quincy

According to Fujifilm, the XF 18-55 at 55 mm has a maximum magnification of 1:6.67, while the XF 90 has a maximum magnification of 1:5. This means, when both lenses are at their close focus distance, the XF 90 should see a slightly tighter crop. The image area in the plane of focus of the XF 18-55 at 55 mm should be around 16.7 cm x 11.1 cm, while the image area of the XF 90 should be ~ 12.5 cm x 8.4 cm. I've added those frame lines to your image: But please also consider that your depth of field gets smaller as your magnification increases. So even if you buy a lens with better magnification and brighter aperture, you might still end up closing the aperture down to get the whole head in focus. I've added some pictures I took with the XF 80 f/2.8 wide open at f/2.8: (the last bird might even be a pigeon, but you'll know better than me) You can see that at f/2.8, the feathers at the back of the heads as well as the beaks are already very unsharp and out of focus in the portrait images while the eye is sharp. Even with less magnification as seen in the last picture, you can run into those problems.

The Fuji 90 mm f/2 has approximately 12.5 cm x 8.4 cm field of view (1:5 magnification) at the close focusing distance of 0.6 m. I'm not quite sure if that's enough for "head and shoulder" portraits of birds, but it might work. The 80 mm f/2.8 macro will do 2.51 cm × 1.67 cm (1:1 magnification), which is definitely enough, while the 60 mm f/2.4 macro can reach 5 cm x 3,3 cm (1:2 magnification). (The Zeiss 50 mm f/2.8 macro can also reach 2.51 cm x 1.67 cm, by the way.) Your 18-55 has a maximum magnification of 1:6.6, so if that was enough for you, the 90/2 should work. Right now, I don't think there is a native Fujinon lens with an aperture of f/2 or brighter that can focus closer than the 90/2 can. (Except for the 16/1.4 which will distort your birds badly). I think any of the three (60, 80 or 90) could suit your needs, or you could really just add a flash or continuous light with softbox and stay with the 18-55. If manual focus is an option, there are lots of third party lenses you could adapt or even get in FX mount.

I bought a Samyang 135/2, and I can use the Fuji 1.4x TC with it. The front part of the 2x TC looks the same, so it should also work. However, with the 1.4x TC, I see a slight reduction in sharpness. I guess the 2x TC will be worse. The same 1.4x TC on the Fuji 80/2.8 Macro causes no visible degradation of the image, so I think it's the Samyang 135/2 at its limit.

Ok, so when you close the aperture while keeping ISO and shutter speed the same, the live view image in your viewfinder should get darker. You can use that information (or the live histogram) to adapt shutter speed or ISO yourself. (Or you let the camera do the job with one of the auto-settings)

If you turn the aperture ring on the lens (when it is attached to the adapter & camera), does the aperture change size?

FD lenses don't transfer aperture information to the camera. The aperture coupling in the FD bayonet was completely manual. If you look at the back of your lens, there is a lever that runs on a circular track. This lever, if moved all the way to the other side, stops your lens down until it reaches the value you set at the aperture ring. This means you need an adapter with a built in mechanical coupler. The simplest ones just have a pin which moves the lever all the way down while you attach the lens to the adapter, and then you can simply adjust the aperture by turning the aperture ring. More fancy ones have an additional ring on the adapter, to simulate the camera stopping down the lens. I have one of those: https://www.metabones.com/products/details/MB_SPFD-X-BM2 You can see the (movable) pin inside the adapter, at the bottom. If your adapter does not have a pin / ring etc., your lens can't stop down. However, even if it does, your camera does not know the aperture setting. Good thing is, the camera does the metering (for exposure) without knowing the aperture setting, by just simply evaluating the live feed off the sensor, and can adjust ISO / shutter speed accordingly.

With Canon FD lenses, two things will not work automatically anymore: focus and aperture setting. Everything else on your camera still works in auto-mode, if you wish so. Especially automatic ISO as well as automatic shutter speed. If your viewfinder is set to "preview exposure and white balance", then what you see is what you get. If you want your camera to evaluate and set your exposure for you, just dial in the aperture you want to have on your lens, and let the camera do the rest (auto-ISO, auto-shutterspeed). You can even chose one of those (e.g. the shutterspeed) yourself, and let the camera set the right exposure via the other one (ISO in this example). If you want to use the camera fully manual (set aperture, shutter speed and ISO yourself), then you can either use the EV meter or the histogram in your viewfinder, or the viewfinder image itself to set the exposure as you want. Just a small hint: use the aperture to define your depth of field, use the shutterspeed to freeze motion (or to allow movement, if you wish), and then use your ISO to compensate for the correct brightness of your image. And have fun!

Depending on the distance between camera and subject, your lenses might change focal length. This is also called focus breathing. Try both lenses focused at infinity.

that adapter is too short (as written in the description). Try to find a "PK-FX" or "K-mount - FX" adapter. You need a correction of the flange distance from Fuji X-Mount (17,7 mm) to Pentax K-Mount (45,46 mm), so the adapter should be 27,76 mm long.

The old one does, but I'm not sure about the new one that comes with the 200/2.

sell both and get the 27/2.8

As lens&body have the newest firmware installed, I think the rotary encoder telling your lens at what focal lenght it is, is either broken or unattached to the mainboard, hence not communicating. If you stop the aperture down yourself to f/8 or something, while at 55 mm, this will probably show as 18 mm f/8. Anyway, your lens needs to be serviced.

if you take a picture at 55 mm, what focal length does the lens report to the camera (what does the exif data say) ?

thanks, that did it

I've added the neewer and lensbaby lenses and removed Meyer Optik Görlitz completely due to the Net SE bankruptcy. I'll add them again if they find a way to deliver what has already been paid and was promised to their (kickstarter) customers and stay alive as a company. The Samyang 85 will follow when it is released. By the way, something is wrong with the upload function. My (new) lens chart needs ~ 228 kB, but i get an error message that i'm not allowed to upload more than 512 kB.