Polaris moves in polar scope depending on

[AstroMuni]

On 09/03/2024 at 21:27, TiffsAndAstro said:

just trying to update my old macbook

As a Mac user you could also try Kstars/Ekos which runs natively on Mac & Linux based devices. This software also provides the tool for PA.

[TiffsAndAstro]

29 minutes ago, AstroMuni said:

As a Mac user you could also try Kstars/Ekos which runs natively on Mac & Linux based devices. This software also provides the tool for PA.

"as a mac user"  i bought my one and only mac ever because it was such a nice object and looks good in a coffee shop. except i don't drink coffee   its ok for email/browsing  though  

hopefully also for astro stuff now i have boot camp etc. im sure ill find some issues but its been surprisingly easy so far. If i do ill definately give kstars/ekos a go and have a look. cheers.

[TiffsAndAstro]

just in case anyone is interested and/or haven't tried nina for 3ppa....

it was drizzling, so i go play warthunder. go for a cig 20 mins later sky perfectly clear.

so i hurried set up my gear, plonk tripod point north (i couldn't help having a glance through polar scope to check polaris was at least somewhere in view).

connect my laptop, all goes fine but plate solving, error about couldn't download image. tried camera not going through an old crap usb hub and it worked:)

did all 3 polar alignment image and solved them and gave me a reasonably small error, but no matter what i did with alt/az bolts, the error didn't change. 

took me 10 minutes before i looked up and noticed sky full of cloud which i am hoping was the problem.

95% 3ppa on nina, first attempt and only failed due to cloud....i hope

 

ok so clouds went away battery charged up a bit and camera battery changed, had another go. wow. its a bit fiddly (my mount bolts are pretty nasty with a weird dead spot on the alt). got it seemingly good, tightened the big bolts and alt and az both went up to like 3 or 4 minutes.

tried again on both and got the screenshot below and left it. what sort of numbers are good enough? is there a chart somewhere of like focal length, exp time, guiding yes/no etc?

also anything anyone notices i should change. i couldn't see a way to change delay between 3ppa subs.

ive set it doing a sequence (i think) of 20 x 120 sec on m51 at 50mm crop sensor lol just to test

if i can repeatedly set up as quick and accurate (?) as my last attempt, nina is pretty amazing

also want to preview my subs but scared to break anything, my choice of colour screen needs work

Edited March 15 by TiffsAndAstro
coulds bye bye

[TiffsAndAstro]

Just in case anyone's wondering, I think less than 1 minute should be plenty for me.

If there's a gap in the cloud tonight will see how quick less than 1min takes.

Theres a chance I can get the comet and triangulum galaxy in same frame at 135mm

[AstroMuni]

On 15/03/2024 at 20:06, TiffsAndAstro said:

what sort of numbers are good enough? is there a chart somewhere of like focal length, exp time, guiding yes/no etc?

Its not just the PA accuracy that influences the image quality. There are other factors like mount stability, guiding, backlash etc.that affect your image. At the end of the day, its what level of quality is good enough (acceptable) for you.

[TiffsAndAstro]

23 minutes ago, AstroMuni said:

Its not just the PA accuracy that influences the image quality. There are other factors like mount stability, guiding, backlash etc.that affect your image. At the end of the day, its what level of quality is good enough (acceptable) for you.

honestly, i realise i am very, very new to this hobby but i don't think i could agree with you more. i think my entire gas for this hobby demands its because of my unrealistically limited budget.

the mount most people agree is the most important so i spent most of my budget on that. every other bit of equipment is cheap and nasty by comparison, but they at least allow me to practice stuff and connect stuff and one day, long after the heat death of the universe, have everything ready to go for when i can find a decently sharp, fast cheap lens.

delivered in a free Ferrari. 

my 135mm is not good. after really getting focus down via live view in nina and then quick test exposures they look awful wide open. i cba closing it down much because what's the point? so my remaining budget will go on stuff in this order: ok ish lens, better tripod, cheap guide scope and cam and some sort of mount/bracket. ill attach a couple of subs when i get home of what isn't acceptable which is aberation of the stars and/or tricky focusing.

ill try out my 200mm f3.5 next clear skies and see it is not quite as bad as my 135

[TiffsAndAstro]

also while looking at results of "how much pa is good enough" search, i saw a really good quote which seemed very apt:

 

measure with a micrometer, mark with chalk, cut with axe

[alacant]

8 minutes ago, TiffsAndAstro said:

measure with a micrometer, mark with chalk, cut with axe

No, no. You must not do that. Chalk makes dust which could get onto your lens.

Otherwise, good advice😉

Edited March 18 by alacant

[TiffsAndAstro]

no comment 

ok i lied

redbull gives you wings

2024-03-18_01-50-33__15c_90.00s_0000.cr2 2024-03-18_02-44-39__19c_90.00s_0007.cr2

[AstroMuni]

18 hours ago, TiffsAndAstro said:

ill attach a couple of subs when i get home of what isn't acceptable which is aberation of the stars and/or tricky focusing.

Remind me, whats your equipment at the moment? Looking at your images they are certainly out of focus but at first glance this seems quite similar across the frame.

[Cornelius Varley]

15 hours ago, TiffsAndAstro said:

no comment 

ok i lied

redbull gives you wings

2024-03-18_01-50-33__15c_90.00s_0000.cr2 24.48 MB · 4 downloads 2024-03-18_02-44-39__19c_90.00s_0007.cr2 23.97 MB · 2 downloads

Please post images in either jpg or png format so that they can be viewed in the browser.

[TiffsAndAstro]

1 hour ago, AstroMuni said:

Remind me, whats your equipment at the moment? Looking at your images they are certainly out of focus but at first glance this seems quite similar across the frame.

600d/t3i (unmodded) sky watcher gti plugged into nina

those images attached above were taken with an old 135mm f2.8, but i also have a pentax 50mm f1.7 a tokina 200mm f3.5 and a centon 500mm mirror lens  also 18-55mm kit lens which i haven;t tried since i got my tracker. its a bit wide field of view to shoot stars and avoid trees and roofs and a bit slow. maybe i can get its autofocus to work with nina?

the pentax seems by far the best image quality of them, but not much zoom

Edited March 19 by TiffsAndAstro
forgot to mention kit lens

[TiffsAndAstro]

8 minutes ago, Cornelius Varley said:

Please post images in either jpg or png format so that they can be viewed in the browser.

apologies .cr2 are a bit weird to convert.

[happy-kat]

when I was looking at star shapes on my old lenses I kept the exposure length low as the test was star shape not whether there was trailing adding to the mix. Looking at how exposed your images are there is room to take short exposure length test shots. During your testing you could set the camera to jpg and raw then you get two files per image. Where my lenses where quite fast f2 or f2.8 then f4 gave better stars with less compromise on light loss if I needed to stop down though the Q200mm lens I have needed f8 really. For me it's about what final star shape can I work with in post processing influencing aperture choice.

[TiffsAndAstro]

4 hours ago, happy-kat said:

when I was looking at star shapes on my old lenses I kept the exposure length low as the test was star shape not whether there was trailing adding to the mix. Looking at how exposed your images are there is room to take short exposure length test shots. During your testing you could set the camera to jpg and raw then you get two files per image. Where my lenses where quite fast f2 or f2.8 then f4 gave better stars with less compromise on light loss if I needed to stop down though the Q200mm lens I have needed f8 really. For me it's about what final star shape can I work with in post processing influencing aperture choice.

they were only 90 seconds, but, as you say, any problems could be hidden by trailing and stuff, so as soon as next clear nights ill give it another go with maybe 5 sec subs and stopping it down, but im looking to try and get a more suitable lens to use.

also, im bortle 6 (somehow) and im not too experienced with how light pollution varies with exposure and sub time and wonder how to achieve a happy balance. hopeful this will come with time under clear skies and lots of swearing.

Edited March 19 by TiffsAndAstro
fat fingers

[happy-kat]

when looking at the light histogram on the back of your camera I try to keep the peak off the left hand side to a third in, this leaves room for the other data that is not so bright still being captured

[TiffsAndAstro]

3 hours ago, happy-kat said:

when looking at the light histogram on the back of your camera I try to keep the peak off the left hand side to a third in, this leaves room for the other data that is not so bright still being captured

its only up to about 1/3 the way from the left. not even halfway across. ill try and take more pics on my phone next time its clear.

[TiffsAndAstro]

On 19/03/2024 at 18:00, happy-kat said:

when looking at the light histogram on the back of your camera I try to keep the peak off the left hand side to a third in, this leaves room for the other data that is not so bright still being captured

its only up to about 1/3 the way from the left. not even halfway across. ill try and take more pics on my phone next time its clear.

didn't have time to do more than set up polar align plate solve m51 thena couple of exposures on my 135mm stopped down from 2.8 to 4. after a while there were some gaps in the cloud so decided to experiment with my 200mm, stopped down from 3.5 to 5.6. it seemed very dark, but with a bit more time to focus, might be my least [removed word] lens. too early to tell. 

im quite happy i seem to be able to 3ppa reliably (with various focal lengths) and plate solve too. hopefully getting a reasonable lens is all i need to get better results. and some clear skies. 

Edited March 21 by TiffsAndAstro

[TiffsAndAstro]

one image of an example histogram m42 f4 90sec iso 400 (i think, sorry need to make better notes as i go)

 

one image of plate solve for (i think it was) m42. took a few goes i might have my target accuracy (can't remember exact name) set a bit too ambitiously 

if anyone can give any useful insights from just these two jpgs i'd be grateful. and impressed

[happy-kat]

looks promising for you to be able to stop down the lens for improving star shape whilst increasing the ISO to suit but not to more than 1600 to keep the histogram peak clear of the left

[TiffsAndAstro]

1 hour ago, happy-kat said:

looks promising for you to be able to stop down the lens for improving star shape whilst increasing the ISO to suit but not to more than 1600 to keep the histogram peak clear of the left

Tbh I was starting to wonder how others in similar light pollution could take even longer exposures, but just stopping down might account for it. Also filters and likely other factors.

 

Would f6.3 on my 200mm be worth a go ? I don't see many 200mm/320mm f6.3 telescopes about

Edited March 21 by TiffsAndAstro

[happy-kat]

Depends on what star shape you can process from, you're making the best from the equipment you own and picking up more skills as you go, I've found this is a continued learning journey with lots of highlights 

[TiffsAndAstro]

I agree with you and hope you're right.

Better to learn to powerslide in a Mazda rather than a Ferrari. Though maybe substitute good condition trabant for the Ferrari in my case

[TiffsAndAstro]

So moon is out

Sky is clear dark in about 90 mins

I'm tempted to pre focus my lenses on moon then tape them down

Would changing my fstop change focus?

Is this a daft idea?

[Elp]

No, but it does alter the depth of field, for AP this doesn't matter, so if you're focused it shouldn't change. But common sense tells you to confirm your focus last after everything else as it's one of the most critical things you don't want to alter once it's set.