Nikkor 10.5mm f/2.8 - 62mm filter threads modified

[Erik Lund]

Here is a quick shot, composite of two images with the 10.5mm, one in vertical and one in portrait direction.

A gimbal head can be used for this type of shot to avoid misalignment.

Rotunde10_5_2 by Erik Gunst Lund, on Flickr

[Kim Pilegaard]

Erik,

Great result!

A bit of explanation would help. Why did you take the two images in different orientations? Why not just two vertical ones? How do do you handle the alignment? How did you do the stitching? Is the "shaved" version of the 10.5 mm needed for this task?

[Jakov Minić]

Erik is an expert in using fish-eye lenses

Kim, I may perhaps answer your first question.
When you shoot the 10.5 in landscape mode, the top and bottom part of the photo is not fully round, parts are missing.
So you rotate the camera and lens 90 degrees to fill in the blanks in order to get a full circular image.

[Kim Pilegaard]

Thanks Jakov!

I think I am understanding it now. So even with the shaved version, parts of the full circle is cut off. The landscape and the portrait pictures supplement each other, provided the two pictures are centred at the same point?

[Erik Lund]

Yes, that is it. Thanks Jakov

And yes cantered along the optical axis

The 10.5 is designed as a 'Full frame' Fisheye on DX it just turns out that when rotating it 90 degrees you get the full circle, the two missing top and bottom bits of the image.

The advantage is that you can use a much larger area of an FX sensor than an 8mm Circular Fisheye lens on FX, this gives you much more 'pixels in use' so to say and the 10.5mm is a remarkably sharp performer!

[Øivind Tøien]

Erik, I am bringing this old thread to life again as when shaving my 10.5mm, I realized that with the material removed, there is very little left to keep the original cap in place (with the intact shade part inserted) to hold it in place even after adding tape, and I like your approach to this. So on a whim, but without fully understanding the description  , I acquired a set consisting of a 6T and 5T ring with elements (to be removed) showing separation in order to try replicate your filter ring attachment modification,. After receiving the 6T (that differs slightly in the labeling from Erik's) here is my understanding of the dremeling modification that I would appreciates some feedback on. The 6T ring is hereafter just called the "Ring".

0. The retaining ring is loosened and put aside, the optical element is taken out of the Ring not to be used.
1. As the male thread on the Ring would extend too far and cover the focus collar on the 10.5mm, it is to be dremeled off to the base of the ring. (No threads shown in your image on the lens side)
2. The part of the ring that seats the optical elements (not sure how much is left of it after removing the male threads) is too narrow and has to be dremeled down to slightly wider diameter than the female threads of the Ring.
3. The female threads on the Ring might have to be slightly dremeled down a bit to fit tightly over the 10.5mm front.
(Additinoal question: is it to be pushed linearly in, or be fitted by rotating and sort of screwed on the the front of the 10.5mm)
4. Not so sure about this but from the following:

The donor was a Close up nr. 6T filter housing relieved from the glass and the male 62mm threads are used as a spacer inside to make the filter slide on to the lens and position, seat correctly.  A bit of Dremel work,,, and the filter ring slides into position solidly.

The male 62mm threads that are used as a spacer inside, you mean the retainer ring, right?

If used with a standard lens cap, it seems the added filter ring (that has to be added to the Ring) has to be unscrewed at every use unless a circular crop of the field is wanted?

About the shade:

If mounted in a filter ring trimming of the ring is needed

Is this pointing to a regular filter ring opposed to the Ring as the Ring is wider or has already threads partly reduced?

Hope some of this makes sense. Outside and inside of the Ring shown below.

[Erik Lund]

The male 62mm threads that are used as a spacer inside, you mean the retainer ring, right?

If used with a standard lens cap, it seems the added filter ring (that has to be added to the Ring) has to be unscrewed at every use unless a circular crop of the field is wanted?

Yes, by spacer i meant like sleeve -But yes a retainer.

Yes, it will be like an old school Nikon lens cap, screw on - off.

[Øivind Tøien]

Thanks for confirming, Erik, looks like I was on the right track after inspecting the details of the Ring. I already have a 62mm filter stacking cap that can be used with a filter ring as part of that makeshift classical screw-in Nikon cap.

And after more considerations regarding #2-3, it looks like the Dremel approach will be to remove material from inside at the non-female-threaded portion of the Ring, and the male thread of the Ring (closest to the mount) will go away by itself, so hopefully no need to make a vertical cut from the outside to remove those threads, which could be difficult to do cleanly.  It will be quite a bit material to remove so this project might take some time and patience and the need to borrow or acquire something more powerful than my old Dremel with its ailing batteries, or perhaps use the abrasion tool in a drill press for more control.
 

[Hugh_3170]

Øivind, I can see a lathe and a milling machine and a whole lot of related tooling & jigs coming into your life sometime in the not distant future....

 

BTW, Good luck with this project,

............................................

 so this project might take some time and patience and the need to borrow or acquire something more powerful than my old Dremel with its ailing batteries, or perhaps use the abrasion tool in a drill press for more control.