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Old 12-02-2010, 10:21 PM
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Vanda (Ian)
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Piggybacking a DSLR - manual guidence

I know lots of people out there have electronic guides etc but has anyone tried the old method of doing it by hand? Assuming the cross hair is on a good lock through the main scope is it possible to manually guide accurately enough on a properly set up equatorial mount for 3 minutes? (150 mm refractor) Thanks.
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Old 12-02-2010, 11:04 PM
Ian Cooper
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Hi Ian,

you are best to get a hold of an illuminated cross-hair reticle eyepice for manual guiding in any telescope, providing that you can control both drive axes of course.

Believe it or not there are some of us that haven't passed it all onto robots! My young protege, Rhiannon McNish, is seen in the first picture guding on a star through the off-axis guiding eyepiece of the Palmerston North Atronomical Society's 30cm f/7 Newtonian at the Manawatu Observatory in the Lower North Island of New Zealand. Rhiannon is carrying on a tradition of hands-on film photography at our observatory that goes back to 1985.

The other photos attached are from last friday night also. All are using off the shelf Fuji Superia 200 ISO film. The negs were scanned and the digital image improved slightly from there. M 42 was a 15 minute exposure, whilst NGC 2070 and NGC 3293 & 3324 were 20 minutes.

The Fuji Seperia 200 ISO film is the best that I have encountered in over 35 years of active astrononmy. A 12 shot roll is only $6.90 here in N.Z. Peocessing is under $10! Some of the ikjet printers available are better than the professional lab results.

The only thing, and a very critical thing, that we didn' nail down was perfect focus! We can do better.

Cheers

Ian
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Click for full-size image (2010.02.05 c NGC 3293-3324 20mins FS 200 30cm f7.jpg)
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Click for full-size image (2010.02.05 d NGC 2070 20mins FS 200 30cm f7.jpg)
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Old 13-02-2010, 12:59 PM
Rob_K
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Hi Vanda! I do it by hand with a Canon 400D piggybacked on a cheap, 'home-built' 80mm refractor, using the slo-mo knob on an EQ1 mount. But I don't use a reticle - just a cheap webcam in the refractor so I can keep a star still on a laptop screen. The EQ1 is very flimsy and the 'guiding' has to be done with extreme care or the star flies around everywhere. It does have one advantage in that you only need to turn the RA knob (excruciatingly slowly!). Any slight Dec drift over 3 or four minutes can be corrected with a gentle pull one way or another on the knob. Set-up is attached below - I brace myself on the ladder to reduce additional 'wobble'.

One problem is the limit of your wrist flexibility. 2 minutes is OK, but it gets harder from there - 5 mins is the maximum I've gone. Mind you, I can't change grip once I've started or the star goes ballistic. With a solid mount it mightn't be a problem.

If you have a solid mount, you won't have any problems guiding a widefield shot through either a webcam or reticle, but I'd suggest that it would be a good idea to do a decent polar alignment so that you don't have to tweak the Dec knob (or maybe it's just that I can't do two things at once! )

Some examples here:
http://robsastropics.googlepages.com...full;init:.jpg
http://robsastropics.googlepages.com...full;init:.jpg
http://robsastropics.googlepages.com...full;init:.jpg (1MB)

Good luck with it!

Cheers -
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Old 13-02-2010, 01:56 PM
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jjjnettie (Jeanette)
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It's very hard on the eyes, manual guiding.
But you can get very satisfactory results.
You don't even need a traditional telescope mount, a simple barndoor mount can work a treat. (and if I can build one, anyone can.LOL)
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Old 13-02-2010, 02:28 PM
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hotspur (Chris)
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re manual guiding

I have heard people use the DD1 controler on The Vixen mounts

having a guide star on computer screen,and just touching the buttons on the controller to keep star centered.Works very well,I know one chap
who used this method,he said he was very happy with results,in fact he stated that images were better than when he used his auto guiding kit.

But hey,For around $600 to get a Orion auto guider and cheap $200 guide scope,anyone doing large amounts of astro-photography,can't go wrong with such a set up,for such a price.

But still nice to see some doing it the old fashioned way.

Cheers
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Old 13-02-2010, 06:51 PM
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seeker372011 (Narayan)
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well Scott Alder has produced some magnificent results and he manually guides-dont know if he is still doing it though
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Old 15-02-2010, 12:34 PM
Rob_K
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Seeing as I'm 'laptopless' at the moment, I've been inspired to purchase a cheap illuminated reticle ($79 from Andrews). Should arrive tomorrow. The low-tech approach really appeals to me, so I'll see how it goes. Should be easier finding a guide star anyway than with my other manual guiding set-up. My short fl scope (80mm f5) is a bit of a worry, but I'll never know if I don't have a go!

Lot of satisfaction in effort made to get shots, rather than just chucking a bucket of money at it (if I had it in the first place, LOL!). Sometimes it astonishes me the amount of money that people have to throw into what is after all just a hobby.

Cheers -
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Old 17-02-2010, 10:31 PM
Rob_K
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OK, reticle arrived and gave it a test run tonight, successfully I feel - just short exposures @ 55mm, but that's what I normally shoot at anyway. Illumination is adjustable, and low illumination was fine for the purpose. Used a 2x Barlow to 'increase' fl. I felt that there wasn't as much control as using the webcam to guide (tiny view transferred to big screen).

So this was fully manually guided with RA knob on an EQ1 mount, no drives (ie different to just intermittently correcting drift with slo-mo knobs while tracking). The insert is an actual pixel crop, no sign of trailing.

Cheers -
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Old 18-02-2010, 10:09 PM
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Vanda (Ian)
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I'm impressed Rob. this was a piggyback with a 55mm lens? Not sure as you mention a barlow. ISO 400? 3 min? F stop? Noise reduction on?
Looks great!
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Old 18-02-2010, 11:06 PM
Rob_K
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Quote:
Originally Posted by Vanda View Post
I'm impressed Rob. this was a piggyback with a 55mm lens? Not sure as you mention a barlow. ISO 400? 3 min? F stop? Noise reduction on?
Looks great!
Thanks Ian. Yes, it was piggybacked - the Barlow was on the reticle to give increased scale as the scope is a short fl - 80mm f5. Only did short exposures while I got the feel of using the reticle - Canon 400D, 55mm in 55-200mm zoom lens, 7 x 30 sec, ISO 1600, F/4, ICNR on. My feeling is (given that my mount is very flimsy) that the shorter time you expose for, the less the chance of something going wrong. Hence lower ISOs are out. Even out the noise with lots of subs.

If you have a solid mount and an RA drive, by all means drop your ISO back as you'll be able to go a long time, just making corrections with the slo-mo knobs. Once I start, I have to maintain an extremely controlled, even pressure on the knob because like it or not I've exerted flex on the mount. If I stop that pressure for any reason, the star flies away, same if I start again. But really it's pretty easy - lots of people used to do it this way once!

Link to a higher res image (actual pixel size) of the Southern Cross/Coal sack here:
http://i727.photobucket.com/albums/w...ghirescrop.jpg

Attached is a pic of my imaging set-up as it stands.

Cheers -
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Old 19-02-2010, 11:24 AM
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Vanda (Ian)
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Considering your results Rob I think you must have one of the most efficient $ - image quality ratios in the country! Very high tech!
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