Originally posted by SOldBear Yeah, it's mainly trial and error. I just stack a bunch of step-down ring adapters to the lens and try to meter and/or focus. If the metering changes or focusing becomes more difficult, I go back one step of step-down ring. 50mm lenses in particular work very well, even on a film camera.
This is very cool! I'm surprised to hear that this works even on film cameras - I would've expected there to be vignetting.
Originally posted by SOldBear So far, all the lenses I try from 24mm to 90mm focal length can go down to 30.5mm opening. The longest is Tamron 90mm macro F/2.8, the shortest is Pentax-M 24mm F/2.8. The DA 21mm Ltd. can go down to 30.5mm too but it needs a thin 49-37mm ring (Sonia). The B&W ring, only 1mm thicker, results in vignetting. In the photo, the DA 70mm is on the camera, the other two lenses are DA 21mm and DA 40mm (with its original lens hood).
This concept of an "inverted hood" is really neat, but I find it counter-intuitive. How come it works? It sort of makes you wonder if they could've made the front elements smaller? But I'm no optician so maybe there's something that I'm missing. Anyways, I really like this idea as it looks good, saves space, and affords more protection to the front element.
Actually, I just thought of something - would this setup be more likely to cause vignetting when focusing on closer subjects?
Originally posted by SOldBear The Vivitar 135mm Close-Focusing F/2.8 can go down to 49mm from 62mm. I then add a Pentax 49mm hood:
This kind of lens hood doesn't work well with zoom lenses. They should use their dedicated hoods.
Yes, I like this a lot! I hate carrying bulky hoods for my telephoto lenses. Time to go hunting for some cheap step-down rings!
Thanks again, and by the way, apologies to joelc for this thread hijack...