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#1 hunterval

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Posted 27 January 2013 - 02:42 PM

:tonofbricks:Hi everybody, Im brand new to your site and to AP. I have a Celestron Nexstar 6SE and a Canon 60D camera. I have had some success at photos of the moon and jupiter with its bands although pictures are a little fuzzy. My problem is when i try to do long exposure shots of the orion nebula. If i focus through the telscope i get a reasonably good focus but when i take the eyepiece out and then replace it with my camera its way out of focus. My shots come out like little white donuts. I checked the procedure out terrestially and its doing the same thing which is pin point focus in the eyepiece and blurred when i attach my camera. The trouble is when im doing stars i cant see anything through the Viewfinder because the stars are so faint so i cant adjust the focus because i have nothing to focus on. Has anyone had this problem before and am i committing a rookie mistake or do i have a more serious problem. Thanks for reading this and any rplies would be grateful to a frustrated new starter. Regards from Terry

#2 Jon Isaacs

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Posted 27 January 2013 - 02:54 PM

Hello and welcome to Cloudy Nights.. :waytogo: I am sure you will have your focusing problem solved here shortly, though focusing at night is never easy.

Jon

#3 jerwin

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Posted 27 January 2013 - 03:53 PM

The eyepiece and the camera are 2 very different things and achieve focus differently. Typically what I've done in the past is take several test shots with the camera. Then zooming in on the display to see how big the stars are, and repeating until I feel good about the quality. They also make focus masks that can assist. They work by changing some of the light and as you get the scope into focus the position of the spikes change.

http://en.wikipedia....i/Bahtinov_mask

I wouldn't suggest running out and buying on of these right now, but if AP is truly your thing then it might be something to add to your tool kit later on. There is an post at the top of the beginners forum titled "why of why ap for beginners" that I'd suggest reading. I personally sunk a lot of money into AP before realizing defeat due to my light polluted location, my mount that wasn't designed for AP, my lack of photography and photoshop skills and my utter lack of patience.

So before you think you're just that one $100 part from the perfect AP rig, you might read up on all the other people who thought that 10 times over.

Good luck and clear skies.
Jim

#4 Madratter

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Posted 27 January 2013 - 04:11 PM

Easiest way to get good focus with the 60D camera is put it in Live Mode. Then zoom in 10x. You can then focus while watching the screen on the back of the camera.

In general, you cannot just focus for an eyepiece and expect a replaced camera to be in focus. Any particular model of camera will have varying distances to the sensor. In the same way different eyepieces also need to be refocused (unless they are of the same brand and are what are called parfocal).

#5 Mike7Mak

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Posted 27 January 2013 - 04:12 PM

The scope produces a focused image all by itself. That focused image forms a certain distance from the telescope objective lens. Eyepieces, and cameras, have to be placed just right to 'see' the focused image. That's the job of the mechanical focuser.

Eyepieces are esentially magnifying glasses that need to be some distance above the focused image to 'see' it correctly (in focus). Cameras need their ccd chip placed so the focused image falls exactly on it.

For that reason cameras generally need the focuser tube 'racked in' to bring the focused image out to meet the ccd chip.

You 'can' set an eyepiece to match the camera focus by focusing the camera first and then, without moving the focuser, slide the eyepiece out till it also is in focus and locking the setting with a parfocal ring.

Ideally though for imaging you're gonna want to always focus the camera for best results. Slew to a bright star, use a Bahtinov mask, set focus and then slew to the target. Controlling the camera with a laptop should make things easier.

#6 hunterval

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Posted 27 January 2013 - 04:12 PM

Hi Jim, Thanks for your reply, it was very helpful. I spent about $2500(budget) to start and was expecting miracles i suppose. Ive figured out another way to try and focus, What im going to do is use the viewfinder to focus instead of trying to use the live view lcd screen tonight. See if i have any better luck tonite. Do you know if jpeg files are better to take or raw when doing multi long exposures and which free processing program is better. Any answer would be grateful, Regards Terry

#7 hunterval

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Posted 27 January 2013 - 04:15 PM

Ive found that when doing shots of stars, nebula etc, you cant see anything in the live view. Regards Terry

#8 hunterval

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Posted 27 January 2013 - 04:18 PM

Im not computer savvy enough to attach a laptop yet plus it was -14 last night so im always running in and out of the house to keep warm

#9 Inverted

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Posted 27 January 2013 - 04:21 PM

I would strongly recommend a bahtinov focus mask. You can make them or buy them. I bought some nice plastic ones, a few years back from focus-mask dot com. Unfortunately, they do not appear to exist anymore, but maybe someone knows of an equivalent. Basically the idea is you aim at a bright star, put the mask over the telescope, and take an exposure. There are some funky diffraction spikes and the center, horizontal one indicated focus. It moves up and down with focus and if in the center, the. You are in focus. Really easy. There are other ways with software, for example, but I found the bahtinov masks to be the simplest and you don't need to be hooked up to a computer. And actually on a bright enough star, with a DSLR, you probably don't even need to take an exposure.

#10 hunterval

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Posted 27 January 2013 - 04:34 PM

Just checked out your Bahtinov mask and that is for focusin on a bright star. So i would have to do that with my camera attached and then slew to the Orion nebula which is what im interested in. Am i understanding you or have i got it all wrong

#11 Alex McConahay

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Posted 27 January 2013 - 05:17 PM

>>>>Just checked out your Bahtinov mask and that is for focusin on a bright star. So i would have to do that with my camera attached and then slew to the Orion nebula which is what im interested in. Am i understanding you or have i got it all wrong

Yup. you got it.

Some other hints......First off, during the day aim your scope at a faraway telephone pole or mountain. THe further away the better. And, with your camera in place, focus the telescope. That will tell you if you are going to have any other problems. (Sometimes the scope cannot reach focus without adding or taking away some distance behind the focuser. It is best to work those things out during the day.)

Then, if you have a moon out, at night, focus on the moon at one power using live view on the back of the camera (if a DSLR) or on the screen of a computer, even better, but more complicated.

Then, shift down to low power again and find and center a bright star.

Put your Bhatinov mask on. (You can make one out of cardboard like we used to do in the olden days (Three or four years ago!!!!) Or you can buy one. The bought ones are nicer, but no more effective.

Focus on the bright star using the Bhat mask, and then shift over to the M42. TAKE THE MASK OFF!!!! and shoot away.

Alex

#12 Inverted

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Posted 27 January 2013 - 09:38 PM

If there is at least a moderately bright star in the field of view, you may be able to use them. You can always take longer exposures, as long as tacking issues don't become a problem. I usually do focus on a bright star and then slew though, I haven't found it to be an issue to do so, at least in my experience....

#13 CJK

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Posted 27 January 2013 - 10:46 PM

I have two of these Bahtinov masks -- they are awesome, made from laser cut aluminum. Focusing is truly a non-issue for me: just pick a bright star, then turn the focusing knob till the image looks like the one below. Lock down the focuser and image away. Takes about 90 seconds.

-- Chris

Attached Files



#14 Whichwayisnorth

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Posted 28 January 2013 - 01:17 AM

I know you said you were not ready for that yet but once you decide to go foward with this you'll want to use a laptop. As I type this I have my little portable mount outside on my front porch with my DSLR attached. I have a usb cord running into the house so I can sit here in my recliner where it is warm.

I use BackyardEOS. Google it. There is a free trial. You just need a USB cable and you are all set.

Find the brightest star you can in the area you want to image. Slew to it, center it. Go into BackyardEOS and click frame and focus. Now center it while watching the screen. If your focus is really off you may not see it as the donut will be too big. Once you have it in the center cross hairs click on the star. Now it is magnified on the right side. You'll see FWHM and a number. Focus until that number is as small as you can get it. If you focus too far, focus the other way. Make very small adjustments. It'll jump around. That is expected with seeing problems. Just play with it until you can't get a lower number. That is about as good of a focus as you can get.

Also a bahtinov focus mask was mentioned. You can google for a generator that will let you print out one. Then just cut out the mask and trace it on some card stock, foam board, cardboard or anything else that won't bend easily. Place that over the front of your telescope and focus until it looks like the photo above. The spikes in the center equally between top and bottom. It'll be come obvious what I mean once you start.

Now slew back to your target. If you are still with me on using BackyardEOS or the EOS Utility that came with your camera, set it to BULB and start at about 1600 ISO. For DSLR you will be taking small exposures and stacking them. I'd start at 30 seconds and see how it goes. Takes a lot of trial and error before you get the ISO and exposure times figured out.

#15 guyroch

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Posted 28 January 2013 - 07:24 AM

I use BackyardEOS. Google it. There is a free trial. You just need a USB cable and you are all set.


Thanks for the BackyardEOS plug. I appreciate the reference.

Guylain

#16 Jeff2011

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Posted 28 January 2013 - 12:05 PM

The method that I currently use to focus is to zoom in with live view on Jupiter or an early moon before it sets. Focus best I can and then lock it in and then point to my target. I understand that it is best to focus on an object close to my target, but this method has worked well for me.


Bahtinov masks are still available and are around 20 bucks for a plastic one. A quick google should find them. My friend is loaning me his mask to try out but it has been cloudy. If it works out for me, I plan on ordering one. For 20 bucks it does not make sense to build my own.

#17 JoLo

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Posted 28 January 2013 - 04:27 PM

Once you get the Bahtinov mask you will wonder why you waited so long. Focusing for me with a 450D takes less than a minute - slew to bright start, slap on mask, focus using Live View (or even better, Backyard EOS as mentioned), slew to target, off to the races. You hit the target like Chris shows above, problem solved. Never use planets with the Bhatinov, always a bright start.

To answer your other question, always shoot camera RAW. jpegs will compress your precious data and throw some out...RAW gives you much more control when converting (to .tiff or .fits, not .jpeg)and does not compress the data you worked so hard to gather.

#18 hunterval

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Posted 28 January 2013 - 07:21 PM

Hi Guys, Thanks for all the tips, im away from home now for a week so wont be doing anything for a few days but i anticipate everything i do and get so excited when i get new ideas. Cant wait to try your ideas out but will wait a bit before i look at a laptop. I also have a 150-500mm sigma lens to use with my canon 60d and a barlow x2 converter. I reckon that takes my capabilty to over 1500mm with my 1.6 crop factor and i was wondering while im getting free advice if anybody can give me some tips using just the lens and the camera on a fixed tripod. I.e iso and exposure times say for orion nebula. Regards Terry

#19 hunterval

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Posted 02 February 2013 - 03:36 PM

Hello everybody, Back home now for a couple of days. Got myself a laptop and am now hooked upto my camera. cant wait for tonite (clear for a change) to try it out. Gonna try and get a shot of the Orion Nebula, dont know why ive got such a fixation on it but i do. It was the first deep space object i seen when i was a kid. Gonna try and get my Nexstar 6 se tracking properly as well. Once again thanks for all your advice guys. It might not look like im taking everything seriously but rest assured i dont forget anything. Regards from Terry

#20 ponz

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Posted 02 February 2013 - 03:52 PM

Greetings and welcome to this wonderful forum.

Your only a few weeks behind me trying out this fascinating and daunting hobby.

I just ordered one of these. Adorama seems to have the best prices:

http://www.adorama.com/FARFP401.html

Later
Ponz






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