Improving the image?

[recceranger]

Guys,

I got out last night for some great viewing and had a crack an my first AP. HEQ5 aligned, ED80 with D3000 attached via T Adapter and followed all the advice I have read.

On looking at some of the images (Orion Neb, Double Cluster) I noticed the focus wasnt quite as sharp as it should be. I used a focal mask but on looking through the D3000 view finder it wasnt at all easy to get the correct focal image, even when using the brightest stars.

Another query is how do you guys get such large images? I have read lots of posts and seen photos of the moon, DSO and planets taken with the ED80 and either a DSLR or CCD. These shots show amazing detail, but when I attempted last night my image of Orion Neb for example was quite small.

I'm a novice but keen to learn so any advice would be greatly appreciated.

Cheers

[Tinker1947]

There are a couple of way to get good focus, take a image and adjust the focus, take another then repeat until its sharp, get a Cannon 1100D and use the Liveview this is very good, it also allows the purchase of APT imagine software really cheap but very good, or a Bahtinov Mask, this shows 6 defraction spikes you centre the middle spikes and you in focus, it does require a bright'ish star to work with.....

[Jannis]

Can you upload one of the pics you took? Will be easier to give advice once we see what you've been able to capture so far.

As for the large and detaild pictures you often see here - they are not single pictures. They are usually many pictures stacked together, often with total exposures of 4-8 hours or more, and often 100-200 pictures or more.

Also, it's not just that, but we also take many calibration frames to correct errors in the camera as far as noise and hot pixels, as well as correcting for the telescopes optical errors.

Not to mention the many hours spent in photoshop or similar afterwards to drag out those fine details.

So it's far away from pointing the scope at the target, pressing the shutter, and you have a great looking picture ready to print or upload...

as for the small nebula, it depends on the focal lenght of the scope. The longer your scope is, the closer to the target you get. But normally, with a high res DSLR you can easily crop the picture quite a bit to make the final picture look larger.

Focusing is a critical thing. It's not easy through teh view-finder, and also unfortunatly never as accurate as if you take sample picture to check unless you have live-view on your camera (i din't think you have on teh d3000 if i don't remember wrong).

Also remember to recheck focus if there's a notisable temperature change to the camera optics - be it a normal lens or telescope.

[recceranger]

Thanks,

Thats sound advice. I will do some more tonight hopefully and download from my Mac onto the site.

Your right the D3000 hasnt got live view and its a bit of an achilles heel if I'm honest. But it will have to do for now unless I find a company that allows me to trade an old DSLR for new.

Rick

[ollypenrice]

If you use a bahtinov mask the lack of live view isn't that significant, is it? Just keep taking but not saving single subs. I wouldn't try getting focus by looking at images to see if they look sharp. Not accurate enough. Believe the Bahtinov. It would be a lot easier for you to have the laptop outside, though, so you could see what you're doing on a decent sized screen. Once you have focus measure or pencil-mark the drawtube so as to save time next time out. You'll still need the mask, though.

I'm surprised by your saying that the target looked small. I'd have thought that the ED80 and DSLR chip would be about right for M42. Maybe in short subs you were only picking up the bright region around the Trapezium. Longer subs should pull out a screenful of nebulosity or outlying dust.

The book Making Every Photon Count is an excellent way into imaging from an experienced astrophographer. FLO supply it.

Olly

http://ollypenrice.smugmug.com/Other/Best-of-Les-Granges/22435624_WLMPTM#!i=2277139556&k=FGgG233

[Jannis]

Live view isn't critical. Just take sample shots at high iso and short exposures like 1-3s if you use a focus mask. It's recommended anyway instead of live view as it averages out any air turbulense that can, when using livie-view, make focus jump in and out even when you don't move the focuser at all.

Most astro programs are for canon dslr, not nikon, but that doesn't mean your d3000 takes any worse pics at all. it just means you might have to do a bit more of the work yourself when it comes to controling the camera and taking the pictures.