M57 early this morning

[Kaptain Klevtsov]

Got this snap, iso1600 stack of 4 3 minute out of focus images with the Newt. 2x Barlow and CLS filter on the D50.

As you can see I'm still struggling to get good focus even with the Stiletto focussing device, either that or the 'scope was blown about by the wind. Anybody know how to tell the difference?

Forecasters, they're rubbish. Forecast was for clouds but the early holes kept me up long enough to go outside for a look at midnight and it was clearing. Clear until 2AM, as in REALLY clear.

Hope you like.

Captain Chaos

[FLO]

Stiletto focussing device?

[Kaptain Klevtsov]

Its a Rochi screen thing that comes with a mount to suit your camera. Stick it on on place of the camera and focus until there are no stripes across the image. It is then in focus, allegedly. Doesn't work so well if there's so little light that there are no stripes whatever you do to the focus.

http://www.stellar-international.com/ is where to get them and the info.

Captain Chaos

[OXO]

Good effort CC as to focussing i would normally just focus on a bright star first checking the focus with the LCD screen(Zoom in on the pic) then aim at your choosen target..........

James

[Kaptain Klevtsov]

The problem with the D50 is that the zoom doesn't zoom enough. I can't get close to 1 pixel on the finished picture = 1 pixel on the LCD, so even when it looks good zoomed all the way in on the screen it is often out of focus. Really good when you think you have the best shots ever and then you load it up on the laptop.

I've considered various options:-

a) Use the laptop next to the 'scope to check focus.

Use a portable TV and put the DSLR TV output to that.

c) Save up and drop a grand and more on a D200.

Captain Chaos

[OXO]

Use a portable TV and put the DSLR TV output to that.

That works really well funny enough CC i did this using a Nikon coolpix 4500 after getting problems with focus. I went one better and got a TV card for the Laptop and stuck the camera into that this gave better resolution for focussing..

James

[FLO]

Its a Rochi screen thing that comes with a mount to suit your camera. Stick it on on place of the camera and focus until there are no stripes across the image. It is then in focus, allegedly.

I learn something new every day

[MartinB]

Try a bright star on a laptop and keep trying tiny little shifts of focuss and playing with different brightness.gain settings. To fine tune you need to look at the tiny little halo that forms around the bright star and get that down to a minimum, it's not good enough just to focus until the star itself looks reasonably sharp. I'm learning that it's not something to be hurried. Very difficult if it's breezy though.

[Kaptain Klevtsov]

Steve, that wont work for the DSLR type camera as the LCD image isn't live. You can only look at pictures that you have taken, not the live image.

MartinB, that works fine for SC type webcams, but not for DSLRs, again the image is not live.

Captain Chaos

[FLO]

Steve, that wont work for the DSLR type camera as the LCD image isn't live.

Does it not work visually thru the viewfinder?

[FLO]

What about a Haartman mask?

[MartinB]

MartinB, that works fine for SC type webcams, but not for DSLRs, again the image is not live.

It's never live CC. It's long exposures after all. Worse still on an SCT which has mirror shift, every adjustment to focus messes up the image. To be getting focus on a bright star if using a 7 second focus I have to see the image, make a tweak to the focus, wait for the next image which will be smeared because of mirror shift then have a close look at the next image and try to compare it from the last but one image from 14 seconds before! No luxury of a live image there!!

[Kaptain Klevtsov]

Sorry Steve, I meant to reply to James re. his Coolpix trick and didn't scroll enough / read the post to get the name right. The Ronchi screen fits on iinstead of the SLR or DSLR using the same bayonet. The idea is that its set up to make sure that the camera is already focussed when you fit it.

Captain Chaos

[Kaptain Klevtsov]

Martin, two 14 second frames is more live than waiting 3 minutes before you can see the things. With the DSLR I fiddle with short exposures coumting the number of stars at max. zoom in the centre. When there are the most stars, that's the best focus. I wonder if I just invented that?

Captain Chaos

[CELESCOPE]

good try CC ,as you say get the focus improved and the image will look very good mate , must be hard getting it right with that set up ,

Rog

[Kaptain Klevtsov]

Rog, its no harder than winning a tenner at the lottery.

Life is like a full D50, you never know what you're going to get.

Captain Gump