New camera but which one?

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denababy
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New camera but which one?

Post by denababy » Mon Aug 27, 2018 10:17 am

Hi everyone I am thinking about upgrading my camera, it will go onto both my Lunt ha50 and ( not at the same time) my Explore Scientific ed80 apo (triplet) with a Quark (chromosphere) at the moment I have a DMK 21, zwo asi 120mm and 120c also an Altair gp8. I have been looking at the ZWO 183mm, don’t need a cooled camera just something that, hopefully, will give improved results. I know the Solar camera in the past was the ZWO 174mm but I believe the 183 has taken over. Anyone comment as to which camera I should look at I.e other makes, size Etc. or should I stick with ZWO? There seems to be Myriad cameras out there and my upgrade has to be right.

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Re: New camera but which one?

Post by Bruce G » Mon Aug 27, 2018 6:36 pm

You might also tell us a little more about what you consider "improved results", as your imaging objectives should help you determine where your money is best spent. You had some imaging problems earlier and I don't know if you have resolved those or not. If not, a better camera isn't going to help much. If you have taken care of those issues and are still dissatisfied with your images, what aspect do you want to improve? By focusing on specifics of what you want to improve in your images, you get a better picture of whether you need improvement in hardware or technique.


I suggest that you consider the following:

1) Frame rate
In my limited experience (only a little more than a year), I have found that I would rather sacrifice some resolution for a higher frame rate. I find the telescope very frustrating to focus if I can see only, say, 5 frames/sec. A rate of 30 or more per second makes things far easier. High resolution or a large pixel count on the image sensor leads to slow readouts. CCDs are usually slower than CMOS.

2) Global/rolling shutter
I recommend the global shutter, primarily because of the way lucky imaging works. Rolling shutters can introduce some odd distortions in the image. I have seen suggestions that rolling shutters exacerbate Newton's rings, but that is not my experience. I have one camera with a rolling shutter and one that has a global shutter (QHY163M and ZWO ASI174MM). I find that Newton's rings are present even with the global shutter.

3) Cooling
If you can afford the cooling, I would get it. It can get pretty hot sitting out there in the sunshine. I'm not 100% sure that cooling is the problem, but at times I have noticed my camera's frame rate decreasing (a lot!) and dropped frames increasing as the imaging session goes on sometimes. I don't always plug in the cooler. I attribute the frame errors to increased temperature, but I haven't taken careful notes.

4) Resolution
I'm sure that someone has done an arc-second resolution to pixel dimension computation for various optical configurations, but if I were looking for another camera right now, resolution wouldn't be top on my list of specs. It turns out that high resolution only matters after you get everything else taken care of. I wish you could see some of my early microscope photos and the more recent ones of the same subject, photographed with the same equipment. Worlds apart in quality. The main difference is a few more years of practice on my part. And, as I noted earlier, a high resolution sensor usually means a slower maximum frame rate.

Hopefully, you will get some more suggestions from those here who have more experience in astrophotography than I.

Bruce G

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Re: New camera but which one?

Post by denababy » Mon Aug 27, 2018 7:48 pm

Hi Bruce, the reason I am thinking of a new camera is that I understand that with the zwo120 it is harder to find the Sun but with a larger chip, hence the zwo183 it becomes easier. Since I purchased the Quark I have had untold trouble trying to get anything other than a black screen on my laptop. It has been Suggested that I change some settings in Sharpcap but have not yet had the opportunity to try it. This probably does not make sense to you as I am still very inexperienced and wondered if a new larger chip would help. The images I have achieved to date are OK but I am looking for more detail. I have not yet got any images using the Quark, still trying to work out number of spacers Etc. There is a chap on another forum who has the same scope as me but he uses a ZWO 1600 his pics are excellent, I can only dream. The videos I watch,( Marty Wise) are really good but how can I begin to get near their pics using different kit.

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Re: New camera but which one?

Post by denababy » Tue Aug 28, 2018 8:57 am

Cont; the real reason I am looking for a new camera is that since I purchased a Quark and put it on my Explore Scientific I cannot get anything on my laptop. I start off using an eyepiece and get the Sun in view, I then put the camera on (zwo120) but all I get is a black screen. It has been suggested that I up the gain and Gamma and move the scope until there is something on the screen, I have as yet not done that due to constant cloud cover. Am I right in thinking that things may be easier with a bigger chip on the camera?

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Re: New camera but which one?

Post by Montana » Tue Aug 28, 2018 9:09 am

I agree with Bruce, if you haven't resolved the issues with your present camera then buying a new one will result in extra cost and extra frustration. Even with a cheap £11 webcam with the lens removed I can take fairly basic images of the Sun, so if you have an expensive camera already you should see the Sun, you should not be seeing a black screen. You haven't got a filter installed which blocks light above 600nm do you?

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Re: New camera but which one?

Post by denababy » Tue Aug 28, 2018 9:30 am

Hi Alexandra, thanks for the reply, the only filter I have when using the Quark is the one I put onto the front of the diagonal that is a Baader uv/ir cut filter. The camera I currently use is ZWO 120 mm. If I get another camera I.e. the ZWO 183, or another make would it give more detail than I am currently getting? As I say I have just about resolved the imaging issues using the Lunt ha50 but decided to buy a Quark after watching a few videos which are achieving the kind of results ( detail) I would like. Also when processing the videos I can follow step by step knowing I have a better chance of getting similar results I.e Marty Wise video that lasts for about 52 minutes.

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Re: New camera but which one?

Post by Montana » Tue Aug 28, 2018 11:31 am

So the ZWO 120 has a pixel size of 3.75µm
A ZWO 183 has a pixel size of 2.4μm

The explore 80mm is f6
Lunt 50 is f7
I need to use my calculator at home to work out whether you will be using the correct pixel size. It maybe that the 2.4um is far too small unless all you are interested in is full discs. I would have thought 3.75um would give you more than enough detail.
Low f numbers need small pixel sizes, large f number needs large pixel size for detail. I could do with a 3.75um camera for my PST as my DMK41 at 4.75um is too big pixels for full disc work but is excellent for a 2x Barlow shot. So detail is dependent on f number and pixel size.

If you are not getting enough detail with the Lunt 50 and the 3.75um pixel then use a 1.6 or 2x Barlow and do a mosaic. I do this this with my Solarscope. You don't need a new camera for this unless you are rich.

Alexandra

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Re: New camera but which one?

Post by Bruce G » Tue Aug 28, 2018 5:06 pm

Yes. If you are still at the point where you're not getting a usable image with what you already have, then you should hold off buying anything new until that is sorted out. I'm sure if we could all stand together in one spot with your gear we could have it solved in a few minutes but alas, we'll have to do it the hard way.

The first thing I suggest is that you strip everything out of the optical system that isn't absolutely necessary. If you have a Continuum or other white light solar filter, use that on the Explore Scientific scope. No barlows, no Quarks. You should have nothing but the telescope and the camera. Can you obtain a properly focused image with that setup? If no, there are non-optical problems, like bad program settings, bad cables or even a dead camera. If yes, then it's time to try Ha.

Assuming that you can get a good white light image, I suggest setting up the Lunt for Ha because 1) the system is passive - you will see something even if settings are way off and 2) I'm familiar with the Lunt scopes and have never used a Quark.

Set up the telescope for direct viewing. The Lunt scope should already have a TeleVue Sol-Searcher, but if it doesn't, get one. They're cheap and extremely easy to use. You might want one for your ES scope as well. Simply temporarily holding one in place on the OTA is enough to hand guide the scope to the correct orientation. This may take a while, so turn on tracking for the mount. Find the Sun, get it in focus and adjust the etalon so that you can see detail in the chromosphere. Center the Sun in the field of view.

Connect the camera to your computer and start your acquisition program (I think you said you're using SharpCap). You already know that the camera and the connections are good because you tested them with white light.* Screw a 1.25" T-ring adapter into the front of the camera and slip the camera in place of the eyepiece. If the computer screen is still black, don't panic. Gamma control, if present, should be set to neutral. Avoid either extreme. Increase exposure and/or gain until you see an indication of the Sun. It will probably be very blurry, since the eyepiece and camera don't focus at the same point. Set the focuser of the telescope to about the middle of its range. Support the blocking filter and camera assembly with a hand so that nothing falls on the ground and loosen the screws that hold the draw tube. Slide the draw tube in or out as needed. As you approach good focus the size of the Sun's image will decrease. If the fuzzy blob increases in size, you're going the wrong direction. Don't worry about getting the focus perfect, just get it sort of close. You will do the final focus with the focuser.

If you get this far, you've made it. Focus the image and try a capture. Somewhere along the line, something isn't working for you. Try what I suggest and let us know the results. Keep the system as simple as possible so that there are fewer pieces to possibly cause a problem.

Good luck. I look forward to hearing your progress.

Bruce G


* If you have disconnected the camera since the white light test you may want to give the camera and connections one last operational test. Do this:

Don't connect the camera to the telescope yet. Leave the cover over the image sensor. When the program displays the camera image, it will be black. Uncover the image sensor and point the camera toward a window or a light. You should see some indication of the light source on the screen. Don't expect any sort of image, just lighter and darker as you move the camera around. If you don't see any indication of light being received by the camera, then increase exposure and/or camera gain until you do. Gamma should be in the center.

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Re: New camera but which one?

Post by Montana » Tue Aug 28, 2018 6:45 pm

OK for the best sampling and detail with your 3.75um camera you need to use a 3x barlow on the Explore 80mm, you need a 2x Barlow for the 2.4um pixel camera. So the difference is negligible really in practicality, both will give an excellent solar image. Yes it will give a touch more detail (at lower mag) but I wouldn't say it was worth getting just yet. I bet you would get far more difference by improving photo processing skills instead. I would do exactly what Bruce states above.

Alexandra

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Re: New camera but which one?

Post by PDB » Tue Aug 28, 2018 6:51 pm

Don't forget the Quark has a 4.3 telecentric built in already.
If you have a Continuum or other white light solar filter, use that on the Explore Scientific scope. No barlows, no Quarks. You should have nothing but the telescope and the camera.
Be CAREFULL and make sure you have a decent whitelight filter in front of the scope or you might toast the cam or worse.

Paul

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Re: New camera but which one?

Post by Montana » Tue Aug 28, 2018 6:54 pm

Oh right, I'll do the calculations with that in mind then

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Re: New camera but which one?

Post by Montana » Tue Aug 28, 2018 6:57 pm

With the 4x of the Quark in, then with no Barlows at all the optimal sampling is a 4.50um pixel camera. So if you use barlows eg 2x you would need a 6.75um pixel camera. So going down to 2.4um would be crazy. Thanks Paul I didn't think of that.

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Re: New camera but which one?

Post by Merlin66 » Tue Aug 28, 2018 11:00 pm

DON'T buy an ASI 183mm for solar narrowband imaging.
I went through the same thought analysis - using the ED80 (600mm fl) and the PST mod (>1000mm fl) and the ASI 174 I have...
I did buy an ASI 183mm - and had "issues" - these were final recognised and accepted by ZWO who stated "due to technical issues the ASI 183mm is not suitable for Ha solar imaging" They offered me a full refund.
I eventually went for an ASI 1600mm for the shorter focal lengths. I'm happy with the outcome.
Hope this helps.
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Re: New camera but which one?

Post by denababy » Wed Aug 29, 2018 12:57 pm

Thanks for all of your replies, today as the Sun is hiding behind cloud I setup my scope (Explore Scientific) and pointed it at a tree about a mile away just to test that the camera is seeing, I put my Powermate on to give me a similar distance from the camera sensor, probably not right but I needed to find out if the camera is working. When I put the Quark on the other day I could not get anything through the camera but managed an out of focus view with an eyepiece. So I need to wait until the skies are blue, at least I now know I need at least one spacer on, so although no where near sorting my problems with the Quark I know things are working as they should. Thanks Merlin for the heads up on the ZWO 183. My problem is that now I have a bee in my bonnet about getting a new camera !!!!

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Re: New camera but which one?

Post by marktownley » Wed Aug 29, 2018 10:44 pm

Post a picture of your setup in action, not getting results through the camera, it will be easy for people to see what the problem is then.
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Solar images, a collection of all the most up to date live solar data on the web, imaging & processing tutorials - please take a look!

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Re: New camera but which one?

Post by denababy » Thu Aug 30, 2018 9:43 am

How can I thank you all enough, the skies are fairly clear so I setup and tried some of the things suggested here and I actually managed to get a slightly out of focus image but I have never seen Newton’s rings as bad. I tightened everything down just to make sure it was/is not due to lose fittings, could it be due to poor seeing or (back to my moan) the camera? is a quick pic showing the rings;
Capture_0001 10_16_02.png
Capture_0001 10_16_02.png (631.91 KiB) Viewed 632 times

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Re: New camera but which one?

Post by Merlin66 » Thu Aug 30, 2018 9:52 am

After all the discussion, what camera were you using???
"Astronomical Spectroscopy - The Final Frontier" - to boldly go where few amateurs have gone before
https://groups.yahoo.com/neo/groups/ast ... scopy/info
"Astronomical Spectroscopy for Amateurs" and
"Imaging Sunlight - using a digital spectroheliograph" - Springer

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Re: New camera but which one?

Post by denababy » Thu Aug 30, 2018 10:08 am

Hi I used a ZWO 120mm

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Re: New camera but which one?

Post by bart1805 » Thu Aug 30, 2018 10:37 am

Getting there! To get rid of the Newton rings you could use a tilt adapter or Atmospheric Dispersion Corrector.

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Re: New camera but which one?

Post by Merlin66 » Thu Aug 30, 2018 10:56 am

The T2 tilter works very well for me with the ASI 174mm.
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Re: New camera but which one?

Post by PDB » Thu Aug 30, 2018 7:08 pm

Yes the ASI120 is famous for Newton Rings, but a tilt adapter will do. You probably will need a lot of tilt. (At least I do have with mine, still surprised the complete field of view is still sharp)

Rgrds,

Paul

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Re: New camera but which one?

Post by Bruce G » Thu Aug 30, 2018 7:21 pm

PDB wrote:
Thu Aug 30, 2018 7:08 pm
Yes the ASI120 is famous for Newton Rings, but a tilt adapter will do. You probably will need a lot of tilt. (At least I do have with mine, still surprised the complete field of view is still sharp)
That took me a while to grasp as well, but think of it in photographic terms. What would the depth of field be like for a lens focused at infinity and with an f-ratio of f/30? It would be huge. OK, technically, we're talking about depth of focus, not depth of field, but depth of focus is also large when higher magnifications are used. So, particularly when using barlows or telecentric "amplifiers", we are operating the lens under conditions where tilt has little effect.

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Re: New camera but which one?

Post by PDB » Thu Aug 30, 2018 7:45 pm

Done the calculation once how far the sensor diagonal could be tilted before moving out of the critical focus zone, but will have to redo it. (Lost in my never ending pile of rubbish). Even when using a focal reducer behind the Quark, bringing it back to f/12, still needs a considerable amount of tilt.

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Re: New camera but which one?

Post by denababy » Fri Aug 31, 2018 9:29 am

Hi everyone after yesterday’s success I really want to get a new camera and have whittled it down to two; ZWO 174 mm or Point Grey imx 174, there are a few hundred pounds difference in price but cannot decide which one please advise me. I know I could get a tilt adapter for my ZWO 120 but I really am set on upgrading the camera. My scope is an Explore Scientific ed 80 apo triplet with a Daystar Quark. I don’t want to make the wrong choice so I need your help, when is it any different? My laptop only has usb 2 and both cameras are usb3 are they backward compatible? Thanks in advance.

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Re: New camera but which one?

Post by bart1805 » Fri Aug 31, 2018 9:38 am

Hi denababy, I use the PGR and it does exactly what it should do, a pleasure to work with.
But....
1) A lot of Newton Rings when I use a Powermate.
2) A USB 2.0 laptop just won't let you use the camera the way it should. You really need USB3.0 and a fast SSD. Otherwise you get a lot of hickups and low fps.
If I were you I would learn to make great images with the 120. It is a fine camera. If you have exploited that camera to the max, we are a bit closer to a new maximum and maybe there are other / better / cheaper camera's. CS Bart.

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