Topcon 50DX Focusing Question

Sat, 8 Feb 2014 01:54:28 GMT

Which direction do you turn the focusing Knob for the Inner Retina ( closer to the camera) as oppose

to the Choroid ( farther from the camera ).

Thanks

Bill

RE: Topcon 50DX Focusing Question

Sat, 8 Feb 2014 11:26:47 GMT

W. Busch said:

Which direction do you turn the focusing Knob for the Inner Retina ( closer to the camera) as oppose

to the Choroid ( farther from the camera ).

Thanks

Bill

Hi Bill,

We have Zeiss 450 camera. When I notice the nerve are sharp while the macula is a little soft, I nudge the dial toward me. Therefore I would think the opposite would work in your case. If you have a sharp mac and a soft nerve..... turn the dial away from you.

Gary

Sat, 8 Feb 2014 16:13:31 GMT

Gary,

Thanks for the quick response. My first post.

So given the example below starting in the ( Vitreous ) First set --> and focusing towards--> Fifth set (Choroid ) would mean turning the Focusing Knob away from me?

You said nudge the Knob . How much of a turn would it take from First set to Fifth set?

As you can probably tell , i'm having a hard time mastering focusing the fundus camera.

Any other focusing tips you could share would be appreciated .

Thanks

Bill

Figure 9: Clinical examples of focusing on different levels of the retina are shown in these stereo pairs. From the top First set— Focusing the fundus camera in the vitreous allows the ophthalmic photographer to docu- ment various opacities. Second set—The flame-shaped hemorrhages found in the inner retina are in sharp focus in this photograph. Third set—The avascular zone surrounding the fovea may be best appreciated when the central portion of the retina is the object of focus. Fourth set—The outer retina has been focused on for this stereo pair of a young girl's bull's eye maculapathy. Fifth set—Maximum information at the level of the choroid is achieved through the use of a red (650 nanom- eter) filter and careful focusing on the choroi- dal nevus.

RE:

Sat, 8 Feb 2014 18:04:00 GMT

W. Busch said:

Gary,

Thanks for the quick response. My first post.

So given the example below starting in the ( Vitreous ) First set --> and focusing towards--> Fifth set (Choroid ) would mean turning the Focusing Knob away from me?

You said nudge the Knob . How much of a turn would it take from First set to Fifth set?

As you can probably tell , i'm having a hard time mastering focusing the fundus camera.

Any other focusing tips you could share would be appreciated .

Thanks

Bill

First time poster! Welcome, Bill!!

Your original post lead me to believe you were talking minor changes in your focusing, since that is where most of MY issues are. I don't feel I could tell you how MUCH to turn your focus dial, that depends on how much of a difference there is in the layers you are capturing. The "nudge" I mentioned was for a tweaking retinal layer focus. Sort of like what they are saying in 2nd - 4th set. These focusing differences will be very slight.

Compare those layers to the vitreous (first set) where you'll be turning your focus dial more in order to bring the camera's plane of focus forward in the eye. We had an interesting patient just yesterday who had a huge retinal detachment. Imagine looking into the posterior pole and seeing nothing but wrinkled up tissue. Even with the focus racked out to the maximum position and I still couldn't get the closer part of that detachment in focus.

Once you get really accustomed to your fundus camera, it should be second nature as to which way and how far to turn your focus knob.

Gary

Wed, 12 Feb 2014 18:47:17 GMT

Thanks Gary, Actually minor focusing differences is what I was getting at. I get a pretty good photo most of the time. Just not always happy with the focus. When I go to adjust it I often times make it worse. Now that I know to get the focus deeper just need to nudge the knob away from me a tiny bit and that you stated between step 2 and step 4 is small amountI have a good starting point to tweak what I see on screen. Used to old 4x5 view cameras so starting to see similarities while focusing. Mounted clear ground glass in old 4x5 and put lines on the glass. Same direction for focus and very close to focusing distance. Thanks again for the help ;-)