Tips and advice

[amateur-astro]

Tips and advice for deep sky objects 

[Elp]

Where do you want to start?

[amateur-astro]

I've got a very basic set up. Dslr canon 2000d and around t diffent stock lenses. 75mm to 300mm is the main one I use, I find it very tricky to get foucs when I think I've got it spit on, I take my images load them onto my laptop and delete atleast 75 percent of them because they are out of focus 

Thank you for the reply

 

[Elp]

What are you trying to image?

What lenses are you using, some cannot focus to infinity for astro use.

You can try making a bahtinov mask for your lenses to help with focussing if you're not using a computer to assist with your image acquisition.

Edited November 19, 2022 by Elp

[WolfieGlos]

Definitely get a bahtinov mask, you can find them on eBay for your specific lenses. FLO also sell them but only for telescopes afaik.

All you do, is find a bright star, zoom in on your camera screen and then put the mask on the end of the lens. Adjust the focus until the spikes all go through the middle, like below. Then you’re in focus. Done. 

[Mandy D]

11 hours ago, amateur-astro said:

I've got a very basic set up. Dslr canon 2000d and around t diffent stock lenses. 75mm to 300mm is the main one I use, I find it very tricky to get foucs when I think I've got it spit on, I take my images load them onto my laptop and delete atleast 75 percent of them because they are out of focus 

Thank you for the reply

 

Are you sure this is a focus problem? If 25% are spot on and you have not touched the focus, then every image will be in focus. It sounds more likely that you have camera shake. Are you using a tripod and is it stiff and rigid with no movement? How do you release the shutter? You really do not want to touch the camera at all once it is on target and in focus. Use a remote release.

[alacant]

17 hours ago, amateur-astro said:

75mm to 300mm

Hi

I think it's fair to say that the 75-300 isn't perhaps the best lens Canon have produced. 

As the lens does not focus all colours at the same point, a focusing mask will not give the best focus.

With the lens set to AF, decide on focal length and leave it there. Depress the shutter to focus centre frame on the moon. That will get you close to infinity. Back to MF.

To refine it from there (difficult), centre a bright white star. In live view at x10, twist the focus so that the halo just disappears. Sirius is good.  Depending upon where you are in the zoom range, the halo could be either blue or red. Your aim is to compromise between bloat and false colour. Tape the focus ring to prevent it drifting.

That's the best we could do. 

You might want to consider a fixed lens. There are some good examples, e.g. 135mm and 200mm, available cheaply on auction sites.

Cheers and HTH 

Edited November 20, 2022 by alacant

[amateur-astro]

Thank you for help, that sort of explains where I've gone wrong. Would you be referring to the 135 mm samyang? I've been looking at this lens for a couple of months now, but I've got my eye also on the redcat 51 which would take me in a different direction and away from lenses regarding my rig.

At the moment my mount choice is either a heq5 goto or the eq6r undecided because I'd like the rowen belt mod on the heq5 from the research I've done a pure feed back it's a must.

I could live with a standard dslr and a red cat 51 for a while, until I decided to get a zwo astro camera.

Thank you once again for the information 

Astro

 

[alacant]

12 hours ago, amateur-astro said:

samyang

If you're good at -e.g. eBay- auctions, there are good alternatives. The Zeiss and Takumar 135mm perform well. OK, you don't get f2 but hey, for around €50 they give very good results.

Here's an example we took with the Zeiss.

HTH

Edited November 21, 2022 by alacant

[Ratlet]

SMC Takumar 200mm provide some VERY nice framing for a lot of objects and has exceptional optics also.

This was taken using alacant's method of focusing and an smc takumar 200 which I got for £40-50.

Vintage glass is fun.  Its cheap compared to alternatives too.