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Which camera fits best my setup? 1600 vs 294

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#1 SolarSystem96

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Posted 09 May 2021 - 10:03 PM

Hi everyone,

This is my first post on this wonderful forum that has helped me many and many times and I hope I have opened it in the right section.

 

Well, I own a complete 12" LX200 ACF for the planetary imaging (with its Super Wedge) and a classic AiryApo80, a TApo 80ED f/6.25 (and its 0,8x reducer) from PrimaLuceLab for DSO imaging mounted on a NEQ6 Pro, and finally with an ASI1600MM PRO on the way.

But now the big sister of this camera has recently come out, the fabulous ASI 294MM PRO, and I was wondering (only after taking the 1600 will you tell me?! Unfortunately or fortunately yes, now we'll see...):

 

considering a sky with an average resolution of 2 "given by atmospheric turbulence, it is convenient to make a change on the fly between the two cameras, i.e. switching the 1600 with the newer 294, considering the small price difference?

 

I know the 294 outclasses the 1600 in many ways, but my main gripe lies in the sampling. For simplicity I make a small summary of the calculations made for both scopes:

 

  • for the LX200 I would have a theoretical optimal sampling at 0.122"/pixel: with the 1600 (3.75um) I would reach 0.126"/pixel (with a 2x barlow), while with 294 (2.315um, bin 1x1) 0.157"/pixel (without any barlow);

 

  •  for 80ED I would have a theoretical optimal sampling at ~ 0.463"/pixel: with the 1600 I would have 1.547"/pixel; with the 294 (bin 1x1) I would have 0.955"/pixel.

 

I am aware that the sampling for DSO follows different rules and the reasoning of the optimal sampling is not so important that for the long focal length planetarium, but I wanted to report it for completeness.

 

Having said that, in your personal opinion, being able for the moment to allow me only one camera, which of the two could best meet my needs taking into account my equipment and the average sky in which I operate?

Am I fussing over anything and should I go to 294 right away?

 

Thanks in advance for your answers.

 

Manuel


Edited by SolarSystem96, 09 May 2021 - 10:03 PM.


#2 JamesTX

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Posted 09 May 2021 - 10:21 PM

Can't really help you on planetary side other than to say I wouldn't use either for planetary.  I have both (although I'm waiting for my 1600 to return from zwo for repair) and also an asi178mm and IMHO the asi178 is the better planetary camera due to its significantly faster frame rate.  DSOs are my primary use so my views on planetary could be wrong.

 

For imaging DSOs.. the 294 in bin 2x2 mode is a better fit for your 12" than the 1600 due to the larger pixels... although you'd need some exceptional tracking with either camera to get great results IMO.

 

For the 80ED both are fine.  The 294 is more efficient.

 

My own personal take on the 1600mm vs 294mm:

  • If you already have a 1600 you don't need to rush out and pick up a 294mm unless you really want to.  Its an upgrade but not super huge.. unless you are just tired of the 1600s diffraction/halo issue (you might want to research that if you are unaware).
  • If you have neither.. and you are about to make a new purchase between these two.. go for the 294.  The price difference is worth it.. talking new prices here.  1600s seem to be heavily discounted on the used market these days.  A great way to break into mono imaging cheaply.

 

Sounds like you already ordered a 1600 and are now having second thoughts... 



#3 bobzeq25

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Posted 09 May 2021 - 10:36 PM

You want to do two things, planetary and DSOs.  These are _totally_ different activities.  Just as you have different scopes for these, you should have different cameras.

 

For planetary an uncooled one shot color camera is fine.  A key parameter is being able to define a small region of interest and so downloading frames very fast.  More speed = better images.

 

For DSOs you need cooling.  Mono versus color is just a personal decision.  Mono is better, but counting filters and a wheel far more expensive.  Whether or not it's worth it is personal, many factors come into play.

 

The best compromise camera is the 1600, but you're shortchanging both activities.  A good planetary camera actually is quite low cost, the new ASI462 is excellent and $299.

 

For DSOs the modern 294 (which has been out for a while) is significantly better than the ancient 1600, which does not work well with short exposures (so you're forced to use dark flats instead of the simpler bias), has artifacts around bright stars, and major "amp glow".  But the 294 is not designed as a planetary camera, and is pretty slow.

 

All the above factors are more important than your concerns about image scale.

 

I have a 290MC (the 462 was not yet out) for planetary, and a 2600MC for DSOs (will be adding the mono version later this year).  I'm mostly a DSO person, as you can see from my two samples.  Mars used a 130mm F7 refractor and a Barlow, best 1000 frames out of 10,000) the Jellyfish used a C8 RASA.  Better versions than the (required) crummy CN jpgs here.

 

https://www.astrobin.com/6ise11/

 

https://www.astrobin.com/kis712/

 

The image scale for Mars was about 0.3, for the Jellyfish it was 1.9.  It's not as important as many think.  For DSOs larger image scale (assuming the same total imaging time) gets you better to signal to noise ratio, just as important as resolution.  And you may easily not get the resolution you think from small image scales, because of seeing and tracking.

 

Mars 2020 V4.jpg

 

Jellyfish, SH2-249 -small.jpg


Edited by bobzeq25, 09 May 2021 - 10:52 PM.

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#4 ravenhawk82

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Posted 10 May 2021 - 12:00 AM

I bought a 294 because it was out when I was looking but, having used it for a while, I'm sure I'd be happy with the 1600 as well. There are a couple things I'd point out when comparing the two-

First, the 294 is really meant to be used in Bin2 mode. In fact, it wasn't until after it was released that they added a firmware tweak that allowed 1x1 mode to be unlocked. It shoots at 14-bit by binning the pixels on a higher resolution 12-bit sensor. So when you shoot in 1x1 mode a few things happen. Your full well capacity drops dramatically, you're limited to 12 bits, and your file sizes get enormous (Almost 100MB per frame) without adding any real resolution in most cases because the super small pixels are oversampling beyond a useful level. The 1600 is also 12-bit but without all these other downsides so in a comparison between both cameras at 1x1, I'd take the 1600. 

These downsides in 1x1 mode don't really matter for planetary imaging but I agree with Bob that these really aren't planetary cameras. The 294 (using as an example because it's what I'm familiar with) has a framerate quite a bit lower than most planetary cameras which is key for lucky imaging. It can take planetary photos in a pinch and I've used it for some beautiful moon photos but that's definitely not its strong point.

All things considered, if you're interested in DSO and planetary photography, I'd keep the 1600 and use the money you save by not buying a 294 to get something like an ASI462MC. That IS a planetary camera and its cost happens to be just a little more than the difference between the 1600 and the 294. The 1600 being an older model doesn't make it any less capable of a camera. No matter which you go with you're going to be capable of taking killer photos :)



#5 SolarSystem96

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Posted 10 May 2021 - 05:31 PM

First of all, thanks to all three for the detailed answers.

In particular:

 

Sounds like you already ordered a 1600 and are now having second thoughts... 

 

You got exactly the point. 

 

 

You want to do two things, planetary and DSOs.  These are _totally_ different activities.  Just as you have different scopes for these, you should have different cameras.

 

For planetary an uncooled one shot color camera is fine.  A key parameter is being able to define a small region of interest and so downloading frames very fast.  More speed = better images.

 

 

Pure gold sir. 

It is always good to hear back to say certain things and specify them well.

 

For DSOs you need cooling.  Mono versus color is just a personal decision.  Mono is better, but counting filters and a wheel far more expensive.  Whether or not it's worth it is personal, many factors come into play.

 

Needless to say, I totally agree. On the other hand I already have excellent Astrodon filters that I would like to exploit also with the planets: it is true that a monochromatic camera on the one hand lengthens the shooting times which can be a problem for rapidly rotating plants like Jupiter or Saturn, but derotating everything is compensated; on the other is not possible not to mention a greater sensitivity given by the lack of the Bayer matrix, focus indipendently each channel and integrate with UV/Ir/CH4 filters etc.

 

 

First, the 294 is really meant to be used in Bin2 mode. In fact, it wasn't until after it was released that they added a firmware tweak that allowed 1x1 mode to be unlocked. It shoots at 14-bit by binning the pixels on a higher resolution 12-bit sensor. So when you shoot in 1x1 mode a few things happen. Your full well capacity drops dramatically, you're limited to 12 bits, and your file sizes get enormous (Almost 100MB per frame) without adding any real resolution in most cases because the super small pixels are oversampling beyond a useful level. The 1600 is also 12-bit but without all these other downsides so in a comparison between both cameras at 1x1, I'd take the 1600. 

 

Others precious reminds. 

 

 

All things considered, if you're interested in DSO and planetary photography, I'd keep the 1600 and use the money you save by not buying a 294 to get something like an ASI462MC. That IS a planetary camera and its cost happens to be just a little more than the difference between the 1600 and the 294. The 1600 being an older model doesn't make it any less capable of a camera. No matter which you go with you're going to be capable of taking killer photos smile.gif

 

Having all that said, in conclusion the most important thing is to use two different cameras: one for the planetary and one for DSO imaging even before choosing whether to keep the 1600 or change it for the 294.

 

  • For the first point: planetary imaging. Wanting to opt for a monochrome camera, my biggest problem remains that of sampling, the recent cameras (ie 178MM or 290MM mini) all have very small pixels: the Opt. S. I would have it with 0.122"/pixel and with 3.75um pixels and a 2x barlow I get ~ 0.128"/pixel, so I would say acceptable. While, although both the 178MM (2.4um) and 290MM mini (2.9um) surely better performing vs 1600, I would get (without barlow) 0.163 and 0.198 and converting them to ~ 0.12 would require a 1.3x or 1.6x barlow but the problem is: are there any good ones at a reasonable price out there? Because I only know 1.5x (already hard to find). 

 

  • Second point 1600 vs 294: from what you have told me the differences are there and also quite evident although it is necessary to evaluate well (ie the possibility of bin 1x1 that could mislead).  On the other hand I realize that having the possibility to change a product that is still new, probably starting with something newer (mainly a difference of 5 generations of sensors and a significant increase in EQ: 60% vs 90%) could have its advantages as long as the 1600 always remains a great camera.


#6 ravenhawk82

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Posted 10 May 2021 - 07:42 PM

Hmm, regarding the first point, comparing the sampling values is really splitting hairs but I also think your math is a bit off... Smaller pixels and more focal length should *decrease* your arcseconds per pixel, not increase them. I can't calculate myself without knowing what focal lengths you are comparing, but if your sampling rate is 0.122" per pixel, adding a 2x barlow will definitely not generate 0.128" per pixel so I'd double check your work. 

I'm not sure if there's a question in your second point but it sounds like you're leaning toward the 294. I certainly won't argue against that as it's the decision I made as well (albeit before I ordered a 1600 ;) ). I'd just be hesitant of sweating the small details. Every new sensor generation brings new features and abilities but they don't cancel out what the older tech is capable of. Quickly perusing through Astrobin, you'll find hundreds of photographers taking beautiful pictures with the 1600 and I doubt you'd be able to pick out which camera took which photo if the same person processed images from each and let you try to tell. In my mind the biggest real world advantage of the 294 is its extra dynamic range, so high contrast scenes like the Orion nebula with the bright Trapezium stars in front of a diffuse nebula are easier to pull off. The 1600 can be used to accomplish the same results, you just might need to layer some shorter exposures to recover highlights that the 294 wouldn't blow out as quickly. 

Whichever you pick I think you'll enjoy it :) The key is learning your gear as best as possible. That'll yield better results every time than merely relying on new tech. If you want new tech, by all means get it! Just understand that the photographer, not the camera, is what makes the image look good.


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#7 SolarSystem96

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Posted 10 May 2021 - 10:31 PM

Hmm, regarding the first point, comparing the sampling values is really splitting hairs but I also think your math is a bit off... Smaller pixels and more focal length should *decrease* your arcseconds per pixel, not increase them. I can't calculate myself without knowing what focal lengths you are comparing, but if your sampling rate is 0.122" per pixel, adding a 2x barlow will definitely not generate 0.128" per pixel so I'd double check your work.

 
For the first point the telescope I am referring to has an aperture of 12" at f/10, so D = 304.8mm and FL=3048mm, hence the following calculations:

  • optimal sampling:Screenshot_20210511-043101__01__01.jpg
  • 3.75um pixel sensor (such as 1600MM Pro) with 2x barlow:Screenshot_20210511-043101__01__02.jpg
  • 2.4um pixel sensor (such as 178MM) without barlow:Screenshot_20210511-043305__01__01.jpg
  • 2.9um pixel sensor (such as 290MM mini) without barlow:Screenshot_20210511-043320__01.jpg

 

P.S. The results are slightly different from what I had previously reported because I had used a FL of 3025 instead of 3048, same for D. 

 

Concerning the second point with this

 

Every new sensor generation brings new features and abilities but they don't cancel out what the older tech is capable of. Quickly perusing through Astrobin, you'll find hundreds of photographers taking beautiful pictures with the 1600 and I doubt you'd be able to pick out which camera took which photo if the same person processed images from each and let you try to tell.

 

and this
 

Whichever you pick I think you'll enjoy it smile.gif The key is learning your gear as best as possible. That'll yield better results every time than merely relying on new tech. If you want new tech, by all means get it! Just understand that the photographer, not the camera, is what makes the image look good.

 

you pointed it out so well: I couldn't agree more, you are d*mn right!

I still have so much to learn and by the time I will be able to take full advantage of the 1600 enough to get tired of its defects and level up to pretend more, who knows how many other models will be released...!

From time to time I recognize that I have little patience, but you just need to stop and think a bit and the answer spontaneously comes out.

 

So yes, you convinced me: I will keep the 1600 even if this was probably not your initial intention lol.gif


Edited by SolarSystem96, 10 May 2021 - 10:36 PM.


#8 ravenhawk82

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Posted 10 May 2021 - 11:55 PM

Ah, I see now :) I missed that you were comparing against the scope's resolving power so I got confused. I usually focus on DSO imaging instead of planetary so there may be some formulae I'm unfamiliar with but I've always seen critical sampling used as 1/2 the Dawes limit of a given scope, which in this case would be ~.19 arc seconds. This is likely my own ignorance though as my low elevation and long exposures means I rarely get the chance to make full use of my scope's resolution. 

Enjoy your new camera! I think you'll have a blast with it :D


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#9 nfotis

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Posted 11 May 2021 - 01:11 PM

Note that some oversampling isn't a problem on planetary imaging. Since you'll be using the "lucky imaging" technique, you aren't under the same constraints as a long exposure DSO imaging system.

 

An ASI462MC is one of the best planetary cameras you can buy, with optimal resolution around f/20 (so, you can add a 2x Barlow to an f/10 SCT for extra focal distance).

First time I used this camera on a Skymax 127 on the moon, and I was quite happy with the results. The IMX462 sensor is also quite sensitive into IR range (there's a planetary camera using the IMX464, which offers double the sensor area, at 4 Mpixels - nice for Moon mosaics). Get both and IR cut and IR pass filters for this sensor, as you can use it both ways.

 

I haven't used a DSO cooled camera yet, but it's my understanding that the IMX294 (colour) and IMX492 (mono) sensors are quite nice. The dual binning option of the monochrome sensor offers additional flexibility, as you can record 47 Mpixel images on wide scopes like an ED80 (with a bit lower dynamic range). If you can change your order from the ASI1600 to the ASI294, I would advise doing so. Less prone to microlensing, much higher well capacity etc are real improvements.

 

Just IMHO, of course.

 

N.F.

PS. Check with Astronomy tools site for your field of view offered with your scopes and various sensors:

https://astronomy.to.../field_of_view/


Edited by nfotis, 11 May 2021 - 01:12 PM.

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#10 SolarSystem96

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Posted 15 May 2021 - 05:09 AM

Note that some oversampling isn't a problem on planetary imaging. Since you'll be using the "lucky imaging" technique, you aren't under the same constraints as a long exposure DSO imaging system.

 

Thanks for your valuable advice, I will certainly take it into account. 

 

Regarding the choice of the planetary camera I would like to buy a monochromatic one to exploit all its available sensitivity; for the DSO imaging instead, every time I make a decision then I read comments like yours and change my mind... it's frustrating! confused1.gif  lol.gif




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