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Old 18-05-2021, 10:34 AM
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ausmensan (Simon)
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Astrophotography with an Alt-Az Mount

Hi,

Wasn't sure where exactly to put this, as the Beginners astrophotography seems to be full of pictures, not questions.

Anyway..

My equipment build up so far is as follows:

CPC1100 - Alt - Az mount
F6.3 Focal reducer
Dual Band OIII/Hydrogen Alpha Filter (ASI), plus holder
ASI462MC Camera
Canon EOS400D camera, not currently IR modded, but planning to
Various adapters, to connect all of these together in a chain.

My questions are:

I understand I am limited by the Alt-Az mount, to 30-60 second exposures, is it ok to take lots of them and stack them? Will the results be significantly worse than using an equatorial mount?

I have heard that the Wedge that Celestron sells, is not quite stable enough for the CPC1100, is that true? If so, what are my alternatives?

Do I need a focuser replacement to work effectively with my imaging? If so, what are the options?

Given my current setup, what is the likelihood that I will produce acceptable images? The Alt-Az setup seems to be my biggest issue.

Thanks for any input.

Cheers
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  #2  
Old 18-05-2021, 11:48 AM
jahnpahwa (JP)
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This thread might be useful insofar as identifying wedge options
https://www.cloudynights.com/topic/7...ps-fastar-xlt/

You will be restricted to well under 30seconds on alt-az with the focal length of your OTA, even with the reducer. If it was me, I'd be going the wedge option ASAP, and off-axis guiding will be an important part of the mix.

Actually, if it was me, I'd get a second, cheap set up for imaging with a shorter focal length at first. If you're thinking about dropping $1000+ on a wedge, think about spending that on a lighter Eq mount and a short refractor to get things dialled?
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Old 18-05-2021, 01:49 PM
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Forget your current scope mount and camera.

One wastes so much time and money on short cuts that simply dont work and moreover ignoring just what everybody is using to take great astronomy photos.

If you want to save money build your own wedge it will work as bought one, then take very short exposures and that will work if you take thousands...but your compromise will probably never make you happy unless you just want to produce results with using inappropriate equipment...and have folk always saying " not bad considering you are using the wrong gear".

Save money and go for a decent equatorial mount..start big say EQ 6.... but a HEQ5 with a triplet 80mm scope and a mono cooled camera and 8 filters gives excellent results... or get a decent triplet refractor 100mm to 120mm or a 8 inch to 10 inch Newtonian with a coma corrector ( me I would get a second set of additional mounting brackets, I did, and at some point a decent focuser ...manual is ok just one that works well)...and dont forget...a dedicated astronomy camera..cooled mono with at least RBG and L filters but also Ha, S11 and O 11 better still.

Believe me you will not be saving money sticking to what you have...but what you will do is waste much time realising that I just now gave you the best advice...now I bet you will say buy Alex I dont have $10k or $12k...well of course you wont ...either get it from your account at the bank that has money in it our from their account which has money in it..they will almost certainly lend it to you..if they wont lend any money you should concentrate on your career and forget about any hobby you currently have...if you need to borrow it, whilst you earn more money or rearrange your assets, borrowing should get you on the right track...$12,000 over five years will cost you interest but believe me its worth it ...find out how much it costs a week...I bet less than what many folk spend on take away coffee...what do spend on coffee or take away meals?...even with interest it will be under $10 a day...and remember..this will never work if you keep telling yourself that you cant afford it...just stop talking yourself out of it...and if at the end of five years you sell it and get more than half back...do you think you will not be more than rewarded by the experience of taking satisfying deep sky photos...
Sell you current equipment if you dont want to keep it for terrestrial photography and visual observation but please dont throw money at a mod unless it relates to your interest in terrestrial photography.

Now it will be interesting to see who disagrees with me and determine if we can air an alternate opinion.

Good luck start buying tomorrow.
Alex
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Old 18-05-2021, 02:22 PM
Dave882 (David)
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Hi Simon
I think the answer to your questions may be based on what direction you want to head in your astrophotography.

If you still love looking through an eyepiece and just want to take some photos home with you afterwoods to keep / show friends/family then your current alt-az setup is wonderful. Using a sensitive camera and stacking 10-30sec images you can achieve some ok live images that can be processed later. But they will never be of the quality of some of the amazing detailed work you see on these forums that do require longer exposures and multiple nights of narrow-band precision.

I'm doing exactly this with my CPC800 in alt-az / asi294/asiair pro and EAA livestacking generally approx 160x 10sec subs (20min integration) at either f6.3 or f4 (double stacked reducers). I just love how quick it is to setup and start imaging, or swap between imaging and visual. No guiding. No PA.

You ask if it will be acceptable images - that depends! They say a picture is worth a thousand words so I'll add a couple below that are extremely novice and some light adjustments on photoshop express (quality reduced for upload). Note the eggy/bloated stars and coma/vignetting in the corners so not everyone would be pleased with this as a final result- as I say it depends on what you're after.

You can add the wedge but the cost and extra setup time required may be a problem and I still reckon you won't get the results that a dedicated imaging rig will bring. Sorry I'm not speaking from experience here though.

If you really want to go down the dedicated imaging route, I agree with the previous response that a smaller aperture / short fl refractor or imaging reflector will be much more suited and with a half decent eq mount you may not be spending much more if you can pick something up 2nd hand. I've had a few goes down this path too, but since I still love the visual / EAA stuff the CPC keeps getting the most use!
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  #5  
Old 18-05-2021, 02:23 PM
jahnpahwa (JP)
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Quote:
Originally Posted by xelasnave View Post
Forget your current scope mount and camera.

One wastes so much time and money......

Good luck start buying tomorrow.
Alex
Fantastic
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  #6  
Old 18-05-2021, 04:16 PM
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xelasnave
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Talking

Quote:
Originally Posted by jahnpahwa View Post
Fantastic
I forgot to include an observatory for Ausmensan...still less than $10 a day over 10 years

I am laying in bed trying to give folk encouragement to spend their money..not a good as me spending my money or the banks money but I tell you it comes close.

Thinking it thru and to change position entirely...just build a wedge, cant be real hard...drift align it and take short exposures...and you can combine photos from both camera using Registar...

Maybe just buy an eq6 which should/possibly may manage your scope with short exposure.

I think what I was really trying to say was I have made these mistakes ..I started trying to do Deep Sky with a horrible mount equatorial but useless and using a Meade LPI ( lunar and planetary camera) using a 1200 mm f/l double refractor...Great Moon shots if one ignored the blueish purple fringe and that you had a max of 12 seconds exposure..or was it 15? But at the start I thought my attempts were fantastic...
Alex
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Old 18-05-2021, 04:19 PM
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ausmensan (Simon)
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Thanks Alex, I think I get where you are coming from! I have thought about just not doing it all, but another scope will probably not happen, but a wedge mod is something I have considered. I have been given one off a Meade, and maybe that can be modified to suit, maybe not.

Having spent thousands on this (not astrophotography) already, it just gets easier each time to spend a little bit more, then a bit more...

Thanks for your thoughts.
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  #8  
Old 18-05-2021, 04:24 PM
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ausmensan (Simon)
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Hi David,

Thank you for your thoughtful reply, and I guess the thinking was really along the lines you put down yourself. I want to produce something that I can be reasonably happy with, but not a competition winner. I was just a small challenge for myself, and honestly, visual astronomy is more interesting to me.

The Alt-Az setup is more convenient, and having had a C10-NGT with massive counterweights, I don't really want to do that again. (esp. after a recent heart attack..).

I think I will stick with what I have, and see what is possible with current equipment. It is so easy to just go and get something else, and then something else again.

I did have a Nexstar 8i, and it was possibly the best scope I have had. It was the right aperture, and totally portable. The Newtonian possibly had the best views, especially after I laser collimated it.

Your pictures are awesome, and you should be rightfully proud of them, thanks for sharing!

I think I will leverage what I have, then sell it if it doesn't do what I need it to do. There is always another eyepiece to buy right?

Thank you
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  #9  
Old 18-05-2021, 04:25 PM
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ausmensan (Simon)
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Thanks for your thoughts JP, a smaller scope would be nice, but I think I will stop and consider what I am doing for the moment. TBH, I would rather have another eyepiece than a wedge, and I am not looking to win any competitions, just find something pleasing to look at with family and friends.

There is always something to buy!
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Old 18-05-2021, 04:26 PM
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ausmensan (Simon)
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ahh Alex, an observatory. One of my dreams in life, maybe one day before I kick the bucket!
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  #11  
Old 18-05-2021, 04:48 PM
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alt/az astrophotography with an 11inch sct is possible but has some serious limitations, for many years I was using alt/az astrophotography with a 12inch sct and pushed the set up about as far as I could getting very average results. (See photos links below as an example)

Lessons I learned:
1. Have well aligned and balanced scope to gain stable tracking
2. Use high camera gain (iso1600) and maximum of 30sec exposure (10-25 works best)
3. Need to have well over 100 subs with 50 darks to reduce noise and increase signal to noise ratio (200-300 works best)
4. All subs will show field rotation, final stack of all subs will need to be cropped to remove areas worst effected by field rotation.

I would recommend getting a wedge for your 11inch sct, I found a cheap field de-rotator and it works well with my 12inch sct but it has limitations also.


My Last Image in Alt/Az No Guiding is NGC 5128
https://www.astrobin.com/82705/?nc=user

Eta Carinae Nebula "Keyhole" NGC 3372
https://www.astrobin.com/45433/?nc=user
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Old 18-05-2021, 04:48 PM
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Tulloch (Andrew)
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Don't forget about planetary imaging - with a 1.5x barlow that setup is a real planet killer!

However, for DSO imaging I'm afraid that a new (or second hand - check the classifieds ) eq mount is the best way ...
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Old 18-05-2021, 04:54 PM
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Outcast (Carlton)
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Hey Simon,

+1 for starting out with what you have... give it a crack, see how it goes & whether or not it meets your expectations... or not...

I've added some pics taken very early in my astrophotography adventure: Lunar & planetary taken through a Meade LX90 8" using a ZWO ASI224MC and M42 Great Orion Nebula which, from memory was using an f6.3 reducer & a Canon 1100d at prime focus (1.25" nose piece)...

Edit: Looking at some of the other posts, you'll see you can do way better than my early Orion attempt but, I was pretty happy at the time...

The image of Lagoon Nebula was taken a couple of years ago after I got my first EQ mount, a 2nd hand Celestron CG5 Adv. GT coupled with a Meade 80mm Triplet, also 2nd hand. I include this only so that you can compare early DSO AZ/Alt & SCT Vs early DSO with 80mm triplet & EQ mount....

Are they any good... well, I thought so & to be honest, I'm still pretty happy with the lunar & Jupiter shots... the DSO... well, as you can see from the Lagoon image, I've moved on through a couple of different mounts & scopes & whilst I still dabble... visual is my main thing...

Anyways, give it a crack with what you have.... you never know what you can do til you have a go...
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Last edited by Outcast; 18-05-2021 at 05:00 PM. Reason: Extra info
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Old 18-05-2021, 05:11 PM
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ausmensan (Simon)
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Thanks Wayne,

I think you have outlined what I believe to be true about my own setup, and that is pushing for something which it is not really suited for. That is ok though, as my expectations are not for any grand prize, just for something that I can say I did, maybe good, maybe not, but that's ok also.

The imaging camera I bought was really for planetary stuff anyway, and I would be happy with some shots of Jupiter and Saturn with a few moons in the picture TBH!

I appreciate the heads up on frames, how do you do the darks/bias frames etc? Is there a tutorial handy for this?

I am also aware of the field rotation issue, but as I said, the planets would keep me happy really. If I manage a few DSO's, then that would be fine.

Met my dad today, and he actually gave me the money for the wedge, if I want it, so that was pretty decent of him. The problem with the wedge, is actually finding one that will be stable enough, and I am pretty sure the standard Celestron one isn't, so maybe a custom job as mentioned by Alex is the way to go?

Cheers!
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Old 18-05-2021, 05:17 PM
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ausmensan (Simon)
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Hi Andrew,

Yes, planetary imaging was what I bought the 462 for in the first place, and I would be pretty happy with any shots of the major gas giants TBH.

Will keep an eye out for an EQ, someone has offered a Meade one, but not sure I can mod it for this, or even if it would take the 11 inch.

Cheers!
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Old 18-05-2021, 05:20 PM
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ausmensan (Simon)
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Hey Carlton,

Your images are great my friend, you should be proud of them! I love the Jupiter one, and if I could get anything that remotely resembles that, I would be pretty happy. Just no clear skies in Perth right now

The key really is, as you say, your own happiness and pride in your output. It doesn't have to be world standard, and I would not expect that with my modest equipment.

Honestly, I love the aperture of the C11, and it feels really good once it is out and I am having a bit of a view of the planets, and some DSO's The astrophotography was always a bit of a wish list item, and I will do what I can with what I have for now, and see what happens.

Thanks for sharing your expertise and great photos!
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Old 18-05-2021, 05:29 PM
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The key to planetary & lunar imaging is video, video, video... since you already have a planetary camera, make sure you use SER format... don't use mp4, it's way too compressed...

Then use autostakkert (assuming you are on windows) to select & stack the individual frames (you just load the video & select the percentage to stack based on a quality analysis done by autostakkert) & then use registax wavelets module to sharpen the stacked output... these two programs are free...

Both those images were shot with about 30secs to a minute of video which will give you thousands of frames... I think I stacked about 50%, maybe less using autostakkert... wavelets in registax takes a bit of getting used to, it's easy to overdo it but, the beauty of digital is that if you save each iteration, you can always go back to the start & do it again...

I then give it a tweak in affinity photo (equivalent of photoshop) but, if you want another free imaging program give Gimp a go...

If you try & take individual images, you will be disappointed...
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Old 18-05-2021, 05:29 PM
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One of the guys who posts here, Ittaku, has a wedge with his CPC1100 - you can see it here. Apparently it's no mean feat to mount it
https://www.cloudynights.com/topic/7...on-2021-04-30/

If you want to take images of the planets, this is a good place to start.
http://planetaryimagingtutorials.com/
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Old 18-05-2021, 06:50 PM
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What would maybe be satisfying is to get a small equatorial and use your DSLR...like a Star adventurer
Alex
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Old 19-05-2021, 09:29 AM
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Hi Simon...

All the advice above is good advice....im only a beginner myself,
and these guys know their stuff.

I have an 8" lx90 with which i have obtained some very pleasing pictures,and have used similar camera equipment to you. Some food for thought:

The 400d i had suffered from lots of noise at ISO1600 and above -
i did not find it all that good for astrophotography (great camera for its day and price in all other respects.)

I have attached a 7d to the back with a 6.3 reducer, and was very happy
with my eta carina pics, but with the weight of the thing it was very hard to balance, especially the closer to vertical the tube got.

Field rotation is an issue, but less so for subjects that are close to the meridian - so for those targets you can take longer exposures.

I have a ASI224, and with a 2.5x barlow this setup takes great planetary pics.

I can get reasonable DSO pics with an el-cheapo .5x reducer - wouldn't publish them in a magazine, but wows my friends.

I also just happen to have a 70-200 canon lens which i piggyback on the OTA, and attach the 224. this works really well for DSO's. the lens stops at f4 and has a very pleasing field of view for something like orion. I only need to take 15 second exposures with this, and stack hundreds.
No field rotation issues(that i can see)
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