antares disappointment

[alacant]

Hi everyone. Super clear after an early evening downpour, I'm disappointed with this. Loadsa questions e.g. what's happened to the blue around rho? What sort of exposure should I be using? Is the cls cutting too much light?  Any answers and help most gratefully received.

26x210s, Takumar 135, 700d, cls.

 

[MarsG76]

Why use a CLS for photography? I'd say thats your blue problem.

 

[LightBucket]

Yes the CLS does put a blue / green tint to images and halos on bright stars...but usually only on an unmodded DSLR with a modded one the colour balance is normally just about perfect... ?

[MARS1960]

Your histogram will tell what exposure to use, IE, if i am shooting east over the town i can get 10min subs with my LP, i like to stop down a click or two, so then i adjust my ISO to give me the histogram i need.

By CLS do you mean a CLS LP filter or something else? there are lots of different CLS filters!

What does your stack look like with just a masked stretch?

[alacant]

38 minutes ago, MARS1960 said:

By CLS do you mean a CLS LP filter

Hi. It's this one. Usually the blue is fine. Here's a snap from a similar area.

1 hour ago, MarsG76 said:

Why use a CLS for photography?

It was recommended for cutting out old style street lighting. 

Thanks everyone.

[alacant]

1 hour ago, MARS1960 said:

What does your stack look like with just a masked stretch?

[carastro]

I have recently returned from the costa del sol where I took this region with a DSLR.  It was light polluted where I was too, only about 5km south of Estepona.  I couldn't see the Milky Way.  I also used a clip in CLS filter and was rather disappointed with the results.  I had to do some very heavy handed post-processing to bring out the best of this.  My subs were 240 secs, but I ended up using two different lenses and combining all the data.

A zoom lens at approx 120mm f5.6 (the lowest it would go)

Nifty 50 lens (widefield) @ f3.5  This greatly improved the data, but I still want to get better data. 

This is my thread:

 

[alacant]

9 minutes ago, carastro said:

about 5km south of Estepona

Hi Cara. Yeah, thanks. We're about the same latitude. We can see the mw from here but sw there is lp. You had more success with the rho blue than I. I wonder if the Takumar glass absorbs blue? Did you try any exposures without the CLS? TIA.

[carastro]

Quote

Did you try shorter exposures without the CLS? 

No, to be honest I forgot the filter was in the camera, so the whole lot was with CLS filter.  It was in total almost 4 1/2 hours all the subs added together and as I said some "heavy handed processing", especially with the blue in selective colour and layering.

Am planning to get the whole nebula with a CCD camera and luminance lens (no scope) to add to this data to try to smooth it out a bit and hopefully enhance the dark nebula.  But this will have to be from the UK, and might have to be next year as I think I'll only get 1 hour per night max next new Moon.  If I stay 3 nights I might just get 3 hours worth in if it's clear every night.

This is a labour of love.  

Carole 

[alacant]

3 minutes ago, carastro said:

I forgot the filter was in the camera

I've done that too but at least this time it was intentional. I've got the guys on the Spanish forum on this too. They reckon head inland and lose the cls. So far. Do post if you get a working formula next moon. 

[carastro]

When I say "stay 3 nights",. this will be at a dark camping site in South England assuming the weather is good. 

[Uranium235]

With this you really need to get out to a dark place with a fairly unspoilt horizon (but you dont have to be able to see it naked eye in order to image that part of the sky).

Secondly, use the fastest, flattest lens (or setting) you have. I imaged this area @ f2, and it really does make a difference to the amount of signal gathered.... so having that in mind you can reduce the exposure time, or decrease the ISO setting if using a very fast lens. I chose the latter (180s @ ISO200) as a maximum the last time I took the DSLR out imaging, because it allows me to retain quite a lot of the star colour. If youre using a CCD (or both!), even better - that will make your trip out more worthwhile.

Lastly, you should be maximising the amount of light you are getting - so if youre at a dark site, no LP filter is required (use UV/IR blocking only - if your camera requires it).

45min per panel (x5), from 52 degrees North:

 

[alacant]

15 hours ago, Uranium235 said:

I imaged this area @ f2

Hi.  Thanks for the pointers. Your shot seems to be black and white only though (?). My lens is f3.5 so 4 may be reasonable and it'll get twice the photons as at 5.6. I think. The problem now is the moon and Antares crossing the meridian around midnight already. I should have started this earlier in the year. Bad planning:(

[Uranium235]

10 hours ago, alacant said:

Hi.  Thanks for the pointers. Your shot seems to be black and white only though (?). My lens is f3.5 so 4 may be reasonable and it'll get twice the photons as at 5.6. I think. The problem now is the moon and Antares crossing the meridian around midnight already. I should have started this earlier in the year. Bad planning:(

I used a CCD for that shot (hence the mono), but the image is mainly to illustrate that Antares is not such an impossible target - even for a DSLR, it just needs the right location/conditions/optics. Indeed, it should be a lot easier where you are!

[ollypenrice]

It's a tough one, even from southern Spain. Tom O'Donoghue managed a stunning and award winning result from down there but he is very, very expert.

https://apod.nasa.gov/apod/ap120828.html

'Up' here at Lat 44 this is, honestly, too low for us.

Olly

[Uranium235]

13 minutes ago, ollypenrice said:

 but he is very, very expert.

Lol... understatement of the year!

(nice chap too!)

[ollypenrice]

2 minutes ago, Uranium235 said:

Lol... understatement of the year!

(nice chap too!)

Yes and yes!!!

Olly

[alacant]

Thanks everyone. The apod looks great. Thanks for posting. Wondering whether I maybe better losing some of the fov. I've also a Takumar 200. Also, the light frames looked too dark. I'm wondering what setting the aperture was, Gotta get a bit more discipline into all this. Anyway, got one last chance next month  I think, Clear skies.

[Adam J]

On 30/06/2017 at 12:48, alacant said:

Hi everyone. Super clear after an early evening downpour, I'm disappointed with this. Loadsa questions e.g. what's happened to the blue around rho? What sort of exposure should I be using? Is the cls cutting too much light?  Any answers and help most gratefully received.

26x210s, Takumar 135, 700d, cls.

 

What F number are you working at as the CLS will not work correctly below F4.

[alacant]

23 minutes ago, Adam J said:

What F number

Alas, no idea. When you say below f4, is that faster? TIA.

[Adam J]

4 minutes ago, alacant said:

Alas, no idea. When you say below f4, is that faster? TIA.

Numerically below. So faster.