Things not to under estimate in imaging

[swag72]

Before anyone reads this, I suppose it's just a few observations of my journey in imaging thus far, nothing more, nothing less. If you don't want to get bored and would rather watch paint dry, then please do - Watching paint dry may be more useful to you

I have discovered in 18 months that there are a number of things in imaging that I have severely under estimated. I say severely as I have ignored things at my peril thinking that it 'would do' or 'couldn't affect an image that much'. I wish that I'd paid more attention to these things and not dismissed them as non issues. Perhaps someone will read this and think about what their problems may be and perhaps they have been as guilty as me!

1) Polar Alignment - I have read people ask if polar alignment is THAT important, and I have to say that it is probably the single biggest thing that has blighted my imaging. I used various methods to check PA and thought it was OK - Until I finally got a grip of it and realised how far out it was and how it absolutely stopped me getting round stars. I can not emphasise enough how important this has been in getting round stars and non trailing images. 'That will do' in reality probably won't.

2) Good optics - Recently having got a scope with what is considered to have good optics, and already having a scope that had, I thought, good optics - They are like chalk and cheese. Boy what a difference that made.

3) Getting exposures in hours - I have been so guilty in under estimating how much exposure time you really need. For me now, a couple of hours just won't cut it. I will gladly run into 15 hours plus. It makes a massive difference. I have been as guilty as anyone else of getting 30 mins and thinking that's it - But really push for more and more, it makes a world of difference.

4) Good focuser - Having been 'blessed' with a standard Skywatcher focuser, changing it for a Moonlite and then getting a scope with a decent R&P focuser, I want all scopes to have a decent R&P focuser. They are a joy to use (far more so than the Moonlite even) and really can not be beaten, for accuracy as well as load bearing. I think I've turned into a Crayford disliker, even the premium ones.

5) Guiding and high cloud - You know when we image from night to night and there is NO difference at all in our setup's but on that second night we cannot get a good guiding graph and it's all over the place. I would never have believed what high wispy and almost imperceptible cloud can do. In fact until last week I still didn't believe it, but my proof was there. Guiding goes well on clear nights.

6) Processing skills - Ahh, still learning that one!! I think that when we start out we all under estimate the amunt of time as well as the amount of knowledge required of various processing packages to start getting a half decent result. You captured 10 hours worth of data - Add another 10 hours to that in processing. I'd love to see people putting a processing time by their drop dead gorgeous images, I think we'd all be shocked.

7) Effect on bank balance - How on earth did I get THAT bit so wrong? I started out with £2k for an imaging setup (minus camera) - Woops, I think now I'm slightly over budget!! This hobby is devastating on the pennies.

8) Importance of focusing - I never really got that this can make or break an image. I thought a quick focus would do it, but no. I found that to get good focus I can spend literally 5-10 minutes on it. Never under estimate the difference between alright focus and nailed focus.

There's a few more, but I'll not go on. I hope that I don't sound like a complete know-it-all as I'm really not and not half as much of a twit as I probably sound! It's just that these few things have had such a profound effect on my imaging that I thought by writing them down they may strike a chord with someone else.

Happy imaging!!!

[Viv]

Nice & so very true write up Sara.

I think all of those points, I went head nod & a laugh.

Still very much learning, but very valid good check list.

[BigDanDaw]

Sara, as a novice, I find your advice incredibly useful and your images on flickr are an inspiration. IC1396 in particular is absolutely stunning.

Thank you.

Dan

[JamesF]

A very worthwhile posting, Sara.

James

[Black Knight]

Great thread Sara, full of excellent points. If you have some more observations based on your experiences, you should post them as well. I enjoyed reading it

[AndyUK]

A very good and useful thread Sara - I certainly wouldn't argue about any of those... And I'm still struggling on a great many of them myself!

[swag72]

Glad that this is considered useful. I have another that I didn't write last night as I thought I may come across as some know-it-all twerp

9) Good collimation - I only have a refractor, but I suppose that this will be as important for guys with reflectors and the like. Collimating my focuser, I realised that being 1-2mm out from the centre of the optical path, seemed so very unimportant so as not to matter, I thought that near enough was good enough. It wasn't. A dificult and tiresome job, but getting that spot on was important.

[ollypenrice]

I haven't had your issues with Polar Alignment - I have never been bothered by relatively indifferent PA so maybe it just wasn't that bad - but the other things all strike a resounding chord. It's a great post.

Time is a big one. Once when I asked Maurice (MFToet) how long he was going to spend on the Leo Triplet he replied, 'as long as it takes' and that has become my unbending motto. Tom O'Donoghue is just the same. And we know aboout RObH's exposure times. Noise reduction? Go and shoot more data. I can think of a multi-APOD imager who produces striking and oriinal images which I often like, but his short exposure times and post processing noise reduction do show clearly. You have to put the time in.

So glad to see your comments on Crayfords. I launched a campaign about a year ago and was considered a bit of a nut for it, but there is no doubt that the anti-Crayford movement is gaining momentum. Let's keep up the pressure!

Sky? I only image for myself when it's perfect. Clearly guests will want to image when it's not quite perfect so we do work arounds like getting colour when it isn't tip top and waiting to get the Lum when it is.

I guess you are happy with the Pentax?

Olly

[ThomasBR]

Nice post - good points! I am currently learning the dark art of imagining and I am wondering how/if suboptimal polar alignment affects guiding?

Kind regards

Thomas

[Willarnold]

Great post. I'm going to start imaging, so i'm always happy to learn

[Kbramley]

I would also add

10) Always try out your new kit on those less than perfect nights to iron out any gremlins, especially if you plan to go the whole auto-guide route. I have spent too much time this year with my new kit (EQ6 mod, modded webcam, PHD and the whole ASCOM thing etc) under crystal clear skies not acutally observing but fighting the technology lol.

oh and another one which improved my imaging a great deal.

11) If you are a DSLR user, using the highest ISO is a bad thing even though it appears to give the brightest image, choose the optimum ISO for your camera model (I use ISO 400 on my 450D), the signal to noise will be improved, but remember you will need longer subs but with guiding this wont be an issue .

[Jessun]

Good writeup! Very useful tips there.

Somehow though I think that the journey through all the failures and set backs is almost one that everyone should do. Perhaps not to the effect that it starts to cost dear money, ie wasting it on the wrong gear, bit the other brick walls are there to slam into in order to fully appreciate your own work and especially the work of others.

Or am I seeking comfort with my reasoning just for the most recent fact that AA5 no longer debayers my raw subs as it used to - just like that, an overnight random brick wall...

[dph1nm]

11) If you are a DSLR user, using the highest ISO is a bad thing even though it appears to give the brightest image, choose the optimum ISO for your camera model (I use ISO 400 on my 450D), the signal to noise will be improved, but remember you will need longer subs but with guiding this wont be an issue .

Hmm - to first order ISO does not affect exposure time (same number of photons). To second order, most of the data on the web (mostly for Canons it must be said) suggest that the highest ISO gives a slight improvement in signal-to-noise (for unsaturated objects of course).

NigelM

[kookoo_gr]

12) If your imaging/guiding is going down the drain from the start of the session it is better to just quit it and either go home or turn the night into an odbervins session. You will do much good to your nerves and an observing session will make you calmer

[RobH]

Very good post Sara, and great advice.

[Spikey]

Excellent points Sara

[SamAndrew]

Hmm - to first order ISO does not affect exposure time (same number of photons). To second order, most of the data on the web (mostly for Canons it must be said) suggest that the highest ISO gives a slight improvement in signal-to-noise (for unsaturated objects of course).

NigelM

indeed I have found 1600 to be the best setting on my 450D

[SamAndrew]

I would say that after 8 months, the area I'm still making the biggest improvements in is processing, I continually go back and reprocess my images, as I learn and improve techniques, it's never ending !

I like to keep some of the originals as well just to see how far I've come

I've only just started experimenting with seperate star layers.

[Sirius Bizness]

Sara, this is briliant and really useful. I am just starting to get into AP so will keep these points in mind.

A couple of questions if I may:

You mention PA being important and you tried various methods - what is your current method that works well and are there any key points?

You say optics are important which I am sure is more so when you are more experienced and focusing on the finer points. Which was the scope which you thought had good optics and which is the one which has given you a different perspective? Is in the SW 120ED and Pentax? I have the SW 120ED and with my inexperience can't imagine what could be better (although I can appreciate there must be a difference which justifies the top end prices). What exactly have you seen an improvement in from the better optics?

I couldn't agree more with the point on budget. I fell into the trap of only budgeting for the scope and mount. There is so much more that is needed, from small things like a bahtinov mask to larger expenses such as the camera...it all adds up very quickly!

I am still on a very big learning curve with everything so appreciate the sharing of your experiences.

Martin

[swag72]

Hi Martin,

I was going to PM you, but thought that others may find some of the info useful.

I currently use PEMPro to polar align. I have it on a 60 day trial at the moment, but will be looking at a purchase when that runs out. I had used the EQMOD polar align method prior to this and thought that my polar alignment must have been pretty good. PEMPro showed how very poor it was and after a couple of goes it really tightened the PA up nicely. A really simple programme to use, although it looks daunting. The only thing is that you need to be using ASCOM for the scope control and Maxim or another programme for capture (Can't remember which one) - With everything recognosed, it was a case of pressing buttons for the programme to work out the information needed. That's my kind of programme!

Regarding optics - Yes the SW120ED was the scope that I thought had great optics. But the little Pentax has blown it away. Everything is so much clearer and sharper. How much of that may be down to resolution as I am comparing a 900mm scope to a 500mm scope I'm not sure. Also the build on the Pentax is just so much better. Take the focuser for example, a sturdy and brilliant R&P. I have a Moonlite fitted to my SW but now much prefer the focuser on the Pentax.

[squeaky]

What a list!

I reckon in the last three months I've built myself much the same list... only as yet, with so few viewing chances lately, not quite so many answers!

I'm using every possible night, even when not brilliant, to practice. I don't care if there's a high thin haze (though I'd prefer there wasn't) when I'm trying to improve my alignment and tracking, camera focus, lenses... I'm hoping that by the time winter's skies arrive I'll have all the technicalities off pat, along with more processing skills, so that from the first good Autumn sky I can really get to work. Even if it means becoming a totally nocturnal beast.

Right, gotta go... it's a practice might tonight

[squeaky]

Just added a new one. I have no idea how long this list is now.

* Always remember to recharge the batteries of anything that uses them as soon as you've finished a session. Especially your DSLR battery. <sigh>

[NickK]

A lot of these ring true for me too.

Dark sky - a clean canvas. Polar Alignment, Focus and tracking are the key parts in bringing clarity and definition to the picture, painting with a finer brush. Next Time brings out the details from the dark.

I adopt the programming mantra - rubblish in, rubbish out. So processing for me is really to make up for the fact that the input (in my case) is rubbish

Oh.. nice scope btw I would seriously love the 125SDP..

[Shibby]

That's weird, I'm sure I replied to this topic before...

I was going to add that while we're not underestimating things, don't underestimate the value of any night's imaging. Even if everything goes wrong, it's all a valuable learning experience that should allow us to streamline things for the next session!

Oh, and BE AWARE of the meridian!

[squeaky]

That's weird, I'm sure I replied to this topic before...

I was going to add that while we're not underestimating things, don't underestimate the value of any night's imaging. Even if everything goes wrong, it's all a valuable learning experience that should allow us to streamline things for the next session!

Yep! That's why I'm going to be doing some serious cloud dodging. Starting in five minutes...