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Old Sunday 13th July 2008, 21:44   #1
BillB
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Defocusing to get better focus

Has anyone ever tried this? I purposely defocused the scope so that the in- focus point was in front of the target (a resolution chart). I took pictures in focus mode Infinity, Macro, and Auto Focus. All images were equally fuzzy. I repeated the test defocusing the scope so that the in-focus point would be beyond the target (very fuzzy to the eye). I took the same sequence of pictures. At Infinity setting, the image was fuzzy. At Macro and Auto Focus settings, the image was completely sharp.

I am guessing that the camera can only adjust focus one way; the other way the lens is already racked out to the infinity position and no more correction is available. I am now trying to see if this is a viable way to guarantee in-focus pictures all the time. Is it possible that those of us who have trouble getting in-focus pictures are really adjusting the scope in a way that the camera cannot compensate (maybe due to the nature of our eyes)?

I am using a Nikon P5100 and a Swarovski 65 HD.

Bill
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Old Sunday 13th July 2008, 22:09   #2
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Hi Bill,

I have the same camera and a Zeiss 65mm T* FL with a 30x B WW eyepiece. I also have a problem focusing. I had thought it was my vision, since I wear trifocals. I will have to try this myself. Let us know how you experiments come out.

Robert
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Old Sunday 13th July 2008, 23:58   #3
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Bill,

I was just describing that very solution to someone on this thread:

http://www.birdforum.net/showthread....07#post1242407

The issue is that with your scope focused for your eye your camera cannot focus closely enough to come to sharp focus through your scope.

In the other thread I describe how I work around this issue.

You should be able to make the same move away from focus for shots of similar distances. I will have to be more aware of how far from visual focus I need to move to achieve sharp focus through my camera.

Mike
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Old Monday 14th July 2008, 17:15   #4
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Mike:

Indeed you did recommend the same thing. Had I read your thread before, I might have saved myself some trouble. However, it was fun figuring it out for myself. In a later experiment, I defocused the scope even further, and found that the camera brought it into sharp focus in the macro mode, but not in the standard AF mode. I suppose this is because the macro mode allows greater focus latitude for the camera to compensate. Could this be the reason some people report better results using macro mode autofocusing?

I have trouble with a scheme that involves looking for focus using the display, as I can hardly see it in bright light conditions. I am hoping to work out exactly how much I need to cheat the scope focus before attaching the camera. I have not experimented with this yet with the lens zoomed in -- hope it works.

Bill
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Old Monday 14th July 2008, 18:09   #5
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Robert:

I guess it is still a matter of personal vision. If you are off a little one way, the camera corrects. The other way the camera cannot correct. I shot some pictures yesterday in the bright sunlight, using Infinity mode. Almost none were in focus. At home, in the shade, most are. So the the sunlight seems to change my perceived focus point (contracted pupils?).

If you try out this focus biasing scheme, I sure would like to hear about your results.

Bill
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Old Tuesday 15th July 2008, 15:00   #6
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I am the grateful poster that jmepler was responding to on the other thread. I tried his method yesterday and got significantly better results (that is actually quite an understatement!).

All the photos I just posted on the other thread were taken with AF, so I'll try macro as well and see if things improve further.
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Old Tuesday 15th July 2008, 19:03   #7
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Well, I went out this morning to try the defocus technique in the field. I had good results at close to moderate distances, but the system was ineffective at long distances. Maybe Jmepler knows why this is; I haven't figured it out yet.

I have attached a shot taken of a Savannah Sparrow at about 10 meters. I cropped and lightened it, but have done no sharpening. The process was:
1. Focus on the bird with the scope (Swarovski 65 HD).
2. Rotate the focus sleeve about 10-15 degrees CW (as though focusing beyond the bird). The image will now be slightly fuzzy.
3. Attach the camera and shoot (the autofocus was in macro mode).

Bill
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Old Tuesday 15th July 2008, 20:47   #8
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Following this thread with interest as I have this problem with focusing as I too wear glasses and I only have noted this whilst using the Nikon P5100.
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Old Tuesday 15th July 2008, 20:57   #9
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Stephen:

Now that you mention it, my previous camera was a Canon S70. It was a bit heavy and slow, but I never had focus problems with it. I have only had the problem with the P5100. I really do not know what the difference may be. Is it possible that the Canon (and whatever camera you were using before) was capable of focusing past the infinity position? I still have the Canon. I need to do some experiments.

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Old Tuesday 15th July 2008, 21:43   #10
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Have just done some test shots with my Canon S70. The results are that it is able to compensate for out-of-focus condition either side of the "correct" point. However, it has a much more limited range of compensation for the near side, unlike the Nikon, which has none. I can only speak for the Canon, but it appears different cameras may give different results.

Bill
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Old Tuesday 15th July 2008, 22:05   #11
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Bill,

I think you may be on to something! I used a Fuji F30 before I got the Nikon C5100 and I don't remember having this problem so much before I got the C5100. I will not have time to check the Fuji out for about 10 days, but will try to do it then and post the results.

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Robert
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Old Wednesday 13th August 2008, 19:55   #12
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This is an interesting thread and explained to me why some people like macro, if it works with your camera, great but what if there is a twig in front of your subject? I prefer to focus the scope using the monitor which was difficult for me since I wear trifocals. The method I used was a monitor shading device with its own adjustable eyepiece. This eyepiece was adjusted on a back lite $ bill to work with my glasses and then attached to the adapter, then I knew what I saw focused on the monitor would end up being in focus as long as I was looking through the proper trifocal.
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Old Thursday 14th August 2008, 20:29   #13
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Yes, a twig in front of the target defeats autofocus for me. My only solution in that case has been to set the camera focus to infinity (if enough time), focus the scope to a sharp image, and hope for the best.

You have an interesting setup. Could you please explain it a little more? I imagine a little box over the camera screen with an eyepiece with diopter adjustment. Is this the case? Does the eyepiece also magnify the screen?

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Bill
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Old Sunday 17th August 2008, 07:09   #14
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BillB

"You have an interesting setup. Could you please explain it a little more? I imagine a little box over the camera screen with an eyepiece with diopter adjustment. Is this the case? Does the eyepiece also magnify the screen?"
Yup, pretty close and yes it magnifies the monitor. I screw the camera on the adapter(the same as you would a tripod)and then the adapter slides onto the scope. The little box came from photosolve.com and the fellow there was Phil Williams. By now they probably have many size boxes for various monitor sizes. My box is hinged on the adapter and pivots up to the camera and held there with a small spring so I can view the monitor whenever I want.

I use an angled scope and look over the top of the boxes eyepiece which acts as a rear sight and a sight mounted on the scopes shader to follow the bird through the bushes, when the bird stops I focus and shoot with a cable release.

Even though my adapter slides on and off the scope (as well as rotates) easily I usually have the camera on the scope when working and prefer to take the pic home to identify.

Joe
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Old Sunday 17th August 2008, 07:22   #15
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Oh, I forgot to mention I usually have my camera set on Landscape with a person in the forground. I'm very sure the focusing of the scope through the monitor is analyzed by the camera for focus which results in a steady green light as I apply pressure to the release.

Joe
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Old Tuesday 19th August 2008, 09:30   #16
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Quote:
Originally Posted by BillB View Post
Stephen:

Now that you mention it, my previous camera was a Canon S70. It was a bit heavy and slow, but I never had focus problems with it. I have only had the problem with the P5100. I really do not know what the difference may be. Is it possible that the Canon (and whatever camera you were using before) was capable of focusing past the infinity position? I still have the Canon. I need to do some experiments.

Regards,
Bill
Hi Bill

I had the Samsung NV3. I really wish I could have the lightning fast and accurate focus of the samsung and the IQ of the P5100...that would be heaven

Interesting this thread coming about as I have as yet not previously been able to put my finger on what issue I was having. The focus is shocking really and this was highlighted when I tried using it as a regular camera for some snaps and the focus failed to focus and when it did it took an eon to lock. The weather was sunny and normally you would expect no problems.

The IQ is why I persist to be honest so I guess I shall have to wait for the same IQ with good focus. Come on Nikon!
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Old Tuesday 19th August 2008, 16:57   #17
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Hello, Stephen:

What focus mode do you use when digiscoping? I have mine in center (manual, really, as I like to be able to move the spot about). Provided I have done the scope defocus trick, it usually works out, but I have had many serious failures to converge to good focus. The "twig in front of the target" case, of course, requires some other scheme, like Joe uses. I personally have had mixed success with focusing the scope using the camera screen.

As far as IQ goes, I prefer my old Canon S70, but it was just too slow for digiscoping.

Bill
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Old Wednesday 20th August 2008, 18:44   #18
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Hi Bill
I use Centre Focus and single focus as a rule. I usually focus the scope on the object then swing the camera in place and press. When it gets it right I am happy but on to many occasion I get a flashing red square......try again....subject gone!

It feels like I am complaining about this cam but am still very happy in general. Like I say if I could have the good focus issue addressed in the next camera I would buy two!
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Old Thursday 14th May 2009, 03:06   #19
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Hi all,
I conducted an experiment using my Zeiss 85T*Fl and Coolpix P5100 to test limits of defocussing. I've posted results on my blog:
http://jerryjourdan2.blogspot.com/20...-may-2009.html
In short, setting the camera to Macro allowed me to defocus the scope to a greater extent (and still maintain sharp exposures) than using AF mode. Backfocusing was also more forgiving than front focusing. But, the more you zoom the camera, the less forgiving everything becomes in terms of allowable defocusing. It was a bit of work, but I've learned some important things about my limits of focus.

Bottom line-for my setup I'll still focus the scope first, then let the camera focus (in Macro mode).
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Old Thursday 14th May 2009, 14:59   #20
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Hello, Jerry: Thank you very much for sharing your fine piece of research. It further clarifies what I have found in practice, particularly the part about difficulties focusing when zoomed in (which is unfortunately too frequent with small birds at distance). I really suspect that with my eyes, the scope is normally focused short of the target, making the problem worse. Getting sharp focus is still often difficult, but I continue to get the best results "back focusing" the scope and letting the camera auto focus in Macro mode.

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Old Friday 22nd May 2009, 07:33   #21
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Quote:
Originally Posted by BillB View Post
Has anyone ever tried this? I purposely defocused the scope so that the in- focus point was in front of the target (a resolution chart). I took pictures in focus mode Infinity, Macro, and Auto Focus. All images were equally fuzzy. I repeated the test defocusing the scope so that the in-focus point would be beyond the target (very fuzzy to the eye). I took the same sequence of pictures. At Infinity setting, the image was fuzzy. At Macro and Auto Focus settings, the image was completely sharp.

I am guessing that the camera can only adjust focus one way; the other way the lens is already racked out to the infinity position and no more correction is available. I am now trying to see if this is a viable way to guarantee in-focus pictures all the time. Is it possible that those of us who have trouble getting in-focus pictures are really adjusting the scope in a way that the camera cannot compensate (maybe due to the nature of our eyes)?

I am using a Nikon P5100 and a Swarovski 65 HD.

Bill
Have you observed at which distance the camera think it is?
Does the camera think the object is very close or that the object is located close to infinity?
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Old Saturday 23rd May 2009, 17:26   #22
BillB
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Well, I was hoping that someone who understands optic better than I do would answer the question. Originally, I took an older film type SLR camera and focused on the scope after focusing the scope by eye. The lens of the old camera had to be set to around 15 meters to bring the image in the viewfinder into focus (not infinity). So for me, I believe the image at the eyepiece appears closer than infinity. I think that as you focus beyond the desired target, the image to the camera would appear to move closer. As you focus short of the target, I believe the target image will move toward infinity (and beyond?). I certainly would welcome anyone to correct me on this.

Bill
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Old Sunday 24th May 2009, 10:45   #23
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I wear bi-focals so have always had problems focusing manually, in fact I can't do it and be accurate. So when I focus the scope so that the image looks sharp to me I nudge the focus just a little passed the subject before I put the camera on (P5100,8400,A640). Using macro mode this seems to give me the best results. I very rarely use the camera zoom passed half zoom though as I find the results more unreliable. If I need more magnification I use a different eyepiece. A zoom at 60x will be more than enough usually except for stints out on the mudflats.
Thanks to Jerry for his detailed testing too.
Neil.
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Old Sunday 24th May 2009, 22:27   #24
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Neil: I too wear bifocals and have exactly the same problem with focus, and I use the same approach. I am very interested in your use of other eyepieces for greater magnification. If I zoom in with my Swarovski 20X - 60X zoom eyepiece, I get severe vignetting, basically making it necessary to zoom in the camera. Are you mounting a more powerful fixed eyepiece?

Bill
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Old Sunday 24th May 2009, 22:38   #25
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Neil: I too wear bifocals and have exactly the same problem with focus, and I use the same approach. I am very interested in your use of other eyepieces for greater magnification. If I zoom in with my Swarovski 20X - 60X zoom eyepiece, I get severe vignetting, basically making it necessary to zoom in the camera. Are you mounting a more powerful fixed eyepiece?

Bill
Bill,
I mostly use the Swarovski 45x which has 18 mm of Eye Relief and allows me to use the P5100 lens in the Green Macro zone with no vignetting. I would be better off with a special adapter for it though as I need to back of the camera a bit with the DCA and it can show shadowing if you are not careful.
With the zoom go straight to 60x and you will be able to get reasonable results if the light is good. For reliable AF when the light is dull use Manual Focus (INFINITY). I zoom into the Digital Zoom range on the camera for focus and then back the zoom out again. You will need to use the Self-timer here.
I also have the Swarovski 77x telescope eyepiece but the ER is small and it's difficult ( but not impossible ) to digiscope with. Neil.
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