This morning I have been mostly fighting Registax

[JamesF]

Took 120 frames of the Moon last night and having cropped them all down and converted them to TIFF with PIPP, I fed them into Registax, which persists in giving me a final image with nicely-sharped double vision. Many of the features have a "ghost" copy shifted perhaps a dozen pixels away from the original.

I've tried increasing the number of align points, changing the reference frame, increasing the frame quality limit, reducing the total number of frames loaded and nothing appears to make a difference so far. I'm beginning to wonder if the Moon has actually developed some sort of high-frequency vibration and no-one has noticed...

James

[JamesF]

No, I hadn't been drinking heavily when I took the subs

James

[knobby]

Did you remember to put your 3d glasses on, you may have just found a new feature in Registax!

[JamesF]

Did you remember to put your 3d glasses on, you may have just found a new feature in Registax!

It's a bit like that

Must be a problem with my data though. I've just stacked a restricted number of frames in AS!2 and the same problem occurs. I think I need to have another look at the capture files.

James

[knobby]

If anyone can sort it, I'm sure you will!

[cgarry]

Have you tried increasing the 'Max Alignbox Movement' setting in RegiStax? I have found that I need to do that if I accidentally rotate the camera ever so slightly in the middle on an image run. This is very easy to do as there is a little play between my T-ring and T-mount.

Cheers,

Chris

[JamesF]

Well, I don't know what the problem is, but it looks like it might be present in the raw data. It's hard to tell because of the noise, but if I load a single frame into Registax and sharpen it I seem to get the same effect.

I think it's time to abandon this one and get some more data tonight to see what happens. Perhaps I'd somehow managed to catch some sort of internal reflection or something in the images.

James

[JamesF]

I think I now have this one sussed and I really didn't suspect what I believe to be the cause until I did some experimentation this evening.

For anyone who might read this thread in the future, I'm creating a full-disc lunar image using a 450D straight on the back of my 127 Mak. Normally I take the subs at 1/1000th sec @ ISO400, but last night I was experimenting to try to get a better histogram fill. I didn't really want to increase the ISO setting and add to the noise, so I dropped the shutter speed to 1/500th thinking that wouldn't be a problem. How wrong could I be?

We've all seen the Moon "ripple" in the eyepiece when the seeing is less than perfect, I'm sure. It appears that at 1/500th it's too easy to catch this ripple and end up with images that won't align properly. I've been out this evening and taken two sets of exposures, one set of 1/500th @ ISO400 and the other of 1/1000th @ ISO800. The first set shows the problem, the second doesn't. Well, not much, anyhow. I can still see it in a very small part of the image if I look for it.

I think this is an interesting result and I should probably write it up, but given a clear sky later this week I think I might go out and do three sets, increasing the shutter speed to 1/1250th for the third to see how that goes.

It makes me wonder about white light solar imaging, too. I usually run at 1/1000th @ ISO100 for that. I might experiment with a faster shutter speed at ISO200 to see how that works out.

James

[boris sputnik]

Took 120 frames of the Moon last night and having cropped them all down and converted them to TIFF with PIPP, I fed them into Registax, which persists in giving me a final image with nicely-sharped double vision. Many of the features have a "ghost" copy shifted perhaps a dozen pixels away from the original.

I've tried increasing the number of align points, changing the reference frame, increasing the frame quality limit, reducing the total number of frames loaded and nothing appears to make a difference so far. I'm beginning to wonder if the Moon has actually developed some sort of high-frequency vibration and no-one has noticed...

James

It happened to me once that ghost or doubling effect...I found out that I didn't let my SCT cool down enough ! Since I let the scope cool down for 1.5 hours , doubling never happened again.

[JamesF]

It happened to me once that ghost or doubling effect...I found out that I didn't let my SCT cool down enough ! Since I let the scope cool down for 1.5 hours , doubling never happened again.

I'm fairly sure that wasn't the case in this instance. I usually put the Mak out mid-afternoon or very early evening if I think I'm going to be using it that night, so it's rare that it hasn't had several hours outside before I actually put it on the mount.

James

[ilove1995]

This is an interesting thread because I've recently attempted to stack full disk images of the moon in registax 6 from data captured on the 16th & 18th Feb with ghosting apparent in both sets of results. The shutter speeds I had set was 1/80 on the first night and 1/200 on the second. ISO was set either at 200 or 400 (I don't have the files at hand to confirm the ISO setting.)

There is the additional problem that I am using an alt/az setup and have experimented with the Max Alignpoint Movement setting to counter field rotation but this has failed to improve the images. It's possible that the 102 mak which I use was not cooled down enough as I think I only gave it half an hour to cool down. (I hadn't thought about the effects of not having the scope cooled down enough until I read this thread).

Next opportunity I get I will attempt to increase the shutter speed though I suspect only having a 4inch mak is going to restrict me somewhat. I'll also leave the scope out a good couple of hours before I start taking pictures.

Al

[JamesF]

I don't reckon you need to leave it out that long. I don't always do so with mine. If I know I'm going to want to use it in the evening then I'll often leave it out for a few hours beforehand, but if I'm just grabbing shots between the clouds often it will only have been out half an hour. Getting it outside early can't hurt, obviously

The Moon is pretty bright. I reckon you shouldn't have that much trouble with the 102 Mak. I'm only using the 5" model myself. Experimentation is definitely the name of the game.

James

[ilove1995]

I'll have a go at increasing the shutter speed, that will hopefully sort out the issues I'm having with ghosting.

[knobby]

Any SLR shots of the moon that I've taken that came out O.K. were at 1/320 sec or above ...

[JamesF]

It does occur to me now though it didn't earlier that what works probably also depends on the focal length. Shorter focal lengths may well get away with lower exposure times than longer ones perhaps, as greater image scale may make the effects of atmospheric distortion more obvious. In my case I'm using my DSLR on the back of my 127 Mak with a focal length of 1500mm.

James

[ilove1995]

Off the top of my head the Nexstar 4se has a focal length of 1325. It's been nearly a month since I last had a chance to shoot the moon but I recall that it was quite dim on my laptop at around 1/200 with iso set to 400. Not sure how short I'm going to be able to go with exposure time even if I double the iso to 800.

James, is the image very dim for you on your laptop with a shutter speed of 1/1000 with the 127 mak?

By the way, I'm looking to upgrade to the Skymax 127 myself very soon :-)

Al

[peroni]

I had a similar problem when I took my first moon shots a few weeks ago. Being a newbie with all this I didn't realise what the problem was.

I was stacking a range of exposure times from 1/50sec up to 1/1000sec at ISO 100 using my ED80 (600mm focal length).

I couldn't get the images (250 in total) to stack at all until I did this...

1) save the images as .tifs in PIPP

2) open up registax 5.1, for alignment choose Default, and then check "Align using center of gravity", and then hit align.

3) move the bottom slider to the right and then hit limit.

4) hit optimize

5) in the stack tab, then go down to the "create AVI" section. Choose ".png", Choose "Maximum area", and then hit "Save Registered"

It sounds like your solution is much better.

Can you post an image example of the ghosting you refer to. I would help me, and others to confirm if this problem is the same.

On another night I'll try uping the ISO and shortening my exposure times.

[cgarry]

I had a similar problem when I took my first moon shots a few weeks ago. Being a newbie with all this I didn't realise what the problem was.

I was stacking a range of exposure times from 1/50sec up to 1/1000sec at ISO 100 using my ED80 (600mm focal length).

I couldn't get the images (250 in total) to stack at all until I did this...

1) save the images as .tifs in PIPP

2) open up registax 5.1, for alignment choose Default, and then check "Align using center of gravity", and then hit align.

3) move the bottom slider to the right and then hit limit.

4) hit optimize

5) in the stack tab, then go down to the "create AVI" section. Choose ".png", Choose "Maximum area", and then hit "Save Registered"

It sounds like your solution is much better.

Can you post an image example of the ghosting you refer to. I would help me, and others to confirm if this problem is the same.

On another night I'll try uping the ISO and shortening my exposure times.

Although steps 2 to 5 will probably give a very slightly better centring of the moon, what it is really doing is converting your data from 16-bit to 8-bit which means less memory is required to process it. You could do this directly with PIPP by saving as BMP files (8-bit only) instead saving it as TIFF files.

Cheers,

Chris

[JamesF]

James, is the image very dim for you on your laptop with a shutter speed of 1/1000 with the 127 mak?

It's certainly not bright. The histogram in APT shows about 1/3rd full and I stretch it to get the final image. That was the reason I wanted to increase the exposure time in the first place -- to get a better histogram fill and increase the dynamic range. When the opportunity next presents itself I shall try taking sequences at 400 and 800 ISO to see how that pans out.

James