Any tips for lunar imaging.

[Danjc]

As all my efforts and research has all been centred around DSO AP tonight I fancy having a go at some lunar imaging. 

I will be using a SW ED80 and a canon 1100D but can’t find to much on a good iso and types of exposure lengths. From what I have read some say iso 100 some 400 and very short exposures but any advise would be greatly appreciated. 

Many years ago I used Registax is this still the preferred software for lunar stacking. 

Cheers, Dan. 

[vlaiv]

Does "Move swiftly and stay in shadows" qualify as good advice?

Joke aside, I don't know if I'm qualified to give you good advice on planetary imaging with DSLR, but here is what I would do:

1. Decide on barlow - with ED80 you will probably need barlow to get to higher resolution for imaging details. You don't have to use one if you are going for full disk shot.

2. Go with higher ISO, something like ISO400, 800 or even 1600 - that will depend on particular camera, but you want to avoid clipping due to quantization.

3. Use really short exposures. For planetary imaging there is something called "coherence" time - and it depends on current seeing conditions - it is the longest time before atmospheric disturbance changes. This change produces motion blur. At any given instant atmosphere produces distortion, but if you let distortion change over time it turns into motion blur. This time is order of 5-10ms depending on conditions.

4. Maybe give AS!3 a go? I've found it easier and better than registax for stacking. Use PIPP before to calibrate images. Calibrate with equal exposure darks and think about using flats/flat darks as well.

5. Do Wavelet sharpening in Registax

6. Consider using mirror lock feature if your camera supports it. When you trigger shutter on camera - mirror needs to move out of the way - this creates shake which is no issue in long exposure (because it's comparatively really short) - but can cause problems with very short exposures - camera won't even have time to settle from vibrations before exposure is over.

7. Explore using movie feature rather than single subs. This will allow you to get between 30 and 60fps - much more frames than you could get in burst or single trigger for a given time. Downside is that movies use compression that downgrades results (maybe offset by number of captured frames, don't know for sure).

8. Do as many subs as you can, both for target but also calibration subs.

[Danjc]

Cheers @vlaiv appreciate the info ??

[David Smith]

With my 1100D and Mak127 the other night I was shooting 1/100th second at ISO 100, so I would be surprised if you need ISO much higher than 200 although a barlow may change things a bit.

[vlaiv]

2 minutes ago, David Smith said:

With my 1100D and Mak127 the other night I was shooting 1/100th second at ISO 100, so I would be surprised if you need ISO much higher than 200 although a barlow may change things a bit.

Higher ISO is not about signal strength, it's about avoiding noise. Quantization noise in particular. With CMOS sensors you get less read noise if you go with higher ISO, and certain ISO is close to a "unity gain" - you want to be at this or higher ISO to avoid quantization noise part.

So if you go higher ISO and image is to bright - just go lower in exposure - that can only help with seeing effects.

[David Smith]

1 minute ago, vlaiv said:

Higher ISO is not about signal strength, it's about avoiding noise. Quantization noise in particular. With CMOS sensors you get less read noise if you go with higher ISO, and certain ISO is close to a "unity gain" - you want to be at this or higher ISO to avoid quantization noise part.

So if you go higher ISO and image is to bright - just go lower in exposure - that can only help with seeing effects.

Thanks for that explanation. I will try that next time,