Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

can´t obtain sharp images

  • Please log in to reply
6 replies to this topic

#1 Kermitto

Kermitto

    Lift Off

  • -----
  • topic starter
  • Posts: 3
  • Joined: 06 Aug 2018

Posted 16 October 2018 - 03:51 PM

I'm having trouble getting sharp images taken with my Canon 500D, the camera are attached to an original T-adapter from Meade.

I have a Meade LX90 8 "that I have collimated as accurately as possible, I have tried to take a picture of the collimation ring, but the picture of it will not be good because I find it difficult to get a sharp focus, but you can reasonably see the rings are concentric.

 

I use BackyardEOS to achieve as sharp a focus as possible, but it will not be better than what you see in the picture of the moon.

 

When I just look through the telescope without the camera, I do not experience this phenomenon, so the picture is very sharp.

 

The camera takes sharp pictures when I put on a lens as you can see.

 

What am I doing wrong with that camera, are there any settings I have not put right?

 

 

Kind Regard

 

Kenneth

Denmark

Attached Thumbnails

  • Blurred Moon.jpg
  • Collimation_1.jpg
  • Collimation_2.jpg
  • Sharp image from Canon 500D.jpg
  • Test 4-2 w focal reducer.jpg
  • Test 4-2 wo focal reducer.jpg


#2 carolinaskies

carolinaskies

    Apollo

  • *****
  • Posts: 1078
  • Joined: 12 Dec 2014
  • Loc: Greenville SC

Posted 16 October 2018 - 04:39 PM

Images through the telescope could have problems if the seeing conditions are bad, or if you're imaging at objects low on the horizon, or the OTA is experiencing tube currents.   Your terrestrial photos are looking through either trees or shrubs or something and any heat/evaporation going on from ground to air and can be problematic even on what seem to be great conditions overhead. 

With the camera attached to the telescope check to make sure there is no looseness or sag. 
You should lock up the mirror and use Live View if you don't already.  (Custom Settings >> Mirror Lock up) 
Are you focusing using the zoom feature?  This helps as it's easier to see focus conditions at this point.  For the moon you can focus at the edge of the lunar disc or at the shadow edge of a crater.  

If you feel like you can't get a nice fine-focus using the focus knob slip a foam or plastic lid top around the focus knob and use that as a fine focus. 

I think you're just a tad out of focus on the moon picture so try the zoom as I suggested.  Should help! 



 



#3 Luna-tic

Luna-tic

    Viking 1

  • -----
  • Posts: 818
  • Joined: 26 Jul 2017
  • Loc: Foothills North Carolina

Posted 16 October 2018 - 04:51 PM

What mode are you using the camera in when you are shooting through the telescope, and how are you tripping the shutter?

 

I would imagine you'd be using Live View, so you can see the target in your rear screen, but more importantly because it locks the mirror, which prevents vibration. Also, a remote shutter release as well, for the same reason. The other thing to try is raise your ISO and use a faster shutter speed to shorten the exposure as much as possible, in order to prevent blur from target movement.



#4 Toddeo

Toddeo

    Viking 1

  • *****
  • Posts: 568
  • Joined: 19 Jan 2012
  • Loc: Sierra Vista, AZ

Posted 16 October 2018 - 05:04 PM

Your 8" sct with a dslr should give you just as sharp pictures as when looking with an eyepiece. Before you use the camera, put in a lower/medium power eyepiece and make sure you can see sharp images after focusing. Now you know nothing is wrong with your scope. Now switch to the camera and refocus(using "live view" if your camera has it-works the best). If the photos are still soft- your are either out of focus or the set up is moving when you take the picture. I always use a remote/shutter release cable when taking pictures of the Moon with a dslr. The Moon is a little more "forgiving" than the planets as far as collimation of the scope. As long as there are no "thermals" and you can focus- your pictures, single frame shots- should look good.



#5 Steve C.

Steve C.

    Messenger

  • -----
  • Posts: 492
  • Joined: 24 Jan 2008
  • Loc: Sugar Land, TX

Posted 16 October 2018 - 05:45 PM

If you don't have a remote cable for tripping the shutter, set the timer to take a picture. That, and the mirror lockup already mentioned, should eliminate any blur caused by vibration.



#6 davidc135

davidc135

    Viking 1

  • -----
  • Posts: 532
  • Joined: 28 May 2014
  • Loc: Wales, UK

Posted 16 October 2018 - 07:11 PM

I had a similar experience with my Olympus OMD 10 and B&L 4000 sct. With a sharpie I drew a series of targets corresponding to 35, 70, 105 and 140 line pairs per mm when placed at 200 yards for the B&L and around 6.5 yards for the 45mm Olympus lens. When stopped down to f/14 the camera plus lens resolved 105lppm. Visually, the B&L, also at F/14, resolved 105lppm too but when coupled with the camera body could only resolve 35lppm. I wondered, at the time, if the digital sensor is more sensitive to degradation of the image due to the scopes central obstruction than the eye is. 

Hopefully, as some above are saying, that's wrong. Could a 3.5'' Questar match a similar sized apo for image quality. I would have thought so, or close.

 

David


Edited by davidc135, 16 October 2018 - 07:15 PM.


#7 Kermitto

Kermitto

    Lift Off

  • -----
  • topic starter
  • Posts: 3
  • Joined: 06 Aug 2018

Posted 17 October 2018 - 08:35 AM

Hi all nice Guys
Thank you very much for answer my question, because I am a little frustrated from not being able to get sharp pictures.

Yes you are right at long distance at ground footage the warm mist from the earth has a big influence, so I have to pay attention to evaporation and generally good seering conditions that I have to keep in mind, I usually let my telescope stand for half an hour before I start observing the sky.

Live View on the camera itself!!! I will try that, thanks all of you for the tip it's been a long time since I've done that because I'm using BackyardEOS which is a PC program developed for Canon and Nikon to check and schedule the recordings without touching the camera, live view works super well on BackyarEOS and you can zoom in on details and focus on it, but unfortunately, I have these pore bugs anyway, but I will try out live view on the camera itself.

Live view on BackyardEOS is also great as you can put in a lot of filters to help focus and you can lock the mirror and delay recording for as long as you want to avoid vibration between recordings, I highly recommend the program.
Viking 1 great idea with the fine-focus using the focus knob slip a foam or plastic lid top around the focus knob, I will try that great!!

Again Thanks all of you very much for answer my question, It is very much appreciated that you will share your knowledge and experience




CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics