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What Equipment to Buy First for Planetary Imaging?

ZWO ASI294MM Pro Equipment Planetary Camera Buying Advice
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Jonny Bravo avatar
Jonny Bravo avatar
Hi all,

This isn't a generic "what should I get" post. My situation is that I already own kit for deep sky imaging. I have:

Mount - CEM40
Scopes - 8" EdgeHD, GT81
Main Camera - ASI294MM Pro
Guide Cameras - QHY 5L-II M, ZWO ASI174MM Mini
Lenses - Celestron 0.7x reducer, WO 6AIII 0.8x reducer/flattener
Focusers - ZWO EAF, Pegasus FocusCube v2
Wheel - ZWO 8 position 1.25" / 31mm
Filters - Chroma LRGB and Chroma 3nm SHO

I have recently been bitten by the planetary bug. I used my 294MM Pro in bin1 mode on the 8" EdgeHD native at f/10 to capture both Saturn and Jupiter:


Saturn Near Opposition - My First Planetary Image


My First Jupiter

Given the above list of equipment, what would be the first thing you'd buy for planetary imaging? I'm leaning towards an ASI178MM as my first purchase for a couple of reasons. First, it has the small 2.4µm pixels. That would get me an image scale of 0.24"/px. Second, it is quite literally plug and play with my existing setup. Unscrew the 294, screw in the 178. 

However, I'm very new to imaging the planets, and if there's one thing I learned in deep sky imaging, it's that your gut instinct is almost ALWAYS wrong. So, what would you do first?

Thanks in advance!

Jon
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Hartmuth Kintzel avatar
Hartmuth Kintzel avatar
Hi Jon,

you can do quite a lot with the equipment you already have.
If you want to get a color camera for planets, the ASI178MC is definitely a good choice
But most importantly, a good apochromatic 2x to 3x Barlow lens to increase the focal length of your C8.
2m is too short for planets.

CS
Hartmuth
Concise
Jonny Bravo avatar
Jonny Bravo avatar
Hartmuth Kintzel:
Hi Jon,

you can do quite a lot with the equipment you already have.
If you want to get a color camera for planets, the ASI178MC is definitely a good choice
But most importantly, a good apochromatic 2x to 3x Barlow lens to increase the focal length of your C8.
2m is too short for planets.

CS
Hartmuth

So, your first choice would be a 2x to 3x Barlow. Interesting!

If we assume I pick up a Barlow, how do I integrate that into my existing imaging train? Do I put it somewhere between the scope and filter wheel? Do I put it between the filter wheel and camera? Like, does my imaging train become C8 -> Visual Back -> Barlow -> EFW -> Camera?

Thanks again
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andrea tasselli avatar
andrea tasselli avatar
If we assume I pick up a Barlow, how do I integrate that into my existing imaging train? Do I put it somewhere between the scope and filter wheel? Do I put it between the filter wheel and camera? Like, does my imaging train become C8 -> Visual Back -> Barlow -> EFW -> Camera?


Yep, that's exactly where it should be, before everything else. Make sure that the barlow lens you get is good rather than just expensive. If I were to put money on anything, however, is aperture. If you're going the MC route an ADC is advisable, very strongly so if the altitude is lower than 35 deg.
AstroNikko avatar
AstroNikko avatar
Yep, that's basically it.

Keep in mind though that with a typical 2-element Barlow, the multiplier varies based on working distance from the sensor. You can figure out what the actual magnification is by getting the image scale through plate solving and calculating focal length.

I use a Tele Vue 2x Powermate 4-element focal extender, which maintains close to 2x multiplier regardless of distance from the sensor. Each of the other Powermates (2.5x, 4x, 5x) behave a bit differently, though.

If you add an Atmospheric Dispersion Corrector (ADC) to your image train, it should come after the tele-extender so that adjustments to the ADC don't have to be as fine, making it easier to use. There should also be some space between the ADC and sensor. Using the 1.25" eyepiece holder should be sufficient.

For example, this is my image train:
- Meade 2080/LX3 8" f/10 SCT
- Baader Diamond Steeltrack 2" focuser
- Baader 2" Clicklock
- Tele Vue 2x Powermate
- Tele Vue T-adapter for 2x Powermate
- ZWO M42 to M48 adapter
- ZWO M42 filter drawer
- ZWO 2" to 1.25" filter adapter
- Astronomik L-2 UV/IR Block, or
- Astronomik ProPlanet 642 BP IR-Pass, or
- Astronomik ProPlanet 807 IR-Pass filter
- ZWO ADC
- Player One Neptune-C II (IMX464)

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Hartmuth Kintzel avatar
Hartmuth Kintzel avatar
So, your first choice would be a 2x to 3x Barlow. Interesting!

If we assume I pick up a Barlow, how do I integrate that into my existing imaging train? Do I put it somewhere between the scope and filter wheel? Do I put it between the filter wheel and camera? Like, does my imaging train become C8 -> Visual Back -> Barlow -> EFW -> Camera?

Thanks again


The further away it is from the camera chip, the higher the magnification.
So I would put the barlow in front of the filter wheel if you use one. 
But if you buy a color camera, you don't need the filter wheel for planet photography.

CS
Hartmuth
Rouz Astro avatar
Rouz Astro avatar
I wrote a complete four part guide with of all the gear needed for planetary imaging and posted them, you might find these helpful:

https://rouzastro.com/guides/


Jonny Bravo avatar
Jonny Bravo avatar
Hey @Rouz Astro I've actually read through your articles and found them to be exceptionally informative. However, they take the approach of "building a planetary imaging system from the ground up". In my case, I've got a deep sky kit and am looking to do a bit of dabbling in planetary imaging. Given my existing kit, what would you change out, if anything?

For example, would introducing a Barlow / Powermate have a larger impact than introducing a new camera or would being able to shoot hundreds of frames a second be more meaningful? Or, would you instead get an external focuser because the moving mirror is what's really holding the system back?

I guess ultimately what I'm asking is, will spending a few hundred dollars have a noticeable impact, and if so, where should I spend it? Looking at your guides (especially part 4), it would seem the camera is what would help most. Then again, that might just be my interpretation since I'm already biased towards buying a camera
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andrea tasselli avatar
andrea tasselli avatar
Getting the right sampling is n.1 hence the barlow.
Rouz Astro avatar
Rouz Astro avatar
Hey @Rouz Astro I've actually read through your articles and found them to be exceptionally informative. However, they take the approach of "building a planetary imaging system from the ground up". In my case, I've got a deep sky kit and am looking to do a bit of dabbling in planetary imaging. Given my existing kit, what would you change out, if anything?

For example, would introducing a Barlow / Powermate have a larger impact than introducing a new camera or would being able to shoot hundreds of frames a second be more meaningful? Or, would you instead get an external focuser because the moving mirror is what's really holding the system back?

I guess ultimately what I'm asking is, will spending a few hundred dollars have a noticeable impact, and if so, where should I spend it? Looking at your guides (especially part 4), it would seem the camera is what would help most. Then again, that might just be my interpretation since I'm already biased towards buying a camera

*Hope you found them helpful.

Its hard pick between just one item, the lowest cost and highest impact items would be a
1-proper high speed planetary camera
2-Barlow (needed most of the time)


With thousands of frames, lucky imaging will do wonders.


CS
Rouz
www.RouzAstro.com
Jonny Bravo avatar
Jonny Bravo avatar
So, while perusing the different camera options, I saw the ASI678MC. With its 2.0µm pixels, it would seem to already be properly critically sampled with my 8" EdgeHD (i.e. no need for a separate Barlow).

Now I'm thinking I should pick it up with an ADC (skipping the Barlow).

Thoughts?
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andrea tasselli avatar
andrea tasselli avatar
I'd buy this one:

https://astronomy-imaging-camera.com/product/asi-662mc

Better QE, better (less) colour crossover and higher FPS. In fact I'd if I didn't already have an ASI462MC.
kuechlew avatar
kuechlew avatar
andrea tasselli:
I'd buy this one:

https://astronomy-imaging-camera.com/product/asi-662mc

Better QE, better (less) colour crossover and higher FPS. In fact I'd if I didn't already have an ASI462MC.

The 662 is marketed as the upgrade of the 462. I'm a bit puzzled since the 462 has lower read noise and and higher frame rate.  I have some doubts whether slightly higher PE and the higher full well capacity really compensate for this - in particular given the fact that the 38.2 ke vs the 11.2 ke both get compressed to 4096 ADU by the 12 bit ADC output. Am I missing something?

Clear skies
Wolfgang
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andrea tasselli avatar
andrea tasselli avatar
Higher frame rate of the sort indicated by the specs is immaterial to the end result, I strongly suspect. In my experience once you top 60-90 FPS (assuming the rest of the computer hardware can keep up, a big if) you're at the highest meaningful frame rate even for a intrinsically bright planet such as Mars (here I assume youre at optimum sampling, i.e., around 4-4.5 pixel per resolution limit). Besides, once you are subframing, something you should do anyway for all planets, the limit is really the PC hardware.
Jonny Bravo avatar
Jonny Bravo avatar
All,

I appreciate the feedback given. I ended up purchasing the following for my planetary imaging kit:

ZWO ASI662MC
Tele-Vue 2x Barlow
ZWO ADC
Optolong 1.25" UV/IR cut filter.

I was well into analysis paralysis and decided I'd spent enough time looking at charts and specs. I think I changed my cart about 50 times with different combinations.

My biggest struggle was deciding whether I wanted a Barlow. The 678MC would already be critically sampled with its 2µm pixels. However, this would keep my focal length at 2m. I looked at the 224MC and 2.5x Powermate. This would bring my focal length up to 5m and the combination frames up Jupiter rather nicely. It actually stayed in my cart for quite a while and I hovered over the "buy" button a number of times.

The combination of 662MC and 2x Tele-Vue puts me in a good position, too. If I find the 2x is over-sampled, I can unscrew the lens cell, which puts the Barlow closer to 1.5x. It also frames up Jupiter nicely and gives me a bit more room should I want to capture some of the moons farther out. Those two things are ultimately why I decided on the 662MC with 2x Barlow.

Again, thanks to everyone for your input! I'm looking forward to trying out the new gear and hopefully will be able to figure it out by Jupiter's opposition on 26 September smile

Jon
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kuechlew avatar
kuechlew avatar
Looking forward to see your images with your new gear!

Have fun and clear skies
Wolfgang
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