Well, I’ve decided to have go at planetary imaging. As someone who has NO experience in AP at all, I seek your expertise as a newbie, and have some questions I hope you can advise me on. As you can see from my signature, I have a Televue NP127is (f/5.2) as my main scope, and Meade LXD75 mount (yeah, the LXD75 isn’t so great, I know). I don't have a DSLR, although from what I can tell, the optimum equipment nowadays is via a dedicated planetary colour webcam (eg. ZWO series) and stack images. So, three questions to begin with:
1) Choice of webcam. I have my eye on the ZWO’s, either:
(i) ASI 120MC (about $220)
(ii) ASI 120MC-S (usb 3.0) (about $320)
(iii) ASI 224MC (usb 3.0) (about $420).
The 120MC seems ideal (up to 30 FPS) for the entry level newbie, and only $220. On the other hand, the 120MC-S for only $100 extra allows USB 3.0 for faster data transfer and up to say 60 FPS, thus potentially giving better resolution. As a third option, for an extra $200, the 224MC has this ‘low noise’ ability, allowing extensive short exposure stacking for more potential for deep sky images via a webcam. I am leaning towards to 120MC-S (for $320), but is the 224MC better in the long run ? ie. more multipurpose potential just in case I get the AP bug and would like to have a go at deep sky down the track...
2) From what I understand, with the NP127is, the optimum focal ratio should be around f/20. I therefore need say a 4x barlow to get this. Should I get the TV 4x Powermate ($490) to give f/21, or would a good 5x barlow (a lot cheaper than a Powermate) (ie. f/26) be “close enough” and quite acceptable ?
3) I don’t have a PC laptop at all (always been an Apple desktop owner). I’m quite happy to get a basic PC laptop with USB 3.0 for out in the field data acquisition for the webcam. I figure I can just transfer to my iMac and then use PC emulation from thereon to do the stacking, image manipulation etc. Is a PC laptop the most sensible way to go ?
I guess that’ll do for now in terms of just getting the equipment right. Am I on the right track at all...? All advice is welcome...
Cheers
Fox
Last edited by Fox; 22-02-2018 at 10:21 AM.
Reason: Picture added just to attract attention...
Regardless of scope, go for the 224. It’s just soooo much more sensitive with low noise. If you stick with the “small” scope, you’ll need all the sensitivity you can get. Give it a go.
What you will find is that the weather conditions, notably “seeing” affect the results you get.
Depending on your expectations, you may find you want larger aperture to get the results you desire.
Thanks ‘Dunk’, such info is invaluable for me. What do you think of f/20 vs f/26, is it essentially inconsequential overall? Eventually I intend to get a better mount, and yeah I also know an 8inch SCT or larger is the better way to go, albeit I can have fun with what I have at present. Fox
I wouldn't get too caught up with an expensive powermate just yet.
Planetary sensors typically have small sensors, so you will want to practice reliably getting the target on the chip before substantially increasing the focal length...as it gets proportionately harder!
Great advice, one step at a time, I like that approach and thinking. I’ll go with the webcam and laptop only, plus my existing 2.5x Powermate to learn the ropes first. Cheers Fox
Great advice, one step at a time, I like that approach and thinking. I’ll go with the webcam and laptop only, plus my existing 2.5x Powermate to learn the ropes first. Cheers Fox
I dont know if you are interested in the Moon but I think that is a good place to start.
Firstly it is easy to get on the sensor and you can learn how the gear works.
The stacking software is the same or similar I think ...registax I recall is what I used way back.
And we all want to jump in the deep end but you could get put off taking on the complexity.
I think of it like moto cross...many want to jump on a large capacity bike when the best approach is to start on a 125 cc and make sure you can ride it to the limit before you go to the next level.
And with most things getting the most from what you have is very satisfying.
I wish you luck and hope you can get some results that you are happy to share here.
Alex
Hi Alex, yes definitely will shooting the moon for starters.
One question about laptops, given USB 3.0, is there any minimum chipset I need to get so there’s no problem with webcam data acquisition ie. will those bargain basement $250 PC laptops listed at JB HiFi be okay, or should I aim higher? I’d hate to find that I’m not addressing the minimum specs for PC laptop properly.
Hi Alex, yes definitely will shooting the moon for starters.
One question about laptops, given USB 3.0, is there any minimum chipset I need to get so there’s no problem with webcam data acquisition ie. will those bargain basement $250 PC laptops listed at JB HiFi be okay, or should I aim higher? I’d hate to find that I’m not addressing the minimum specs for PC laptop properly.
Fox
I dont know but I asked specifically for usb 3 and was told it was usb 3 by the salesman and I found out only yesterday that I may have been sold usb 2.
I am so mad about it I have not been game to make sure that it is a 2 or a 3...my GZO works but ....I am fighting an impulse to go to the store and destroy the salesman and the shop...in otherwords a touchy subject at the moment...I am putting off confirming exactly what I have until I settle down...I am a calm person but when I find I have been lied to I simply lose it...I am happy I am 750 klms away ...
In any event I am not the guy to ask as I know nothing, but be careful and double check before you buy and when you buy.
Hi Alex, yes definitely will shooting the moon for starters.
One question about laptops, given USB 3.0, is there any minimum chipset I need to get so there’s no problem with webcam data acquisition ie. will those bargain basement $250 PC laptops listed at JB HiFi be okay, or should I aim higher? I’d hate to find that I’m not addressing the minimum specs for PC laptop properly.
Fox
chipset will not likely have much bearing for data aquisition...
I have a "craptop" that runs a dual core brazos (read: not even enough grunt for a good tablet)
What is more relevant is disk speed....i replaced the HDD with a solid state drive, prior to which the avi capture fps was a joke
Plugging my 224 into the usb3 port now works like a bewdy for planetary avi - up to 60 fps.
For long exposure (DSO) work a HDD will be fine as there is not that much data coming from the camera
I don't do any stacking or image processing on this pc - i have to copy the files off
and let my desktop do the hard work.
If you want one machine to do the lot - a $250 special ain't going to cut it
Alex,
I think the piece of plastic in the socket that only allows you to insert the USB plug the right way up is blue as standard with USB 3, instead of the original black.
raymo
Alex,
I think the piece of plastic in the socket that only allows you to insert the USB plug the right way up is blue as standard with USB 3, instead of the original black.
raymo
Yes I know and its not blue I had worked that out when buying a back up drive....and I should have bought my lap top from the same place..Casino Country IT...the slightly higher prices has come back again and again in service and help..really great shop...but I bought the lap top in Sydney at Harvey Norman at North Ryde.
I am fighting my anger.
If I go and confront the store and the salesman I know they won't do anything and start with excuses etc and at that point I will go off...As I said I am a calm person but when I lose it you may as well start counting the bodies...I know what I am capable of and I have come so close to overstepping the line it frightens me.
I chased a guy to the doors at the police station and I was so lucky he got to safety before I got my hands on him...
Its not nice but I have to keep away from situations that can escalate.
Another grand for another lap top and give the current lap top to my daughter is better than going getting locked up...
I am already seeing the bright side because she said she would like a lap top...
The bright side is this is onlt the second time in my life I have been conned.
The first time it was almost worth it.
This guy outside the office greeted me like we were old friends and I thought I knew him but could not place him. You get that in real estate with so many faces in your life.
Anyways he chats away, it was just before xmas, and he says I,m off to get some beer only $x a carton ..do you want me to get you one..sure and gave him the cash...never saw him again but I thought what a good act it was worth my loss to see a really good con man at work.
I thought he was good to con me.
Maybe the salesman made a mistake so I will leave it there...by the time I get back I may see him...Or write a letter to Harvey and vent...I would sue them but I have no evidence ...still I could make them suffer.
match descriptions made by the salesperson, on packaging and labels, and in promotions or advertising.
match any demonstration model or sample you asked for
be fit for the purpose the business told you it would be fit for and for any purpose that you made known to the business before purchasing..
In other words - if the salesperson said it was USB3 and it is not - they must refund the money.
I'd ring them up and ask nicely...
and have the ACCC website ready to quote from.
Having said that - i would find it strange if a modern lappie does not have at least one USB3 port - especially one costing a Gorilla.
What model of lappie is it?
Alex: check the little USB logo (the pitchfork image) next to the port: USB 3.0 will have an "SS" in front of that logo, the plastic blocker isn't always blue. On some laptops you'll have a mix of 3.0/2.0 (the toshiba I'm typing this on has 2x 2.0 and 1x 3.0, so I have to mind which port I use for what). Also important is that USB 2.0 works fine with the default self-installed drivers that windows sets up but 3.0 invariably needs the actual chipset maker's drivers to work (otherwise it behaves as 2.0), which might require a manual install.
Fox: Bintel had pretty decent deals on ZWO cameras round the end of 2016 when we needed one for a summer project, round 190 for the 120MM-S (monochrome 3.0) from memory if you want to hold out for a sale. The high speed USB is definitely the way to go: on a bright enough target (eg Mars is bright enough at opposition from memory) the extra framerate is really good at freezing the atmosphere (what you want for lucky imaging planets). What I'm talking about isn't 60vs30fps, because the real strength of these cameras is their arbitrary ROI (region of interest) capability. You define a box of the sensor around your target and the camera only reads those pixels, which it can do much faster than polling the whole sensor. With good tracking and guiding you can get a nice tight ROI and 200fps is possible with the standard software (we saw 500+ with custom interface).
At that speed you see the higher order contributions to wavefront error from atmospheric seeing though, so a scope much bigger than yours will not always give you better images: on a 16" LX200 we could actually see the sag of the primary over its triangular support on a star image.
My suggestion would be: ZWO USB 3.0 camera of your choice, avoid barlows (altogether even, but especially new ones) and start on the moon (big=easy targeting, bright=max framerate) and your current scope. Use smaller ROIs to push up framerate on native prime focus magnification until you find the limits of the camera combating the seeing, then if your pixel scale calculation shows you should be able to see finer detail consider barlows, then if the light runs out buy a bigger lightbucket.
Big (amateur) reflecting telescopes have a hard time matching with extra photons what they lose to good refractors in PSF quality, and the bigger your aperture the more you "see the seeing": at a good site the isoplanatic patch or size-of-atmosphere-that-only-causes-image-motion (no ripples) is rarely bigger than 30cm, so even an 8" SCT is pushing it unless you live at Siding Spring. Plus all the far-apart elements don't do you any favours with scattered light on a bright object like a planet (for deep sky much less of a concern, then diameter wins the day) - smearing out details the aperture should mathematically resolve.
For reference: Last year we chucked our 120MM-S behind a very nice Tec 140 (f7) and pointed it at Saturn, albeit on a **** mount (I had to manually track the target with the controller, for 3+ hours) and doing ourselves no favours with a 3nm Ha filter. I think we managed about 80fps and it was quite blurry (~30 degrees elevation, terrible atmospheric dispersion if we didn't have the filter). Meanwhile next door said LX200 0.4m f10 flying Canon's super high ISO camera with no filter was about the same image quality, albeit with more pixels covered thanks to ~3m extra focal length. I never saw the other team's raw data but from the screen displays of each setup I wouldn't pick the big SCT over the refractor, I'd just point the thing straight up
Thanks Shark bite.
I know from legal days I would have them and its seems the new laws are a revamp of the old law.
Evidence could be the problem.
But first I will establish if it is not usb 3 maybe they were out of blue on my run.
The computer is a Lenevo.
Pretty little thing.
Anyways if the worst case I need to move on and not let it worry me.
I often tell people the greatest loss is the stewing over things...I have lost time to that and realise that is the real loss.
Thank you for your input.
Alex
Hi Mark.
I will look see but when I connected the external hard drive it said something like...things would run better with a usb 3...anyways I will check and may even take it to country IT for confirmation.
I am getting over it.
Thanks for your input.
Alex
Thanks guys! Alex, that's really bad about your laptop. But if you specifically asked about UBS 3., then by law they must supply USB 3.0 ie. goods must match your specific description you asked for. Consumer affairs would be on your side, but it may now depend how long ago this all happened... i.e. whether or not its now worth pursuing.
Mark, a lot of what you said has gone over my head, but i hope to understand, one day. At this stage, I'm only planning to use the laptop for acquisition, albeit it may not be wise for to go too rock bottom in model and price.
