17 replies to this topic

[HsnRza]

Hi, I've Celestron C11 f/10 with CGX mount. 

I was using an old DSLR 700D for astrophotography but now I want to buy astrophotography dedicated cameras and guiding for telescope. Can you recommend any? Following is the list that I've prepared for equipments. Is there anything that I should change?

 

Camera for DSOs: ASI294MC

Camera for Guiding: ASI220MC

Camera for Planets: ASI678MC

Off Axis Guider (currently looking at Ali express and there are alot of affordable OAGs but I'm not sure if there is any difference)

 

I cannot go beyond this budget so if there is something that I can change to save my money or something please let me know. plus I dont have field flattener and also I live in bortle 6-7 city (outside europe/america). 

[Sheremy01]

Have you considered the asi533? It’s great for dso and will work for planets as well. I use it for both with my c11. It’s not the best for planets but will work.

[Sacred Heart]

If you are looking to image at F10 then I would want large pixels, the 294 has that or the 2400.  If you go with a 3.76 micron pixel camera  you may have to bin 2 x 2.  

 

OAG, just get one that has about the same size opening for the camera to look through as the camera chip.  Don't want the guide camera chip larger than the hole it looks through.

 

Joe

[HsnRza]

Have you considered the asi533? It’s great for dso and will work for planets as well. I use it for both with my c11. It’s not the best for planets but will wor

I actually was looking at it as well, but I think it has smaller sensor as compared to 294 which will decrease FOV which I dont think is a good thing for c11. What do you think

Edited by HsnRza, 14 March 2025 - 09:59 PM.

[bobzeq25]

I actually was looking at it as well, but I think it has smaller sensor as compared to 294 which will decrease FOV which I dont think is a good thing for c11. What do you think

What I think.

A number of beginners have found it very difficult to calibrate the 294s lights. A significant number of them have given up, in spite of posting here about the problem, and getting answers (which don't work for them.

It's an unacceptable risk.

Going with the 533, even with a smaller field of view, is a much better choice for any beginner. This is not a close call.

This business is HARD. Anything that makes it easier is a good idea. Anything that makes it harder is a bad idea.

That's a lot more important than field of view. You're trying to learn DSO imaging. Winning Image of the Day will just have to wait. <smile>

Even more important. A C11 is a miserable scope to try to learn DSO imaging with. It's fine for lunar/planetary. A small refractor is much better to learn on. Not something I've invented, I'm just reporting.

These are typical experiences, I have MANY of these quotes.

"I regret spending the first 6 months trying to learn <DSO> imaging with an 8" Edge SCT, 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!"

"I put together a video of my imaging rig along with some info on how I went from years of failure trying to image with a long focal length SCT, to achieving success on my first image."

https://www.youtube....h?v=MNQU1hdqz4M

"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 <traditional> imaging basics on THAT frac instead of on the SCT. Trust me"

Trust him.

Think a small refractor can't do much? Click on the mediocre thumbnail to get a good version, and details. It was taken with a 72mm refractor. 2.8 rompin stompin inches. DSO imaging bears NO relationship to visual astronomy.

Edited by bobzeq25, 14 March 2025 - 10:55 PM.

[Notdarkenough]

Initial reaction? Imaging with a C11 isn't going to be cheap. I don't know what OAG you are looking at, but it is a critical piece of kit. A cheap OAG will do nothing but cause problems. For an OAG, I would highly recommend an ASI174mm-mini. To fit in an OAG, a "mini" camera is needed.

 

Regarding a dedicated astro cam, this would be the one place you can skimp, maybe. A 2600 would be great, but a 533 would work, too. I had a 294 for several years; the key is to make the shortest exposure 3 sec or longer. Honestly. There is some great work done on CN about the 294 sensor, and you can read it for days. The short of it is exposures shorter than 3 sec are trouble. So, the purchase of an adjustable led flat panel is a must, because even flats must be 3sec or longer. Otherwise, it is still a great camera. You can't use bias frames with a 294, and Darks, Dark-Flats, and Flats are a must. Additionally, if you are looking at a monochromatic camera, you also need a filter wheel and filters.

 

My biggest concern is the mount. Any imaging rig starts with a great mount; imaging with a C11 will make any mount struggles into Mt Everest. It is, by far, the most critical piece of kit for any imager. This is one reason a short refractor is best for learning; they are very small, light, and fast. Most mounts can sling a 5lb payload with ease, but slinging 50lbs, at much tighter tolerances, is a whole different deal. 

 

Just my 2 cents.

[Spaceman 56]

This business is HARD. Anything that makes it easier is a good idea. Anything that makes it harder is a bad idea.

What....

 

Bob are you suggesting that the C11, with a Focal length of 2800mm, is not a good scope to learn AP ?  

 

Surely its a cracker.  (smile).     

 

allright. to answer the OPs question. at 2800mm focal length, its unlikely you would be shooting wide field deep sky.

Which means the 533 would be a good choice, especially for smaller targets. Galaxies and the like.

 

what are peoples thoughts on the mount requirements ? will the CGX be good enough ?

Edited by Spaceman 56, 15 March 2025 - 06:53 AM.

[bobzeq25]

Bob are you suggesting that the C11, with a Focal length of 2800mm, is not a good scope to learn AP ?

I'm saying it's a horrible scope to try to learn Deep Space Object astrophotography (traditional, with intensive processing). About as bad as it gets.

It's fine for planetary/lunar astrophotography, which are completely different. Completely.

[mayhem13]

I actually was looking at it as well, but I think it has smaller sensor as compared to 294 which will decrease FOV which I dont think is a good thing for c11. What do you think

The C11 won’t give you a flat or fully illuminated FOV beyond about 16mm so don’t concern yourself with the larger sensor of the 294. The 533 sensor is a better sensor overall….but you will need to bin it to 2x2 for full focal length imaging.

 

The other choices are fine. STRONGLY CONSIDER a focal reducer when budget allows….the Starizona SCT reducer is a perfect match for the C11.

[Spaceman 56]

I'm saying it's a horrible scope to try to learn Deep Space Object astrophotography (traditional, with intensive processing). About as bad as it gets.

It's fine for planetary/lunar astrophotography, which are completely different. Completely.

OK. investigating imaging with the C11 a little further.

 

I went to the online calculator.   is this indicating an image scale of 0.28 ?

 

am I reading it incorrectly ?

 

 

if the 0.28 image scale is correct, and the guiding recommendation is 0.5 x image scale, then we would need to guide at about 0.14 RMS ?

 

is this target of 0.14 RMS realistic with a CGX ?

 

my CEM-120 has achieved 0.14 RMS but only on very rare occasions. normally it runs MUCH higher than this. 

[Sacred Heart]

Spaceman56,

 

You would probably need 10 - 12 micron pixel to have a shot.  6 micron binned 2 x 2.  Or an AE mount from AP, 10 micron, ASA.

 

A 3.76 pixel needs to be binned 3 x 3.

 

Joe

[smiller]

I actually was looking at it as well, but I think it has smaller sensor as compared to 294 which will decrease FOV which I dont think is a good thing for c11. What do you think

I also shoot with a long focal length and if you are interested in not being limited to shooting only smaller galaxies and planetary nebula, then field of view is going to be one of your main challenges.

 

People jumped in with solutions, but I don’t think we know enough about what your problems are yet.

 

 Here are some clarifying questions:

 

1) you are using your Canon 700D today which older, but is a fairly nice sized APS-C sized sensor.  What are your main issues you are trying to solve today that drives you to want a dedicated Astro camera for deep sky?   Is it H-alpha sensitivity and you want to use a dual narrowband filter more effectively?  Are you willing to trade that off with field of view because of your budget constraints?  Have you budgeted for a nice dual narrow band filter which can be another $200?

 

2) You say you want guiding because, I presume, you want longer exposures.  Or perhaps your mount is very inconsistent with a lot of periodic error.   What exposure length are you getting today without star trails and what have you done to improve this to date?

 

3) You talk about getting a nice field of view, but you haven’t mentioned a reducer.   I’m curious why a reducer is not top on your list for one of the options to enable you to get a good field of view and a much larger pixel scale without having to invest in a very expensive APS-C sized dedicated Astro camera.   I believe used reducers can be had for as little as $80-100 and there are very high quality reducers available from Starizona.   A 0.63x reducer will increase your field of view by 2.5 X which is equivalent to buying a camera with a sensor that is 2.5 times larger, which is a much more expensive camera.   So it may be more cost-effective to buy a reducer and a more modest sized camera than to try to solve FOV with only a larger camera.   Obviously the reducer and an APS-C camera combined would be a sweet combination, but outside of your budget unless you stay with your Canon and use a reducer and go for a field of view rather than H alpha sensitivity.

 

 

Anyway, just trying to understand your drivers.

 

Without knowing anything about the answers to these questions my guess is that a high-quality reducer with your current camera may provide a lot of value for the money.  Also, that reducer is extremely useful with that scope no matter what camera you have in the, so that may be a great low-risk place to start.  Not too much money and fairly low risk as it's highly likely to be a critical element of your setup anyway and is immediately useful with your current camera.  There are three big advantages to you for a high quality reducer:

 

 

1) 2.5X field of view (by area).  That is a ton!    That is more than going from an APS-C to a Full Frame camera.  An APS-C ASI2600MC is $1500 while the full frame ASi2400MC is $3000.   The reducer is much much less than the $1500 difference between these two cameras.

 

2) Pixel scale is 1.6x larger which means your constraints on your unguided tracking is 1.6x easier.

 

3) 2.5X the photon fill rate on your pixels (i.e. "speed of your scope"), this means 2.5x shorter exposures with the same brightness and read noise contribution.   This further reduces your need for ever longer exposures.

 

In total, this would be an enormous upgrade, at least on paper.

Edited by smiller, 17 March 2025 - 09:08 AM.

[jwheel]

Not a C-11 but I image using a C-14 and focal reducer with an ASI 2600mc Pro. Here is an image that I took recently of a planetary nebula in Taurus called NGC 1514.

 

[jml79]

The C11 won’t give you a flat or fully illuminated FOV beyond about 16mm so don’t concern yourself with the larger sensor of the 294. The 533 sensor is a better sensor overall….but you will need to bin it to 2x2 for full focal length imaging.

 

The other choices are fine. STRONGLY CONSIDER a focal reducer when budget allows….the Starizona SCT reducer is a perfect match for the C11.

What is this about image circle problems. I am building my "Big Rig" this summer and a reduced C11 was on the short list. I have a 294 Mono to pair with it using 36mm filters. It will be going on my EQ8. The 294 requires a 23-24mm image circle. Not big but a fiair bit bigger than 16mm.

[smiller]

What is this about image circle problems. I am building my "Big Rig" this summer and a reduced C11 was on the short list. I have a 294 Mono to pair with it using 36mm filters. It will be going on my EQ8. The 294 requires a 23-24mm image circle. Not big but a fiair bit bigger than 16mm.

Search astrobin and then contact people with C11s.  Here is an astrobin image of C11 with the ASi294MC WITH a reducer:

 

https://app.astrobin...=rshcwn#gallery

 

Here is a C11 with a reducer and an APS-C ASI2600MC:

 

https://app.astrobin...=spamn7#gallery

 

Images look pretty nice to me and they both have multiple images with those setups, but perhaps they are cropped or they had to do special things to get it to work.

 

Contact those astrophotographers and you'll get your answer from people that are successfully using those scopes with large sensor cameras and reducers today and see what issues they have.

 

I've found it very productive contacting people that have successfully used equipment that I'm considering.

Edited by smiller, 19 March 2025 - 01:28 PM.

[rgsalinger]

I use an Edge 11 Reduced. Here's a sample processed image. I love my QHY533M camera with that setup. I doubt that you can use a larger chip with regular C11 and still get good stars in the corners. 

[EncryptedSorrow]

Has anyone tried an ZWO ASI2600MC Air on a C11 edge hd. 
 

I’m curios to see if it’s even possible to work well with that’s scope. 

[astroian]

I’ve tried an ASI2600MM with 1.25 filters on an Edge HD11. You will definitely need the larger filters otherwise you will get reflections.

The 294 will work with the Edge (I’ve done it) but the difficulty of getting decent calibration frames lead me to change it for the 2600. I’ve now changed to the 533 mono to avoid the reflections. The image scale is high, but it’s easy enough to bin in post processing, and if you want you can use it for planets without having to swap cameras.

Cheers,
Ian