Larry Rexley wrote:
R2D2 wrote:
YehudaKatz wrote:
R2D2 wrote:
Can you tell us what your definition of a "multilayer" is? Thx.
R2
Thanks. Basically a Tele-adapter for EF-M.
None that I’m aware of either. I suppose because there aren’t any dedicated EF-M telephotos to make use of it.
The “Rexley Special” would be the next best thing (375mm actual).
R2
This thread inspired me to make another attempt at the 'Rexlar' native EF-M teleconverter... I wanted to see if I could get it working with at least one EF-M lens. I've documented my attempts to make an EF-M native TC in 1 or 2 other threads, out of a 'cheap' vintage Vivitar 2x teleconverter. Its optical assembly is very short --- giving it the best chance of success in the very short EOS M optical path... but knowing that it would probably not have great image quality.
Here's my home-made TC, with the vintage Vivitar 2x optical assembly mounted into the 10mm MOVO EF-M native DG extension tube:
Rexlar native EOS M teleconverter (1.43x) - front
Rexlar native EOS M teleconverter (1.43x) - rear
After trying my home-made EF-M teleconverter again on my newly expanded set of EF-M lenses (I've added the 55-200, 28 macro, and kit 18-55) I was not surprised to find that none of my native EF-M mount lenses will focus to infinity with the TC. However --- the EF-M 55-200 was very close --- focusing just short of infinity on tonight's Full Moon.
After studying the TC and the lens, I decided that the 55-200 was my best shot to get this working.... so I shaved off everything I could from the metal barrel of the optics to put them as close as possible to the rear of the 55-200. It helped a little, but still no infinity focus.
So I studied the rear of the 55-200, and realized that if I could just widen the rear plastic opening of that lens, the TC's optical assembly would slide further forward into it and then would almost certainly focus to infinity.
Deciding the risk was worth it (I'll keep the 55-200 for many years as I'm fully dedicated to the EF-M system) I modified the rear of my 55-200 by 'nipping out' the slightly raised section of the rear opening with a small pair of vise-grips, making a clean opening that was just big enough for the optics to slide forward into it:. I did NOT want to take this lens apart or do anything that would have any chance of damaging it:
Rexlar native EOS M teleconverter (1.43x) - front
This worked great --- the TC optics could now be pushed further forward into the barrel, enough to get infinity focus! Success!
To my knowledge this is the first (and perhaps only) optical-path native EF-M teleconverter.
Here are some sample shots with the TC and the EF-M 50-200: Tonight's Full Hunter's Moon, and the banks of downtown Tampa from a mile away - taken with the EF-M 55-200 IS STM without, and with, the teleconverter. Even though the original vintage teleconverter was labeled '2x MC' in my optical path, measurements from the Moon images yield a magnification of about 1.43x and a light loss of one f-stop.
The Moon images are cropped to pixel resolution, the other two images are at full resolution - no images were downsampled. Processing was the same within each 'set' of images, using DxO Photolab 5.
Hunter's Moon. Canon M6ii, EF-M 55-200 f4.5 - 6.3 IS STM, 200mm, f6.3, 1/800s, ISO 100
Hunter's Moon. Canon M6ii, EF-M 55-200 f4.5 - 6.3 IS STM, Rexlar 1.43x teleconverter, 286mm (200mm x 1.43), f9 (f6.3 x 1.43), 1/400s, ISO 100
Tampa Banks from 1 mile away. Canon M6ii, EF-M 55-200 f4.5-6.3 IS STM, f6.3, 2s, ISO 800
Tampa Banks from 1 mile away. Canon M6ii, EF-M 55-200 f4.5 - 6.3 IS STM, Rexlar 1.43x teleconverter, 286mm (200mm x 1.43), f9 (f6.3 x 1.43), 4s, ISO 800
- Note that this home-made teleconverter will only work on a Canon EF-M 55-200 IS STM whose rear has been modified (opening widened) to accommodate its optics
- The lens + teleconverter appears to resolve more detail across the center 30-40% of the frame than the lens alone
- Since the optics were from a cheap Vivitar MC teleconverter, the corners of the image are soft - this isn't surprising. The optics were also probably not perfectly aligned.... so there is likely some decentering.
- The TC is non-reporting as its optics are mounted in a MOVO EOS-M DG extension tube which knows nothing about the optics. The tube just passes the lens' info straight to the camera, so the EXIF data needs to have the focal length and f-stop multiplied by the TC's magnification, 1.43x
Correction - I went through my parts box and it was not a Vivitar teleconverter I made the EOS M teleconverter from, it was a Promaster Spectrum 7 MC 2x teleconverter in Minolta M/MD mount, exactly like the one in this current ebay listing:
The Vivitar 2x TC I have has a slightly longer optical tube assembly and I can't achieve infinity focus with it in my home-made converter --- only a very short optical tube assembly like the one in the Promaster will work with a MOVO EOS M 10mm extension tube (and only by modifying the rear of the EF-M 55-200 lens).
