Skywalker688
Active member
So Duncan, what do you think would solve that issue on the redrock? If it had a collumating lens mount, would that fix it?
Amazing new redrock product!!!!!
- Thread starter Skywalker688
- Start date
aurantaurant
Well-known member
I've never used that lens so I wouldn't know about that. My 24mm lens works great.
"Properly" means following the instructions given by redrock to use their hardware. Sometimes you might have to zoom in a little more.
I would however suggest the LETUS Extreme for newbies to 35mm adapters. I suggested one to my ex girlfriend, because most people just want to take it out of the box and go and shoot. The m2 isn't really like that. It's like a horse... you gotta let it get used to your scent and you gotta feed it snacks a bunch before it starts to do what you want. Then when you're robbing a bank you can just whistle and it shows up.
The LEX is like a donkey. Sure it can get Jesus to the stables, but it won't help you outrun the law.
"Properly" means following the instructions given by redrock to use their hardware. Sometimes you might have to zoom in a little more.
I would however suggest the LETUS Extreme for newbies to 35mm adapters. I suggested one to my ex girlfriend, because most people just want to take it out of the box and go and shoot. The m2 isn't really like that. It's like a horse... you gotta let it get used to your scent and you gotta feed it snacks a bunch before it starts to do what you want. Then when you're robbing a bank you can just whistle and it shows up.
The LEX is like a donkey. Sure it can get Jesus to the stables, but it won't help you outrun the law.
Skywalker688
Active member
Nice analogy
If that's collimation as in what they usually refer to as "setting the backfocus" then that would help a whole bunch in terms of usability of the product. The existing set-n-test-n-reset-n-retest method is a bear (though as long as you don't change lens mount types, it is a one-time thing, thankfully.) I don't think that will help the vignetting, other than the vignetting which is caused by incorrect backfocus (which is not nearly all the vignetting.)
Duncan
Skywalker688
Active member
Hmmm. Interesting....
Skywalker688
Active member
Well what is it in the redrock that you believe causes the vignetting, that the other lens adapters don't have?
Matt Gottshalk
Resident Preditor
Didn't know Jim Jannard had an account here.....
This just makes no sense to me. You're actually citing the LEX's user friendliness as proof that it's a worse adapter? Apparently the people who prefer not to spend hours tweaking their adapter to get a useable image just aren't hardcore professionals. Time is money and I just can't afford to waste time on set babysitting the gear.
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An Ultimate and Blade competitor? I guess that is exactly what it is... now it may be cheaper than even the Blade but which will be best when they are all out not only remains to be seen but will likely be such a close call that it will be open to personal taste. At least that's what I hope for.
Now if it is a new adapter and it is as good as the Blade but cheaper then that would be even better.
Now if it is a new adapter and it is as good as the Blade but cheaper then that would be even better.
As near as I can tell, they all vignette with wide angle lenses. I am desperately searching for one that doesn't, eagerly eyeing developments noted here in this forum, for instance. The vignetting is heavily affected by the design of the ground glass, so if I had to guess I'd say RedRock did a great job with their design in terms of "film look" (everyone, including me, seems to like their look), without so much noticing what it did with wide angle lenses (or really, any lens with a small rear exit pupil.)
Duncan
You can't imagine the time and effort I put into trying to sort out a way for my wide angle lenses to work with my M2. I spent so much time tweaking and retweaking it... none of it helped by the off-center HVX200 sensor of course, argh...
Here was a significant expenditure of time:
http://www.betlikeduncan.com/duncan/redrock/lenscharts/canon_fd/
Comparing to the still images you can see even with "zooming in a little more" and reducing the horizontal field of view, I was still getting pretty awful vignetting on certain lenses. The dark area on the left was the interaction of the HVX200 off-center sensor and the no-room-for-error tunnel through the MicroX.
Duncan
Skywalker688
Active member
I would agree about the wide angles and small rear lens elements. I have always wondered why that was a problem, and my only thought was that because the cone between the front and rear element was so extreme. I figured that being able to move the lens mount backwards or forwards would help. I think any time you have so much glass in between the image and your chip, it gets complicated. However, I think you will be excited with what Redrock is releasing.
If you have the backfocus set wrong, you are almost certainly going to increase the vignetting, even if you compensate for the incorrect backfocus by refocusing the lens. (Obviously your ability to compensate runs out at one end of the scale or the other, depending on which way it's off!)
There seem to be two issues at work with the vignetting:
-- Depending on the ground glass design, it might pass light rays through differently, depending on the angle at which they strike the ground glass. Film emulsion doesn't so much care at what angle a photon hits it. You get more extreme angles at the edges of a wide angle lens image, so this vignetting is particularly an issue with wide angle lenses.
-- Depending on the ground glass design, more or less of the unfocused rays of light from the back of the lens might pass through it. Hold a lens up to a bright scene and look at the back of it - you see light coming through into your eye that is not the focused image light that is the main function of the lens. The more transmissive a ground glass is, the more of this "hotspotting" you are going to get. If you're trying for an adapter that doesn't lose too much light, you are going to be fighting this. The hot spot should actually be a worse image, seeing as how it's random light washing out the nice focused light rays, but the problem is the difference in light levels between the two areas. If you meter for the center, the edges look dark, so they look like the worse area. This hotspotting looks worse the smaller the lens' rear element is, regardless of how wide angle it is. On that chart of lenses I posted, note particularly the results from the 50/3.5 and 50/1.8, which have itty bitty rear elements. Horrific hotspotting even though they're not wide angle lenses.
The 24/2.8 is the perfect storm of these two problems - fairly wide at 84 degrees and fairly small rear element (like any wide angle would have, unless it's something like the 24/1.4 monster.) I've shot a whole lifetime of stills through that lens - I use it as my "normal lens" instead of a 50 - so imagine my disappointment to have it peform so wretchedly on a 35mm lens adapter. Nothing wrong with the lens itself, just how it interacts with the adapter.
Duncan
There seem to be two issues at work with the vignetting:
-- Depending on the ground glass design, it might pass light rays through differently, depending on the angle at which they strike the ground glass. Film emulsion doesn't so much care at what angle a photon hits it. You get more extreme angles at the edges of a wide angle lens image, so this vignetting is particularly an issue with wide angle lenses.
-- Depending on the ground glass design, more or less of the unfocused rays of light from the back of the lens might pass through it. Hold a lens up to a bright scene and look at the back of it - you see light coming through into your eye that is not the focused image light that is the main function of the lens. The more transmissive a ground glass is, the more of this "hotspotting" you are going to get. If you're trying for an adapter that doesn't lose too much light, you are going to be fighting this. The hot spot should actually be a worse image, seeing as how it's random light washing out the nice focused light rays, but the problem is the difference in light levels between the two areas. If you meter for the center, the edges look dark, so they look like the worse area. This hotspotting looks worse the smaller the lens' rear element is, regardless of how wide angle it is. On that chart of lenses I posted, note particularly the results from the 50/3.5 and 50/1.8, which have itty bitty rear elements. Horrific hotspotting even though they're not wide angle lenses.
The 24/2.8 is the perfect storm of these two problems - fairly wide at 84 degrees and fairly small rear element (like any wide angle would have, unless it's something like the 24/1.4 monster.) I've shot a whole lifetime of stills through that lens - I use it as my "normal lens" instead of a 50 - so imagine my disappointment to have it peform so wretchedly on a 35mm lens adapter. Nothing wrong with the lens itself, just how it interacts with the adapter.
Duncan
Have I mentioned spending wayyyyy too much time and energy on this whole thing? I decided to see once and for all what is coming out the back of my 24/2.8 lens. Light rays to film. No ground glass, no achromats, no prisms, just every single photon exiting from the lens captured on film.
I constructed an FD lens mount board for my 4x5 camera, set the backfocus, then exposed some film. (B&W so I could do my own processing at first. If I decide to run through all my lenses with this rig, I'll do it in color.) Here it is scanned in, with a to-scale 24x36mm rectangle superimposed, so you can see what portion of the image is used in a still camera. Note that like any optics, there is vigentting near the physical edges... but that the usable area is well inside those edges:
http://www.betlikeduncan.com/duncan/redrock/lenscharts/canon_fd/lenscircles/24_28_boxed.jpg
For comparison, I also did the 24/1.4. Indeed, slightly less vignetting, but still nowhere near the usable image area anyway.
http://www.betlikeduncan.com/duncan/redrock/lenscharts/canon_fd/lenscircles/24_14_boxed.jpg
(My son puts up with all my weird projects like a trooper...)
Duncan
I constructed an FD lens mount board for my 4x5 camera, set the backfocus, then exposed some film. (B&W so I could do my own processing at first. If I decide to run through all my lenses with this rig, I'll do it in color.) Here it is scanned in, with a to-scale 24x36mm rectangle superimposed, so you can see what portion of the image is used in a still camera. Note that like any optics, there is vigentting near the physical edges... but that the usable area is well inside those edges:
http://www.betlikeduncan.com/duncan/redrock/lenscharts/canon_fd/lenscircles/24_28_boxed.jpg
For comparison, I also did the 24/1.4. Indeed, slightly less vignetting, but still nowhere near the usable image area anyway.
http://www.betlikeduncan.com/duncan/redrock/lenscharts/canon_fd/lenscircles/24_14_boxed.jpg
(My son puts up with all my weird projects like a trooper...)
Duncan
aurantaurant
Well-known member
Duncan you have a lot of sweet lenses.
dlang
Well-known member
alright skywalker how much are you getting paid for this thread?? These guys know us so well, I've seen some far more interesting topics with waaay less responses, yet this one has managed to acquire 10 pages in 2 days...buzzzz is all I gotta say, it's the curiosity that gets us, almost like a suspense thriller(;
These guys know us so well, I've seen some far more interesting topics with waaay less responses, yet this one has managed to acquire 10 pages in 2 days...buzzzz is all I gotta say, it's the curiosity that gets us, almost like a suspense thriller(;Skywalker688
Active member
I wish they were paying me in redrock products I am just a customer who apparently spent too much time asking questions
The good news is that I have been assured that the official announcement will be coming very very soon...
I am just a customer who apparently spent too much time asking questionsThe good news is that I have been assured that the official announcement will be coming very very soon...
I've been shooting through Canon FD glass (and slowly acquiring more of it!) for over 30 years. I've always imagined how wonderful it would be to be able to shoot movies through them, but always figured that was not to be. Then along came the M2 and others! Oh joy oh joy! But the problem is that I'm a complete wide angle fanatic, and those turn out to be the Achilles' Heel of the current crop of adapters.
I'm very used to the gorgeous edge-to-edge clean bright image I get through these lenses and it just killed me to see the vignette/hotspot images that resulted through the M2. So I sold it again a while back (the stupid off-axis CCD HVX200 also) and am back in "it was not meant to be" mode until equipment exists that can do right by my lenses. Which is why I'm here - looking, researching and hoping, ever hoping.
Duncan
Yes, I've been eagerly awaiting the results of people testing the Blade, as the example footage I've seen looks remarkably problem-free. I'm glad someone actually has a 24/2.8 to try on it.
It's also worth pointing out that I'm incredibly picky about this and footage that most people are quite happy with simply drives me up the wall. It completely baffles me when people go out of their way to add vignetting to footage! (I almost can't watch the BBC show Top Gear sometimes for all the post-vignetting they do.)
Duncan
It's also worth pointing out that I'm incredibly picky about this and footage that most people are quite happy with simply drives me up the wall. It completely baffles me when people go out of their way to add vignetting to footage! (I almost can't watch the BBC show Top Gear sometimes for all the post-vignetting they do.)
Duncan