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Disappointing moon shots....

Jarndyce

By Jarndyce
in Imaging - Discussion

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Jarndyce

Jarndyce

Posted
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Looking for some advice here, please, as I'm new to this.

I've bought a C80ED for imaging and I'm still experimenting with it.

However, tonight, I had a go at some moon shots with the C6S on the 6SE mount.

I'm not impressed with the results. No matter how hard I try, I can't get sharp images. I have a bahtinov mask, which is great, but can't be used on the moon.

I hook the D70 up to the laptop and use camera control pro to operate it. I've tried multiple shots with tiny incremental focus changes and viewed the images on screen and it doesn't get any sharper than the rather blurry image attached.

So what's going wrong?

1) Collimation's out?

2) Mount vibration? (It's not really designed for astrophotography, but it's only 1/125 sec)

3) I'm stupid...?

post-15738-133877364878_thumb.jpg

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barkis

barkis

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It certainly looks as though your focus is off a little.

Is the telescope a SCT? I am not familiar with the cS6. It is a 6" objective I guess.

Collimation may be an answer as to why. If it is out of colli, then focusing would be difficult, and possibly unattainable.

You could also try an IR Filter, or a red filter. All this takes second place to perfect collimation though, especially on a SCT. Also, is you front plate clean, it may be scattering some light.

Ron.

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Psychobilly

Psychobilly

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I've wondered whether the moon can fit in focus through the depth of field of a scoped pic ? The nearest part being some 1700 K's closer than the limbs.

I would be extremely suprised if thats the cause... I know I have had issuses with "focus" which have been due to bad collimation.

I would up the ISO and shutter speed and see what happens

Peter...

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Jarndyce

Jarndyce

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Thanks for your replies.

Yes Ron, the C6 is an SCT. I have never collimated it as I've always been impressed with the images through the eyepiece. Think I may need to get some Bob Knobs and have a go. Have to say, collimation is not something I've been looking forward to....

Peter - why do you suggest increasing the ISO and shutter speed? To minimise camera/mount shake? I'm going to try it on the CG-5 mount as that's fairly sturdy and should give a stable platform, but I'll try what you suggest. Thanks.

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jgs001

jgs001

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How were you shooting, raw or jpg ? If raw, what processing did you do on the image ? I've been shooting at 1300mm with my Skymax 102 mounted on a camera tripod. It's a bit wobbly, but using a remote, 2s self timer and mirror lockup has been working fine, so I'd have thought if you're running something like that with the NexStar SE mount you should be ok.

I hope you don't mind, I've just had a quick play, a two pass high pass sharpen and a small contrast boost.

Img0090.jpg

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jgs001

jgs001

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Shots in raw will always require some processing, even if it's minimal. The in camera processing won't be applied, so some sharpening, contrast, and saturation possibly and maybe more. In PS on the raw file, use ACR (Adobe Camera Raw) give it some tweaks on the sliders, bit of sharpening too, that's on one of the other tabs in ACR. You can also mask sharpen, which stops sharpening of the plain surfaces, and only sharpens the edges. For the high pass sharpen, new layer, set it to soft light, run the high pass filter (under other I think) set to about 8. Also worth having a play around with highlights and shadows.

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Jarndyce

Jarndyce

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I'm going to check the collimation, as it was not possible to focus the SCT last night.

If I can compare it with images from the C80ED (which also has a bahtinov mask), it'll give me a good indication that it's the collimation...

Interestingly, I can focus it perfectly using the mask - gives an excellent "target" pattern.

However, presumably, I could still do this, even if the collimation is way-out?

So my question is, can you achieve a perfect bahtinov target pattern, even if the collimation is off? This would fool you into thinking that it's focussed when it isn't.

In other words, when using a bahtinov mask, it's essential to have perfect collimation if you want good planetary focus?

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jgs001

jgs001

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What were the exposure settings (the image appears to have had the EXIF data stripped) ? When I'm shooting the moon through the Skymax on the camera tripod, I'm normally using ISO100 at about 1/40 or 1/50. Using mirror lockup and 2s self timer with the remote shutter release has been giving me good results.

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