The term “relay lens” is fairly new. In the strictest terms, a relay lens is a lens that is used in between a camera body and another lens. As it applies to us, a relay lens is the lens we would mount to a 1/3, ½ or 2/3 inch B4 mount camera or camcorder to allow use of a depth-of-field adapter like a Letus, Red Rock, Blade or others.
It is the lens that does the first focusing of the camera to the oscillating or spinning glass in the adapter thus capturing the reflected image coming through the adapter.
In truth, if you have a camera with a fixed lens (Sony PMW-EX1, Panasonic AG-HVX200A, etc.) and are using a DOF adapter, then that fixed-position lens is your relay lens.
I receive many questions on detachable-lens small-frame camcorders like Canon XL-H1 and Sony PMW-EX3. On these cameras, and a few others, the primary lens comes off allowing the use of other lenses. Odd thing is, there are often very few lenses the manufacturers offer outside the lens the unit shipped with. Yes, there is a Fujinon XS8X4AS-XB8 8X wide angle for the EX3 that nobody buys because nobody can remember the model number. And if they did, it would cost them about $3800.00.
Remember the Canon XL-1? Canon did it up big time and offered four different XL-mount lenses. A 3XL wide, a 14X Full Manual, a 16X Servo ENG-style, and even a 3D lens that has only been seen in pictures. People bought them up and they worked well, even though the original 16X was generally sufficient. Sadly, the offerings of late have been a bit weaker.
In Sony-land, there is a Fujinon-built adapter that allows the EX3 to use a 2/3in. standard B4 mount lenses. It is called the ACM-21 and runs about $1850.00. If you needed a really long shot, much longer than the stock lens can achieve and such as might be necessary at an LA Coliseum sports event, then you would be able to use a 40X long zoom. B&H has a sweet little Canon HD 40-by for only $71,500. Almost too good to pass up. But the question remains - Would you? No, but you could.
How often does a person need $73,350 in lenses & accessories for their $8300 camcorder?
Having said all of this - I will now extend that logic to relay lenses. Letus has a few offerings for those that own a native 2/3in. mount camcorder like an SDX900, a F900 or similar HD or SD. The Letus adapter works quite well with these camcorders and the purpose-built relays are spot-on. 2 2/3in. Versions exist, and one for 1/2in. mount camcorders.
The larger 2/3in. Mount adapter runs about $6000, the small (compact) about $3500, and the one for 1/2in. Mount that runs about $4000. But are these investments necessary? Pehaps, but I took a different path and seem to have found equal success.
I purchased a simple Canon 15X B4 mount lens that I think came from a SDX900. It’s front-of-lens thread was 82mm. My HVX-optimization module was (no coincidence) threaded for 82mm. I had a friend bring over his Panasonic Varicam and we proceeded with the test. Off came his really nice 18X HD Fuji lens and on went the 15X. We set up the remainder of a Letus Elite system in the normal way, as if it were a non-detachable lens camcorder. Within minutes, we found the sweet spot in the 15X’s focal range, put on a Nikon 55mm f.1.2 lens and found focus.
(I should mention at this point that I have set up the Letus adapters with a JVC GY-HD110U many times, it too has a detachable lens, albeit a 1/3in. Each time a success, but I need to confirm this optical logic and process can extend all the up to the big boys).
We set-up our camera room and shot Century Seimens Stars and Resolution charts, displayed the output via HD-SDI on a Sony LMD-9050 1100TVL monitor and just as I thought – we achieved at least 1100 TVL, and with Star Interpolation it appears that we hit the 1920 Holy Grail of full HD resolution.
And why not? The SDX lens is real good, designed to pass 50Mb “Digital Betacam-level” resolution and then some. The Nikon’s can clear photo-grade resolution of who knows how much, and the Letus has no real resolution limit.
I paid $275 including shipping for the Canon 15X from Ebay.
So what is the lesson learned here? Well, there may not be one. All I’m saying is that I didn’t spend $6000. Nor did I spend $3500, and I believe I achieved all that I could have if I were to have spent the money on dedicated relay lenses.
All of this hard to believe? Call me up, bring your Varicam or F900 and I’ll repeat the experiment for you if you promise to spend the difference between $6000 and $275 on rentals.
Tags: detachable lenses, Relay lens
It’s hard not to love your blog. Your issue was well broken and I can’t help but be in agreement with your feeling. Great presentation, as well!
Just thought i would comment and say neat theme. Can not wait for the launch of the SDT750 3D Camcorder. Its the worlds first 3D consumer camcorder.