80 replies to this topic

[crawdady]

Celestron 11" on a CGX with focuser.  The QHYCCD 5ii guide scope focused right in.  However, I have had no success getting the ZWO to capture a shot that isn't grainy and tinged with red. I can get fairly sharp stars, but the graininess / noise(?) is extremely frustrating. Same results with SharpCap, NINA, and APT.

 

I hope someone has suggestions or references that would help ... 

 

 

crawdady

[Borodog]

You need to provide much more information. Start with posting an image. Then: What is your gain? What is your exposure length? What is your temperature set on? Are you talking a single frame or are you stacking?

Edited by Borodog, 27 June 2022 - 11:23 AM.

[Bob Campbell]

Celestron 11" on a CGX with focuser.  The QHYCCD 5ii guide scope focused right in.  However, I have had no success getting the ZWO to capture a shot that isn't grainy and tinged with red. I can get fairly sharp stars, but the graininess / noise(?) is extremely frustrating. Same results with SharpCap, NINA, and APT.

 

I hope someone has suggestions or references that would help ... 

 

 

crawdady

Hi

 

I agree with borodog regarding much more info is needed. However, let me jump (slightly) ahead and make a couple comments.

 

I saw you were using sharpcap. Under the livestack (really the only way to get rapid feedback of what you are imaging) are you adjusting the histogram? Read up on it if you are not. A simple color balance in the histogram might solve your problem of the reds.

 

If it is grainy, you simply may not be gathering enough frames. Stacking is used to increase signal (the DSO) to noise (everything else).

 

Something to think about as you are compiling the other info borodog was alluding to

 

Bob

[matt_astro_tx]

Are you referring to red astro images or red images of a terrestrial object during the daytime?

I ask because I own the same camera and when I was first practicing with it on terrestrial objects everything was red. This was because the camera is more sensitive in the red and UV bands. Once I added a UV/IR cut filter to my imaging train all my colors were nicely balanced.

You need a UV/IR cut with this camera as the sensor window is AR only.

Hope this is helpful.

[bobzeq25]

Celestron 11" on a CGX with focuser.  The QHYCCD 5ii guide scope focused right in.  However, I have had no success getting the ZWO to capture a shot that isn't grainy and tinged with red. I can get fairly sharp stars, but the graininess / noise(?) is extremely frustrating. Same results with SharpCap, NINA, and APT.

 

I hope someone has suggestions or references that would help ... 

 

 

crawdady

Boy, do I have suggestions.  <smile>

 

I have both 183s and five years plus of experience.  Sample image with the 183MC below.  This is sincerely intended to be helpful.  It may come across as harsh.  But there are multiple problems here, and I wouldn't be doing you any favors to gloss things over.  These go from least to most important.

 

One problem is that you're not looking at the right thing.

 

With a 183 you calibrate the lights with bias, flats, darks (or you'll see a ton of amp glow noise).  Align, stack.  This is true:

 

"Don't go by the visual appearance of a sub – short broadband subs with the 183 may look very thin, but when stacked, the final result will be fine."

 

https://www.cloudyni...hl= 183 tables

 

Next problem.  That's a terrible camera for that scope.  The tiny pixels want short and fast optics.  I bought both 183s for my C8 RASA, 400mm, F2.  That's what the camera works well with.

 

Image scale in arc sec per pixel generally should be between 1 and 2.  For a beginner closer to 2 is better.  Your image scale is 0.17.  (focal length divided by 200.  take the result and divide the pixel size by it.)  Absolutely guaranteed to be a noisy mess.  I tried the 183 on my 130mm F7, and got my least liked image on astrobin in quite some time.  I've removed it.

 

Above all else.  Truly, above all else.  That's a  bad scope for a novice to try to learn AP with.  The wrong tool for the job.  Like trying to learn to build fine furniture, while banging in nails with a crescent wrench.  These experiences are absolutely standard, I have about a zillion of these quotes.

 

"I regret spending the first 6 months trying to learn imaging with an 8" Edge, with that scope it was a losing effort. Fortunately got a nice little refractor, and not only have the quality of my images improved but I'm actually enjoying the process of learning how to do it!"

 

"After months of learning and overcoming challenges <with the SCT>, and finally buying a shorter FL APO refractor, I really really really wish I had listened to everyone on here and started learning the imaging basics on THAT frac instead of on the SCT.   Trust me"

 

Don't trust me, trust him.  <smile>

 

My number one recommendation.  it will work well with the camera.  Or something similar, there are many good choices.

 

https://optcorp.com/...hotography-lens

 

$389.  It could easily save you a year of frustration and wasted effort. And a _lot_ of money, also.  Reducer, off axis guider, sensitive guide camera...  they'll cost way more than $389.

 

General considerations.  No more than 480mm.  No more than 10 pounds.  No slower than F6.

 

That year?

 

"I have a C8 and this was the scope I learned AP on.  It was a long, tough struggle and I have no good pictures to show for it.  I could have easily saved a year by starting with a more image-friendly scope."

 

If you eventually want to image small galaxies with that scope, you'll reach your goal significantly faster/better/cheaper if you learn the ropes with something small.  This is complicated and difficult, think months not weeks.

 

Edited by bobzeq25, 27 June 2022 - 01:38 PM.

[Borodog]

You should listen to Bob.

 

If you feel absolutely must stick your hand in the fan with the C11, at the very least you should buy an f/6.3 reducer/corrector and bin the 183 2x2, if not 3x3. 

[crawdady]

Wow, thank you all for the comments and constructive criticism.  I realize this setup is overkill for someone new to AP.  I had one shot to get setup and apparently got some shaky advice.  

 

However this is my setup, so I have to find a way to "grow into it."

 

bobzeq25, I also have access to a Hyperstar, but that only increases the image scale to .88 .  Your #1 suggestion was to get a smaller scope to learn AP with, while still using the 183MCPro, right?  You're saying that I just add that scope to the C11 (like a guide scope) to leverage the mount and QHYCCD 5ii Guider with it.

[Bob Campbell]

Wow, thank you all for the comments and constructive criticism.  I realize this setup is overkill for someone new to AP.  I had one shot to get setup and apparently got some shaky advice.  

 

However this is my setup, so I have to find a way to "grow into it."

 

bobzeq25, I also have access to a Hyperstar, but that only increases the image scale to .88 .  Your #1 suggestion was to get a smaller scope to learn AP with, while still using the 183MCPro, right?  You're saying that I just add that scope to the C11 (like a guide scope) to leverage the mount and QHYCCD 5ii Guider with it.

In addition to the other advice, and learning sharpcap histogram, colorbalance and stacking, try binning your 183, still using the c11. In sharpcap, its just a switch you turn on, very easy. That could bring your effective pixel size more in line with your focal length.

 

Bob

Edited by Bob Campbell, 27 June 2022 - 02:41 PM.

[bobzeq25]

Wow, thank you all for the comments and constructive criticism.  I realize this setup is overkill for someone new to AP.  I had one shot to get setup and apparently got some shaky advice.  

 

However this is my setup, so I have to find a way to "grow into it."

 

bobzeq25, I also have access to a Hyperstar, but that only increases the image scale to .88 .  Your #1 suggestion was to get a smaller scope to learn AP with, while still using the 183MCPro, right?  You're saying that I just add that scope to the C11 (like a guide scope) to leverage the mount and QHYCCD 5ii Guider with it.

Better ideas, still not best.

 

The CRUCIAL point.  The problem is NOT that the setup is overkill.  The problem is NOT image quality.  "Growing into it" is _far_ better done with a new (small) scope.  Struggling with the big scope does not teach you astrophotography.  It teaches you how to struggle with a big scope, which is _not at all_ the same thing.

 

The problem is that DSO AP is complicated and hard to learn.  The _last_ thing you want to do is make it much harder.  And much more expensive (particularly if you think your time has any valus).  That not only limits your ability to learn. 

 

It's not impossible to do.  The really really really (do I hear an echo? <smile> ) big deal is that it's just not much fun.

 

Good mount.  Small refractor.  Breakfast of Champions.  <smile>

 

That scope throws rocks in your path.  Big boulders.  It blows a 60 mph headwind in your face.  I know, that's not intuitive.  It's a great visual scope.  Why shouldn't it be great for imaging?  Which is why this happens over and over and over.....

 

Most everyone chooses to get off that path, one way or another, as the two people above got off that path.  I suggested a $319 way off.  I've seen beginners here spend _far_ more in a futile effort to get the big SCT to work.

 

It is a fine scope for imaging.  In the hands of an expert.  The best way to become that expert is to start small.

 

Hyperstar is expensive.  And still not the best learning tool.  It's tricky to get working.  You do not need tricky.  You need simple.  You'll have a lot of weight on the mount.  See Dr Stark, below.

 

Piggybacking the scope is not ideal.  See "less than 10 pounds" above.  The heavier the setup is, the worse it responds to guiding corrections.  Which makes learning guiding harder.  You do not want harder.

 

Here's Dr Craig Stark, the author of the PhD2 program you'll be using for guiding.  Noted astrophotographer, who writes and lectures.  Dr Stark, on the best scope to start out with.   The format is his.  He's talking straight to you.

 

"As light as possible.

 

 

 

Seriously.

 

 

 

No, seriously."

 

<smile>

 

Enough, you get the point.  Lets get constructive.

 

This book will be the best $50 you ever spend in DSO AP.

 

https://www.amazon.c...d/dp/0999470949

Edited by bobzeq25, 27 June 2022 - 02:52 PM.

[Borodog]

Bob,

 

At 180mm, especially with the 183 binned 2x2, the lens you recommended likely won't even need guiding. My first toe dipping into DSO was 60, 120, and 240 mm lenses on a 2.9 micron pixel pitch camera riding piggy back on a C8 with a Byers drive. My images sucked, but it wasn't the lack of guiding that was the problem. I also had great fun and learned a lot. But I probably wouldn't do it again. ;O)

[matt_astro_tx]

Bob is right. I heeded similar advice and bought a 60mm refractor to use with my ASI183MC Pro and have had a great experience learning over the last year.

[crawdady]

I understand mistakes were made and that I should learn AP with a smaller setup.  After investing all that I have, how much more are we looking at?  If I can not mount a smaller scope on the C11/CGX I have, then I have to invest in another EQ mount to go with the new scope?  I don't mind hard work, but it's not feasible to spend a lot more.  

 

Bob: That book was the first one I bought over a year ago.

[Borodog]

As I said above, in my opinion you can 100% piggyback a camera and lens on your C11. When the image scale is large enough you do not need guiding.

Is it the optimum way to go if you haven’t already shelled out thousands of dollars? No. But it may well be the lowest hanging fruit given the equipment you already have.

[Tapio]

Or, you could start with moon and planets.
Your scope and camera are better suited to that.
There's a learning curve there too but not as steep as with DSO.

[Bob Campbell]

I understand mistakes were made and that I should learn AP with a smaller setup.  After investing all that I have, how much more are we looking at?  If I can not mount a smaller scope on the C11/CGX I have, then I have to invest in another EQ mount to go with the new scope?  I don't mind hard work, but it's not feasible to spend a lot more.  

 

Bob: That book was the first one I bought over a year ago.

Bobzeq is right on many counts, as are his references. I do EAA (electronically assisted astronomy) and I did nearly everything 'wrong' (and still do) mainly because my budget does not allow me to own multiple scopes/cameras/mounts.

 

If you can post the original image you were alluding to, that could help a lot. You are already using a guide camera, can locate DSO for imaging, and get round,  focused stars so you have mastered some of the things that bedevil people when they use long focal length OTAs. In other words, you are way further up the learning curve than you realize.

 

I did try an f5 90mm refractor to see what it was like (and to capture M31), and it was almost too easy to find and track objects. Since I didn't have a large piggy bank, I got an achromat so the CA finally became too irritating, so I sold it.

 

I now have a c6 because it was at the upper limit of what the SW az-gti mount can handle, and the smallest sct that can do hyperstar (haven't sprung for that yet).

 

So try a simple object, like M27 bin at 2x or 3x use sharpcap live stack with histogram adjustments and see what you get.

 

Cost of that experiment: zero (13 pounds a year if you get a sharpcap pro license)

 

Hope thishelps

 

(the other) Bob

Edited by Bob Campbell, 28 June 2022 - 09:14 AM.

[bobzeq25]

I understand mistakes were made and that I should learn AP with a smaller setup.  After investing all that I have, how much more are we looking at?  If I can not mount a smaller scope on the C11/CGX I have, then I have to invest in another EQ mount to go with the new scope?  I don't mind hard work, but it's not feasible to spend a lot more.  

 

Bob: That book was the first one I bought over a year ago.

Many of us have more than one scope (just as every photographer has more than one lens).  We just switch them on the mount.

 

Again, I posted a $319 solution.  Do remember it when people tell you, that, with the SCT, you need a reducer, an off axis guider, a sensitive guide camera...

 

A near zero cost solution (you have a DSLR and a lens, correct?) is to mount a DSLR and a lens with this.

 

https://www.amazon.c...e/dp/B0000XMYFQ

 

Either a small refractor or a camera lens is an _excellent_ way to learn.   And to make some nice images.  People do it a lot.  Here are 49 pages of images made with small refractors and camera lenses.  Did I mention this is unintuitive?  <smile>

 

https://www.astrobin...ch/?q=skyguider

 

From above "I did try an f5 90mm refractor to see what it was like (and to capture M31), and it was almost too easy to find and track objects."

 

The first light with my 70mm, I was just about giggling.  It was _so_ much fun.  An image with the 70 below.  This is imaging, and it's 2.8 rompin' stompin' inches.  <smile>

 

I want you have fun.

 

Edited by bobzeq25, 28 June 2022 - 11:14 AM.

[Oort Cloud]

Not that we need my +1 to know that Bob is right, but he is.

I too, tried to learn AP on an SCT because it was what I already had. I didn't know what I didn't know, so I struggled. A lot. Would I have eventually figured it out? Probably. But who knows how long that would have taken.

I followed the advice of those who did know what I didn't know, and bought a refractor. Like magic, my first images with that scope literally blew away anything I had done with the SCT.

Now that I am no longer _learning AP_ I image well with both scopes. But that likely still would not be the case had I not bought that refractor to learn on.

Edited by Oort Cloud, 28 June 2022 - 11:20 AM.

[fewayne]

Had I attempted to start with the scope I'm using now (8" RC), I would have probably just given up. I started with that exact scope (70 rompin' stompin' millimeters!) and it was still anything but a cakewalk.

 

"Aperture is king" is so common a meme, it's understandable that many folk get the wrong idea or bad advice when they start astro. But all that weight, all that focal length, and that extreme focal ratio really do make it significantly harder to learn -- troubleshooting is much more difficult when there are so many hypotheses for what's causing the trouble!

 

If you got what you got, well, we'll try to help.

 

183s yield noisy subexposures. At least mine always does. More integration time helps -- you're going to need hours of it unless you're working from super-dark skies.

[Sheridan]

The CGX mount should have the dual vixen/losmandy saddle plate which means it should accommodate any scope you put on it, without piggybacking.
So no you don't need buy another mount. Bob posted a link to a camera adapter from amazon it appears to be arca swiss. This will work on both vixen/arca.

https://landseaskyco...2efb1327e&_ss=r
If you have a dlsr and a 200mm lens I would just start with that.

I did the SCT back in 2006 and it was a pain until I got a focal reducer made for small sensors. 2800mm has it's place, small far off galaxies but F10 is sloooowww.
The larger object will fill that scope, starswill be bloated and it will be grainy. Btw that scope got put in the box for 15 years due to life situations.
I recently got back into the hobby last year with just a nikon and a couple of manual prime lenses. Yes the CGX will look overkill with just a camera, but it will be stable

Attached is a photo using the SCT, but it took along time to get to this point and honestly
it's not impressive. When I first shot Andromeda all i got was this bright blur which was only
the core. It was just to large for the setup i was using.

SCT photos.

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Edited by Sheridan, 28 June 2022 - 11:07 PM.

[bobzeq25]

I speak with confidence.  But it's something of an act.  In the past some people have disliked what I've said, and let me know that in no uncertain terms.  It's consequential.

 

And so, a sincere thank you to everyone in this thread who has supported me.  It makes a difference.  Really, really, really makes a difference.  <smile>

[Sheridan]

Compaired to 80mm refractor.

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[Sheridan]

Dslr 135mm lens with lots of 2s exposures on just a tripod. No tracking.
Not great but I was amazed with my D5200 captured with just a lens.
This is what re-lit the hobby for me.

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Edited by Sheridan, 28 June 2022 - 12:44 PM.

[Bob Campbell]

Dslr 135mm lens with lots of 2s exposures on just a tripod. No tracking.
Not great but I was amazed with my D5200 captured with just a lens.
This is what re-lit the hobby for me.

wow, just wow!

[Bob Campbell]

I speak with confidence.  But it's something of an act.  In the past some people have disliked what I've said, and let me know that in no uncertain terms.  It's consequential.

 

And so, a sincere thank you to everyone in this thread who has supported me.  It makes a difference.  Really, really, really makes a difference.  <smile>

you are clearly a valuable contributor of information and experience. thanks for that!

 

(the other) Bob

[t-ara-fan]

Celestron 11" on a CGX with focuser. 

Bob is right.

 

BTW that is a GREAT scope for imaging planets and parts of the sun and moon.  The small pixels in the '183 camera give you an image scale that you would need a barlow to get with a camera that has bigger pixels.  Jupiter and Saturn will get better and better located (higher altitude) over the next few years, and you have the gear to get great shots. 

 

But for AP of DSOs etc, an 80mm f/6 refractor is the way to start out.  And maybe a camera like the ASI2600 with the bigger sensor and no amp glow if budgets permit.
 

Edited by t-ara-fan, 28 June 2022 - 04:15 PM.