Astrophotography
 

Recently I posted a couple of Milky Way photos taken when on a trip to Australia. I have now just completed processing my images from that trip and have put them on my website.

If you are interested you can view them on http://www.graviton.demon.co.uk
and follow the link to Southern Skies

Dave

Superb, Dave, looks like you had a great trip.

As always, master pieces.
Very well done Dave and thanks for sharing.

Southern sky is so beautiful. Don't know why? Even McNaught when reaching to southern sky showed its best. May be they have the sky in their side (Minus the Northern star:)).

Dave when taking these wide angle picture at 5 minute time, you must have used the camera on a tracking device as no star tracing seen, am I right? Or did you use several short interval images with stocking in pp.
BTW just another dumb question, What could we expect from sky with wide angle lens in Northern hemisphere, in other words, when and were to point the lens next time, if sky was clear of pollution and stray light of city, if opportunity permits. Any suggestions?

Thanks Sharon, yes it was superb - we are already talking about next time. (Well you can dream!)

Quote from Sasson "Southern sky is so beautiful. Don't know why? Even McNaught when reaching to southern sky showed its best. May be they have the sky in their side (Minus the Northern star)."

Things always seem to happen where you are not. Interestingly on this trip we were introduced to Robert McNaught at Siding Springs Observatory. In spite of his name I hadn't realised that he was from Scotland.

Quote from Sassan "Dave when taking these wide angle picture at 5 minute time, you must have used the camera on a tracking device as no star tracing seen, am I right? Or did you use several short interval images with stocking in pp."

Yes you are right I did use a driven mount (the details are on my website) but it took me much of the time mastering how to polar align it. Most pictures were taken in the last two days. For some of the images (longer focal lengths) I did have to take some short exposures and then stack them but the Milky Way pictures were only one exposure.

Quote from Sassan
"BTW just another dumb question, What could we expect from sky with wide angle lens in Northern hemisphere, in other words, when and were to point the lens next time, if sky was clear of pollution and stray light of city, if opportunity permits. Any suggestions?"

The Milky Way is the best target. The centre of the Milky Way is easily the best part but we don't quite see it from the UK. If you are further south than us you may be able to see it late Summer. I think I did post a Milky Way shot from here earlier in the year when I was practicing for this trip.

A standard lens (e.g. 24mm) would be good for constellation shots even from a fixed tripod. Something like 20s using iso 400 should produce something interesting.
Whenever there is a comet around it is worth trying with a standard lens but there is no predicting when that may happen.

Dave

Thanks very much Dave for your extensive description. I wish my physics professor was as descriptive and knowledgeable as you.

Lucky you to see the original McNaugh.

Yes neighbor's grass is always greener...:)

Mount Wilson is located on top of LA, no wonder harboring giant TV radio stations transmitters. It also hold a ground for Astro camp (With a 60 inch telescope) that a photographer friend of mine has participated in it some long back. May be I need to check their summer activities for hopefully any participation chance or find a local astro club that can help. Mean while I will try the wide angle approach when sky permits. I have a tiny telescope with motor drive, Mead AT60 but anytime I tried to initialized it(So called Easy Two-star Alignment....), got so frustrated that went back to my fixed tripod. I guess I can learn things better with interaction rather than from manual.

Well thanks again for your info and hope you get to see crystal clear southern sky many many times and hopefully thread us with the result of your journeys.

Dave,

Great set of images. I had your site bookmarked. I found it from a cruise round Astro sites while studying this aspect of imaging in a bit more detail.

Perhaps you should fire up a Astro Photoraphy thread when you have time, to keep all this valuable info in one place.

Well done again for the inspiartion to broaden our photographic horizons. :)

Stevie was also well impressed. All I could hear as she looked though was .......... cor ..... wow .............. amazing. :cool:

Don

That sounds like an excellent idea Don.

Is it possible for a moderator to retitle this thread as simply "Astrophotography" and move it to the techniques forum, please?

Dave

I see that has now been done, thank you.

Dave

Most people on this forum will not have access to a driven mount but may still want to have a go at some astrophotography. One of the easiest things to take is of the night sky using a fixed tripod and do a long time exposure. Attached is a 15 minute exposure with the camera pointing towards the pole star and you will immediately notice that sky glow can be a real problem. To some extent it can be improved in photoshop as in the second picture. However I have just come across (via an OU forum) a piece of free software that enable you to effectively take a long exposure without the sky glow. You instead take a large number of 30s exposures and stack them. The program will do that for you by just giving it a list of images. The sofware is available at http://www.startrails.de
As far as I can see any camera can be used but an advantage of a DSLR is that it can be set on multiple exposures and a remote lead set on continuous and the camera will keep on doing 30s (or whatever the longest automatic time is on the camera) until it is disabled. A two hour set would produce some interesting pictures. The trick then is to have an interesting forground.
It would be worth having the iso set high e.g. 800 iso if available but will work on lower.

By the way, the dust on my sensor has since been removed.

Dave

Dave's already started a good job here by the look of it :) so this seems as good a time to mention dark frames and the Nikon Noise Trick. The Nikon D70, which has serious noise problems (for astronomers anyway) above 200ISO, actually does some noise reduction even if you don't want it to, and with astro work, a small star could easily be misconstrued as noise.

If you set the D70 for, say, a 5 minute bulb exposure, with the noise reduction system OFF, BUT, then physically turn the whole camera OFF at 5 minutes, you will have a completely unmodified frame, no mistakenly removed stars....

The only other thing you have to do is take a "dark frame" for the same amount of time and subtract this from the original shot. Make a dark frame by taking the same time exposure, with the switch off method, but this time with the lens cap on. This, then, will only take a shot of the thermal noise. Take the thermal noise away from the original and bingo, a perfect no noise exposure.

Did that make sense ??

Certainly did Sir, and pleased to see you here. I tried Registax and that worked well, but my error was converting D2X RAW files to tiff. My pc nearly had a nervous breakdown sorting and stacking 36 70mb tiffs. :) Took ages.

I am still trying to work out wavelet sharpening as opposed to high pass for moon shots.

Don

Those are very nice pictures.

I'm sure you know this, but I'll mention this for anyone here of a DIY pursuasion. (I know Don fits that category.) A cheap home made alternative to an expensive driven mounting is the Haig Mount, also known as the Barn Door Mount, or the Scotch Mount.

http://www.astronomyedinburgh.org/pu...otography.html


I remember the article appearing in Sky and Telescope about 30 years ago and I made one when I was (just) in my teens.

The link explains the principle, but it is no more than two squares of wood, joined by a hinge along one side, with a screw thread passing through one plank, and pushing against the other. The trick is to align the hinge with the Earth's axis, and then turn the screw thread once a minute, thus forcing one of the planks to rotate about the Earth's axis, countering the motion of the stars. The result is that a camera mounted on the moving plank will track the night sky. I think the inventor tried a 200mm lens but it really excelled with wide angles.

I have toyed with the idea of making another one, but the problem is the drive. Mine was digital (I used one finger to push a clothes peg attached to the drive rod). But ideally it should use a stepper motor with associated circuitry and a battery. If anyone knows a good source of the electronic items I would love to know.

And another link:

http://home.comcast.net/~dmiller5879..._animated.html

There are many developments which aim to reduce the tracking error which increases rapidly with time in the original version.

Saturn emerging from behind the moon this evening.

400mm lens and 2x and 1.4x converters.

I think I have beaten Dave to this. ;) :) :D

Don

Yes you have. I did watch it through my 12 inch (300mm) scope but made no attempt to photograph it. I just enjoyed the view together with a number of neighbours.

Excellent picture Don.

Dave

Star trails
 

Following on from my star trails post yesterday, last night was clear so I gave that program a go. The first picture is as it happened. The house is overexposed because my neighbour's security light came on for around two minutes so I ran the program again but missing out the four guilty frames.
Now , of course, there is a gap in the star trails but it illustrates what the possibilities are. There were 43 frames altogether each 30s long set on iso 800. It was so simple to do as I was able to leave the camera running and the use of the program is very straight forward. It gives the facility of taking dark frames which I did (i.e. 6 frames with the lens cap on).

One other nice feature in the progam is that it can make a video of the set of images which is quite fun.

Dave

The view through a spotting scope was really impressive. Better than I have shown here. I kind of rushed the pic processing just to get it posted so I will revisit the origional later.

Don

I have now revisited the file from last night. Stretching the boundry a bit as this image is 1200 x 911. Probably my best challenge to Sassan yet as with the TC201 added image is way soft. Perhaps I need a 600 prime lens at the front end. :rolleyes: :D :D

D2X, 400mm f5.6 IFED AIS lens, Kenko 2x + 1.4x converters. Exposure 1/15 sec wide open at 5.6 ISO 400.

Don

Thats amazing clarity Don with those stacked converters, a brilliant photo.
I missed out on getting saturn so close, well done on this one.

Yep, excellent going there, esp with it being untracked. I bet it took some skill to line that shot up :)

I built a barndoor mount 2 years ago, but I didn't work very well. Might have another go someday, it was easy enough and the maths is dead simple.

Don you nailed it so well.
Excellent.
May be first you want to add on the number of TCs before getting to higher focal length. BTW avoid cheaper manufacturer's 800mm or so prime lenses as the chromatic aberrations and poor quality glass rather significantly destroys the picture quality. Stay with Nikon, doesn't mater if it is manual. If you are buying on ebay, I can send you alert mail when I see some good deals out there.

Sassan,

I agree on the optics front and would only go with an ED lens. I need to learn how to process properly before going in that direction :rolleyes: . Not one for buying sight unseen, so I am not an e-bay lens buyer, but thanks for your offer. Come the time I guess a trip to the BIG CITY ( London ) will be on the cards.

Currently suffering the new toys syndrome. CLOUDY NIGHTS :( . I did manage a few last night that I will try some sort of image merge on, to see if I get any improvement in IQ. RegiStax is not happy with my image size and 70mb Tiffs. I guess this program is more suited to webcams. Works OK with D100 Tiffs but then I got the X for its resolution. :)

Don

In my rummage around the net for info on Astro image processing, I found this tutorial that looks good.

http://www.starrywonders.com/tutorialpage1.html

Don

Another good one is http://www.astropix.com/ by Jerry Lodrigus

He also does a CDbook on Astrophotography with a DSLR which I have and strongly recommend although much of it is on the website.

Dave

2 good links.
Thanks.

Any good tutorial on an easy to follow stocking software?
Then any video oriented tutorial on polar alignment in an easy way that is understandable by a fully unfledged beginner?

BTW here, almost to the end of May and still cloudy nights constantly for past few weeks. I don't know about the April shower, May flower concept but need to add Anxiousness syndrome as sub or supra category to the new toys syndrome. CLOUDY NIGHTS... :(

i just cant believe the clarity of the shots. this is probably a really stupid question, but why cant we see anything like that in the u.k?

Cuz we have weather, not a climate :)

You really need cold still air to do astro stuff properly, which is why all the major obsys are on the top of mountains. Take a trip to La Palma and you'll be OK :)

Do you mean why can't we see the same with a telescope and our eyes? Well there are several reasons.

Firstly Lodrigus is very talented, works hard at his craft, and has some very high quality and expensive equipment. Many of these pictures were taken by exposing a sensor/emulsion to light for a long time. Hence a lot of the images are of things that we cannot see, as our eyes are not sensitive enough.

Secondly, the human eye cannot see colour when the light levels drop below a certain value. So even when we can see some of the objects he photographs, we see them as black and white.

You CAN see many of the nebulae and galaxies, given a reasonably dark sky. I have seen the Andromeda galaxy M31 (it looks like a fried egg), and it is easy to see in binoculars if you know where to look. I have seen the galaxies M81 and M82 with a telescope and they are not too hard to find given dark skies. And of course the Orion nebula is an easy one. But none of these will be anything like in the photos.

Unfortunately UK skies are often polluted with street lights. I used to visit my late mother in South Devon, and would sometimes drive to the countryside to enjoy magnificant pitch black skies that reached down to the sea. IMO one of the great wonders of the world is to witness a pitch black sky, especially if you have some binoculars and perhaps a small telescope.

Incidentally there are some UK photographers producing similar quality images. There is one in Hertfordshire or Bedfordshire. Sadly his name escapes me.

I think you are refering to Nik Szymanek. He is an ex member of my astronomy club and often comes to give us an excellent talk. He takes most of his photos from La Palma and other sites around the world.

Dave

The person I am thinking of some quite expensive American made refractors with triplet objectives, and lived somewhere in Herts/Beds. I am pretty sure he took pictures in the UK especially planets. He had a web site, but I cannot find it.

OK. I now think you are refering to Damien Peach who is probably the best planet imager around. I went to a talk given by him at this year's astrofest. Fascinating it was but he didn't give away any secrets.

Dave

Thanks for the link. Amazing images.

Do

Sadly not. I'm sure this person was fairly wealthy and commuted in to the city to work.

I'm not surprised Peach did not give away secrets. My suspicion is that most photographers give away what is well known, but keep the less well known tricks to themselves. Except here of course, where lots of people give tips on DIY ring flash etc.

Knowledge is to be shared, if it is to grow and yield its fruit.
Or it will die within.

Very commendable, but if you have a family to look after, I suspect you will keep knowledge to yourself. Piers Corbyn is well known as being able to forecast weather months ahead with greater reliability than others, and he will not reveal his secrets, as to do so would lose him an income.

Another site with some great pics.

One to keep an eye on as Astro photography is under review. http://www.digitalsky.org.uk/

Don

Another photographic opportunity?

Just received this from the Society of Popular Astronomy.

***********************************
The SOCIETY for POPULAR ASTRONOMY
***********************************
=================================================
Special Electronic News Bulletin 2007 June 14
=================================================



DAYLIGHT OCCULTATION OF VENUS
June 18, 2007

By Jon Harper, Occultation Section

After the Sun and Moon, Venus, as I'm sure you know, is the third-
brightest natural celestial object in the entire sky (unless a nearby
supernova were to go off!). So unlike the recent difficult daylight
occultation of Saturn on May 22, you will have a much better chance
with this event which takes place on Monday, June 18, owing to the
brilliance of Venus (V ~ -4.0). The Moon at the time of the
occultation is a 3.7-day-old waxing crescent, and Venus itself presents
a broader crescent showing a phase of 0.44. Venus at the time is just
a couple of weeks past its greatest elongation east of the Sun, and
lies some 45° away from the latter; therefore sunlight will not be a
problem. Neither will it be a danger because of the angular separation
distance noted above. This event can be observed with the naked eye,
given a clear, transparent sky, but binoculars are obviously better.
With a good pair, you may just possibly be able to detect the planet's
phase if the binoculars are firmly fixed and well focussed.
Incidentally, if you have never seen Venus with the naked eye in
daylight before, now is your chance to do so. The Moon will help you!
Simply find the Moon, quite easy to do in a clear sky, and look just
two Moon diameters (1°) to the lower left of the crescent at around
lunchtime on the 18th. With any telescope of course the occultation
will be truly spectacular against the daylight sky!

The table lists the times of disappearance of the planet at the Moon's
dark limb (DD), and the reappearance at the bright limb (RB), in the
vicinity of Mare Smythii, near the Moon's true-eastern limb (west as
we see it) for 14 UK cities, one of which may be near you. Don't
forget to add an hour to the times given in order to obtain the local
('summer') time of each event. If you want more detailed information
specifically for your location, do drop me an e-mail specifying where
you live. Any observation reports, timings, and/or images will be
gratefully received at the same address: [email protected] and will be
put up on the Occultation Section's web pages. Peter Grego intends to
do a web cast of the occultation from his location near Birmingham, so
if you have cloudy skies where you are, there is another chance to
watch available, courtesy of the Lunar Section.

CITY DD (UT) RB (UT)

BELFAST 13:52 15:10
BIRMINGHAM 13:58 15:18
CAMBRIDGE 14:01 15:21
CANTERBURY 14:04 15:23
CARDIFF 13:58 15:15
GLASGOW 13:53 15:13
INVERNESS 13:52 15:12
LIVERPOOL 13:56 15:15
LONDONDERRY 13:50 15:08
NEWCASTLE 13:57 15:17
NORWICH 14:02 15:23
PLYMOUTH 13:58 15:13
SHEFFIELD 13:58 15:18
SOUTHAMPTON 14:01 15:19


Bulletin compiled by Clive Down

(c) 2007 the Society for Popular Astronomy


The Society for Popular Astronomy has been helping beginners to
amateur astronomy -- and more experienced observers -- for 50
years. If you are not a member then you may be missing something.
Membership rates are extremely reasonable, starting at just £15 a
year in the UK. You will receive our bright quarterly magazine
Popular Astronomy, regular printed News Circulars, help and advice
in pursuing your hobby, the chance to hear top astronomers at our
regular meetings, and other benefits. The best news is that you can
join online right now with a credit card or debit card at our lively
website: http://popastro.c.topica.com/maagKTTabzdRCa9n9S4b/


================================================== ==================

Dave

Well here is my attempt. The first part was clouded out and to be frank I thought there was nil chance of seeing anything. I noticed that there were some breaks in the cloud so set up SkymapPro to see at what stage the occultation was at. It told me that Venus was about a full Moon's width away from the Moon so I went out with binoculars to see what I could see.
There was the Moon but no sign of Venus. I was rather puzzled by this when a very bright spot appeared on the edge of the Moon.

I was totally unprepared so rushed in to get the camera etc, tried a couple of handheld shots as insurance and during some cloud was able to set up the tripod with the following result. Pity I didn't have my telescope set up. It turned out that SkymapPro was still in GMT :o

Did anyone else observe or photograph the occultation?

Dave

Brilliant photo, well done in getting the capture. I missed it in North Staffordshire the was to much cloud cover.