The Nikon F was revolutionary when it came out in 1959. It was the first ever modular single lens reflex (SLR) camera. When you take a photo, the reflex mirror has to swing up out of the way just before the shutter curtain opens. When the mirror hits the top of the mirror box, it sends a vibration through the camera. This vibration can blur the image at slow shutter speeds, particuraly in high magnification photography. This problem is not unique to Nikon F and is presesnt in even modern Digital SLR cameras.

Nikon F does allow you to lock the mirror in the up position to mitigate this problem. Locking the mirror actually serves two purposes. Apart from reducing the camera vibration, it enables the mounting of lenses like 2.1cm whose rear part protrudes well into the mirror box. The mirror lock up (MLU) was a new feature that no other SLR camera had at the time. However, there was a design flaw with Nikon's implementation of this function. In order to lock the mirror in the up position, you have to cock and fire the shutter once. That means a frame would be wasted every time you lock the mirror. This is less than ideal because MLU is not just a nice to have feature, it is an absolute necessity if you own 2.1cm or any early fisheye lenses.



Questar-Modified F

Nikon released a modified F body to address this shortcoming. An additional button was installed just under the depth-of-view preview button. The mirror can be pre-released by cocking the shutter and then depressing this tiny button. No film is wasted in the process. The mirror will automatically come down once the shutter is released, or may remains up if the original MLU knob is turned to UP position. This modified Nikon F was listed in Questar's sales catalogues and only distributed by them. It is unclear who first developed this solution, but it was evident that Nikon did undertake the modification. Otherise the official Nikon warranty would have been void. It didn't seem likely that Questar would spend resources to solve a technical problem for Nikon who might or might not entertain the idea anyway. Bearing in mind Questar was also selling modified Topcon at the same time. I guess Questar probably took the initiative to approach Nikon first and requested for an improved version that would address this problem. This is of course just my speculations based on circumstantial evidence.


According to Questar's own advertising material, this camera is "only obtainable from us" and " we regret that we cannot have your own Nikon body modified". Since they didn't offer black body in their sales catalogues, there should be no authentic black Questar-modified F in existence. The earliest and the latest serial numbers I have recorded are 6464447 and 7439745 respectively. How many Nikon F have been modified this way is unknown. Based on my observations of how often they appeared in the used market, I would say the total number should be in the same ballpark as the 66 serial block Red dot F. Around 2000 - 4000 units would be my educated guess.


Questar's sales catalogue from 1970. The camera was normally sold with the waist level finder or the lastest metering finder on offer at the time.




Top: An instruction insert that comes with the Questar-Modified F. The style looks just like other official Nikon printed material.

Top: A packing slip showing a typical order from Questar. Photomic T would be the latest metering finder for Nikon F at the time.

Left: Type I button (Recorded #6464447 - 6966911)

Middle: Type II button (Recorded #7016442 -7439745)

Top: Contrary to popular belief, the button differs from the self-timer release button


Top Left: Some of the later cameras have this black label on the top left front cover.

Top right: I have seen one with the label on the back. Not sure if it was the owner who relocated it there though.

A Questar Variation?

I have seen a few Nikon F with the same Questar modification but have the self-timer completely removed. I have created a photoshopped image below to replicate what it looks like. They were never heard of before but suddenly popped up out of nowhere in several camera shops in Japan about 10-15 years ago (2010-ish). The leatherette cover on the left front panel seemed to be made up of upper and lower halves instead of one single piece in at least some of them. (not illustrated in the image below) Whoever did the modification had to resort to harvesting the leatherette from another Nikon F. It was therefore unlikely to be a factory job.

Top: A Questar-modifed F owned by Smithsonian Institution, possibly for photographing artworks. Macro photography is another field where this camera can be useful.




Shutter Button Controlled Mirror Lock Up -- SBC MLU

Among the many aftermarket modifications, this has to be the best of the bunch. In fact, it is even superior to the Questar's solution in my opinion. Externally, it looks identical to other run-of-the mill Nikon F. The mirror lock up is achieved by half-pressing the shutter release button. When the shutter is fully depressed, it releases the shutter and return the mirror to the down position. This unique design allows you to lock the mirror and fire the shot remotely with a cable release. Unlike Questar or other aftermarkets solutions, it eliminates the need to trigger the mirror pre-release button on the camera body. Not something you want to do when the camera is mounted on a telescope in the dark. This two-stage shutter can also be used the same way as normal shutter. All you have to do is fully depressing the shutter in one continous action, just like what you would do with a normal shutter. I believe this is the same version as the one referred to as "Nikon F Rapid-Action Mirror" in Uli Koch's Nikon F book.

This modification was done by the legendary Nikon repairman Pete Smith. I purchased one such camera directly from him in 2003. He would put a white SBC MLU sticker on the top front cover for identification. He could also modify your own Nikon F for a cost of US $50 plus shipping. Sadly, this is no longer possible because Mr Smith passed away in Oct 2011. There may be other repairmen who can still do this modification though.

It would be impossible to know exactly how many Nikon F Mr Smith had converted. He was only one man and there were only so many cameras one man could convert. They are considerably rarer than Questar-modified F. The fact that it has no visual difference to ordianry F would only exacerbate the problem of finding one. I have recorded 3 examples with the SBC MLU sticker and another 3 without. The earliest serial number I have recorded is 6577282 and it goes up to as high as 7444492. 7444492 with the sticker was offered for sale on ebay as part of Mr Smith's estate by his son in around 2013.

This body #6912892 was purchased directly from Mr Pete Smith in 2003

Marty Forscher-Modified F

This is one of the better known aftermarket versions. A plunger was added just below the mirror lock knob. It does the same job as the tiny button on the Questar version. Marty Forscher who ran Professional Camera Repair Service in Manhattan carried out the modification. It would set you back US $60 for this service in 1975. The earliest Marty Forscher-Modified F I have seen has the serial number of 6401544.


An invoice for Marty Forscher modification from 1975.


Questar-like Modification

This version looks like a Questar knock-off. It has the same design and function. The button is in the exact same location except for being larger and more protruding. Recorded serial numbers are 6478357, 6787768 and 7071092.






Two varitaions: 6478357 and 7071092 have black base button. 6787768 has chrome base button.

Rivet Button Modification

The rivet-like mirror pre-release button is installed right next to the mirror-up lock knob. This is the only example I have seen. The serial number is 6529326.


There are a dozen more different afternarket verions. Some look decent, but most are crude and amateurish. It is worth noting that none of them, including the Questar version, completely solve the problem. Once the mirror lock is triggered by the pre-release mechanism, the ONLY way to swing the mirror down is to release the shutter. Too bad if you want to check the focus again after you have already activated the mirror pre-release!

8 Jan 2021