Need help with my step by step instructions please

[ianpwilliams]

And an AG-processed TIFF after I removed the rejects:

https://www.dropbox.com/s/0qpntauk23xd9mv/Processed%20M31%20Excluding%20Star%20Trail%20Subs.png?dl=0

I am absolutely thrilled that I took these photos (M31 has always amazed me), albeit with a little disappointment that I don't have the skills, programs or processing power to process them myself, although hopefully that will come with time.

So here's hoping that attempt #2 can produce even better results!

[ianpwilliams]

You mentioned in the other thread to check the Master Flat to see if my Flats are usable. What I'd it I need to do?

[ianpwilliams]

Also, when checking a test-Flat outside, were you saying that the peak would ideally need to be 1/3 of the way to the top?

[carastro]

It's difficult to tell you how to check your master flat as I don't believe you have photoshop which is where I would check it by stretching it.  Any chance of posting up the tiff of the flat.  You could try to stretch it yourself.

This is a stretched master flat done with a DSLR which shows vignetting and dust.

Individual flats won't look like this as this is a stacked master which has been stretched for demonstration purposes.  I normally stretch in brightness and contrast.  

this is stretched only to prove the flat has been exposed correctly, you wouldn't normally need to do this but it is a good way to check if your exposure was right.

[ianpwilliams]

This is my Master Flat:

https://www.dropbox.com/s/x7admgko9w7fk4u/MasterFlat_ISO100.tif?dl=0

and this is one of the single Flats:

https://www.dropbox.com/s/fzlngzbbktguk82/IMG_0513.CR2?dl=0

[ianpwilliams]

Oh well, according to AG this one doesn't seem to be usable, because it sounds like there was apparently haze or mist or something that I didn't know was there. At least I had a chance to have a crack at Flats though, and it looks like 90-sec subs should achievable.

I think I'll take lots if Bias frames indoors then, and I think I'll practice some Flats too (even though I know they won't be usable for anything). Hopefully I can then work out how many pieces of A4 paper I need over the laptop screen in order to get the peak at one third height on the histogram.

I can't remember the deal with Darks - can I keep the ones that I took the other night, and use them for any future sessions where I take 90-sec subs at 400ISO?

[carastro]

I can't remember the deal with Darks - can I keep the ones that I took the other night, and use them for any future sessions where I take 90-sec subs at 400ISO? 

If it is the same temperature.

I just took a look at your master flat, and whilst I would have expected to see more dust (I've marked the ones I have found with a red line), it does show vignetting, so looks like they were OK. Maybe your optics are particularly clean.  

Haven't looked at the single sub yet.

[carastro]

Can't open the single sub it says it is corrupted.

That's a real shame Ian, but it is par for the course with imaging, there can be many wasted nights for one reason or another, but yours wasn't wasted as you learnt so much and got a lot of things right.

I think you are going to be a bit stuck with dew unless you can get some power sorted out for dew heaters.

Carole 

[ianpwilliams]

If it is the same temperature.

Would that apply to keeping the Flats too? Could I use them another time if through temperature and ISO were the same? That is if my current Flats are worth keeping, which you seem to think they are?

[ianpwilliams]

I have looked at 12v Dew heaters on FLO. £100+ for a dew shroud and controller, and then I'm guessing I would need a splitter so that I could power through dew heater and mount at he same time from through Tracer (assuming the tracer could cope with powering both, and last a while session)?

[ianpwilliams]

Would that apply to keeping the Flats too? Could I use them another time if through temperature and ISO were the same? That is if my current Flats are worth keeping, which you seem to think they are?

Ignore that post, forgot that the camera and focuser have to be the same

[carastro]

Ian you can't re-use flats unless the camera and focus has not been moved.

I have not heard of a dew shroud, what telescope are you using (it would be helpful to put your kit in your signature). Only shroud I have heard of is what astronomers with large open dobs use the bridge the gaps.

I have refractors and before I used dew heaters I got problems with misting.  Since getting dew heaters the only time I have had a problem is when something went wrong with the dew heaters which is twice in 4 years (once was a fuse).  I use them all year round regardless.

Carole 

[ianpwilliams]

I have a 130PDS. I didn't mean the shroud. There are heated dew shields on FLO, so I could get whichever one would fit mine

[carastro]

Right, dew heaters are more complicated with Newtonians.  I believe you can get dew heaters and thread them through the spider to the secondary.

Better make sure you get the right thing for your telescope.

The primary is less likely to dew up, though I did see that happen once at an Astro-camp but it was an extreme circumstance.  

Carole 

[happy-kat]

Won't just adding a shield to the top of the telescope extend the time before dew becomes apparent as a first try?

Relevant post here

http://stargazerslounge.com/topic/222168-sw-130-pds-secondary-mirror-dew/

And Uranian235 post smany cracking images with their setup and talks about their due shield on that thread I linked.

[Mick J]

I have looked at 12v Dew heaters on FLO. £100+ for a dew shroud and controller, and then I'm guessing I would need a splitter so that I could power through dew heater and mount at he same time from through Tracer (assuming the tracer could cope with powering both, and last a while session)?

You may find posts in the diy section with reference to using a cheap camping mat to inhibit dew,  good to see you progressing.

[Tinker1947]

I have a 130PDS. I didn't mean the shroud. There are heated dew shields on FLO, so I could get whichever one would fit mine

A heated dew shield for a 130PDS will achiece nothing, its the secondary needs a bit of warnming love, a dew shield will stop the secondary dewing up for several hours on a bad night, a secondary dew heater will work and they use a small amount of current 

Secondary dew heaters..

http://www.kendrickastro.com/newtonian.html

[ianpwilliams]

I've read around a bit on this and it sounds to me like a dew shield isn't all that essential with it being a newtonian. And I'm also not that keen on trying to thread a heater down my scope.

I have my piece of camping mat, which is maybe 8 or 9" long (didn't want to risk going longer than that), and it wedges onto the scope pretty comfortably, so hopefully that'll be good enough.

[tingting44]

none of the astrozap dew shields fit the 130-pds from FLO, you will have to make your own, i have made mine from a camping mat and on nights of 90%+ dew i have no problems imaging all night, before the camping shield my secondary would dew up within the hour

[ianpwilliams]

Yes that's what I've got now too, seems to work pretty well. How long did you make yours? Mine is about 9", which is quite a bit shorter than I could have gone (which was basically the width of the camping mat), but I didn't want to risk it for various reasons. I just hope I didn't make it too short. But the ones I've seen pictures of online seem to be about that length.

[ianpwilliams]

I want to buy a longer cable for my SynScan handset, because I suspect that that might have been what was causing the mount to reset. It looks like it's just an Ethernet cable, but I just wanted to check before I buy one (or search my cupboards for one). I also wondered if it might be a crossover cable rather than a normal one.

I'm also looking to buy an SD card or two for the camera (1GB only gives me around 50 RAWs). I'm probably looked at 2 8GB cards or so. But I wondered if it was worth going for a higher class (I.e. faster write speed) or not, such as Class 10? Or is it that only required for recording video, which I obviously wouldn't be doing.

[carastro]

Well I managed to download the 2nd image stack and I don;t think it's too bad at all for unguided and the length of subs and the fact that there was a bright Moon.  Added to the fact that this is only Ian's 2nd image and he's not guiding.

It's a bit noisy, gads of gradients and I've probably brightened it a bit too much, but does show the outer reaches of the galaxy.  I found this much easier to process than the first one which didn't have flats applied.

Sorry Ian, I had to rotate it, there are some images I just can't to do unless they are up a certain way.  I also took a crop to get rid of some of the outer gradients, and used gradient exterminator anyway.

Carole 

[ianpwilliams]

Thanks Carole, great job, looking forward to seeing it on the PC monitor tomorrow!

[carastro]

Just seen a typo and it's too late to Edit:

 gads of gradients

Should say "loads of gradients".

[ianpwilliams]

Looks good, you can definitely see more of the galaxy as a whole, albeit with a bit less detail compared to the other one. There was definitely more data in this stack, so I'm guessing that the conditions must have prevented it from being a lot better than the other one. Still, it's great that it wasn't a completely wasted session.

I took 200 400ISO shots last night, and I'm in the process of doing the same for 800 and 1600. I suppose theoretically I could re-stack the second 400ISO batch with 200 Bias if it might help, and I could do the same for the first batch too if I created a 3200ISO batch of Bias. Do you think that it would be worth creating new stacks with lots if Bias shots (not that I would expect anyone to process them again, but maybe I could process them further down the line)?

Which reminds me, what are the types of shots that are related out of Lights, Darks, Bias and Flats? I'm sure I remember someone saying that there was no point or need to have one type if you aren't including another particular type.

And does anyone have any comments regarding my question about a SynScan handset cable and SD cards? Or shall I start a new thread about that?