,R,G,B.... run to ensure you get all required channels if you are not at the stage of shooting entire sessions on a single filter.

 

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I also upgraded from my Canon 450D (moded) to a cooled camera. I choosed the ASI1600-MMC with 8pos EFW, OAG and Baader filters (31mm LRGB and mounted 1,25" HSO).

This camera works just great!

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The 1600 will work with 1.25" filters in the ZWO wheel, but the files are huge.

Sara uses 1.25" filters in her 8300 cameras, which may be more managable.

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20 hours ago, DaveS said:

The 1600 will work with 1.25" filters in the ZWO wheel, but the files are huge.

Sara uses 1.25" filters in her 8300 cameras, which may be more managable.

I haven't been able to find out how "huge" the files are. I'm guessing that compared to my 450D (which is a 12.4 Mpixel camera) the files from the 1600 are roughly 1.25 times as big at 1600 Mpixels. However, the ASI1600 tends to be used at a faster  frame rate, 1 per minute possibly, compared with 1 every 5 minutes (say) with a DSLR. So, for a given imaging session the 1600 will generate roughly    6 or 7 times as much data in the same time. Does that sound right?  I can handle that amount of data because my MacBook has a TB SD drive.  

What are typical download times over USB2 and USB3 respectively? 

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It's not just the downloading and storage of data, it also takes much longer to process.

USB2 / USB3 don't seem to affect the download speeds much, helps with high speed video capture which is irrelevant for DSOs.

Using 1600 will generate at least 10 times the data compared to a CCD, a 1 minute file takes as much room as a 10 minute file and you have more or less the same data in one 10 minute sub as 10 X 1 minute subs.

There are also some targets that need 20 min plus exposures to prise out the detail, your EQ6 should be able to do this.

As others have said an ASI 1600 is not a good starter DSO camera, better to start with a smaller sensor, you can always sell it and move on.

Just my 2p worth.

Dave

This a single 20 min HA CCD sub of the California Nebula, if you have a search around the forum you can compare to a single sub from a ASI1600

Be a lot quicker processing 10 of these compared to 100 of them

California-neb-005HA3.png.5bf2c0f9d47b51106ff0d82e36079018.png

 

 

Edited by Davey-T
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1600 subs are roughly 32 MB in size. Yes, they take a good while to process. The subs from my 694 are 11.5 MB.

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Personally I think the drop in FOV from the DSLR to an Atik 314 (414) will be too big a shock.  I did this myself to start with and ended up re-selling the 314 and bought a large format Atik383.   However there are issues with that too, such as the shutter which makes flats slightly more complicated and unless you are an expert at sorting out spacing and tilt issues, I got a lot of problems with the corner stars with mine, it also requires larger and more expensive filters, plus I found it rather too noisy for my liking.  I didn't particularly find the files took a long time to download though.

I later decided to re-purchase an Atik314 to get some of the smaller targets and found this so much easier to use, no problems with the corners, shutter or noise.  So I am going to suggest you consider the Atik 460EX, which is half way between the 314 and 383 with all the benefits of the 314 chip, doesn't need larger filters.  That's what I use now having sold my Atik383.  

I agree entirely with Olly's comments,

Quote

Olly had a good tip though to get good focus on L and then not worry about the focus for RGB as the detail comes from L anyway, so you could get good L focus and then set up a L,R,G,B,L,R,G,B.... run to ensure you get all required channels if you are not at the stage of shooting entire sessions on a single filter.

it's what I do with Baader filters which are supposed to be par focal.  Many people poo poo this, but I have compared focus in all channels, and there is occasionally a slight difference in one filter, but IMO this only is an issue with star sizes, which with processing can be dealt with.  I don't have an auto-focusser and set up a complete run. 

You might find you need to bring your laptop to the scope whilst setting up initial focus, and then take it back to your warm room and let it run.  (I'll probably get shot down for my comments on focus, but it seems to work OK for me).  

Carole 

 

Edited by carastro
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Just now, carastro said:

....... it also requires larger and more expensive filters.......

I have to disagree in part here Carole - I think that this 'myth' has become something of an internet belief for people looking at this Kodak chip camera.... It does need clarifying.

While I don't doubt that the Atik 383 with an EXTERNAL filter wheel may not be able to use 1.25" filters, there are camera's such as the QSI683 and the Moravian G2-8300 (both using the same Kodak 8300 chip as the Atik) where due to having an INTERNAL filter wheel will happily use 1.25" filters down to F3.9. That is what I am doing and so can vouch categorically that it works.

So while I wouldn't doubt Caroles findings at all....... with the RIGHT Kodak KAF8300 you CAN use the cheaper 1.25" filters :) 

This is a point that really can not be stressed often enough...... Not all KAF8300 sensor camera's need larger filters :) 

Hope you didn't mind me clarifying that Carole.

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That's fine Sara, of course an internal filterwheel is a separate issue.  I have always used an external filterwheel which does indeed require larger filters. 

Yes the OP needs to know all options.

Carole 

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If the 1.25 filters are close enough to the 8300 chip they don't significantly vignette. ('Significantly' means flats will sort it.) If they are further away in an external wheel they will - but beyond the range of flats to correct? I don't know. You just have to think of where the filters sit in the light cone. Narrow end or wide end?

Baader and Astrodon filters are probably parfocal, in my opinion. What is not parfocal (with itself) is often the telescope. The three filter colours will, even in the best refractors, focus at slightly different focal lengths. Does this matter? It depends on your pixel scale. I have setups working at 3.5 and 1.8 arcsecs per pixel where I'm satisfied that it doesn't matter. I have never found any significant difference in focus between L,R,G and B. I just focus in L and scroll away through the filters. But - using the same scope at at 0.9 arcsecs per pixel in a small pixel camera I am finding very significant changes in focal length, possibly exaggerated by the sensitiivity of the small pixel camera at different wavelengths.

What's all this fuss about download time? I know we don't want to waste clear sky time but my full frame CCDs download in 15 seconds in Bin1. Bear in mind that this covers the equivalent of a six panel mosaic in some cameras!

You could use a cheap Skywatcher motor focus with a long cable to focus using FWHM in your warm room. Much cheaper than the robotic focus options and perfectly OK.

Olly

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Olly - some encouraging remarks there making it much less scary, thanks. I think you're right about the cheap focuser and long lead. I've been wondering whether to do that anyway. Focusing my DSLR at the scope is doable but a bit hit and miss on occassion. What looks good on the live view turns out to be pants in an image. 

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4 hours ago, DaveS said:

1600 subs are roughly 32 MB in size. Yes, they take a good while to process. The subs from my 694 are 11.5 MB.

OK. Thanks. Just to put that in relative terms, about 2.5 times as big as raw files from my DSLR. 

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