More Quattro + Lodestar-C images under full moon

[Martin Meredith]

As part of the ongoing testing of the Quattro 8" F4 here are a few more images taken last night. Unless otherwise noted these objects are in Sagittarius so moderately low in the sky. Conditions: 22C falling to 20, humidity rising to 82%, sky quality falling from 18.4 with the full moon at 10 deg to 17.0 a couple of hours later. As a nod towards the moon's presence I rigged up a piece of camping mat to act as a light baffle. All exposure are single 30s subs (no stacking) with dark subtraction in LodestarLive from 11x30s darks collected at the start of the session, and all saved directly from LodestarLive v0.10. Mount: AZEQ6 in alt-az mode.

Here we have the Trifid (M20), the Lagoon (M8 -- mislabelled M16), and the Eagle (M16) in Serpens. As usual with these objects its a choice between burning out the cores/star fields or losing some of the nebulosity, which in the case of the Lagoon is really extensive. Looking forward to nonlinear stretch in v0.11 

Next, three very different globulars: M22, large and condensed, M71 in Sagitta, sparse and resolvable, and NGC6401 in Ophiuchus, difficult to resolve but nicely embedded in the Milky Way along with Barnard's dark nebulae 82 and 83 (not sure which is which -- will look them up on Aladin). 

Finally three consecutive Messier open clusters in Sagittarius: M23, M24 and M25, just to check that coma without a corrector is at acceptable levels for sensor-assisted observing. That's assuming collimation was spot-on (unlikely!). 

thanks for looking

Martin

[shirva]

nice images Martin

[PeterW]

More details of the setup please, I have an 8"f4 imaging newt, interesting to see his you connect things together. I assume you need good polar alignment?

Thanks

PEterW

[Martin Meredith]

More details of the setup please, I have an 8"f4 imaging newt, interesting to see his you connect things together. I assume you need good polar alignment?

Thanks

PEterW

Hi Peter

This is all with the mount in alt-az mode -- I'm somewhat ashamed to say I've never polar-aligned in my life. No guiding either -- the guide camera is the imaging camera in this case.

I'm not sure how familiar you are with LodestarLive produced by Paul81 on SGL so forgive me if I go into too many details.

The setup: stick the Lodestar-C (the earlier, less sensitive model) into the focuser (no coma correctors, reducers or filters were used), connect the other end to the laptop, fire up LodestarLive, perform a 2-star alignment using the alignment cross-hairs in LodestarLive while at the same time getting the focus as good as possible (no focuser mask used). Collect some darks at the exposure I'm using for the session (again using LodestarLive), then start "observing".

What you're seeing above are what I see on the screen in 30s in this case -- they're pngs saved directly from LodestarLive. That software permits real-time manipulation of contrast, brightness and gamma, separately for RGB, and setting of black and white points. That's all I do. (The software also supports live stacking but the images above are not stacked). As you can see, this is all very different from AP.

I don't have a photo of the Quattro on the mount but here's one showing the setup with my little achromat from the first time I used it earlier this year

I assume that collimation needs to be reasonably good and the scope mirror needs to be more or less at ambient, though I haven't paid much attention to these things yet. For collimation I do the final tweaks with a Catseye autocollimator. I'm yet to flock or fit a fan or other the other mods that people do to their F4 scopes, but I'll be getting around to it soon. From my early tests I think 8" F4 is in a good place for sensor-assisted observing i.e. with small sensitive CCDs with largish pixels: fast, but not so much that coma is distracting, and a reasonably wide field of view. 

Let me know if you need other details.

cheers

Martin

[kerrylewis]

Hello Martin

I am struggling to get anywhere with Lodestar Live. What setting do you use in the program for the preliminary alignment and focussing? I can't get anything on my screen other than with quite long (15-30s) exposures.

Any help with getting going would be appreciated. The best I've achieved so far is a stacked image building up of a few random stars

Thanks

Kerry 

[Martin Meredith]

Hello Martin

I am struggling to get anywhere with Lodestar Live. What setting do you use in the program for the preliminary alignment and focussing? I can't get anything on my screen other than with quite long (15-30s) exposures.

Any help with getting going would be appreciated. The best I've achieved so far is a stacked image building up of a few random stars

Thanks

Kerry 

Hi Kerry

You should definitely be able to see a lot more than a few stars without stacking. If you choose something like M13 or M27 or M57 you can see them appear in as short as 1s (or less), especially with the X2 -- and my Lodestar-C is far less sensitive. The *essential* first thing when capturing is to move the gamma or brightness control up until you see the bulk of the histogram appear. Then bracket it with the black and white levels and you should at least see something reasonable on the screen. The advice I got from DoctorD at an early stage and that I follow to this day is to then move the contrast as high as possible to broaden the histogram. Setting the black setting to the left hand end of the histogram darkens the image, reducing sky background; setting the white level close to the right hand end of the histogram ensures that the image brightness is mapped efficiently to the levels present in the image. Sometimes you want to overexpose the brighter stars (moving the white setting lower) in order to see the fainter stuff.

I suggest that you disable stacking until you're getting the kind of images you expect using the above procedure. Paul has written a short document about the stacking controls with the LodestarLive distribution.

You'll soon get some great images with any of your scopes and with X2 Lodestar! I'm looking forward to seeing them. 

Cheers

Martin

[Martin Meredith]

Hello Martin

I am struggling to get anywhere with Lodestar Live. What setting do you use in the program for the preliminary alignment and focussing? I can't get anything on my screen other than with quite long (15-30s) exposures.

Any help with getting going would be appreciated. The best I've achieved so far is a stacked image building up of a few random stars

Thanks

Kerry 

Oh, and to answer your question: 

For alignment I use the focus/alignment/framing mode and set the exposure to 250ms if I can get away with it (ie if there are enough stars to enable me to see their movement as I carry out the alignment). At 250ms and below I believe LodestarLive bins the pixels to increase sensitivity.

I use brightest star alignment on the AZ-EQ6 so 250ms is usually sufficient. The problem though is that unless focusing is more or less in the right range you might not see even a bright star on the screen during alignment, so typically I do some rough focusing prior to alignment, again using the 250ms setting, or, if necessary, going up to around 1s. I manually shift the mount to get the first star so that it appears on the screen then use the keypad on the mount controller to get it centred as well as possible. I do the same for the second star. At that point I fine tune the focusing. 

Once alignment is done I usually check it by goto'ing something bright nearby (M27 is a favourite of late) and then collect my darks at my planned exposure time (usually the same throughout the session) using the dark frame acquisition mode. 

Finally (usually forgetting to uncap the scope...) I start imaging using the image acquisition mode. Typically I start with a short exposure e.g. starting with 5s to make sure I'm in the right field. If I need to centre the object I go back to the focus/alignment/framing mode to do it, shortening the exposure as far as possible so I get fast feedback on my keypad movements. Once the thing is centred (and many are the times when I have to do a bit of star-hopping to make sure I'm in the correct field -- having something like SkySafari open at the same time is great for this) I go back to the image acquisition mode and up the exposure to the value I collected darks at. 

Martin

[kerrylewis]

Martin

That's all extremely helpful - thanks. The key was the bracketing of the histogram and now I am immediately seeing things! In fact I think the 'stars' that I saw before were not stars at all but hot pixels! I was suspicious! I am now getting an image which is helping me to focus and align.

Called it a night now on this session but feeling confident that next time I will have more luck

Thanks again for your help

Kerry 

[HiloDon]

Hi Kerry,

I responded to your other post before I read this one. Looks like you figured it out. You're going to enjoy the Lodestar. Let us know if you need more advice.

Don

[Paul81]

Great new 'scope Martin - F4 is definitely the kind of focal ratio ideal for video - nice set of results! The field of view is spot on too for most objects. I toyed with getting the Quattro but went the RC in the end as it worked out a little cheaper and was more compact (I get moaned at how much space the VX10 and AZEQ6GT take up..).

Reading through your help posts I can defiantly say you have got the hang of LL! I have been mega busy and not made it onto the forum the last few days so I am really pleased other folks are expert on the subject and can help when people need help or advice!