It is currently Tue Oct 22, 2019 9:22 am


Post new topic Reply to topic  [ 8 posts ] 
Author Message
PostPosted: Fri Jan 18, 2019 2:45 pm 
Offline

Joined: Tue Dec 05, 2017 11:53 am
Posts: 501
I am NOT an imager, unfortunately being Autistic I never will be as I don't have the necessary patience, but I am connecting my DSLR to my scopes.

Therefore I have the most basic problem you will all have overcome.

72mm ED Skywatcher and 120mm Triplet ED Esprit.

Can not focus on infinity, assuming not enough inward travel.

See images

I have tried attaching the camera directly to the scope (72mm) NO luck, attaching the camera via 2" diags to the larger scope, NO luck, the only way is to use a reducer? screwed into the front of the camera nosepiece

So, is that it :(

Thanks

Attachment:
P1060273.jpg
P1060273.jpg [ 195.44 KiB | Viewed 1228 times ]


Attachment:
P1060274.jpg
P1060274.jpg [ 189.59 KiB | Viewed 1228 times ]


Attachment:
P1060275.jpg
P1060275.jpg [ 192.27 KiB | Viewed 1228 times ]

_________________
Celestron 8" Edge HD Evolution, Esprit 120mm triplet, 72mm APO, Sky Tee 2, 6" reflecting scope, William Optics Binoviewer, Quark Daystar Ha Chromosphere on 72mm ED, LVW8mm eyepiece and Celestron 19mm Axiom, matched W.O 10 and 20mm, and a few others, D4s, D810,

For info, I am Autistic, Aspergers, ADHD, therefore if I come over as a little "short" on occasions it is not intended, thank you


Top
 Profile Send private message  
 
PostPosted: Fri Jan 18, 2019 2:46 pm 
Offline

Joined: Tue Dec 05, 2017 11:53 am
Posts: 501
reducer ?

Attachment:
P1060276.jpg
P1060276.jpg [ 171.55 KiB | Viewed 1227 times ]

_________________
Celestron 8" Edge HD Evolution, Esprit 120mm triplet, 72mm APO, Sky Tee 2, 6" reflecting scope, William Optics Binoviewer, Quark Daystar Ha Chromosphere on 72mm ED, LVW8mm eyepiece and Celestron 19mm Axiom, matched W.O 10 and 20mm, and a few others, D4s, D810,

For info, I am Autistic, Aspergers, ADHD, therefore if I come over as a little "short" on occasions it is not intended, thank you


Top
 Profile Send private message  
 
PostPosted: Fri Jan 18, 2019 3:16 pm 
Offline

Joined: Tue Dec 05, 2017 11:53 am
Posts: 501
The SCT is fine though

Attachment:
P1060280.jpg
P1060280.jpg [ 153.79 KiB | Viewed 1226 times ]

_________________
Celestron 8" Edge HD Evolution, Esprit 120mm triplet, 72mm APO, Sky Tee 2, 6" reflecting scope, William Optics Binoviewer, Quark Daystar Ha Chromosphere on 72mm ED, LVW8mm eyepiece and Celestron 19mm Axiom, matched W.O 10 and 20mm, and a few others, D4s, D810,

For info, I am Autistic, Aspergers, ADHD, therefore if I come over as a little "short" on occasions it is not intended, thank you


Top
 Profile Send private message  
 
PostPosted: Fri Jan 18, 2019 6:57 pm 
Offline

Joined: Fri Dec 03, 2004 9:58 pm
Posts: 3547
Location: Wellingborough
From what I read you probably need a 50mm extension tube between the focuser and the DSLR.

I find a useful trick is to locate the focus point by pointing at a bright object (Moon) and then move a sheet of translucent paper (tracing paper) back and forth behind the focuser until some details are seen in decent focus on the paper. That is a good indication of where you need to get your camera sensor in order to have the image in focus,
regards

_________________
Brian
52.3N 0.6W
Wellingborough UK.

254mm LX90 on Superwedge, WO ZS66SD, Helios 102mm f5 on EQ1, Hunter 11x80, Pentax 10x50
ASI120MC Toucam Pros 740k/840k/900nc mono, Pentax K110D
Ro-Ro roof shed


Top
 Profile Send private message  
 
PostPosted: Sat Jan 19, 2019 9:37 am 
Offline

Joined: Tue Dec 05, 2017 11:53 am
Posts: 501
Brian wrote:
From what I read you probably need a 50mm extension tube between the focuser and the DSLR.

I find a useful trick is to locate the focus point by pointing at a bright object (Moon) and then move a sheet of translucent paper (tracing paper) back and forth behind the focuser until some details are seen in decent focus on the paper. That is a good indication of where you need to get your camera sensor in order to have the image in focus,
regards



So are you saying that the camera needs to be FURTHER away from the scope, rather than needing "inward" travel ?

_________________
Celestron 8" Edge HD Evolution, Esprit 120mm triplet, 72mm APO, Sky Tee 2, 6" reflecting scope, William Optics Binoviewer, Quark Daystar Ha Chromosphere on 72mm ED, LVW8mm eyepiece and Celestron 19mm Axiom, matched W.O 10 and 20mm, and a few others, D4s, D810,

For info, I am Autistic, Aspergers, ADHD, therefore if I come over as a little "short" on occasions it is not intended, thank you


Top
 Profile Send private message  
 
PostPosted: Tue Jan 22, 2019 6:06 pm 
Offline

Joined: Fri Dec 03, 2004 9:58 pm
Posts: 3547
Location: Wellingborough
Just got that info from the web, so cannot guarantee it.

If you locate the focal plane of the telescope with a piece of tracing paper then you will know exactly where you need to place your camera on your system,

regards,

_________________
Brian
52.3N 0.6W
Wellingborough UK.

254mm LX90 on Superwedge, WO ZS66SD, Helios 102mm f5 on EQ1, Hunter 11x80, Pentax 10x50
ASI120MC Toucam Pros 740k/840k/900nc mono, Pentax K110D
Ro-Ro roof shed


Top
 Profile Send private message  
 
PostPosted: Tue Jan 22, 2019 7:47 pm 
Offline

Joined: Fri Dec 10, 2004 10:34 pm
Posts: 360
Location: Surrey
skyhawk wrote:
Brian wrote:
From what I read you probably need a 50mm extension tube between the focuser and the DSLR.

So are you saying that the camera needs to be FURTHER away from the scope, rather than needing "inward" travel ?


If you try to focus on an extended object such as the moon the image should get smaller and less fuzzy as you approach the focus point. If it gets bigger and more fuzzy you are going the wrong way !

If you reach maximum in and the image is getting smaller but not in focus you need to shorten the path by removing some component. If you get to maximum out and it is not in focus you need to add an extension.

I suspect your path is too long looking at the images.

I added a scale to the drawtube of my Skywatcher 80ED - it is really useful in providing a recoord of the focus position with a particular camera and set of extension tubes. I keep a record of the settings and images of the setup in a word document so it is easy to edit. I still got caught out on Monday morning - I used a different camera adaptor which is shorter than the one I had in my telescope book and was not able to reach focus. At the time (03:30) I did not remember I had purchased a new adaptor to reduce the vignetting :) .

If you have a setup that focuses with an eyepiece you can get a good idea of where the focal point is - the focal point for an eyepiece is normally between the lower lens and the end of the barrel. You can mesure the exact point by (very carefully !) inserting something into the lower part of the barrel and moving it upwards till it focuses. The position this happens is the focal plane - don't blame me if you scratch your eyepiece though.

Your camera will have it's focal position marked on it with a symbol of a circle with a line through it. I can't remember how far it is from the front flange on a Canon Camera but an internet search should find that - if not post a message here and i will measure mine. A (platic) vernier caliper is very useful to measure the lengths of various extension pieces as well as the apparent position of the focal point.

With an SCT you can reach focus with almost any length of path - howver it does not mean you should do this - the optical performance falls off quite fast away from it's designed position even a few millimeters has an effect. Little is published on the designed position for SCTs - there is a paper on the Celestron Edge with a dimension - the other thing is to measure the path length of the supplied diagonal and eyepiece and 'hope' that is the sweet spot. If not you are into measuring the performance at different focal positions which is a bigger challenge.

John


Attachments:
File comment: Image shows the focal plane symbol on a Canon 40D
2019_01_22_9158-small.jpg
2019_01_22_9158-small.jpg [ 81.33 KiB | Viewed 1167 times ]

_________________
Engineer @ Work - Astronomer @ Play


Last edited by JohnM on Wed Jan 23, 2019 11:50 am, edited 1 time in total.
Top
 Profile Send private message  
 
PostPosted: Wed Jan 23, 2019 9:40 am 
Offline

Joined: Tue Dec 05, 2017 11:53 am
Posts: 501
Thanks all, appreciated

_________________
Celestron 8" Edge HD Evolution, Esprit 120mm triplet, 72mm APO, Sky Tee 2, 6" reflecting scope, William Optics Binoviewer, Quark Daystar Ha Chromosphere on 72mm ED, LVW8mm eyepiece and Celestron 19mm Axiom, matched W.O 10 and 20mm, and a few others, D4s, D810,

For info, I am Autistic, Aspergers, ADHD, therefore if I come over as a little "short" on occasions it is not intended, thank you


Top
 Profile Send private message  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 8 posts ] 

All times are UTC


Who is online

Users browsing this forum: No registered users and 9 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB® Forum Software © phpBB Group