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Continue reading »]]> 2nd April.
A very successful Members evening was enjoyed, and has been reported elsewhere on this site.
8th April
Paul Walsh wrote:
Happy Easter folks!

For those of you afflicted by the astrophotography bug, one of the “issues” one has to contend with is the production of “flat” images which are used to remove “dust bunnies” and vignetting from images. This week’s Amateur Photographer has a free “window diffuser” which is intended to be attached to a window to diffuse bright light coming in. It struck me that this diffuser would server equally well in the production of “flats”. The attached is a sample I produced using the diffuser over the end of my “kit” 18-55mm lens. It’s 1/50s at f/5.6, ISO800 with the lens at 51mm. I’ve included the histogram so that those more familiar with flats can see whether the right sort of image is being produced. I’d be interested to hear your thoughts.

The Ice Maiden replied:

I have read about flats but as I am a complete noob I have not used them yet. I also have one of those diffuser photography things- white one side and gold the other which I use for portraits. Guess it may be a similar thing. Although I do think about flats by the time I have got my scope all set up its pitch black. I know you can use a torch but have not tried this yet. Am i right in saying that when you have taken a set of flats you can re use them. Or do they have to be done everytime like darks?

Paul

>
> If your diffuser is gold on one side and white on the other I think it’s
> more likely to be a reflector (though I may be wrong). It’s a question of
> whether light can be transmitted through it.
>
> I think flats are supposed to be taken at the same time, without moving the
> camera, and are specific to a particular session – your camera sensor
> and/or scope might pick up dust in between sessions. Also, if you rotate
> the camera (to get a better framed target, for instance) then a new set of
> flats are required as the orientation of any dust on the camera sensor in
> relation to the target will have changed. As I don’t think flats are
> temperature related, it should be possible to take them at the start or end
> of a session.
>
> A common technique for producing flats is to point the scope (with t-shirt
> or other such evenly white fabric stretched over the end) at a PC screen
> with a blank document open in “full screen” mode to provide even
> illumination. I suppose an alternative, in the case of large aperture
> scopes, would be to point the scope at a white painted wall which is evenly
> lit.

I.M

Yes you are right it is a refelector but do also have a white diffuser so may use that. Flats are now on my todo list along with about 20 other things!

Paul

I think top of my “to do” list is ‘find a way to make the clouds disappear’!

Derek

Yeeeeaaa, then we can get on with the More Marathon before it’s too late (again)!

10th April

I.M.

Hi all! Everyone may be aware of this already. In my effort to understand how to do a drift alignment came across a simulator here:

http://www.petesastrophotography.com/index.html?mainframe=http://www.petesastrophotography.com/tutorial/polaralignment.html

I still dont understand it but then i never was any good at science subjects at school! It may be useful to someone though.

19th April

I.M aka Bev wrote:

QHY5 or QHY5v as guide camera
These two seem very similar and I don’t know which is best for a guide camera? One has a slightly bigger sensor but resolution is less, Whilst the other has smaller sensor but resolution is bigger. The QHY5 is roughly the same price but I dont know enough to know which one to choose for my wish list.The v version says its extra fast but that may be one of the few differences.

21st April

Mick anderton and Patrick Ward replied

Hi Bev. I use the QHY5 guide camera for guiding only it has the larger sensor , iIdont use it for imaging. I think the QHY5v is probably the better camera for imaging of the planets, it just depends what you want to do mainly with it.

I hope that helps

Mick

 

Yes, the QHY5 is better I think for guiding.

Larger and more sensitive sensor for chasing fainter stars

Sam Cooper mailed:

Hi all,

I've just read this amazing fact in one of my astronomy books, it's 
mind boggling:

If you hold a grain of sand up to the sky at arms length, the area of 
sky it covers contains 10,000 galaxies !!!

22nd

Bev wrote

I have just ordered camera and little box gizmo thing so should be

here this week.

         I almost posted this blog in the evening of 30th April, but the forces were at work, as when I checked my mail the next morning, the following had arrived:

Hi all. I’m new (Daniel 26, Redditch) .

Since buying a telescope several weeks ago it has been raining nope stop, in fact its been the worst April since records began. Talk about sods law. I saw a small gap in the clouds earlier today and thought that I would grab and test the new cam I bought. I can barely use my telescope yet let alone the cam. The sky was still blue and the focuser tube wasnt long enough, (more money) but I managed to bodge together a photo. For my first ever attempt with a camera i’ve never used im pleased I only had a few minutes until the clouds wrecked my day again.

 Daniels first shot – The moon

Next target is the Whirlpool Galaxy, i’m currently modifying a finder and soldering a spc900 to lx miod spec for auto guiding, wish me luck All the best, and I look forward to meeting you.

Paul Walsh replied:

Hi Daniel and welcome to the group. That’s not a bad image for a first attempt, well done! You’ve managed more than I have over the last month!

A number of us have an interest in astrophotography and we’ll be only too happy to answer questions / offer advice. Certainly try and make it to the June meeting if you can as I think that’s  a more open format evening rather than one with a guest speaker.

Paul

And Mick Anderton also said:

Hi daniel welcome to the club, that was a great photo of the moon , my first photo was nowhere near as good as yours – well done , and yes come to our next meeting all the members are very friendy and are willing to offer any advice they can
Mick

Well done Daniel, and a warm welcome from me. Come along and see what we get up to, and share our friendliness. Unfortunately we can’t do anything about cloud, and I didn’t bag half of the items in the Moore Marathon, so I didn’t submit my results. I did have a brilliant couple of hours in our garden though with superb observations of Saturn.

So there you go, every silver lining has a cloud!

Onward into May.

Derek

 

 

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Continue reading »]]> With all the talk of the moon and the observation challenges available to us I stumbled on the World Record Lunar Image. This was obviously done in 2009 (IYA) but is still worth a visit.The 2009 project was to create the largest ground-based mosaic image of the Moon, and enter the Guinness Book of Records and you can find the final image here:

http://www.lunarworldrecord.com/index.php

The real full size image is available for a donation to Sir Patrick Moore’s chosen charity.

And if we need another Lunar challenge (to complement Derek’s Lunar cross) how about The Straight Wall.

Find Ian Morrison’s notes on how to locate it in his March 2012 Night Sky notes.

Continue reading »]]> Focusing your telescope is one of the many difficulties you have to overcome to get good quality astro photos.

A Bahtinov mask can be useful.

Example of a Bahtinov Mask

This website provides you with a way to generate a template for a Bahtinov Mask specifically designed for your particular telescope.

http://astrojargon.net/MaskGenerator.aspx

You can print the template out and very carefully!!!! cut a piece of cardboard or other opaque material.

Once you have your mask you simply point your telescope to a bright (ish) star and place the mask right in front of the tube. Move your focuser until all the funny lines line up!

This is what you should see. Perfect focus is achieved once the long line is in the middle of the X formed by the other lines.

Enjoy…