DSLR Focusing

[chris285]

This week was the first time I have had chance to head out with my setup for a few weeks, and I thought i'd try to connect up my 1100D for the first time and get some pictures however they didn't come out as expected and I think it's a focus problem.

I have a NEQ6 mount and a Skywatcher ED 80 scope attached to this connected directly to a laptop and controlled via stellarium, i started out doing some visual work on a few targets before deciding to put the T ring on my camera and try some imaging. I did put the camera into the diagonal which I think may impact to a degree but I don't think it's the problem, I took some shots and decided to put them on my ipad rather than view on the camera viewer due to size but basically they are mostly just dark images where a couple of them have dot's of coloured light.

When i viewed them on my desktop I could see different shades of darkness for lack of a better term, so I am under the assumption that my focus is out and is why i got a few coloured dots but mostly black. Now as right now I don't have backyard EOS to control the camera from my laptop, is there an easy way to try and get things focused correctly as I don't have the angle from my garden to try and pick out a distant object on the ground.

Question has been probably asked loads of times so apologies, but I have struggled to find an answer through my searching.

[sharkmelley]

The moon is a perfect target for trial focusing because you can't miss it!  Otherwise use a bright star such as Vega in liveview.

The diagonal will add quite a distance to the optical path and is the likely source of your problem.

Mark

[Leveye]

An example of it would be helpful here. Using the moon at first before the stars is a good start. Will get you close. I'd lose the diagonal myself. The less in in between the sensor and objective lenses the better at prime focus.

[davefrance]

Without the diagonal you may need a 50mm extension tube in its place to obtain focus.

[Thalestris24]

Hi

I think the ED80 is designed to be used at prime focus with the focal reducer / field flattener otherwise you'll need an extension tube. I'm sure someone here can confirm.

Louise

[davefrance]

Hi

I think the ED80 is designed to be used at prime focus with the focal reducer / field flattener otherwise you'll need an extension tube. I'm sure someone here can confirm.

Louise

Depends whether its an Evostar or Equinox, the former yes, I believe you are right.

[chris285]

It is the evostar tube I have, I'll have to weigh up an extension tube or focal reducer as I'd rather not spend much more right now.

Moon wasn't visible when I tried so will have to try vega next time I get chance to break it out depending on the weather

Sent from my iPad using Tapatalk

[Aeseir]

Use a bahtinov mask for close to mathematically focus on objects. You can make your own here http://astrojargon.net/maskgen.aspx they are a life saver when focusing.

[Notty]

Hi, I recently started with an identical camera/tube setup and I have the same issue. It was down to focus, and this sorted it out:

http://www.harrisontelescopes.co.uk/acatalog/Revelation_80mm_Extension_Tube_2_.html

[baggywrinkle]

I have the ED80 and you will need an extension tube. Also make sure that the focuser is not slipping. I had to tighten mine up due to the mass of the camera making it slip in small increments.

[mcinek82]

I agree that a Bahtinov mask is helpful, especially when combined with sending liveview to a laptop screen (one can see the spikes easier). The other solution is a bit more time consuming: You take a picture of a star, look at the maximum zoom of the picture on a camera's LCD (or a laptop screen) and evaluate its diameter, then take another one after SLIGHTLY changing the focus and evaluate again until it seems the diameter is the smallest. Clear skies!

[esxste]

I don't have the same setup, but for sure a Bhatinov mask is almost essential I would say - it makes focusing a very quick and easy task. 

FLO do a nice range: http://www.firstlightoptics.com/bahtinov-focus-masks/starsharp-bahtinov-focus-masks.html

[6golfer2]

hmm I've been having trouble focusing while looking at the live view screen as opposed to the eyepiece, I bet a Bahtinov mask will fix my problem.

[m37]

Backyard EPs is not too expensive and is very helpful, of allows fwhm and mask based focusing by numbers. if you have a laptop, that is!

[Atreta]

You can use APT too, it won't expire  and it's very useful. Has fwhm, hfd and some other focus aids.

And if you want to buy it, it's not expensive either.

Backyard EOS is a great software too.

[Aquariusman]

I was out last night and used my bahtinov mask and had correct focus after 10 seconds using live view. £15 Very well spent.