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Advice for an Astro Photography Setup for doing Science

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gblasco
gblasco's picture
Advice for an Astro Photography Setup for doing Science

Hi everyone.

New in the forum, I made some visual observations for AAVSO in 90s.... so not new in Astronomy, but dormant for a while...

Looking for help and advice TO BUY A SETUP  FOR DOING SCIENCE, guys!!!  

Thank you very much in advance !!! 

I WILL give you an introduction in this post and links to different posts about every SPECIFIC PART OF THE GEAR for a better follow up

Quote

 IMPORTANT: 

In this post, I will  mark the questions I WOULD like to be answered with this emoticon  and italics, to make a little easier to identify my questions .. Of course, you are invited in all comments you like,but this are the questions I would made if this were a conversation.

 

ABOUT ME 

 

I am an amateur astronomer who was very out of the "business" during many years. I was born in SPAIN and studied astrophysics, but I did not finish my degree, but now I am a professional dedicated to image quality as an engineer in the broadcast industry. I was active from 93 to 2000 , then 20 years dormant, now I am 41 years old and I have some money to spend and star over my passion

...

 

Now I live in GUADALAJARA; Mexico, no in Spain anymore. And I will go soon to Baja California state in mid-AUGUST , probably I will cross the border to the USA... And I have an opportunity to buy a complete setup of my old hobby

 

ABOUT WHAT I NEED

 

I know is long  , but is not easy to tell. You can take your time, or answer in parts. I hope not being overwhelming.

 

HOW MUCH

 

My base budget is USD2,000 for a complete astrophoto- astrophysicist kit. OTA + MOUNT + CAMERA + ACCESORIES . with a range of +-10% (from 1800 to 2200)....

 

 

NOTE AND QUESTION: I read Meade is bankrupt so more forums don't recommend it. I know it was a good brand. What is your opinion about choosing Meade products, apart you have some stock for sure.... and I know Is a difficult question for a seller....

 

WHEN:

 

I will go/buy by mid August 2020 

 

GOALS / NEEDS

 

I need a complete kit for the following objectives:

I have an astrophysicist background so...

 

MAIN GOALS

  • Stellar astro photometry /astrophotography of Variable Stars, Supernovae, and Near Objects (NEO) asteroids, and other stellar objects
  • Astrometry or measurement of  position, of asteroids , NEOs, 
  • Occultation observation of stars by asteroids
  • Observations of far - faint comets
  • Other transient events
  • Precise photometry of exoplanet transits
  • Measurement of orbits of faint moons of outer system planets
  • Measurement of proper motion of fast moving stars
  • Parallax experiments

IMPORTANT! WHAT ARE NOT MY GOALS! .... (but I can do very rare if the gear allow to, btw)

  • Color artistic / cosmetic photography
  • Nebula photography
  • Direct observation by a viewfinder
  • Planetary
  • Solar
  • Near big comets

NEEDS ON THE GEAR (in my humble opinion for accomplish the goals) 

 
MAIN GOALS: MAKING SCIENCE

 

The best quality / price ratio...

 

Light! Light! more light: means aperture

WHY? Most of my goals imply stellar dim objects. I DON'T need specially fast scopes to have fast exposure for nebulae. I won't photograph nebulae. I need Best aperture for price

 

A very sensitive camera /low noise camera:

 

After many thinking about CCD/CMOS, I think I want to do some experiment with some brand new CMOS models with very high QE and very good gain sensitivity. I will talk about this in the post about CCD. I am in love with  two chipsets: one based in IMX178 (CMOS MONO) the other one ICX829AKA ( Orion StarShoot G4 Monochrome Deep Space) - BUDGET!!! I know there are better options.... but $$$
 

A manageable focal length for my needs:

I think between 600mm and 1200 mm are my max range. 850 to 1000 my best. (also depends on the type of telescope I choose, and the type of camera)

 

 

After reading this, this are in a nutshell my best guess for my needs!! PLEASE BE FREE TO COMMENT IF YOU AGREE OR DISAGREE!

 

  • Best Telescope type: Newtonian, Newtonian variants or Ritchey–Chrétien.  (I discarded at first the SC and the refractors)
  • Best mount: German EQ. i think I have not another choice for my goals, what do you think?
  • Best camera: It depends of the focal length, but in the 600 to 1000, a CMOS camera with 2.4um pixels and good sensitivity are my best . Im 90% sure I will choose one based in IMX178 (CMOS MONO) or ICX829AKA ( Orion StarShoot G4 Monochrome Deep Space)
    In larger optics like a RC I would choose a CCD or a CMOS with 4-5 um pixel size
  • Guiding telescope /camera system: I have a 50mm homebuilt finder built 20 years ago with a short local length. I HAVE to check if  I can adapt it to the OTA and if the focal length is good for the OTA I choose. I think I will have not much money left for the guiding gear, so perhaps I will buy afterwards. Or try a no so-good option like an off axis guider. My finder uses 1 1/4 eyepiece holder, so I can fix a small guide camera, or even a barlow (I have one).
  • Other accessories could be, but not necessary, will be power gear, although I will be near my car or at home, I think I would need probably USB hubs, cables, and this type of things. I could need. Also a collimator. if I can afford it

 

SOME EXAMPLES. I WANT TO COPY  THESE SETUPS, OR SIMILAR ONES

I like very much two telescopes built by an amateur astronomer : Robert spellman , take a look. He takes wonderful B&W photos with this gear:

First one is this:

It is a GSO 150mm Astrograph f4 or f5 with the ORION STARSHOOT G4 and a Skywatcher EQM35-Pro.
 Also he uses this bigger and more expensive setups

I think they are -200mm over an EQ-G mount with an ORION Starshoot G4 camera

I will discuss my Options about OTA (Tubes) I have search in this POST:

I will discuss my Options about MOUNTS I have search in this POST:

I will discuss my Options about CAMERA I have search in this POST:

I have all this post written, but in Word, so I am adapting to the forum format.

Thanks everyone for reading!

 

Richard Berry
Richard Berry's picture
Advice for an Astro Photography Setup for doing Science

Hello Gonzalo--

Your large post in four parts is difficult to answer quickly. However, you appear to have investigated the options thoroughly, so I will attempt an answer that is shorter than your questions, Part of the difficulty in framing an answer is that no one person probably has direct experience with all of the products that you mention, so each of those who reply will be limited by our own experiences.

Your science focus is very broad, so my answers are based on a "general purpose" setup.

I concur with your assessment that 20 cm f/4 or f/5 Newtonian offers the best aperture/dollar value, and the focal length is short enough to yeild a decent field of view with almost any camera you select.

The Celestron AVX is a good starter mount. I have two, and they have given good service. However, if you can afford the extra cost, consider the Celestron CGX. Its key advantages are that 1) it has a home position, so that 2) you run ut remotely from a computer and you can 3) build an accurate pointing model. There may be other equally capable mounts, but I am familiar with the CGX and like it. The mount has ample load capacity to carry a larger optical tube.

As a general rule, I prefer a large mount with small optics over a small mount with large optics. In my opinion, get the best mount you can afford. No mattter how good the optics or camera, if you cannot point and track well, you will be vexed and unhappy.

The CCD versus CMOS choice is a trickly one. A cconservative answer is to select an inexpensive 16-bit CCD like the monochrome Atik 414EX. On the other hand, I am using an Atik Horizon camera for photometry, so it can be done. In September this Section will offer a Webinar devoted to the CCD/CMOS tradeoffs.

Remember that you will also need a filter wheel that is comparible with the camera and one or more photometric filters. The usual filter recoomendation is V plus optically a B or I for staring out.

For most photometry, you probably will not need to guide. If the mount is well aligned and balanced, you would be able make 60-second unguided exposures..This of cource depends on the objects you wish to observe and the program of observation.

You have not mentioned how you will use the equipment. If you can place it in a small roll-off shed (that is, an observatory) so it is a simple matter of opening up and turning on, you will be able to do a great deal more science. If you are forced to travel to a site for each observing session, you will get far less done. In a contest between ease of use and a dark sky site, ease of use usually wins.

I trust that others will chime in now that I have "broken the ice" with my answers.

--Richard

gblasco
gblasco's picture
Thanks

First of all, thank you very much for your reply. Many people says that the way is to buy an APO refractor and Newtonians are worthless, but in Variable Star observing or Asteroid orbit determination (NEOs) are useful for dim objects if you are in a budget.

I talk about the products that I find in the markey in the range of price I can afford and the Advanced VX is one of my first options for my first goto (motorized) telescope (I had a Dobsonian in the 90s) I like very much the CGX, but is over budget. I think I could go with a smaller 6" or with a ioptron CEM25P instead.....

Most people say that they prefer to make a good inversion in the mount before than in the optics, so I think is a good rule, I have to find the best equilibrium with a bias towards the mount. in fact I can buy a 300USD tobe over a 1000USD mount, and then try tu upgrade the tube when money come again

About the ATIK 414EX is one of my favourite choices but it cost by itself 1500USD, so its expensive for this first time, and I want to give a chance to play a little with the new CMOS low noise chipsets. It is a bet. Some people are experimenting with them with nice results and there are a lot of pages about discoveries of how to make them work. I like more the good old reliable results from CCDs, but I want to experiment with all this new tecniques around the CMOS... Also the smallest size of the pixel is an advantage for avoininng COMA aberration, and use a shorter tube. If someone say to me that this new chipsets  are worthless for astrophotometry I will give up, but Ive read about the stacking and the techniques around optimizing the curve of gain with the sensitivity of the sensor, and it is a nice playground... If doesnt work, I can use the CMOS as a nice tracking device, and make an inversion in the ATIK in a future.

About the filter, I muts admit I am a little ignorant, and I have to investigate more, and read all the guides about it. I know the basics, about the V B I filters, but in the practice, I have to read more, and then make the correct questions

About guiding is nice to know someone who thinks is not always needed to guide, most people say that is THE KEY. a good autoguider. I think I have to dig more in this subject

At now, I dont have good skies for an observatory, but if the hobby continue growing I have nice spots in Mexico with dark skies and high altitude for renting a place.... I will see ... For now I will do and break the setup at my roof every day in a polluted suburban area, or in the field in a safe place, every time setting up. I have to check If I am still in the hobby during a year, for give the next step.

Ohhh.

I forget in my posts to tell you all my PROPOSAL for combos, or combinations of the gear described in the other post. I will do now here:

 

 

arx
arx's picture
"For most photometry, you probably will not need to guide"

A quick comment. I started out in DSLR photometry with time series studies through the night. Initially I did not autoguide, and it was OK, though even with 'good' polar alignment there was drift of the image across the sensor over a few hours. I don't have an observatory, so could not spend endless time ensuring near-perfect alignment. However, for some time now I have used auoguiding. No drift, of course, but more importantly the precision of the photometry is optimal.

Roy

gblasco
gblasco's picture
CONCLUSIONS - MY PROPOSAL OF COMBOS FOR MY NEEDS

The camera I like more is among two options: the COLDMOS QHY 178M (CMOS) (or the zwo equivalent based on IMX178) and the Orion StarShoot G4 Monochrome (CCD) I think all combos will be with one of this. I have not much more budget... :-( 

It is better to make a good choice in a good mount + OTA COMBO, because are the key

Which is the best COMBO in your opinion? for 2000USD

ALFA COMBO

Celestron Advanced VX 8" Newtonian Telescope # 32062
1229USD 
https://www.highpointscientific.com/celestron-advanced-vx-series-8-quot-newtonian-go-to-telescope-32062   
+
 QHY 178M Monochrome Astronomy Camera # QHY178M
https://www.highpointscientific.com/qhy-qhy178m-mono-cooled-cmos-astronomy-imaging-camera    
768USD
=
1998USD

ALFA COMBO 2

The same but with this camera

Orion StarShoot G4 Monochrome Deep Space Imaging Camera - 53087

https://www.highpointscientific.com/orion-starshoot-g4-monochrome-deep-space-imaging-camera-53087  

499USD
=
1728USD + money for ACCESORIES

 

BETA COMBO

  iOptron CEM25P Equatorial Mount with 1.5" Tripod - 7100P
898USD https://www.highpointscientific.com/ioptron-cem25p-equatorial-mount-with-1-5-tripod-7100p
+
 GSO 8" f/5 Newtonian Reflector Telescope - Steel OTA (White) # GS630
419USD https://agenaastro.com/gso-8in-f5-newtonian-reflector-ota.html+
 QHY 178M Monochrome Astronomy Camera # QHY178M
https://www.highpointscientific.com/qhy-qhy178m-mono-cooled-cmos-astronomy-imaging-camera    
768USD

= 2085 USD

GAMMA COMBO

Sky Watcher EQM-35 Equatorial Go To Mount # S30500 
725USD https://www.highpointscientific.com/sky-watcher-eqm-35-equatorial-goto-mount-s30500
+
Orion 203mm f/4.9 Reflector Telescope Optical Tube Assembly
250USD https://www.telescope.com/Orion-203mm-f49-Reflector-Telescope-Optical-Tube-Assembly/p/9788.uts
+
 QHY 178M Monochrome Astronomy Camera # QHY178M
https://www.highpointscientific.com/qhy-qhy178m-mono-cooled-cmos-astronomy-imaging-camera    
768USD

= 1743 USD + MONEY FOR ACCESORIES

TETHA COMBO

NOT SO GOOD MOUNT

 1099USD ORION https://www.highpointscientific.com/computerized-telescopes/orion-skyview-pro-8-goto-reflector-telescope-24731
  Orion SkyView Pro 8" GoTo Reflector Telescope - 24731  
+
 QHY 178M Monochrome Astronomy Camera # QHY178M
https://www.highpointscientific.com/qhy-qhy178m-mono-cooled-cmos-astronomy-imaging-camera    
768USD 

 = 1867 USD + MONEY FOR ACCESORIES

 

EPSILON COMBO

Sky Watcher EQM-35 Equatorial Go To Mount # S30500 
725USD https://www.highpointscientific.com/sky-watcher-eqm-35-equatorial-goto-mount-s30500
+
  679.95USD : Celestron NexStar 8SE SCT OTA Orange Tube - 11069-OTA
https://www.highpointscientific.com/celestron-nexstar-8se-sct-ota-orange-tube-11069-ota  

Orion StarShoot G4 Monochrome Deep Space Imaging Camera - 53087
https://www.highpointscientific.com/orion-starshoot-g4-monochrome-deep-space-imaging-camera-53087  
499USD

= 1904 USD

The CCD has bigger pixels and the short and light tube can work very well with the long focal range of the nexstar

FINAL WORDS

i know I will have to invest in FILTER KIT + AUTOGUIDER....

Also any combination of another COMBOS with the MOUNTS, OTAs and CAMERAs described in these other posts are welcomed

THANKS FOR HELPING ME!!!!!

Bikeman
Bikeman's picture
I would caution that "filters

I would caution that "filters and accessories" is something that can in the end eat a considerable fraction of the budget. I happen to have a setup that is not unlike the options you consider:

  • 8" Newtonian OTA (a really cheap one, but it throws the photons in the general direction of the sensor, good enough, reflectivity of the mirrors is close t0 95% even for cheap mirrors so I think the OTA is not the part that you want to invest heavily in, in terms of "efficiency")
  • equatorial mount (I have a Skywatcher HEQ5Pro, close to the limits of it's load capacity... A good mount will stay with you for decades and will save you troubles and frustration and can make guiding obsolete, so I would put the $s there in retrospect. )
  • IMX178 based camera , I think this is a good choice. I have an uncooled version, but in retrospect, the cooled version is a much better choice.

The entire setup is approx 3000-3500 US$, and the photometric filters and filter wheel are easily the biggest chunk of extra cost. You'll need at least the V filter, but in the end you'll want at least the B, V, and maybe I filter, so you will buy a filter wheel, and once you have a filter wheel you'll fill it up with filters (this is a well established  empirical law) :-).  About 500 US$ for the filter part of the setup is probably a good estimate to begin with! 

A setup of these dimensions is perfectly portable, and being able to move the rig to some darker sites (or if you plan to do asteroid occultation work, to move it into the path of such occultations) is a great advantage, so you'll want to add power supply solutions and other outdoor gear to your equipment.

P.S.: And of course, AAVSO membership is also a good investment which should be included in the budget :-)

CS

HBE

CrossoverManiac
CrossoverManiac's picture
I own an Orion Starshoot G4

I own an Orion Starshoot G4 Monochrome I do have some issues with it.

  • FOV/pixel size.  The pixel size is 8.6"×8.3" with a resolution of 752 x 582.  For my 6" f/4.8 Newtonian, the angular resolution and FOV would be 2.4"×2.3" and 30'×22', respectively, but it slightly undersamples the stars.  A longer focal length would take care of that problem of undersampling but at the cost of FOV.  Let's say I replace the Newtonian with a 6" SCT at f/10.  That would make the angular resolution 1.7"×1.3", but the FOV would only be 14.4'×10.6' or less than 1/4 the angular area of the Newtonian.  Yes, you can use a f/6.3 focal reducer to increase the horizon and vertical FOV by 59% each and the angular area by 250% but then the angular resolution is now 1.9"×1.8" and barely in the range of normal sampling for okay seeing conditions.
  • Temperature control: the temperature fluxiates more so for the G4 than with other cooled cameras.
  • Driver crash: Of all of the astronomy cameras I owned, the G4 has the most issues with crashing.  And when it does crash, the USB cable has to be physically disconnected from the camera to restart it.  Though, these crashes tend to only happen whenever the camera is taking short subs of a few seconds or less.  It rarely happens with the longer exposures used in photometry.

At $500, it is a great bargain for an astrophotography camera.  Also, it has a very high dynamic range because it has 1/2 the read noise of the comparable SBIG ST-7 and ST-402 (G4's read noise of 7e- vs the ST-7/402's read noise of 15e-).  Because the ICX829 chip has an antiblooming gate, it only has 1/2 of the FWC of the SBIG equivalent (a dynamic range of 50,000 e for the G4 vs 100,000 for the SBIG equivalent, though only for the NABG version) so the dynamic range works about the same, but you don't have to worry about a target star measurements being messed up by blooming from a bright star so it's the same dynamic range but minus the risk of bleed over from a bright star.  OTOH, the ST-7E temperature control much better than the G4 and has less issues crashing.

 

If you have a very accurate GOTO system (or a focal reducer) and a scope with a focal length greater than 1000mm, a G4 is not a bad choice for the cost though there are still issues with temperature control or taking short exposures.

gblasco
gblasco's picture
A possible choice for a lightweight setup: GSO 6" RC

Hi Crossovermaniac,

First a littlte intro, and soon I am back in the G4.

Your post came just in a moment I was thinking in the pixel size of another option I am taking in account.

After discussion of the issue here and in the cloudynights forum ( https://www.cloudynights.com/topic/717830-advice-for-an-astro-photography-setup-for-doing-science-part-1/ ) My conclusion is that I need a more expensive and heavy mount to be in a problem free situation if i choose a  8" Newtonian (which are larger and heavy). Celestron AVX is the only option, and has very variable reviews about problems in the gear, and the longevity... and is quite heavy for transport by plane)

So i decided to downgrade my expectations, and choose a 6" inch telescope and a less exxpensive mount, and also wightweight. 

Today Robert Spellman sent me two recent photos of the G4 with the 6" GSO astrograph

Arent they nice pictures?​

https://www.flickr.com/photos/30493356@N06/50133805677/

https://www.flickr.com/photos/30493356@N06/50130464381/

My problem living in Mexico is that I must cross the border by myself, by foot and then take a plane in Tijuana, international shipping is expensive, and customs also are more expensive, so If I can bring it by foot and in my hands, it will be a great price reduction.

The best option for this is the iOPTRON CEM25P It can hold 28lb in visual and there are good reports in photo with 15 to 17lbs. It has many design in common with the CEM45 and the CEM60 but in a smaller fashion

(the 2nd option is the cheaper EQM35PRo that is worse in terms or PE but has good reviews if it is not overloaded, but I think I will overload it)

I think is a smart design and not an adaptation of old mounts (like the EQM35) and the PE of the gear is rated under 10. So with good guidance and PHD2 there are nice reports of 1arcsec of better in very good polar alignment.

About the tube i am now between three options.

If I use a small sized sensor I think the problems of aberrations of reflectors are avoided.

1st OPTION: The Gso f5 6” which is my best option but again is longer, and more difficult to bring by plane. Also doesnt have included  the dual speed focuser.

2nd OPTION: The 6” f4 astrograph. More portable, but i have doubts about aberration issues. ANd is only 600mm focal. Is sold with a Crayford dual speed hi quality focuser.

3rd OPTION: The quite cheap RC 6” which is f9 (1470mm focal) but is not a good fit with a small pixel sensor (like the ICX178)which is a 2.4um sensor. With this sensor i have a pixel size of 0.36secs and I am  oversampled. Also with this setup I need a longer focal autoguider because my guider is 200mm. SHorter tube is also better for wind effects and equilibrium in the mount

HERE COMES THE thing about the G4:

One solution is choose a orion G4 ccd.WIth their huge Pixels.  And the sensor will fit nice in the 6" RC with a pixel size of 1.3 sec, ant the autoguider can use a cmos with a small sensor. The RC 6” is so small and short that i can bring in my knees inside a backpack and is lightweight. But is more expensive than the newton for only a few advantages, have a huge obstruction in the 6” model and the collimation seem a nightmare with those hyperbolic mirrors

 

With the 1370mm 6" RC Astrograph I have a size of 1.3" per pixel and a FOV of 0.27° x 0.3° with the Starshoot G4.

Also I can use a 2-3um cheap CMOS sensor for my autoguider which is a 50mm F4, that gives me about 2" per pixel

Also The RC 6” is so small and short that i can bring in my knees inside a backpack by plane  and is lightweight.

Perfect solution? NO ... life will be so simple....

The RC 6" is more expensive than the newton for only a few advantages, have a HUGE obstruction in the 6” model (quite less contrast) and the collimation seem a nightmare with those hyperbolic mirrors. It is easy to have focused collimated and pinpoint stars with a 750mm newtonian than in a 1370mm RC.

Also I liked very much the 3072 x 2048 6 Megapixels ( 1/1.8") CMOS IMX178 sensor.... and the ICX829ALA monochrome CCD sensor is only a 752 x 582 pixel 0.4MPX array. 

What do you think?

 

TRE
End the endless shopping speculation

Hurry up and buy something, anything. Your wish lists are  fairly undifferentialted and seem to be  constrianed by budgets and borders. Then use the equipment until it falls apart or dies. Then,  like many of us, you will have taken the first step of the journey that will see updates for a lifetime.

It is doubtfull that anyone's first equipment set-up lasts very long before it wants to be updated. It is best not to spend a lot of effort shopping, but put a lot of effort into using.

The stars are enternal compared to an observer.  You'll want to start taking data somehow. Get some pictures to analyze.

Ray

gblasco
gblasco's picture
Only one chance to buy

I agree with you, this is the best way, but it is difficult to make this from Mexico. I will do a trip next August to California, and I will buy everything in a opportunity to take all by plane, from Tiijuana to Guadalajara.

I can shop whatever, but if doesnt work there are not second market in Mexico, or is not at my view, and if I forget to buy an accesory I will probabbly spend more in shipping and customs that the accesory itself.

Local shops are quite expensive. And they have not much options away from "basic setups to watch the moon",

If I was living in the states, I would agree 100%

gblasco
gblasco's picture
CONCLUSIONS

Hi again...

Thank to your advice  , the advice in other forums and some research I have some conclusions....

What research I did? I looked photos of setups of astrophotographers with the mounts I like, and I looked for the weight of the telescopes+accesories they use.... and you were right  . They use smaller setups with the three mounts I was proposing... but Go to the conclusions:

CONCLUSIONS

  • The quality of the mount is the most important part
  • In all forums, chats, whatever... People say that for a 8" tube . You need at least a ieq30 / HEQ5 / CQM AT LEAST, and even a biggest  40pound rated mount or any of these toys that are around 1500: https://astroforumsp...graphy-in-2020/ (see attached photo)

    I didnt take in count the autoguider weight and the filter sets for astrophotometry and they are not cheap neither. AC adapters, power in field.... more $$$ to the shopping cart

SO if I choose the 8" Science path I will go easily to near $3000.

My choice is to rebuild my plan with a smaller 6" OTA and a quality smaller mount, and I made some Setups here, that I think are more realistic....

You are invited to visit this post. Where I study the options with 6" light reflectors

SUMMARY OF THE POST ABOVE

I compare three GSO 6" OTA tubes light in weight.

And 3 Mounts

Then I take in account two possible SENSORS

which are detailed here:

CMOS OPTION COLDMOS QHY 178M Monochrome Astronomy Camera # QHY178M
768USD
https://www.highpointscientific.com/qhy-qhy178m-mono-cooled-cmos-astronomy-imaging-camera 
(most suitable in the SHORT length OTAs, smaller pixel and little less sensitive)

CCD OPTION: Orion StarShoot G4 Monochrome Deep Space Imaging Camera - 53087
https://www.highpointscientific.com/orion-starshoot-g4-monochrome-deep-space-imaging-camera-53087  
499USD
(most suitable in the LONG length OTAs, BIGGER pixel and more sensitive)

btw if I choose the ccd G4, I can spend a little more in the guider camera and buy the QHY5III178M which is the uncooled version of the COLDMOS 178M, and play with both technologies.

 

I made some calculations about the FOV with this cameras

With the 1370mm RC I get 1.25"/px and 0.27 x 0.30 with the CCD ORION Starshoot G4
With the 750mm F5 I get 0.66"/px and 0.56 x 0.38 with the COLDMOS QHY178M

SUMMARY AND HARD DATA TABLE

With all the data I have found and the reviews, here are what are the costs of several combinations  of the above options, and the weight ratios for the mount, 

After all, the weight ratios are above the 0.5 ideal , but are not so far away.

Less than a 6" I think is not an option, and I have found some good experiences of this range of mounts with 6" small OTAs

I wait any opinions, or advice between this 3x3 matrix of 3 OTAs and 3 MOUNTS

Thank you again for your patience 

gblasco
gblasco's picture
Now deciding the Sensor IMX178 vs IMX183

Hi all,

I have finally decided to get a GSO 6" F4 astrograph with a iOPTRON CEM25p mount. I think will be the best choice for my budget.

At now I am deciding what camera to buy within my budget, and I have some questions about the photometry on CMOS cameras. I have created a post here about if makes sense a 14bit AD converter in a CMOS sensor like the IMX178

https://www.aavso.org/less-one-e-adu-cmosccd-specs-does-it-make-sense

I will appreciate if any with experience/knowledge in CMOS/CCD sensors take a look at there.

I am sure I need ONE CMOS or CCD camera with quality to measure SNs, Asteroids, or Variable Stars, and I want to get the best quality of the measurement per USD within the budget. 

I am quite sure, that I need a second one for the autoguider. I have available an homemade 50mm-F4 refractor. It was my old finder in a homemade dobsonian. It has an eyepiece adapter for 1 1/4". so guide cameras. What do you think? Do I need an autoguider camera or I put all my bucks in my main camera and let the mount do its work?

My first idea was to get a camera based in the only affordable 14bit sensor in the market and buy the cheapest guide camera from ZWO which is around 150USD

 QHY 178M Monochrome Astronomy Camera # QHY178M
https://www.highpointscientific.com/qhy-qhy178m-mono-cooled-cmos-astronomy-imaging-camera    
768USD

specs here:

https://www.qhyccd.com/index.php?m=content&c=index&a=show&catid=94&id=42&cut=1

The only cooled CCD camera in this budget is the ORION Starshoot G4  with the old ICX829AKA, with a gain of about 0.7e- per ADU and RMS read noise at 7e-. It has a 16bit converter

specs here:

https://www.telescope.com/Orion-StarShoot-G4-Color-Deep-Space-Imaging-Camera/p/118205.uts

I think the CCD at this price is a worsese option, and only in very dark skies will have an advatnage with a e- well more high.... so I think it is better to give a chance to the more actual sensors. Also its pixel is higuer at 8.6um

The IMX178 with a pixel size of 2.4um is better for a 600mm focal length telescope giving a size per pixel of about 0.82" per pixel. (I made some nice captures and calculations published here: https://www.cloudynights.com/topic/718612-advice-for-a-6-setup-for-basic-dso-quality-astrophotography-part-2 )

If I don't want to undersample or oversample, by best pixel size is between 2.4um and 4um. 

Here I have a question, and the real reason for thinking in the big brother of the IMX178 based sensor. It is the IMX183 sensor which is a 12bit and a very similar RMS noise of 1 to 2 e- at most gains. ZWO ASi183mm pro at USD999 is a nice option

https://astronomy-imaging-camera.com/product/asi183mm-pro-mono

BUT in this camera, or the QHY equivalent: QHY183 COLDMOS CAMERA

specs here: https://www.qhyccd.com/index.php?m=content&c=index&a=show&catid=94&id=16&cut=1

Then I look at a GAIN=10. For instance. I see that the IMX178 only needs 0.287 e- for get every ADU, gets a read noise of 1.4e- with a QE of about 78% and a dark current quite null in the cooled version

At GAIN 10, the IMX183 needs 1.0e- (3 times the IMX178) , for every ADU, and you get a larger read noise: 1.8e- ... the QE is very similar (84 vs 78)

So at first glimpse, it seems that a 14bit sensor gives me three times more precission in the measurement, But AM I measuring only noise with this sensor? does it makes sense to have a 14bits sensor in a camera with those specs? 

My question about the real or not real SIGMA of certainty in the measurement of the photons that arrived at the sensor in one sensor against the other is based on if with this range of RMS a 14bits AD converter against a 12bits does it makes a difference?

This is the reason I made this post in the photometry forum:

https://www.aavso.org/less-one-e-adu-cmosccd-specs-does-it-make-sense

Sincerely,

--

Gonzalo

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