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Thread: GFX and Pentax Lenses Via Fotodiox Adapter

  1. #1
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    GFX and Pentax Lenses Via Fotodiox Adapter

    One of the things I particularly looked forward to in getting the GFX was electronic first curtain as I had found that with my 120 mm. and longer, shutter shake was problematic and between 1/250 and 1 second, almost precluded use of the 300 mm. f5.6 I owned. even before picking up my new GFX I placed an order for the Fotodiox adapter. Just as well as when I picked up the camera, there were no lenses available.

    When I inspected the adapter, it came with an L shaped shoe, the bottom of which had grooves to match Arca Swiss clamps - very nice, but the two small bolts holding the shoe on were loose. I tightened them as best I could, but within 24 hours they were loose again after doing no more than taking a few test pictures. I remounted them with some lactate, which seems to have done the job.

    I also noticed that the whole rig - adapter on the tripod, lens hanging off the front, and camera off the back was quite unsteady - and close inspection showed that it was the shoe to tube of the adapter that was flexing.

    That said, I was quickly able to establish that images with my 300 were very sharp, problem solved.

    I decided to fill the gap under the adapter tubular body with a block of maple, epoxied in place. I was careful to minimize any spill of the epoxy and wiped immediately, but despite my care, within 10 minutes the lens release lever was locked solid and a great deal of force didn't budge it.

    Nothing for it but to take the lens ring off the front of the adapter and see what was up. Seems the epoxy while quite thick, managed to ooze between the ring and tub and entirely fix down the lever. With a small screwdriver acting as a chisel, I worked away at the epoxy and freed up the lever and cleaned up underneath and got it working again.

    I replaced the lens ring only to find that three of the four bolts holding the ring to the tube had stripped their threads. Yes, I do know which way to loosen a screw. The only thing I can think of was that I applied considerable pressure downwards to make the screwdriver grip the small Phillips bolts.

    Now what was I going to do.

    With some reluctance I epoxied the ring down to the tub, being careful that the springs holding the lens wouldn't get glued, and added epoxy to the shaft of each bolt. I cleaned all surfaces with alcohol beforehand.

    I've been out a couple of times since, and so far can report no difficulties mounting my longest lens, the 300 f5.6 - though I'm a lot more careful about not carrying tripod and camera and 300 over my shoulder like I used to.

    The adapter works very well, and is nicely finished and lenses mount solidly as does the adapter to the GFX body. I did find however that the lens release lets light onto the sensor when the camera is in vertical position, so I've had to put some electricians tape over it.

    So what about the Pentax lenses?

    300 mm. f5.6 FA - excellent to the corners, no concerns
    200 mm. f4 FA - likewise
    120 mm. f4 macro A - not super sharp wide open but it's great once stopped down and my favourite focal length.
    75 mm. f 2.8 A - excellent , goodly area of very sharp even at 2.8
    35 mm. f 3.5 A - sharp to 2/3 of the way out, even stopped down the edges and corners are a bit weak - very useable for now but I plan to replace it with the 32-64 if it tests well.

    I did have a 25 but it's electronic aperture so not an option.

    Did the bock of wood solve the vibration in the adapter shoe - after all the trouble I created for myself - sure did, but watch that epoxy. Is the adapter showing any sign of loosening in the front ring - not so far.

    Good shooting,

  2. #2
    Senior Member thrice's Avatar
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    Re: GFX and Pentax Lenses Via Fotodiox Adapter

    Very interesting that the 35 A is not performing out to the corners.
    My HD 35 FA performs fantastically out to +/-15mm shift within the image circle using the A7RII (equivalent to ~95 megapixel 54x36mm sensor).
    The HD version must be better corrected for field curvature on thick sensor stacks.
    Click image for larger version. 

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    Re: GFX and Pentax Lenses Via Fotodiox Adapter

    Quote Originally Posted by GeorgeB View Post
    One of the things I particularly looked forward to in getting the GFX was electronic first curtain as I had found that with my 120 mm. and longer, shutter shake was problematic and between 1/250 and 1 second, almost precluded use of the 300 mm. f5.6 I owned. even before picking up my new GFX I placed an order for the Fotodiox adapter. Just as well as when I picked up the camera, there were no lenses available.

    When I inspected the adapter, it came with an L shaped shoe, the bottom of which had grooves to match Arca Swiss clamps - very nice, but the two small bolts holding the shoe on were loose. I tightened them as best I could, but within 24 hours they were loose again after doing no more than taking a few test pictures. I remounted them with some lactate, which seems to have done the job.

    I also noticed that the whole rig - adapter on the tripod, lens hanging off the front, and camera off the back was quite unsteady - and close inspection showed that it was the shoe to tube of the adapter that was flexing.

    That said, I was quickly able to establish that images with my 300 were very sharp, problem solved.

    I decided to fill the gap under the adapter tubular body with a block of maple, epoxied in place. I was careful to minimize any spill of the epoxy and wiped immediately, but despite my care, within 10 minutes the lens release lever was locked solid and a great deal of force didn't budge it.

    Nothing for it but to take the lens ring off the front of the adapter and see what was up. Seems the epoxy while quite thick, managed to ooze between the ring and tub and entirely fix down the lever. With a small screwdriver acting as a chisel, I worked away at the epoxy and freed up the lever and cleaned up underneath and got it working again.

    I replaced the lens ring only to find that three of the four bolts holding the ring to the tube had stripped their threads. Yes, I do know which way to loosen a screw. The only thing I can think of was that I applied considerable pressure downwards to make the screwdriver grip the small Phillips bolts.

    Now what was I going to do.

    With some reluctance I epoxied the ring down to the tub, being careful that the springs holding the lens wouldn't get glued, and added epoxy to the shaft of each bolt. I cleaned all surfaces with alcohol beforehand.

    I've been out a couple of times since, and so far can report no difficulties mounting my longest lens, the 300 f5.6 - though I'm a lot more careful about not carrying tripod and camera and 300 over my shoulder like I used to.

    The adapter works very well, and is nicely finished and lenses mount solidly as does the adapter to the GFX body. I did find however that the lens release lets light onto the sensor when the camera is in vertical position, so I've had to put some electricians tape over it.

    So what about the Pentax lenses?

    300 mm. f5.6 FA - excellent to the corners, no concerns
    200 mm. f4 FA - likewise
    120 mm. f4 macro A - not super sharp wide open but it's great once stopped down and my favourite focal length.
    75 mm. f 2.8 A - excellent , goodly area of very sharp even at 2.8
    35 mm. f 3.5 A - sharp to 2/3 of the way out, even stopped down the edges and corners are a bit weak - very useable for now but I plan to replace it with the 32-64 if it tests well.

    I did have a 25 but it's electronic aperture so not an option.

    Did the bock of wood solve the vibration in the adapter shoe - after all the trouble I created for myself - sure did, but watch that epoxy. Is the adapter showing any sign of loosening in the front ring - not so far.

    Good shooting,
    What company manufactured the Pentax 645 lens to Fuji Body Adapter?

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    Re: GFX and Pentax Lenses Via Fotodiox Adapter

    Quote Originally Posted by fotophil View Post
    What company manufactured the Pentax 645 lens to Fuji Body Adapter?
    Fotodiox

  5. #5
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    Re: GFX and Pentax Lenses Via Fotodiox Adapter

    Quote Originally Posted by GeorgeB View Post
    One of the things I particularly looked forward to in getting the GFX was electronic first curtain as I had found that with my 120 mm. and longer, shutter shake was problematic and between 1/250 and 1 second, almost precluded use of the 300 mm. f5.6 I owned. even before picking up my new GFX I placed an order for the Fotodiox adapter. Just as well as when I picked up the camera, there were no lenses available.

    When I inspected the adapter, it came with an L shaped shoe, the bottom of which had grooves to match Arca Swiss clamps - very nice, but the two small bolts holding the shoe on were loose. I tightened them as best I could, but within 24 hours they were loose again after doing no more than taking a few test pictures. I remounted them with some lactate, which seems to have done the job.

    I also noticed that the whole rig - adapter on the tripod, lens hanging off the front, and camera off the back was quite unsteady - and close inspection showed that it was the shoe to tube of the adapter that was flexing.

    That said, I was quickly able to establish that images with my 300 were very sharp, problem solved.

    I decided to fill the gap under the adapter tubular body with a block of maple, epoxied in place. I was careful to minimize any spill of the epoxy and wiped immediately, but despite my care, within 10 minutes the lens release lever was locked solid and a great deal of force didn't budge it.

    Nothing for it but to take the lens ring off the front of the adapter and see what was up. Seems the epoxy while quite thick, managed to ooze between the ring and tub and entirely fix down the lever. With a small screwdriver acting as a chisel, I worked away at the epoxy and freed up the lever and cleaned up underneath and got it working again.

    I replaced the lens ring only to find that three of the four bolts holding the ring to the tube had stripped their threads. Yes, I do know which way to loosen a screw. The only thing I can think of was that I applied considerable pressure downwards to make the screwdriver grip the small Phillips bolts.

    Now what was I going to do.

    With some reluctance I epoxied the ring down to the tub, being careful that the springs holding the lens wouldn't get glued, and added epoxy to the shaft of each bolt. I cleaned all surfaces with alcohol beforehand.

    I've been out a couple of times since, and so far can report no difficulties mounting my longest lens, the 300 f5.6 - though I'm a lot more careful about not carrying tripod and camera and 300 over my shoulder like I used to.

    The adapter works very well, and is nicely finished and lenses mount solidly as does the adapter to the GFX body. I did find however that the lens release lets light onto the sensor when the camera is in vertical position, so I've had to put some electricians tape over it.

    So what about the Pentax lenses?

    300 mm. f5.6 FA - excellent to the corners, no concerns
    200 mm. f4 FA - likewise
    120 mm. f4 macro A - not super sharp wide open but it's great once stopped down and my favourite focal length.
    75 mm. f 2.8 A - excellent , goodly area of very sharp even at 2.8
    35 mm. f 3.5 A - sharp to 2/3 of the way out, even stopped down the edges and corners are a bit weak - very useable for now but I plan to replace it with the 32-64 if it tests well.

    I did have a 25 but it's electronic aperture so not an option.

    Did the bock of wood solve the vibration in the adapter shoe - after all the trouble I created for myself - sure did, but watch that epoxy. Is the adapter showing any sign of loosening in the front ring - not so far.

    Good shooting,
    I used a one inch 1/4-20 set screw screwed into the base of the Fotodiox Adapter and extending just up to the adapter barrel. Do not over tighten and put a drop of epoxy at the contact between the set screw and barrel. Before adding the set screw be sure to check the tightness of the little screws that hold the foot to the adapter. Be careful because they are very small Phillips Head Screws that are easily stripped if the screw driver is the wrong size. I was able to remove the two screws so I expoxy bonded the foot to the barrel for extra strength. The Fotodiox Design for attached the foot is pretty lame so strengthing adds security.

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