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  #1  
Old 20-09-2015, 09:08 PM
Skuppy (Chris)
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Can't focus DSLR thru dob

Hi guys, I am using a bintel 12" dob and am very happy with viewing.
But i would like to connect my Nikon D3100 to the scope
I have a bought a T adaptor and extension tube which fit perfectly
I put the eyepiece in the ext tube and connect to my DSLR
But cant focus at all thru the camera
I have read that this can be difficult to achieve
A few questions :
is this possible with a dob?
if so what do i need to do to get focus ?

thanks for your time
Chris
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  #2  
Old 20-09-2015, 09:22 PM
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omegacrux (David)
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You shouldn't need the extension tube
Didn't on mine , screwed the t-piece straight to the focuser

David
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  #3  
Old 20-09-2015, 09:35 PM
raymo
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You certainly won't need an extension tube with most Newtonians, [which
includes Dobs], in fact the problem is getting the camera close enough to
the focuser. Skywatcher Newts are made to allow the use of a DSLR for
prime focus photography, but most other brands are not. If I remember rightly your brand does not, and would have to be modified.
I am constantly urging would be buyers to check with the retailer
that their choice of scope is suitable for this purpose.
I imagine that someone will soon tell you for sure whether yours is
or not.
I just noticed that you are using an eyepiece; that is called eyepiece projection, and is not the way to start. The camera is
connected directly to the scope, as David said, and the scope becomes in effect a very large telephoto lens.
raymo

Last edited by raymo; 20-09-2015 at 09:40 PM. Reason: correction
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  #4  
Old 21-09-2015, 12:06 AM
glend (Glen)
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It's all about the focal point of the camera and standard Dob won't have enough in-travel for a camera. They are setup for eyepiece use. If you had bought the imaging newt version you could achieve focus. Your options are afocal camera attachment (after an EP) or move the primary up the tube enough that the camera can achieve focus. If your new to this then don't try moving the mirror but just get an afocal EP, Hyperion make some at reasonable cost.
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  #5  
Old 21-09-2015, 12:29 AM
raymo
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All Skywatcher Newts allow prime focus imaging Glen.
raymo
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  #6  
Old 21-09-2015, 01:37 PM
Skuppy (Chris)
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Quote:
Originally Posted by glend View Post
It's all about the focal point of the camera and standard Dob won't have enough in-travel for a camera. They are setup for eyepiece use. If you had bought the imaging newt version you could achieve focus. Your options are afocal camera attachment (after an EP) or move the primary up the tube enough that the camera can achieve focus. If your new to this then don't try moving the mirror but just get an afocal EP, Hyperion make some at reasonable cost.
Hey Glend

Cheers for the response
So am I looking at getting one of these :

http://www.ebay.com.au/itm/Baader-Pl...item3393d51aed

What size should I be getting ?

Thanks in advance
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  #7  
Old 21-09-2015, 02:46 PM
raymo
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I don't mean to butt in here, but the Seben 8-24mm zoom eyepiece is threaded for attaching to a DSLR. Less than half the price, and more versatile of course. It's a very good EP for the price. You would also need a T-ring for your brand of DSLR.
raymo

Last edited by raymo; 21-09-2015 at 02:50 PM. Reason: more text
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  #8  
Old 21-09-2015, 07:41 PM
Skuppy (Chris)
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Thanks Raymo
Will check that out
Thank you very much
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  #9  
Old 29-09-2015, 10:52 AM
Tristan
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Focusing DSLR on a DOB

I found a very simple way to focus, without need to modify my dob in any way. I have a collapsible tube, so simply shorten the extension a few cm and culminate. Still good for normal viewing without having to culminate every time!
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  #10  
Old 29-09-2015, 11:13 AM
raymo
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Tristan, I'm going to assume that if your tube is collapsible, it is a
Skywatcher. [or Saxon] That being the case, your scope will come to focus with a DSLR. All Skywatcher Newts, collapsible or not, will do so. If it is a Skywatcher, you undo the two chrome plated screws on the side of the focuser, take off the bevelled plate with the 1.25" eyepiece tube on it.
Unscrew the eyepiece tube from the bevelled plate and screw the plate
onto your T- ring. Attach the T-ring to the camera, hold the camera with the bevelled plate up to the focuser and tighten the two aforementioned screws, and you're ready to go. You should not often have to collimate your scope, the collapsibles hold collimation
amazingly well. If it's not a Skywatcher, ignore everything I said.
raymo

Last edited by raymo; 29-09-2015 at 11:17 AM. Reason: more text.
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  #11  
Old 11-10-2015, 12:47 PM
davesterx (David)
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Chris, Sorry so late in responding. I have a 10" Orion Dob and occasionally take pictures with my Canon DSLR. What I had to do to get focus was to disassemble a barlow and remove the lens piece and place it at the end of the T-adapter tube. That little trick removed the focus issues and I get great results. I do the same to get focus with my solarmax solar telescope.
Dave
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  #12  
Old 18-10-2015, 12:04 AM
Skuppy (Chris)
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Cheers mate
My dob is a closed tube
Not gunna bother with mods, not worth it
I get a decent pic with my iPhone
But I did buy a seben zoom eyepiece as suggested
Wow ! A great eyepiece for like $79AU from Germany
Sadly it didn't work with my dslr
But this eyepiece is amazing for the price
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  #13  
Old 19-10-2015, 04:19 PM
Skuppy (Chris)
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Images thru dob

Quote:
Originally Posted by davesterx View Post
Chris, Sorry so late in responding. I have a 10" Orion Dob and occasionally take pictures with my Canon DSLR. What I had to do to get focus was to disassemble a barlow and remove the lens piece and place it at the end of the T-adapter tube. That little trick removed the focus issues and I get great results. I do the same to get focus with my solarmax solar telescope.
Dave
Hi Dave,
thanks for the response
I have tried a lot of things but no luck here
Can you please take a photo of your dslr setup with your barlow trick
I would really appreciate that
Btw, have you any examples of the kind of images you are getting with this setup ?
thanks for your time Dave, appreciate it
regards
Chris
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  #14  
Old 20-10-2015, 04:59 PM
chuckywiz (Ben)
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Just on a side note to help you out with your camera as well .. download the latest verson of Digicam Control
http://digicamcontrol.com/
and you can then hook up your camera to your laptop for tethered shooting. I have the D3200 and most softwares out there my little nikon isnt supported. The only thing you will need extra is a intervalometer for shots longer than 30 seconds.
http://www.ebay.com.au/itm/Time-Laps...FQZxNA-jgTIykg

Ben
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  #15  
Old 21-10-2015, 11:16 AM
Skuppy (Chris)
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Quote:
Originally Posted by chuckywiz View Post
Just on a side note to help you out with your camera as well .. download the latest verson of Digicam Control
http://digicamcontrol.com/
and you can then hook up your camera to your laptop for tethered shooting. I have the D3200 and most softwares out there my little nikon isnt supported. The only thing you will need extra is a intervalometer for shots longer than 30 seconds.
http://www.ebay.com.au/itm/Time-Laps...FQZxNA-jgTIykg

Ben
Hey Ben,

Cheers man, awesome software ! Sadly no live view for the D3100
Yes I do have a intervalometer
Now just to get prime focus hopefully

thank you
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  #16  
Old 21-10-2015, 01:35 PM
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rustigsmed (Russell)
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Quote:
Originally Posted by Skuppy View Post
Hey Ben,

Cheers man, awesome software ! Sadly no live view for the D3100
Yes I do have a intervalometer
Now just to get prime focus hopefully

thank you
hi chris where abouts are you located in Melbourne? if you're nearby I can drop past and take a quick look.

cheers

Russ
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  #17  
Old 27-10-2015, 10:47 PM
Skuppy (Chris)
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Finally prime focus with a barlow

Finally prime focus with a barlow
yea hooray
thanks to all for their help
some examples from tonights full moon
Attached Thumbnails
Click for full-size image (DSC_0099 (2) (640x426).jpg)
122.2 KB48 views
Click for full-size image (DSC_0086 (640x427).jpg)
119.4 KB43 views
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  #18  
Old 28-10-2015, 01:24 AM
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Visionary (David)
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Hi five, you have broken the ice! Chris I have a Nikon 3100 and I run live-view via the 3100 HDMI out. I am certain you have already tried, but have you feed the HDMI out to a monitor? You can't tether the 3100 but feeding onto a monitor helps enormously.

Last edited by Visionary; 28-10-2015 at 10:44 AM.
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  #19  
Old 28-10-2015, 12:49 PM
Skuppy (Chris)
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Quote:
Originally Posted by Visionary View Post
Hi five, you have broken the ice! Chris I have a Nikon 3100 and I run live-view via the 3100 HDMI out. I am certain you have already tried, but have you feed the HDMI out to a monitor? You can't tether the 3100 but feeding onto a monitor helps enormously.

Hi David
Actually I haven't tried the software yet
I read that it didn't support the D3100 so I was a little put off
But now you have renewed my interest
Cheers mate
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  #20  
Old 15-11-2015, 01:07 AM
raymo
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Chris, why wouldn't the zoom eyepiece work with your camera? it should
work with any DSLR. The thread under the rubber on the end of the
eyepiece screws into the T-ring.
You haven't achieved prime focus using a barlow; you have doubled the focal length of the scope, and now need exposures four times longer than
you would need at prime focus, which is why your images are dark.
You would get brighter images using eyepiece projection with the zoom
eyepiece set at around 24mm.
raymo
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