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How to use a non-AI lens on a Nikon FG
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miste...@gmail.com
Jan 15, 2012, 8:45:35 PM1/15/12
to
Hello,
Is there way way I can use a Nikkor-P non-AI 300 mm 1:4.5 lens on my FG, using manual mode? I thought I might put a Series E AI 50 mm 1:1.8 on to tell me what shutter speed to use. I want to use my 300 mm wide open, so I would set the 50 mm to f/4 for this. Then I would tape the AI ring to the body to hold this position and install the 300 mm, and use the shutter speed indicated by the 50 mm.
Or do I have to compensate for the differences in maximum aperture?
Is there way way I can use a Nikkor-P non-AI 300 mm 1:4.5 lens on my FG, using manual mode? I thought I might put a Series E AI 50 mm 1:1.8 on to tell me what shutter speed to use. I want to use my 300 mm wide open, so I would set the 50 mm to f/4 for this. Then I would tape the AI ring to the body to hold this position and install the 300 mm, and use the shutter speed indicated by the 50 mm.
Or do I have to compensate for the differences in maximum aperture?
Mike Benveniste
Jan 15, 2012, 9:57:33 PM1/15/12
to
I would recommend converting the lens to AI, unless it's a pristine
copy of interest to collectors.
--
Mike Benveniste -- m...@murkyether.com (Clarification Required)
You don't have to sort of enhance reality. There is nothing
stranger than truth. -- Annie Leibovitz
miste...@gmail.com
Jan 16, 2012, 1:50:50 AM1/16/12
to
Thanks MB. I know the manual says that, but I don't see any problem with it. The bayonet mount works, and the lens does not appear to foul any mechanism in the camera body.
Geoffrey S. Mendelson
Jan 16, 2012, 2:14:03 AM1/16/12
to
The first is that the AI sensor prong
on the camera will snap off if you mount a non-AI lens on the camera. It
was not designed to fold up, like the F3.
The second is that the internal mechanism of the FG may foul (mirror catch,
and other possible things) because the specs for the amount of space the
lens can protrude back into the camera changed. The lenses can not go as
far back on the FG as on a pre-AI camera.
The third is the meter system won't work, even if you AI convert it. You can
get the camera to function in f-stop priority, and it will probably give
you a decent exposure with color negative or black and white film, but
it may not give you the perfect exposure needed for slide film.
It absolutely will not give you a correct exposure in Program mode. It may give
you a proper exposure in terms of light, but the shutter speed/f-stop actually
used will be almost random.
This is because the FG has no proper way of determining the actual f-stop
used, it meters the light, decides upon an f-stop/shutter speed combination,
closes the diaphragm based upon a proportional guess and then re-meters for
the correct shutter speed.
The problem is that AIs lenses have exact proportional motion for the
diaphragm closure lever, AI lenses don't, and pre-AI almost none at all.
The pre-AI lenses were designed with two options, open (for metering and
viewing) and closed (for exposure).
If you really want to use pre-AI lenses, buy a cheap pre-AI body. Note that
any of them are at least 24 1/2 years old, so expect them to need some
work (new light seals, CLA) before using them for serious work.
Or buy a newer camera (F3/F4) that can be used with them.
Geoff.
--
Geoffrey S. Mendelson, N3OWJ/4X1GM
My high blood pressure medicine reduces my midichlorian count. :-(
William Hamblen
Jan 16, 2012, 8:28:30 AM1/16/12
to
lever on the camera. You don't want to do that. You can have the lens
modified (AI'd) if you want to use it on an FG. Unless the lens is a
collector's item, then you just want to put it on the display shelf.
Besides the breakage problem, your scheme won't work. The camera uses
the ring resistor to tell how far the lens is set from the lens's maximum
aperture, not the absolute aperture. The wide open position of the ring
resistor is the same for all lenses. The metering circuitry inside the
camera reads the light through the wide open lens, and the ring resistor
tells the camera to adjust the exposure for the stopped-down aperture.
Some Nikons for aperture priority autoexposure will read the light through
the stopped-down lens, but I don't know whether the FG is one of them.
Bud
Geoffrey S. Mendelson
Jan 16, 2012, 8:39:04 AM1/16/12
to
William Hamblen wrote:
> Some Nikons for aperture priority autoexposure will read the light through
> the stopped-down lens, but I don't know whether the FG is one of them.
The farthest open spot on the sensor ring is after the "no lens" spot,
> Some Nikons for aperture priority autoexposure will read the light through
> the stopped-down lens, but I don't know whether the FG is one of them.
so the camera will detect that there is no lens or the lens has no meter
coupling at all, and assume that the lens is stopped down to working
apeture already.
The FG does not have the ability to stop down the lens manually for a reading,
so it will only work, if at all with the lens wide open (unless the lens
itself has a stop down lever).
Actually I can't remember a Nikon camera that had that feature. :-(
miste...@gmail.com
Jan 16, 2012, 12:01:16 PM1/16/12
to g...@mendelson.com
Thanks for all the good information. Seems to have raised more questions.
"the AI sensor prong on the camera will snap off if you mount a non-AI lens on the camera"
Slides right by it.
"the internal mechanism of the FG may foul...The lenses can not go as
"The real problem is that a pre-AI Nikkor lens can break the auto indexing
lever on the camera."
Break it how? It is operated by a spring. If somehow it was prevented from moving no harm would occur. (As it happens, my non-AI lens lever has been removed.)
"The camera uses the ring resistor to tell how far the lens is set from the lens's maximum aperture, not the absolute aperture."
I did not know that. So I would need to meter at the same number of f/ stops from maximum aperture that I intend to use, not the same f/#.
This method does seem redundant though. Isn't the max aperture already known to the camera? Isn't that what the tab at the bottom of the lens opening does as the lens is twisted on?
"the AI sensor prong on the camera will snap off if you mount a non-AI lens on the camera"
"the internal mechanism of the FG may foul...The lenses can not go as
far back on the FG as on a pre-AI camera."
Actually, the AI lens goes farther back.
"The real problem is that a pre-AI Nikkor lens can break the auto indexing
lever on the camera."
"The camera uses the ring resistor to tell how far the lens is set from the lens's maximum aperture, not the absolute aperture."
This method does seem redundant though. Isn't the max aperture already known to the camera? Isn't that what the tab at the bottom of the lens opening does as the lens is twisted on?
Geoffrey S. Mendelson
Jan 16, 2012, 2:29:03 PM1/16/12
to
miste...@gmail.com wrote:
>
> Slides right by it.
Good, then it should not be a problem. It is however an unusal lens.
> Actually, the AI lens goes farther back.
This is a real telephoto lens (one with a long real focal length and not
an short one with a longer effective focal length), which explains it.
the AI sensor lever sticks into where the f-stop ring on the forked lenses
goes. I doubt it was on purpose, but that way a non-AI lens can be AI'ed
with a dremel tool if you know how to do it.
> "The camera uses the ring resistor to tell how far the lens is set
>from the lens's maximum aperture, not the absolute aperture."
> I did not know that. So I would need to meter at the same number of f/
>stops from maximum aperture that I intend to use, not the same f/#.
That's how AI works. The original method read the F stop off the lens
(using the fork) and you had to index it so that it knew the F stop you
were metering at.
F stops are really irrelevant in this case the meter only needed to know what
F stop you were at in relation to full open.
So that it "knew" the actual exposure would be 1/4 (2 stops down) and so on
depending upon where the lens was st.
> This method does seem redundant though.
>Isn't the max aperture already known to the camera?
>Isn't that what the tab at the bottom of the lens opening does
>as the lens is twisted on?
Actually it's a minimum aperture indicator. Was first used on the 4004, which
controlled the actual aperture via the electronic contacts on an AF lens.
That's the big difference between the Nikon and Canon AF lenses. After the
problems with the F3AF, Nikon decided to move controls to electronic and
the motors to inside the camera.
The difference raised the price of the cameras, but did two things. First the
lenses used rack and pinion focusing instead of a helicoid which made them
30% cheaper. The second is when faster autofocusing came out, you just bought
a new camera, and kept all your lenses.
Canon went the other way and put the motors in the lenses, which was a disaster
for early EOS buyers. I had both, but sold off all my Canon gear after two
years of waiting for lenses that were vaporware, while all they sold were
cheap zooms. :-(
To keep it relevant, the regular full frame AF lenses are AIS, so they
will work fine on your FG, except for the G ones.
>
> Slides right by it.
Good, then it should not be a problem. It is however an unusal lens.
> Actually, the AI lens goes farther back.
an short one with a longer effective focal length), which explains it.
>
> "The real problem is that a pre-AI Nikkor lens can break the auto indexing
> lever on the camera."
>
> Break it how? It is operated by a spring. If somehow it was prevented
>from moving no harm would occur. (As it happens, my non-AI lens
>lever has been removed.)
What non AI lever? On the camera? The FG did not have one. The problem is
> "The real problem is that a pre-AI Nikkor lens can break the auto indexing
> lever on the camera."
>
> Break it how? It is operated by a spring. If somehow it was prevented
>from moving no harm would occur. (As it happens, my non-AI lens
>lever has been removed.)
the AI sensor lever sticks into where the f-stop ring on the forked lenses
goes. I doubt it was on purpose, but that way a non-AI lens can be AI'ed
with a dremel tool if you know how to do it.
> "The camera uses the ring resistor to tell how far the lens is set
>from the lens's maximum aperture, not the absolute aperture."
> I did not know that. So I would need to meter at the same number of f/
>stops from maximum aperture that I intend to use, not the same f/#.
(using the fork) and you had to index it so that it knew the F stop you
were metering at.
F stops are really irrelevant in this case the meter only needed to know what
F stop you were at in relation to full open.
So that it "knew" the actual exposure would be 1/4 (2 stops down) and so on
depending upon where the lens was st.
> This method does seem redundant though.
>Isn't the max aperture already known to the camera?
>Isn't that what the tab at the bottom of the lens opening does
>as the lens is twisted on?
controlled the actual aperture via the electronic contacts on an AF lens.
That's the big difference between the Nikon and Canon AF lenses. After the
problems with the F3AF, Nikon decided to move controls to electronic and
the motors to inside the camera.
The difference raised the price of the cameras, but did two things. First the
lenses used rack and pinion focusing instead of a helicoid which made them
30% cheaper. The second is when faster autofocusing came out, you just bought
a new camera, and kept all your lenses.
Canon went the other way and put the motors in the lenses, which was a disaster
for early EOS buyers. I had both, but sold off all my Canon gear after two
years of waiting for lenses that were vaporware, while all they sold were
cheap zooms. :-(
To keep it relevant, the regular full frame AF lenses are AIS, so they
will work fine on your FG, except for the G ones.
Message has been deleted
Message has been deleted
Pete A
Jan 16, 2012, 5:01:40 PM1/16/12
to
On 2012-01-16 20:56:31 +0000, miste...@gmail.com said:
> [...]
>
> On the newer AI lens, there is a recess on the rear face of the lens,
> only a few millimeters in extent. Why it's there I cannot say. This
> might be what is Dremelled during the conversion.
Do you mean the lens-type signal notch to indicate it's an AI-S not
just an AI lens (series-E and AF lenses are also AI-S lenses):
<http://www.mir.com.my/rb/photography/hardwares/nikonfmount/ais_lars.htm>
> [...]
> [...]
>
> On the newer AI lens, there is a recess on the rear face of the lens,
> only a few millimeters in extent. Why it's there I cannot say. This
> might be what is Dremelled during the conversion.
Do you mean the lens-type signal notch to indicate it's an AI-S not
just an AI lens (series-E and AF lenses are also AI-S lenses):
<http://www.mir.com.my/rb/photography/hardwares/nikonfmount/ais_lars.htm>
> [...]
miste...@gmail.com
Jan 16, 2012, 5:24:12 PM1/16/12
to g...@mendelson.com
Thanks all. Very helpful.
I have a Nikon F Photomic T with its original 50 mm and telephoto lenses, and a Nikon FG, with a 50 mm lens. Here is my comparison.
The old-style rabbit ears tend to foul on the AI ring plastic tab just a little as the 50 mm lens is installed on the newer FG, but they can be pulled away during installation/removal to clear it. Not an issue at all on my old telephoto for some reason.
There are stop-down levers in the same position on both bodies, but the newer FG lever is set deeper into the body, as measured from the front of the lens opening, by 1/32 to 1/16 inch. This lever is set well into the body and it doesn't seem like it could contact anything except the corresponding lever on the lens. (As mentioned, I don't even have this lens lever on my telephoto, although it was there originally. It's set permanently on full aperture now.)
The mirror is set well away from the lens in both cases, so interference is unlikely.
Mechanically, I don't see any issues, except possibly rabbit ears in some cases. Optically, if I place any AI lens on it, the camera will know its maximum aperture and so will correctly assess ambient light. Then it will know light on the film at any given aperture. If I set my AI lens to f/8, it should display a shutter speed for that aperture. Then if I tape the ring down and remove the AI lens, the camera will still think I plan to shoot at f/8. If I then install a different lens, manually set to that aperture, it should illuminate the film with the same amount of light, so that the original shutter speed should still work.
Worth some experiments anyway.
I have a Nikon F Photomic T with its original 50 mm and telephoto lenses, and a Nikon FG, with a 50 mm lens. Here is my comparison.
The old-style rabbit ears tend to foul on the AI ring plastic tab just a little as the 50 mm lens is installed on the newer FG, but they can be pulled away during installation/removal to clear it. Not an issue at all on my old telephoto for some reason.
There are stop-down levers in the same position on both bodies, but the newer FG lever is set deeper into the body, as measured from the front of the lens opening, by 1/32 to 1/16 inch. This lever is set well into the body and it doesn't seem like it could contact anything except the corresponding lever on the lens. (As mentioned, I don't even have this lens lever on my telephoto, although it was there originally. It's set permanently on full aperture now.)
The mirror is set well away from the lens in both cases, so interference is unlikely.
Mechanically, I don't see any issues, except possibly rabbit ears in some cases. Optically, if I place any AI lens on it, the camera will know its maximum aperture and so will correctly assess ambient light. Then it will know light on the film at any given aperture. If I set my AI lens to f/8, it should display a shutter speed for that aperture. Then if I tape the ring down and remove the AI lens, the camera will still think I plan to shoot at f/8. If I then install a different lens, manually set to that aperture, it should illuminate the film with the same amount of light, so that the original shutter speed should still work.
Worth some experiments anyway.
miste...@gmail.com
Jan 16, 2012, 5:24:45 PM1/16/12
to
Yes. Great link.
Robert Coe
Jan 16, 2012, 6:05:31 PM1/16/12
to
On Mon, 16 Jan 2012 14:24:12 -0800 (PST), miste...@gmail.com wrote:
: Thanks all. Very helpful.
Suppose it works. Is there any conceivable circumstance under which you'd find
it worth the trouble to shoot that way?
Bob
: Thanks all. Very helpful.
it worth the trouble to shoot that way?
Bob
William Hamblen
Jan 16, 2012, 6:09:54 PM1/16/12
to
On 2012-01-16, Geoffrey S. Mendelson <g...@mendelson.com> wrote:
> William Hamblen wrote:
>
>> Some Nikons for aperture priority autoexposure will read the light through
>> the stopped-down lens, but I don't know whether the FG is one of them.
>
> The farthest open spot on the sensor ring is after the "no lens" spot,
> so the camera will detect that there is no lens or the lens has no meter
> coupling at all, and assume that the lens is stopped down to working
> apeture already.
>
> The FG does not have the ability to stop down the lens manually for a reading,
> so it will only work, if at all with the lens wide open (unless the lens
> itself has a stop down lever).
>
> Actually I can't remember a Nikon camera that had that feature. :-(
>
> Geoff.
>
Your depth of field preview lever will stop down the lens. Whether the
> William Hamblen wrote:
>
>> Some Nikons for aperture priority autoexposure will read the light through
>> the stopped-down lens, but I don't know whether the FG is one of them.
>
> The farthest open spot on the sensor ring is after the "no lens" spot,
> so the camera will detect that there is no lens or the lens has no meter
> coupling at all, and assume that the lens is stopped down to working
> apeture already.
>
> The FG does not have the ability to stop down the lens manually for a reading,
> so it will only work, if at all with the lens wide open (unless the lens
> itself has a stop down lever).
>
> Actually I can't remember a Nikon camera that had that feature. :-(
>
> Geoff.
>
TTL meter will read the correct exposure is another question.
Bud
William Hamblen
Jan 16, 2012, 6:22:34 PM1/16/12
to
> "The real problem is that a pre-AI Nikkor lens can break the auto indexing
> lever on the camera."
>
> Break it how? It is operated by a spring. If somehow it was prevented
from moving no harm would occur. (As it happens, my non-AI lens lever
has been removed.)
You were lucky. The cam follower on the camera sticks up to engage
> lever on the camera."
>
> Break it how? It is operated by a spring. If somehow it was prevented
from moving no harm would occur. (As it happens, my non-AI lens lever
has been removed.)
a cam on the lens. The old lenses don't have the cutout for the cam
follower and the rear of the aperture ring on the lens may crush the
cam follower on the camera body. This is why the instruction booklet
for your FG says in no uncertain terms never try to mount a non-AI lens.
Your particular lens might have enough clearance at the back to clear the
cam follower. On some camera bodies (F3 and others) you can flip the
cam follower out of the way. The meter prong on the top of a manual
focus Nikkor lens will not hit anything on an AI Nikon camera body.
I've put manual focus AI and AI-S Nikkors complete with meter prong on
all my AI Nikon camera bodies with no problems.
Bud
Mike Benveniste
Jan 16, 2012, 7:00:34 PM1/16/12
to
On 1/16/2012 6:09 PM, William Hamblen wrote:
> Your depth of field preview lever will stop down the lens. Whether the
> TTL meter will read the correct exposure is another question.
The Nikon FG does not have a depth of field preview lever.
> Your depth of field preview lever will stop down the lens. Whether the
> TTL meter will read the correct exposure is another question.
miste...@gmail.com
Jan 16, 2012, 9:38:48 PM1/16/12
to
I know. I got the FG as a Xmas present. It was purchased in a second-hand store, and it wasn't known whether or not it worked. Wanted to shoot a roll and show it to the giver. Probably won't use it much after that. But I love the look of long telephoto lenses at full aperture, so I wanted to include a few shots using one.
Pete A
Jan 16, 2012, 10:03:56 PM1/16/12
to
On 2012-01-16 19:29:03 +0000, Geoffrey S. Mendelson said:
> miste...@gmail.com wrote:
>> [...]
It signals the wide-open f-stop (maximum aperture) via the Maximum
Aperture Indexing Post (near the bottom of the lens mount).
It signals the position of the aperture control ring, relative to
wide-open, via the meter coupling ridge.
With these two pieces of information, AI-compatible cameras are able to
determine the actual f-stop the user has selected on the aperture
control ring.
Cameras that offer P and/or S mode require that the aperture control
ring is set at the fully stopped-down position - the minimum aperture.
The camera is now able to determine the range of absolute f-stops
offered by the lens.
IIRC, these 3 features were first used together in 1982 by the FG, then
1983 FA
1985 F-301/N2000
1986 F-501/N2020 (AF)
1987 F-401/N4004 (AF)
The F-401 did _not_ control the lens f-stop via the electrical contacts
- I think you'll find that the only Nikkors having an electronically
controlled aperture iris are the PC-E series.
The FG and later cameras need to determine the actual rather than
relative f-stop in order to provide Program mode TTL OTF flash. It also
allowed the FA and some of the later bodies to display the f-stop
chosen by P and S modes.
AI-S lenses were introduced in 1981 (before the FG). These have a
standardized aperture stop-down lever enabling precise control of
f-stop by the camera in P and S modes. Using an AI lens may cause a
significant error between wanted and actual f-stop.
G lenses are not AI-S, but retain the standardized aperture stop-down
lever for precise control.
This "S" feature also enables the F-401 and more recent cameras to set
the f-stop via a control on the body, rather than the lens aperture
control ring, in M and A modes.
> miste...@gmail.com wrote:
>> [...]
>> This method does seem redundant though.
>> Isn't the max aperture already known to the camera?
>> Isn't that what the tab at the bottom of the lens opening does
>> as the lens is twisted on?
>
> Actually it's a minimum aperture indicator. Was first used on the 4004, which
> controlled the actual aperture via the electronic contacts on an AF lens.
AI was introduced in 1977 and was known as Automatic Maximum-Aperture Indexing.
>> Isn't the max aperture already known to the camera?
>> Isn't that what the tab at the bottom of the lens opening does
>> as the lens is twisted on?
>
> Actually it's a minimum aperture indicator. Was first used on the 4004, which
> controlled the actual aperture via the electronic contacts on an AF lens.
It signals the wide-open f-stop (maximum aperture) via the Maximum
Aperture Indexing Post (near the bottom of the lens mount).
It signals the position of the aperture control ring, relative to
wide-open, via the meter coupling ridge.
With these two pieces of information, AI-compatible cameras are able to
determine the actual f-stop the user has selected on the aperture
control ring.
Cameras that offer P and/or S mode require that the aperture control
ring is set at the fully stopped-down position - the minimum aperture.
The camera is now able to determine the range of absolute f-stops
offered by the lens.
IIRC, these 3 features were first used together in 1982 by the FG, then
1983 FA
1985 F-301/N2000
1986 F-501/N2020 (AF)
1987 F-401/N4004 (AF)
The F-401 did _not_ control the lens f-stop via the electrical contacts
- I think you'll find that the only Nikkors having an electronically
controlled aperture iris are the PC-E series.
The FG and later cameras need to determine the actual rather than
relative f-stop in order to provide Program mode TTL OTF flash. It also
allowed the FA and some of the later bodies to display the f-stop
chosen by P and S modes.
AI-S lenses were introduced in 1981 (before the FG). These have a
standardized aperture stop-down lever enabling precise control of
f-stop by the camera in P and S modes. Using an AI lens may cause a
significant error between wanted and actual f-stop.
G lenses are not AI-S, but retain the standardized aperture stop-down
lever for precise control.
This "S" feature also enables the F-401 and more recent cameras to set
the f-stop via a control on the body, rather than the lens aperture
control ring, in M and A modes.
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