Hi, 

 First time posting in a while, been busy with school and the constant cloudy nights didn't help much either. Okay, so recently while I was outside star gazing, I thought it'd be nice to record what I'm seeing through my binoculars. So I went ahead and took my father's DSLR and tried afocal imaging. My problem is that the images are always blurry, no matter how much I focus the binoculars, to an extent where I can't even have a clear view of the moon let alone anything else. Recently as an experiment I tried to photograph an apartment building about 1km away during the day time to see what is happening, but nothing seems to increase the clarity of the image (I've attached them here).

 

Sony 70-300mm (at 300mm) with 10X50 Brunton Binoculars afocal

 

 

Sony 18-70mm with 10X50 Brunton Binoculars afocal

 

Sony 75-300mm lens at 300mm

 

As  you can see, there's a blurry, washed-out look to the afocal images compared to the one without them. In addition, the view through the binocular (with eyes) is much sharper than the first two pictures here as well.  Any help on this would be appreciated, thanks.

 Clear skies. 

 Daniel

 

Edit: Here is a picture I took with dad's Minolta AF50/1.7 (45mm) lens with 10X50 brunton afocal

 

 

Some reasons your a-focal images won't come out as clear is because the changes in mediums that light is traveling through before it reaches the focal plane of the camera. i.e the The objective lens through to the ocular through the air space between the ocular and the camera lens then to the camera sensor. The focal point has changed using a-focal photography compared to using the camera lens alone, additionally, your using increased magnification in the a-focal images which distributes the light across the sensor differently, and magnifying the effects of the atmosphere. The coatings on the binocular lenses, the quality of the glass, etc.

There are a number of things that can effect the image clarity. A prime focus lens will alway give you the clearest sharpest image.

 Thanks for the response. The only reason why I didn't use a prime focus lens is because I'm not sure where my father keeps it. Last time I took photographs of the moon it was with a prime focus though, and there were severe chromatic aberrations even though everything looked fine while we were lining up the shot (with a live feed). Unfortunately I no longer have that picture, but today's weather is rather nice and I'll probably go out for a bit tonight. I'll try them again and provide some more specifics.

 Clear Skies

 Daniel

 

Edit: Sorry, the skies have been overcast for the past few days, and for some reason the images on the original posts aren't showing up anymore, I'll try to get it fixed... 

 Okay, went outside last night and took a few pictures (well, lots, but anyway). A few problems I've noticed right away though, and I'll post them here, hopefully it helps you help me.

 Well first there's the focus. For some reason leaving the lens focus at infinity produces a very blurry image, I had to manually focus the camera in addition to focusing the binocs. The camera focus seems to be very close as well, at just above the minimum focusing distance. There are also times when I place the camera close enough to the eye piece that the camera was not able to bring into focus the image even though the binoculars are focused, I had to bring the binoculars out of focus in order to obtain a clear image on the camera.

  Also, looking at the images, it is obvious that the images are blurry, and that is actually the clearest I could have done. It is far worse than both the camera shot (the image with camera and a 300mm lens isn't even the clearest I've had, there was a better one somewhere....) and the view through the binoculars, as those are crisp and clear.

Finally, just to confirm, the red and blue ring around the moon, and the comet-like tail behind Jupiter are the result of chromatic aberration? Would it affect the resolution of the images?

Jupiter, Minolta AF50/1.7 (45mm) lens with 10X50 brunton afocal @ f/2.2, 2" exposure, ISO 800

Moon, Sony 75-300mm lens at 300mm @ f/8, 1/250 exposure, ISO100

Moon, Minolta AF50/1.7 (45mm) lens with 10X50 brunton afocal @ f/6.3, 1/80 exposure, ISO 100

 

Thanks for your help guys. 

 Clear skies

 

Daniel

Stargazer Jr Grade:

&There are also times when I place the camera close enough to the eye piece that the camera was not able to bring into focus the image even though the binoculars are focused, I had to bring the binoculars out of focus in order to obtain a clear image on the camera.

The reason for that is the distance the camera is to the eyepiece of the binoculars. You need to find out the eye relief distance and keep the focal plane of the camera at that distance.

Some of the reason for blurry images are beyond your control. "Astronomical Seeing" is probably turbulent. Astronomical seeing can also make it difficult to focus. The more magnification you use the more you amplify the effect of unsteady astronomical seeing.

typically blue or violet fringing around the limb of the moon or planets would be CA. However Red and Blue fringing is generally caused by another phenomenon and has nothing to do with the optical quality of your equipment. It's Atmospheric Prismatic Dispersion. Usually prominent in bright object in unstable astronomical seeing typically when below 35° above the Horizon. Very common when viewing Venus, Sirius and a few other bright stars.

Thanks tkerr, that previous post contained a wealth of information. I've just checked, the eye relief is 19mm, but since the focal plane of a camera is on the CCD would that mean that I can't put a lens on it? I know that many people just use a T-ring and use the scope as the lens, but I can't remove the eyepiece of a binocular so I'm not sure how it'd work... Also, would eye relief affect the clarity of the image or does it have more to do with the vignetting of the image?

 The information on APD was great, I never knew it'd have such a significant effect even with something as small as a 10X50. So to minimize the effect I should try to take pictures of objects near the zenith right? Also, can APD account for all of the rather disproportionally large tail on Jupiter? the red portion (over exposed and thus looks white with a little red hue around it) is rather large, extending away almost as much as the diameter of Jupiter, could there be a little light scattering in there as well?

 Thanks for the help, I'll keep trying. 

Clear Skies

 Daniel

 

Another issue could be field curvature, meaning that the focal plane coming from the binoculars is not flat. Some of your images seems to be focused in one region but not in the others.

TeleNoob:

Another issue could be field curvature, meaning that the focal plane coming from the binoculars is not flat. Some of your images seems to be focused in one region but not in the others.

I might be wrong but that looks to me more like a focal ratio and focus point issue with the camera and camera lens, and different from field curvature which is inherent to short focal length lenses. I would think the focal length and focal ratio of the binoculars should be enough that you shouldn't have field curvature. At least I've never seen it in binoculars yet.. If it were field curvature things would appear to be leaning inward to the center. (Not to be confused with Field Rotation in Astroimaging which is a polar alignment issue of an alt-az fork mount where everything would appear to revolve around the center of the FOV).

If your referring to the daylight images above, with the exception of the bottom picture taken with his dad's Minolta AF50/1.7 (45mm) lens which does seem to have a little curvature, what I see is "Depth Of Field" where the focus is sharper in the center with the background and foreground less sharp or blurred, (bokeh). I do see some Lens Light Fall Off or Drop off of peripheral illumination on the sensor chip. In those pictures I think a lot of that can be attributed to mechanical and optical vignetting because the size of the binocular eye lens, exit pupil and eye relief and the angle of the camera and distance the camera was held from the binoculars. Some of them worse and more obvious than others. There is also a little pixel vignetting which could be from the camera lens. That's something that is quite common when using various lenses(or telescopes) with a DSLR.

tkerr:

I might be wrong but that looks to me more like a focal ratio and focus point issue with the camera and camera lens, and different from field curvature which is inherent to short focal length lenses. I would think the focal length and focal ratio of the binoculars should be enough that you shouldn't have field curvature. At least I've never seen it in binoculars yet.. If it were field curvature things would appear to be leaning inward to the center. (Not to be confused with Field Rotation in Astroimaging which is a polar alignment issue of an alt-az fork mount where everything would appear to revolve around the center of the FOV).

If your referring to the daylight images above, with the exception of the bottom picture taken with his dad's Minolta AF50/1.7 (45mm) lens which does seem to have a little curvature, what I see is "Depth Of Field" where the focus is sharper in the center with the background and foreground less sharp or blurred, (bokeh). I do see some Lens Light Fall Off or Drop off of peripheral illumination on the sensor chip. In those pictures I think a lot of that can be attributed to mechanical and optical vignetting because the size of the binocular eye lens, exit pupil and eye relief and the angle of the camera and distance the camera was held from the binoculars. Some of them worse and more obvious than others. There is also a little pixel vignetting which could be from the camera lens. That's something that is quite common when using various lenses(or telescopes) with a DSLR.

Oh no I wasn't implying you could be wrong, I just like to jump in to a conversation and see if I can learn from other peoples problems. So, thanks for your detailed explanation.

On the second image, it appears to me sharper on the right side than on the left. Could that me due to misalignment of the eyepiece and the camera?

What I'm trying to understand is, if the ray lines coming out of the eyepiece are all parallel, why does it matter at which distance you put the lens?

TeleNoob:

Oh no I wasn't implying you could be wrong, I just like to jump in to a conversation and see if I can learn from other peoples problems. So, thanks for your detailed explanation.

I know you weren't I was only pointing out how it appeared to me and the detailed explanation was, I hope, for the benefit of all who might read this.

On the second image, it appears to me sharper on the right side than on the left. Could that me due to misalignment of the eyepiece and the camera?

Yes, that is a form of mechanical or optical vignetting.

What I'm trying to understand is, if the ray lines coming out of the eyepiece are all parallel, why does it matter at which distance you put the lens?

Focal point! The eye-relief is where all the rays of light (cone of light) exiting the ocular, (exit pupil) comes to sharpest focus forming the image.

Thanks Tim. So you mean to say, spatial frequency is reduced when I bring my eye closer to the eyepiece, or further away?

 Hello guys:

Thanks a ton for the information. They've been greatly informative even though I haven't had much chance to put any suggestions here into practice. Unfortunately this is my freshman year, and I've been buried under a pile of readings and work already so photography isn't going to be high on my agenda for a while to come... (at least until christmas...). So thanks for all the help, I will get back with any other stupid questions in a few months. 

 

Clear skies

 

Daniel