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Nikon 7.5mm f/5.6
Fish-eye-NIKKOR (1966-1970)

© 2012 KenRockwell.com. All rights reserved.

Intro   Specs    Performance    Usage    Recommendations

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Nikon 7.5mm f/5.6 Fisheye

Nikon 7.5mm f/5.6 Fisheye (built-in filters, 10-½ oz./300g). enlarge. The back of the lens pokes way back from the chrome mount. This free website's biggest source of support is when you use these links, especially this link directly to them at eBay (see How to Win at eBay) when you get anything, regardless of the country in which you live.Thanks! Ken.

May 2012, April 2008   More Nikon Reviews   Nikon Lenses   All Reviews

 

Introduction   top

Intro   Specs    Performance    Usage    Recommendations

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The 7.5mm f/5.6 is one of Nikon's earliest 180 degree circular fisheye lenses.

It is a primitive design which requires poking into the camera. If you don't lock up your camera's mirror, you'll smash it attempting to mount this lens.

Since you can't look through your camera to see what you're photographing, you use a special finder that comes with the 7.5mm lens. You slip this finder on the weird accessory shoe of your Nikon F or F2. The finder does not slip into a standard hot shoe!

Nikon 7.5mm viewfinder

160 degree viewfinder and its own screw-in midget cap.

The 7.5mm has been a collectors' item with limited photographic usefulness for many years. The only serious reason to consider this over the 8mm f/2.8 fisheye is that this 7.5mm has a more linear r = fθ projection.

Even as a collectors' item Nikon hasn't forgotten it. It's mentioned on page 380 of my USA D3 user's manual. Sadly the mention is on the list of incompatible lenses.

 

Compatibility

It only works on film cameras which allow full-time hard mirror lockup, which means the F, F2, F3, F4, F5 and some of the earliest pre-AI amateur Nikons, like the Nikkormat FT, from the early 1970s.

With the Nikon F, you need to remove any Photomic finder since it will interfere. Likewise with the Nikon F, locking up the mirror is a multi-step affair requiring you to waste a frame of film.

This is one of the very few Nikon lenses which simply won't work on any digital camera unless you rig up some sort of complex optical relay system beyond the scope of this website.

 

History

1962-1965

Nikon's first 35mm-format fisheye was the very similar 8mm f/8. It had a 24mm image circle, which was a great idea for science, but a bad idea for photography because slide mounts and enlarger film holders cut off the tops and bottoms of the circles. Nikon made about 1,500 of these.

 

1966-1970

This 7.5mm fisheye replaced the 8mm. It is a stop faster, and its slightly smaller 23mm image circle fits more slide mounts and negative holders. Nikon made about 2,500 of these.

 

1970-1997

The far more practical 8mm f/2.8 replaced this mirror-up 7.5mm. Nikon made close to 10,000 of these.

Nikon has not made any circular fisheyes since 1997; the world has enough to go around. Nikon has also made 220 degree 6mm fisheyes, 10mm orthographic projection and other fisheyes I won't cover here — yet.

 

Nikon 7.5mm

Nikon 7.5mm f/5.6 fisheye with some of its special caps.

 

Specifications  top

Intro   Specs    Performance    Usage    Recommendations

Name

Nikon calls this the Nikon Fish-eye-NIKKOR 7.5mm f/5.6.

Nikon product number 229.

 

Included

This sold with the 7.5mm lens, 160 degree viewfinder, specialized front and specialized rear caps for the lens, specialized front cap for the finder, leather CL-1 case and 16-page 5-3/4 x 4-1/4" English instruction manual.

If you're missing anything, God help you trying to find it.

 

Optics

9 elements in 6 groups.

One additional flat filter ahead of the diaphragm.

Spherical design, single-coated.

 

Actual (Design) Focal Length

7.6mm.

 

Focus

Fixed.

Everything is always in focus.

 

Nikon 7.5mm f/5.6 optical formula

Nikon 7.5mm f/5.6 optical formula.

 

Nikn 7.5mm aperture lever

Nikon 7.5mm f/5.6 fisheye showing its aperture control lever.

Diaphragm

6 straight blades. Manual. Stops down to f/22 with clicks at full stops. All intermediate settings are usable.

 

Filters

Internal turret with 6 filters: L1A, Y48 and Y52 yellow, O57 orange, R60 red and X0 light green.

 

Nikon 7.5mm Filters

Nikon 7.5mm mounted on an F4. The filter control is on the bottom of the lens.

To change filters, simply move the control which rotates the internal turret.

 

Filter Factors

   
Daylight Filter Factor, Stops (time)
Tungsten Filter Factor, Stops (time)
Film Type
L1A
Skylight
0 (1x)
0 (1x)
Color and B/W
Y48
Medium Yellow
2/3 (1.7x)
1/4 (1.2x)
B/W
Y52
Deep Yellow
1 (2x)
1/2 (1.4x)
B/W
O57
Orange
1-3/4 (3.5x)
1 (2x)
B/W
R60
Red
2-2/3 (6x)
2-1/3 (5x)
B/W
X0
Light Green
1 (2x)
2/3 (1.7x)
B/W

 

Size

Nikon's original instruction manual specifies 3-5/32" long (overall) by 3-7/32" diameter (80 x 82mm).

 

Weight

Nikon's original instruction manual specifies 10-½ oz. (300g).

 

Hood

None, silly.

 

Nikon 7.5mm case

Nikon CL-1 soft Corinthian leather case.

Case

CL-1, soft Corinthian leather; the mother of all Nikon lens cases.

Caps

Black-enameled screw-in brass front cap.

There is a band of rubber along the inside to prevent glass damage when attaching it. These safety bumpers continue on Nikon's 95mm screw-in caps and the 120mm screw-in cap on the larger 8mm f/2.8 fisheye.

 

Nikon 7.5mm front cap

Nikon 7.5mm front cap.

Because the cap is brass, it glides right on and off the aluminum lens' threads. The newer 120mm aluminum cap of the 8mm f/2.8 often "spins" in the threads of the aluminum lens, making the 8mm f/2.8 a noisy affair to cap and uncap.

The plastic rear cap is very deep to accommodate the protruding rear elements. This weird cap also attaches to any other Nikon SLR lens as you swap lenses.

The finder front cap is anodized spun-aluminum. The finder has no rear cap.

The finder slips into grooves in the large rear cap to keep this all together.

Nikn 7.5mm, finder and caps

Nikon 7.5mm and finder, all capped up and ready to go.

 

Performance   top

Intro   Specs    Performance    Usage    Recommendations

Overall     Focus      Color    Color Fringes    Projection    

Falloff    Ghosts     Mechanics     Sharpness

 

Overall    back to Performance    back to top

This is a lens for collectors, not users. It was such a royal pain to use even in its own day that it was replaced in just four years by the much larger, but far more practical, 8mm f/2.8 in 1970. Nikon made the huge 8mm f/2.8 for 27 years!

Optically this 7.5mm is fine, but not as good as the 8mm f/2.8.

This 7.5mm can only can be shot on film, not digital.

 

Focusing   back to Performance    back to top

Focus is fixed (pan focus).

Depth of field is so all-encompassing that focus is fixed at about 3.3 feet (1 meter) and everything is in focus. If you see my "Perfect Sharpness" article you'll see that a 7.5mm lens at f/5.6 really can get everything in optimum focus from 2 feet (0.7m) to infinity.

 

Color Rendition     back to Performance    back to top

It seems a little greener than the 8mm f/2.8 AI. It's a complex single-coated lens, so it's not unusual to have a slight color bias.

 

Projection    back to Performance    back to top

This 7.5mm fisheye has a more linear r = fθ projection than newer fisheyes. In other words, things aren't as squished at the sides, which I prefer.

Because the edges aren't as squished, the image diameter is actually slightly larger than the image from the 8mm f/2.8. On full-frame 2k x 3k scans, the images from this 7.5mm measure 2,037 pixels in diameter while the images from the 8mm measure 2,020 pixels in diameter.

Here's Nikon's projection data from the users manual for the 7.5mm f/5.6.

Image
Radius
(mm
)

Subject
theta,
degrees

delta
theta,
deg.
     
0
0
 
   
3.58
0.5
3.58
 
   
3.59
1.0
7.17
 
   
3.59
1.5
10.76
 
   
3.59
2.0
14.35
 
   
3.61
2.5
17.96
 
   
3.61
3.0
21.57
 
   
3.64
3.5
25.21
 
   
3.65
4.0
28.86
 
   
3.66
4.5
32.52
 
   
3.69
5.0
36.21
 
   
3.71
5.5
39.92
 
   
3.73
6.0
43.65
 
   
3.75
6.5
47.70
 
   
3.78
7.0
51.18
 
   
3.78
7.5
54.96
 
   
3.83
8.0
58.79
 
   
3.79
8.5
62.58
 
   
3.83
9.0
66.41
 
   
3.82
9.5
70.23
 
   
3.87
10.0
74.10
 
   
3.84
10.5
77.94
 
   
3.81
11.0
81.75
 
   
3.75
11.5
85.50
 
   
3.71
12.0
89.21
 

While it's not a perfect r = fθ projection, it's far more linear than any newer fisheye.

What's weird is that it specifies projection out to r=12.0mm, which implies a 24mm, not 23mm, image circle. The 8mm f/2.8, which has the same rated 23mm circle and a very slightly smaller measured image circle than this 7.5mm, has almost the exact same numbers for small angles, and only is rated to r=11.5mm. This tends to suggest that I've caught Nikon in a 1966 typographical error, since it seems that this table above, based on data from Nikon's users manual for the 7.5mm f/5.6 dated June 1966, is actually data for the previous 8mm f/8, and not this 7.5mm f/5.6.

If this really is the table for the 8mm f/8, to get better data for this 7.5mm, I would multiply each r value by 0.95. As an example, I'll bet you that where r = 7.0mm and θ = 51.18 degrees, that the real data probably is r = (7 x 0.95) = 6.6mm for θ = 51.18 degrees.

 

Falloff (darkened edges)    back to Performance    back to top

The edges fade to black softly, unlike the 8mm f/2.8, whose edges cut to black sharply.

I'd rather have the edges sharp today, since I always can fade them later, but if I want a fade-to-white for online use, I can't use the darker edges of the 7.5mm lens' images.

 

Ghosting   back to Performance    back to top

It has more ghosts than the 8mm f/2.8. It usually has a few dots from the sun someplace. These dots are usually hexagons.

 

Lateral Color Fringes   back to Performance    back to top

This older 7.5mm has some minor lateral (side) color fringes, while the more modern 8mm f/2.8 doesn't. I can see just a little bit when comparing Velvia from one lens to the other.

It isn't bad; I wouldn't worry about it unless it's critical for your use.

 

Mechanics    back to Performance    back to top

Everything

Metal.

 

Barrel

Enameled and anodized aluminum.

 

Front Cap

Enameled brass with rubber bumpers.

 

Mount

Dull-chromed brass.

 

Markings

Engraved and filled with paint.

 

Serial Number

Engraved and filled with paint on the main identity ring Nikon was paying attention, and started the serial numbers for the 7.5mm lens at 750,000.

 

Nikon 7.5mm finder

The finder has no rear cap.

 

Finder

All metal, black crinkle finish, engraved markings (not filled with paint; engravings show bare aluminum underneath), serial number stamped on chromed brass foot.

 

Sharpness   back to Performance    back to top

The 7.5mm fisheye isn't quite as sharp as the more modern 8mm f/2.8. It's not a big difference, but it is obvious if you shoot them side-to-side. If you don't, this 7.5mm looks great.

Few people care; this is a collectors lens that when it was used photographically was used for special effects, not mural-sized straight prints.

 

Usage   top

Intro   Specs    Performance    Usage    Recommendations

 

NEW: See the newer Usage section of my Nikon 8mm f/8 Fisheye Review for far more details for use on DSLRs.

Nikon 7.5mm and finder

Nikon 7.5mm fisheye and finder.

This fisheye is a pain to use. You can't see through your camera's viewfinder, so you never really know what you're shooting until you have your film developed. (It doesn't work on any digital camera.) This is why this lens has been mostly a collectors' item, not a shooters tool, since it was replaced by the 8mm f/2.8 in 1970. The 8mm f/2.8 is a huge and expensive lens, but at least you can see what you're doing and use it on digital cameras.

Since this 7.5mm pokes into your camera, you must remember to lock up your mirror before jamming it on, otherwise you'll smash your SLR's mirror. Because the mirror is locked up, you can't see through this lens to compose, gauge focus or meter.

Nikon's manual suggests waving a 3" diameter plate on the end of a coat hanger in front of the lens to shield the disc of the sun.

Nikon and I both suggest keeping the front cap on all all times, except to shoot. It's easy to destroy the lens walking around since it pokes out like a naked pregnant woman's belly.

 

The Finder

You get a door-viewer finder with a foot on it to use as a rough compositional guide. It doesn't help much, because:

1.) The finder doesn't cover quite the same angle (160 versus 180 degrees).

2.) The finder's view is partially obstructed by the camera.

3.) Most importantly, the finder is several inches away from the lens, so it sees a different perspective. With lenses this wide, these few inches mean everything. You'll want to look through the finder, and move the camera so the lens is in about the same position as the finder when you shoot. Even if you think your subject is at infinity, this fisheye is still seeing the ground at your feet below!

 

Check List

Since you're flying blind and can't see anything through the lens or camera's viewfinder, you need to follow a check list to avoid taking pictures of the lens cap. I'd suggest always checking:

1.) Before mounting, is your mirror locked up? and

2.) Remove front cap, and

3.) Confirm filter setting. Is it on the click, or did it get knocked in-between? (for color, only the L1A filter is used) and

4.) Confirm f/stop and shutter speed before each and every single shot.

 

On the Nikon F

If you're serious about this 7.5mm lens, you've seen the picture of it mounted on a Nikon F with non-metered finder and the dedicated fisheye finder over the rewind crank.

This is the easiest way to use this 7.5mm lens, since the F was the camera that was current along with this fisheye in the 1960s. The biggest gotcha with an early Nikon F with non-metered finder is that you lose one frame of film in order to engage the mirror lock-up. If you leave this lens on a Nikon F, you don't lose any frames if you always leave the mirror up.

Nikon 160 degree finder botom

Weird proprietary mounting foot.

There are big catches to using this finder on any camera other than the most primitive Nikon F:

1.) The newer Photomic (metered) finders of the newer Nikon Fs were so big that the 7.5mm lens can't mount at all; you have to go find one of the original non-metered prisms or simply remove the Photomic finder and cap-off the top of the Nikon F.

2.) The Nikon F and F2 never had standard flash shoes! Flash shoes were for amateur cameras in the 1960s; pros used flash guns mounted with a bracket on the side of the camera.

The finder slips over the weird dedicated contact over the rewind crank of the F and F2, which means it does not fit a standard hot shoe of any modern camera!

 

On the F2AS

Nikon 7.5mm on F2AS

Nikon 7.5mm f/5.6 and finder mounted on Nikon F2AS.

Mounting everything on the Nikon F2AS is relatively straightforward. Unlike the Nikon F, it's easy to lock up the mirror any time you like without wasting film.

Remember to lock-up your mirror first, slide on the finder, and off you go. A nice thing about all F2s is that their mechanical shutters have infinitely variable speeds between 1/80 and 1/2,000 of a second. No big deal, since the 7.5mm's diaphragm is also infinitely variable.

There is one big hang-up with the DP-12 finder of the F2AS:

Nikon 7.5mm on F2AS

7.5mm finder hanging up on the DS-12 EE contacts of the DP-12 Finder.

The finder won't mount all the way. Not only won't it slide on all the way, but now there is a huge obstruction when looking trough the finder.

If you want to use this with an F2, try to find a meterless DE-1 finder to keep out dust. If you're a slob, you can remove the larger finder and focus screen, since they aren't used with the 7.5mm lens, but this will let dust get into the camera.

 

On the F3

The F3 is the most sane electronic camera on which to use the 7.5mm. This is because you can mount the finder without too much hassle today, and shoot hand-held.

Nikon 7.5mm on F3

Nikon F3HP with 7.5mm lens and its finder mounted with an AS-3 adapter.

There's a small catch: you need to buy an AS-3 adapter to let the finder mount on the different dedicated flash shoe of the F3. (the F3 uses a different non-standard shoe than the non-standard shoe of the Nikon F and F2!) The AS-3 converts the F3's weird mount into the Nikon F and F2's weird mount for which the finder is designed. That's right: the F3 has no hot shoe either!

Since you still can buy the AS-3 for about $10, you're AOK with the F3. The AS-3 lacks the spring-loaded clamping of the Nikon F and F2's mount, so a rubber band might be needed to keep the finder from slipping off backwards.

Nikon 7.5mm on F3

Nikon AS-3 flash adapter on an F3HP.

 

On the F4

Nikon 7.5mm on an F4

Nikon F4 with 7.5mm lens, but no finder.

The problem with the F4 is that it has a real hot shoe. The 7.5mm finder can't mount to a standard hot shoe!

You would need a Nikon AS-2 adapter to convert a standard hot shoe to the weird old Nikon F mount needed by the 7.5mm finder. Sometimes Adorama has these used, and if you get one, you ought to be golden — almost.

Once you get all set with a finder on your F4, you can't hand-hold it because the 7.5mm lens will see your fingers wrapped around the big, permanent battery grip!

Nikon 7.5mm on the F4 from above

Nikon 7.5mm on F4.

When I shot this 7.5mm, I shot it on a tripod on my F4 because I had other lenses, like the newest 24mm PC-E, that I also needed to shoot on the same roll.

I composed by first putting on an 8mm f/2.8, which lets me meter and look through the finder, composing, metering (manual) and then locking up the mirror, changing to the 7.5mm, and shooting. Clearly this is a silly way to shoot the 7.5mm, since it requires an 8mm f/2.8 and changing lenses! I did this to compare them; no reasonable person would shoot the 7.5mm this way.

Nikon 7.5mm on F4

Nikon 7.5mm on an F4.

There's another problem on the F4: the finder pokes out enough that an American finger can't reach the aperture nubbin once it's been pushed to f/16 or smaller. You need to get out a poker, like a knife, to push the nubbin back to where you can reach it, or remove the lens and reset the lens to a larger (f/5.6) aperture. Thankfully I see no reason to use anything smaller than f/11 anyway, so this is the least of your worries on the F4.

Oddly, the older 8mm f/8 doesn't have this problem.

 

On the F5

I didn't try it on an F5. The F5 ought to have the same problems as the F4.

 

On the F6 and Digital

Forget it: the F6 and digital SLRs have no full-time mirror lockup.

Even I wasn't brave enough to lift the mirror of my D3 with a tongue depressor and slide in this borrowed 7.5mm lens, I doubt the lens would be damaged, but didn't want to risk bonering-up my D3's finder or AF system, which depend on critical adjustment of the many mirrors that flip up and down under spring pressure.

If you try this on your D3, I'd love to know what happens.

 

Recommendations   top

Intro   Specs    Performance    Usage    Recommendations

Nikon 7.5mm rear

Back of Nikon 7.5mm f/5.6 Fisheye.

Don't buy one of these for photography. For taking pictures, get the far more practical 8mm f/2.8 AI or AI-s. Get one of these 7.5mm lenses to collect.

The 7.5mm is most likely is the best mirror-lockup fisheye there is, and it's much smaller than the modern 8mm f/2.8. This 7.5mm replaces the older 8mm f/8 mirror-lock-up fisheye that I have not tried.

If you're going to shoot with this lens, get an ancient Nikon F with a non-metered finder and dedicate it to the 7.5mm. I'd leave the Nikon F and 7.5mm mated for good since the cost of a Nikon F body is a small fraction of the cost of this lens. Newer cameras, even a Nikon F Photomic, are more trouble to use.

The huge problems are that mirror-lock-up lenses are a royal pain to use compared to any modern lens, and that they only work on film cameras.

Even if you get over the technical clumsiness, the fact that you can't compose through the lens is a critical shortcoming. Changes of just fractions of an inch make very significant changes in composition with a lens this wide. Even if your subject is at infinity, this 7.5mm fisheye lens is still going to see the ground below it, about five feet away . Having a finder a couple of inches away from the lens, and having parts of the field of view obstructed by the camera make this a very silly lens with which to shoot today.

Because of these issues, the value of a used 7.5mm lens reflects its value to collectors, not users. If you're considering the purchase of one of these, be sure you realize that its value depends greatly on the completeness of the unit. If you're missing the case, missing the manual, missing the original finder, or God help you, missing any of the three very specialized caps, it has far less value. The few I've seen for sale are usually missing at least the finder and at least one of the three irreplaceable caps. Don't even consider one missing the front cap; there's no way to pack or ship it safely without. I've seen people offering these on eBay with a standard rear cap cut-out so the back of the lens pokes out; that doesn't count!

If you're intrepid, so long as you get a 7.5mm lens and correct front cap, you can build your own rear cap, and tape a door viewer (the $2 kind or a fancy $15 one) to the top of your camera and go. Good luck!

 

Acknowledgment

Many thanks to my friend Fernando Yepez who enabled me to get access to one of these.

 

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Thanks for reading!

 

 

Mr. & Mrs. Ken Rockwell, Ryan and Katie.

 

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