AP help

[Kenboy]

Hi all! 

Looks like finally some clear moonless skies near me tonight

I've got a beginner setup and just wanted to ask few quick questions 

Setup: Astro modified Canon 550d, Svbony CLS clip filter, Canon 50mm F1.8STM lens in Bortle 5 skies. 

What ISO and exposure length would you recommend to image at? how many shots to stack?

Any ideas how I can prevent mist on my lens? (it's going to be -8 degrees, and I don't have any warmer)

thx so much 

[PeterCPC]

I would go with ISO800. You'll have to set the exposure time depending on your histogram but if we are talking non tracking then you will be limited to maybe 15 secs. Stack as many as you can. Hairdryer on lens maybe.

Edited February 10, 2021 by PeterCPC

[scotty38]

Trial and error is the name of the game, at least it always is for me. I would take my first stab around 6-8 seconds and iso 1600 to avoid trails. I have a different camera, different skies and different lenses (f4 so you're a lot quicker at 1.8)  but I'd stab around there first and increase the shutter speed (so you know the limit) until you see trails then I'd work on ISO. I'd use it at 1.8 too first

Edited February 10, 2021 by scotty38

[Rustang]

Make a cone around the lens using card, funky foam or similar to act as a dew shield!? 🤔

[scotty38]

Regarding lens heaters look on amazon at the coowoo straps. Fairly inexpensive although you will need some sort of USB doohickey 🙂

[Kenboy]

2 hours ago, PeterCPC said:

I would go with ISO800. You'll have to set the exposure time depending on your histogram but if we are talking non tracking then you will be limited to maybe 15 secs. Stack as many as you can. Hairdryer on lens maybe.

Sorry I didn't mention. I am using a SA star tracker. So ISO 800, with 1 minute exposures x 30 sounds ok? 

[Kenboy]

2 hours ago, Rustang said:

Make a cone around the lens using card, funky foam or similar to act as a dew shield!? 🤔

ooo thx I can try this

[PeterCPC]

That sounds ok to me.

[scotty38]

12 minutes ago, Kenboy said:

Sorry I didn't mention. I am using a SA star tracker. So ISO 800, with 1 minute exposures x 30 sounds ok? 

Perhaps ignore me then, bets are off on that front..... However I would still experiment but from a different starting point so yep start as you suggest and fine the point where the tracker starts to trail. You then know that limit and can adjust other things to suit....

I am assuming at least a reasonable polar alignment too.

Edited February 10, 2021 by scotty38

[Kenboy]

what f ratio shall I use?? 

[Kenboy]

apparently the canon 50mm f1.8 is best at around f/2.8?? 

[happy-kat]

Try f1.8 and f2, f2.8 etc and see what you prefer, star will be bloated and or towards the edges the stars won't be round if the aperture is too open for the lens being used. 

You will need a remote trigger release for your camera, at the minimum use the onboard timer delay if you have no other way to trigger the shutter

Edited February 10, 2021 by happy-kat

[Kenboy]

1 hour ago, happy-kat said:

Try f1.8 and f2, f2.8 etc and see what you prefer, star will be bloated and or towards the edges the stars won't be round if the aperture is too open for the lens being used. 

You will need a remote trigger release for your camera, at the minimum use the onboard timer delay if you have no other way to trigger the shutter

yup I've got a intervalometer. 

ok I'm going to use ISO 800, f/2.8, 1 min exposure x 30. 

[shropshire lad]

And post your results on here.

Good luck, I'm just setting mine up.... looks like its staying clear

 

[Skipper Billy]

You dont say where you are but up here the air is unbelievably dry at the moment - you might get away without dew control. Here last night it was -7 and the dew point was -12.  

[JamesF]

1 minute ago, Skipper Billy said:

You dont say where you are but up here the air is unbelievably dry at the moment - you might get away without dew control. Here last night it was -7 and the dew point was -12.  

Same sort of thing here, though not quite that chilly.  The air is so cold that it's holding very little moisture even before the temperature drops overnight.  We've had no frosts this week despite the temperature being below freezing most of the time.

James

[Kenboy]

ok will post, might need some help with processing.

btw, do I take the flat frames with the CLS filter on? 

[Kenboy]

camera lens did end up misting.... 😛 

but still got a some decent shots I think 

[Kenboy]

19 hours ago, shropshire lad said:

And post your results on here.

Good luck, I'm just setting mine up.... looks like its staying clear

 

Anyone wanna try processing this? thx

Orion 11-02-21.TIF