Cheap Canon lens for Astro?

[Cuto100200]

Any cheapish canon lenses that are better than the kit (EF-S 18-55mm 3.5 - 5.6) for astro worth getting?

When I say cheap I mean under 200

Thanks

Edited June 17, 2020 by Cuto100200

[Davey-T]

If it's only for astro' use then old screw fit Pentax SMC Takumar lenses are good.

Dave

[happy-kat]

I'm happy with the 40mm pancake lens they are sub £100 second hand, for astro the 24mm isn't so good in my experience. Though unless I had an Android phone and compatible camera for dslr controllero or a laptop I wouldn't get a fly by wire focusing camera. 

I can use my old takukar 50mm F2.2  (used at f2.8 I think) faster aperture then I can use on the pancake (f4 on mine for star shape) so the vintage lens gets more vote purely for astro and was cheaper.

[R1k]

What’s it for? Widefield or DSO?

 

i took the attached photo with a 75-300mm f4-5.6 last weekend. Picked the lens up for £30 on Facebook marketplace. 

[Knight of Clear Skies]

The Takumar 135mm f3.5 is a good budget AP lens. This is my most recent effort with it, with Ha data blended in from my Samyang 135mm f2.

[Alien 13]

Its a difficult one, I had the std 18-55mm kit lens although it was the IS version and found it far superior to my more recent 50mm f/1.8 STM lens for AP. To get better performance at that focal length you need to look at the Samyang range but they do cost a few pennies, the Takumar M42 lenses with an adapter are worth looking at but if you want more focal length then nothing beats a used Canon 70-200mm f/4 L lens for the price, I paid £240 for mine admittedly a few years ago.

Alan

[Cuto100200]

15 hours ago, R1k said:

What’s it for? Widefield or DSO?

 

i took the attached photo with a 75-300mm f4-5.6 last weekend. Picked the lens up for £30 on Facebook marketplace. 

This is very cool, how would you go about doing this? Do you just take many long exposures and then stack them or do you have a tracker?

[R1k]

6 minutes ago, Cuto100200 said:

This is very cool, how would you go about doing this? Do you just take many long exposures and then stack them or do you have a tracker?

Sorry I should have qualified this. This is a Canon 800d with the aforementioned lens mounted on a SW HEQ5pro. No guiding, no capture software. Just the camera, lens and mount. Intervalometer used to capture exposures (26 x 90s lights, 15 darks, 60 bias, no flats). Stacked in DSS and  processed in PS CS6

[Cuto100200]

3 minutes ago, R1k said:

Sorry I should have qualified this. This is a Canon 800d with the aforementioned lens mounted on a SW HEQ5pro. No guiding, no capture software. Just the camera, lens and mount. Intervalometer used to capture exposures (26 x 90s lights, 15 darks, 60 bias, no flats). Stacked in DSS and  processed in PS CS6

Ahh understood that's really cool, I still need to learn how to do darks and bias's. When finding an object in the sky, do you just aim the camera at it and shoot or do you zoom or crop somehow to get it enlarged? 

[R1k]

4 minutes ago, Cuto100200 said:

Ahh understood that's really cool, I still need to learn how to do darks and bias's. When finding an object in the sky, do you just aim the camera at it and shoot or do you zoom or crop somehow to get it enlarged? 

my mount is GoTo so it will find the object for me, the image I posted is only a little cropped. I have uploaded the uncropped version below. The effective focal length is 300mm x 1.6 (as I am using a crop sensor camera).

 

Edited June 18, 2020 by R1k

[RobST]

I got myself a 50mm 1.8f canon lens from mpb, they sell used camera equipment, managed to get this of andromeda on my first night, using that lens and an unmodified 400d on a terrible mount, i was still chuffed to bits.

[Cuto100200]

3 minutes ago, R1k said:

my mount is GoTo so it will find the object for me, the image I posted is only a little cropped. I have uploaded the uncropped version below. The effective focal length is 300mm x 1.6 (as I am using a crop sensor camera).

Thanks for telling me all this it really helps! I honestly just didn't know if cameras were that capable of capturing objects, I thought it'd be a lot more complicated and finicky, thought you'd need to zoom somehow or something. I have a canon 250d, would this be enough to do astro with by stacking short long exposures of brighter objects like Andromeda etc? (I'd like to get a Goto tracking mount in future, I was looking specifically at the sw heq5 that you have as it looks very good value for money)

[Knight of Clear Skies]

50 minutes ago, Cuto100200 said:

I honestly just didn't know if cameras were that capable of capturing objects, I thought it'd be a lot more complicated and finicky, thought you'd need to zoom somehow or something. I have a canon 250d, would this be enough to do astro with by stacking short long exposures of brighter objects like Andromeda etc?

The 250D should be good for AP although it would require modification (removal of one of the IR filters) to give the best results on nebulae by improving its sensitivity to Hydrogen-Alpha emission. There are some very large DSOs up there that don't require long focal lengths to image. For example, this is a 2-minute exposure of M31 at 135mm after a quick image process, taken from a dak site.

[happy-kat]

You don't even need to have a tracking mount to start taking images. Star trail images are taken with a static mount. Even interesting areas of the sky will show with a static mount.

Details link here

[Cuto100200]

3 minutes ago, happy-kat said:

You don't even need to have a tracking mount to start taking images. Star trail images are taken with a static mount. Even interesting areas of the sky will show with a static mount.

Details link here

Understood, this looks amazing! So will taking a lot of 2 second exposures to avoid star trailing and then stacking these in software provide decent results? I'll need to learn how to do blacks to reduce noise, if i understand correctly blacks are done by using the exact same settings as you use for lights but you put the lens cap on?

[happy-kat]

That was a 24mm lens but could have been a 50mm lens and say 8 second exposures and lots of them.

Some dslr and darks add more noise, however flats are good to take.

Get started keep it simple take lots of light exposures light over 100.

[Cuto100200]

On 18/06/2020 at 17:01, happy-kat said:

That was a 24mm lens but could have been a 50mm lens and say 8 second exposures and lots of them.

Some dslr and darks add more noise, however flats are good to take.

Get started keep it simple take lots of light exposures light over 100.

Thanks for this! Just another question I've been wondering, when actually taking long exposures, obviously it takes a long while to complete if you're doing over 100, so would you need to move the camera at all during shooting or does stacking software just know how to stack the images and make up for the fact the stars will be in slightly different positions in each photo?

[happy-kat]

I thought you were using a static tripod where taking loads really does make a difference

Stacking software ensures the stars line up but when processing you would then look to crop away the edges leaving the bit of the image where all frames are aligned.

 

[Cuto100200]

15 minutes ago, happy-kat said:

I thought you were using a static tripod where taking loads really does make a difference

Stacking software ensures the stars line up but when processing you would then look to crop away the edges leaving the bit of the image where all frames are aligned.

 

Okay cool that makes sense, yeah i'm using a static I just didn't know exactly how the stacking software worked. Thank you for the advice by the way, much appreciated!

[happy-kat]

Exposure length as a starting point 400/focal length of lens (or 600 if using full frame camera). East and West would show less quickly star trails where as North and South show faster and how much trailing is tolerated is personal choice.