needing advice on focusing

[danccat]

I've been practising my DSO imaging on m42, but on most photos, images are often blurred.

The scope is a nexstar 8se, mount is az eq6, with a modded Canon 1100D, each has an exposure of 120, using premium backyardEOS as software to capture. I manually focus on the scope whilst viewing a star prior to capture.

Even with this, photos are blurry and out of focus, can backyard provide additional focus? I did try but the adjustments to focus are simply not highlighted.

Any tips/advice would be nice.

Cheers, clear skies

[Xplode]

120 second exposures without guiding with a 8se at 2000mm focal length? Sounds like you are getting fuzzy stars because you are doing too long exposures for your setup.

It might not be what you want to hear, but your scope isn't really suited to image DSO's with a DSLR because of the slow optics. To get good images you need a faster scope with shorter focal length, prefferably something around f/5 and less than 750mm FL.

[iksose7]

Above post sounds about right. However, if you are managing to pull off 2 minute un-trailed subs, i would suggest buying a Bahtinov mask. I focused without one up until a month ago and they make a huge difference!

Callum

[danccat]

Right... so I need to upgrade the scope... shame.. I was thinking of getting a William Optics Zenithstar ZS71 ED from FLO... its focal ratio is F/5.9 with a focal length of 418mm... would it  suitable?

Here's what I mean by blurry (last night's M42)... and these have been stacked.

[graemlourens]

I made a mistake too at the beginning buying the Nexstar evolution 6", then saw i'm only into AP and visual doesn't interest me currently.

I'd consider grinding your teeth and changing OTA.

That picture you attached, either you have a gigantic amount of disturbance in the air (were you shooting over rooftops or at a distant location?)

or you're scope is out of collimation maybe?

[jtlandreneau]

Above post sounds about right. However, if you are managing to pull off 2 minute un-trailed subs, i would suggest buying a Bahtinov mask. I focused without one up until a month ago and they make a huge difference!

Callum

this +1. Buying (or making, there are websites that will print templates for you) a bahtinov mask was a total game changer for me.

[Xplode]

William Optics Zenithstar ZS71 ED with flattener/reducer is a good choice for a starter and should give you pretty good results straight away  

[toxic]

just make a Y mask get a piece of card and rap it round your scope then tape it so that it  just slides then tape 3 pieces of fishing line or thin wire or what ever you have in a Y shape you will get the same effect as if you where using a Bathinov  mask.

[lensman57]

I've been practising my DSO imaging on m42, but on most photos, images are often blurred.

The scope is a nexstar 8se, mount is az eq6, with a modded Canon 1100D, each has an exposure of 120, using premium backyardEOS as software to capture. I manually focus on the scope whilst viewing a star prior to capture.

Even with this, photos are blurry and out of focus, can backyard provide additional focus? I did try but the adjustments to focus are simply not highlighted.

Any tips/advice would be nice.

Cheers, clear skies

Do not rush out to change the scope. Are you using a reducer ? If not then using one  will bring the FL down to about 1300.00mm which is still long but manageable with an AZ EQ6. If you are using BYEOS then the easiest way of focusing is to use the FWHM focus assist, just aim for the smallest number of the FWHM. The problem however is 1- Lack of guiding and accuracy of your PA and 2 the focuser knob of the 8SE is not exactly the most responsive so getting the point of sweet focus is hit or miss. Some like to use a motor to do this and some like to add gadgets to the knob to make the turning of the knob smoother and more responsive. On the bright side the mount is more than capable of handling the 8SE.

A.G

[ollypenrice]

Without a reducer you are trying to image at 0.53 arcseconds per pixel. Most UK imagers seem to like about a quarter of that resolution because it is possible. Usng a premium Mesu 200 roller drvive mount, accurately autoguided, I've imaged down to 0.66 arcsecs per pixel. Unguided on an EQ6? Impossible. Like trying to pick up a pea with five metre long chopsticks.

The reducer would bring you down to about 0.79 arcsecs per pixel. Still impossible unguided and not at all easy autoguided. You could bin your images 2.2 with a monochrome camera to increase your pixel size but with a one shot colour you can't.

For a DSLR your focal length is simply too long and that, honestly, is about that.

Olly