Surprised myself with this quick M31

[Dazzyt66]

Wowsers! Second outing for my used 200mm 3.5 lens after a clean.

I knew cloud was going to set in so I really just wanted to practice focusing with Ekos focus module. When I'd got it focused using the module (I didn't have much luck using the Bahtinov algorithm so just used the standard tool) with my laptop next to the lens as I tried to get the numbers as low as possible. As it was still clear at this point I thought I'd have another go at M31. I got about 50 mins of useable ISO1600 60s subs until cloud set in.

This morning I wasn't really expecting much as I stacked and processed the 50 subs in Siril using the bias and flats I did last time I used the lens (so no additional cleaning taken into consideration) but after a final tweak in Gimp I got this... I nearly wet myself!!! lol

 

[CCD-Freak]

What 200mm lens are you using? 

[Dazzyt66]

16 hours ago, CCD-Freak said:

What 200mm lens are you using? 

Its a M42 Kalimar fixed 200mm f3.5 lens I got from Ebay for £20 - as I  know little about photography I cannot tell you if this is a good make or not (I'm guessing not for the price  ) - used an M42 adaptor on my now astro modded 1100D.

[powerlord]

very nice. I've got 3 old 200mm lenses - a chinon f3.5, F4 takumar and an f3.5 tamron. all got for buttons on ebay.

the hardest thing about using them is focusing them. And then the focus rings tend to be very loose, so KEEPING it focused is tricky.

I have bodged a rig up to use my skywatcher EF with them which helps a lot.

But when you see results like this, you wonder why folk spend hundreds on ED telescopes don't you!

It's certainly pretty distorted towards the edges, but could that just be you being out a bit on the back focus ? where did you end up getting focus on the lens scale ?

stu

[Dazzyt66]

37 minutes ago, powerlord said:

very nice. I've got 3 old 200mm lenses - a chinon f3.5, F4 takumar and an f3.5 tamron. all got for buttons on ebay.

the hardest thing about using them is focusing them. And then the focus rings tend to be very loose, so KEEPING it focused is tricky.

I have bodged a rig up to use my skywatcher EF with them which helps a lot.

But when you see results like this, you wonder why folk spend hundreds on ED telescopes don't you!

It's certainly pretty distorted towards the edges, but could that just be you being out a bit on the back focus ? where did you end up getting focus on the lens scale ?

stu

Thanks. I am really impressed with what can be done with basic lenses and I've decided for imaging that is all I'm gonna use now. My HEQ5 is definite overkill for this (as I thought I may go down the ED route at some point) but as I've got it and its permanently set up why not eh? 😂 

Anyway, the distortion doesn't bother me but I guess I could crop it out. I was fully open at f3.5 and as others have said I could stop it down which will probably improve things. I left it at 3.5 cos I wanted to get enough data before the clouds came back in - this was only meant to be a test image 😂 

I used the Ekos focus module for obtaining the focus which was a little backed off from infinity (which is what I would've expected) - I have got a Bahtinov mask too which I use but didn't this time. I was planning on building an auto focuser for my ST80 to use with Ekos, which I could modify to fit the focus ring on the lens - this may improve things more.

TBH - this is a perfect, 'easy', cheap way to image for me. I'm not planning, or expecting, to win any imaging awards. I just like to see what I'm able to do from my Donny back garden and my wife and daughter like to see whats out there.

Glad you like it.

Daz

Edited September 13, 2021 by Dazzyt66

[tomato]

I think your approach to getting started with imaging is spot on. There have been a couple instances recently on SGL where folks have bought a lot of gear and struggled to make it all work together and alas it has ended up in the classified section a couple of months later.

Get some images in the bag early on which you can be proud of (like your M31) to share with family and friends and SGL. That’s where my motivation came from to go deep into the AP rabbit hole.👍

[CCD-Freak]

This is a system I cobbled together some years ago with a 200mm Takumar lens and a SS-Pro camera.  The focus motor makes it easy to get precise focus and it holds it once you are done. 

 

 

[Dazzyt66]

2 hours ago, CCD-Freak said:

This is a system I cobbled together some years ago with a 200mm Takumar lens and a SS-Pro camera.  The focus motor makes it easy to get precise focus and it holds it once you are done. 

 

 

Thats exactly the approach I am going to take - I run all my stuff of a Raspberry Pi and had already looked into the autofocus build 👍

[CCD-Freak]

Here is another one I did with a Zeiss Sonar 180mm F2.8 lens.  It worked but i was disappointed with the amount of chromatic aberration it had.  You can never tell until you test it.  

 

[Dazzyt66]

8 hours ago, CCD-Freak said:

Here is another one I did with a Zeiss Sonar 180mm F2.8 lens.  It worked but i was disappointed with the amount of chromatic aberration it had.  You can never tell until you test it.  

 

That setup is very nice!

[powerlord]

15 hours ago, CCD-Freak said:

This is a system I cobbled together some years ago with a 200mm Takumar lens and a SS-Pro camera.  The focus motor makes it easy to get precise focus and it holds it once you are done. 

 

 

Can I ask what shed that is ? looks neat with the expanded plastic, etc.

 

[CCD-Freak]

It was a "smart shed" I had about 20 years ago.  It was made by a company called "Thinking Outside" which is no longer in business  these days.  It was very easy to remove some fasteners and then slide part of the roof off to get access to the sky.   It was fairly secure since it didn't call attention to itself as it looked like a common garden shed when it was closed up.  I enjoyed having a permanent setup until we moved to a place that had a poor view of the sky.   I have been using my portable "SkyBox" observatory since then and will soon be building a ROR observatory at my new low Bortle 2 dark site (SQM 21.99)