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Square front anamorphic barrel distortion


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#1 Freya Black

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Posted 19 September 2007 - 02:13 PM

How bad is it?
I have a set of Lomo Anamorphic Square fronts.

I think they are 35, 50 and 75.

I'm wondering how bad the barrel distortion is likely to be at each focal length.
I think the most recent of the lenses dates to 1976.

Is the barrel distortion likely to be less of a problem with an Anamorphic Foton Zoom?

Also does barrel distortion appear less pronounced if the subject is further away? Obviously you could then use lenses that are more telephoto but I was wondering for the same focal length?

I've heard that having the subject to one side or another of the lens will help reduce the effects of barrel distortion. Anyone got any other tips?

love

Freya
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#2 Max Jacoby

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Posted 19 September 2007 - 02:51 PM

I don't understand why you are asking about barrel distortion when you say that you have a set of Lomos yourself. Why not just put them on a camera and look through to make up your own mind?
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#3 Freya Black

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Posted 19 September 2007 - 02:59 PM

I don't understand why you are asking about barrel distortion when you say that you have a set of Lomos yourself. Why not just put them on a camera and look through to make up your own mind?


You know thats a very good point! *giggle*
I havn't stuck them on the camera because shortly after I got them a friend came round my house and took it upon herself to throw out my anamorphic gate. :(

It actually just never occured to me to try and look at them through the viewfinder. Too long using non reflex cameras!

The other problem I will have is that I really want a human subject and I don't have one right now but I could look at various objects and stuff I guess.

Ultimately I will have to shoot tests and find out, so maybe the whole questions a bit stupid.

Theres a part of me thats already leaning more and more towards using the normal primes for films with human subjects however, even tho I love scope.

love

Freya
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#4 Max Jacoby

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Posted 19 September 2007 - 05:35 PM

The other problem I will have is that I really want a human subject and I don't have one right now

Do you live in the Antarctic?
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#5 Freya Black

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Posted 20 September 2007 - 01:47 AM

Do you live in the Antarctic?


It feels like it sometimes, it's certainly very cold in the place where I am right now.

love

Freya
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#6 James Steven Beverly

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Posted 20 September 2007 - 03:27 AM

Freya, find a geometric pattern, a building with a set of the exact same size windows spaced equally apart or a clapboard house. This will make any barrel distortion readily apparent. I've heard Lomo square fronts flare and breath a lot but I haven't heard any complaints about them having a significantly abnormal amount of barrel distortion. The 35 will probably have the most of your set as with pretty much all anamorphics, from what I've read, you usually start having problems when you go under 40mm. You can and should read Max's anamorphic post in the FAQ section if you haven't already. Despite his colorful replies here, he is really quite knowledgeable in this area and there's a lot of good information there so it's definitely worth a read. BTW, WHY would your friend, (and I use the term loosely if he's messing up your camera equipment,) toss out your anamorphic gate??? Is he "slow" or something? Fortunately the Konvas gates are pretty cheap unlike the Kinors but still!!! :blink:
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#7 Freya Black

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Posted 20 September 2007 - 07:04 AM

Freya, find a geometric pattern, a building with a set of the exact same size windows spaced equally apart or a clapboard house. This will make any barrel distortion readily apparent. I've heard Lomo square fronts flare and breath a lot but I haven't heard any complaints about them having a significantly abnormal amount of barrel distortion. The 35 will probably have the most of your set as with pretty much all anamorphics, from what I've read, you usually start having problems when you go under 40mm. You can and should read Max's anamorphic post in the FAQ section if you haven't already. Despite his colorful replies here, he is really quite knowledgeable in this area and there's a lot of good information there so it's definitely worth a read. BTW, WHY would your friend, (and I use the term loosely if he's messing up your camera equipment,) toss out your anamorphic gate??? Is he "slow" or something? Fortunately the Konvas gates are pretty cheap unlike the Kinors but still!!! :blink:


I've read Max's anamorphic FAQ and I've caught his other postings on the subject. Someone posted that Anamorphics were much more prone to barrel distortion a while back, which got me thinking about the subject , it might have even been Max. I guess the stuff about pixelvision and going to see a movie last night kind of came together to make me wonder about it all some more.

Yes the gates are cheap but the lenses aren't, and it's been frustrating not having the gate and all these fancy lenses! Ironically at the time I first bought the gate on ebay they were common place and I paid virtually nothing for mine. These days all the Konvas gear seems to be really, really drying up and I've had trouble tracking down a replacement gate.

It was another girl who tossed out the gate. She is an old friend and she was trying to help me out because things have been very bad for me recently. Sadly she was helping me wiythout asking me and she saw a seemingly empty box of bubble wrap on the shelf and chucked out the contents. Of course there was a tiny film gate in there! She meant well so I partly forgive her, it's just things are bad right now, best not to dwell on bad things.

I'm actually finding Max's "colourful replies" somewhat useful, as they are making me think about things, especially as they are vague and open ended. It's helping me think the process through. Now I'm realising that it might not be so easy for me to detect the barrel distortion as I don't have an anamorphic desqueezer viewfinder. I also don't really want one as apparetly they are darker, they are certainly more expensive, and lastly because I've been shooting anamorphic DV for a while and have been happy just composing shots with the squished image. It's not been a problem for me so far. Then again maybe any distortion will be just as noticable, if I'm concentrating properly and not being distracted by the fact the image looks weird anyway.

I'm also realising that I had completely forgotten that I still havn't found a support solution for the lenses. I was thinking at one point that I would build something, but I've never got around to it. It always suprises me how little Konvas supports you ever see for sale! It seems like they should have survived more easily than the lenses which are made of glass! Supports seem as rare as rocking horse s***. I actully have a support for my foton zoom lens, although it needs altering as it doesn't actually fit any Konvas I own quite. It nearly fits one of them tho. Thats a very strange bar however It won't work as a support for the anamorphics. I could just hold the lens in place by hand of course but...

...I need to find a solution to that.

I'm actually toying more and more with the idea of shooting acadamy for some of the projects I have in mind. I don't really like the idea of 1.85:1 that much. I'd rather shoot scope for a whole host of reasons, but it seems like it might be awkward to supoort the lenses and secondly the barrel distortion could be an issue. I'd like to avoid it.

Ultimately I will need to shoot tests of both either way. At the moment the support issue might be the thing that swings it. I've had things on my mind lately and I just completely forgot that I hadn't sorted out any support for the lenses, so I just thought it was more of a straightforward choice than it really is. I have these lovely scope lenses sitting in a box waiting for me but the reality is, it's not that straightforward.

Thanks for your reply Steven. I may be yanking out a Konvas and having a look shortly.

love

Freya
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#8 James Steven Beverly

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Posted 21 September 2007 - 01:04 AM

I'm sorry to hear you're having a rough time but as my dad always says, "They can't eat you!" so try and not let it get you down. It's probably money or a guy and either of these are NEVER gonna last forever so just hang tough and you'll get through it.

NOW on to GOOD things!

$55 dollars plus shipping will set you free! :D rafcamera.com/konvas-film-gate-p-46.html

also for another $75 plus shipping US you MIGHT just run across a few rocking horse road apples (very funny BTW, I've never heard that expression before):

rafcamera.com/universal-dovetail-support-p-59.html

The dovetail plates that these supports slide on come up fairly regularly on ebay and sense I check it everyday, I'll give you a heads-up when one is listed.
I actually want to get a set for the older Lomo mouse eared OCT-18 mount anamorphic lenses for my KSR-1 turret Konvas because I wanted to possibly do some MOS shakycam, steadicam and hand-held work on Blood Moon as the Werewolf's POV if the footage will cut together with the Lomo round-front stuff I'll be using for the rest of the picture which will be shot on a Kinor 35C. The only ones I've found however are anamorphic square front attachments for the 35mm which makes me wonder if they ever made another focal length for the mouse ear Lomos. If that's all I can find, and they will cut together, that's what I'll use, barrel distortion be damned!

That being said, I REALLY wouldn't worry all that much about barrel distortion, the Russians use the damn things for YEARS so they probably work just fine. Just watch how you use the 35mm is all, save it for scenes where fall off might help hide any potential distracting distortion or where the outer edge is not critical or where the subject or composition lends it's self to the distortion by being less noticeable then say a straight line or geometric pattern, that is IF there is actually any "problem" at ALL.

I'd be much more careful about rack focusing and wild flares that may distract from what you're trying to accomplish in any given shot. At SOME point, you should probably get a de-anamorphic veiwfinder, down the road, just to check your composition. David recommended this in a thread I had about anamorphics a while back. What I have to do (aside from FINDING a Kinor gate and having it machined to anamorphic, thank you very much, because I will probably NEVER find an original Kinor anamorphic gate) is send Steve Morton a Konvas de-squeezer and a Kinor 35C standard viewfinder and have him BUILD me a Kinor 35C desqueezer which is going to cost the equivalent of a small nation's GNP, BUT then I should be able to change the viewfinder over to check composition then put the standard back to check what's actually in the frame in a larger image to look for mistakes before I roll the camera. I'll probably have to throw a blanket over the camera during the operation so as not to flash the film but it should work and do the same thing a Panavision switchable viewfinder can do with a little more effort.

I guess what I'm saying is don't worry about it until you SEE there actually IS a problem. EVERYONE is going to find fault so wait and see if THEY'RE the one's with a problem and not you lenses. Anamorphic is a WONDERFUL option to have as a filmmaker so don't start building up a wall of doubt around one of the absolutely COOLEST tools you have in your arsenal! B)

Edited by James Steven Beverly, 21 September 2007 - 01:08 AM.

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#9 Christian Appelt

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Posted 21 September 2007 - 11:35 AM

Freya,

the only lens in your set that will show some barrel distortion that actually matters in real-life conditions is the f=35mm square front lens.

So if you are shooting geometric patterns like the window front of a building or a wide fence with this wide angle lens, don't expect the lines to be straight. If you use an 18mm lens in spherical format, the problem will be the same.

Just yesterday I telecined some Konvas footage shot with f=35, 50 and 80mm square front anamorphics only, and it looked slightly better than the Foton-A zoom footage I shot before under same lighting conditions. In wide position which is f=37mm the distortions are not very different from the f=35mm fixed lens.

I recommend doing some test shots, then you get a feeling for the rendition of space these lenses will give you. Both the 35&50mm lenses have very good sharpness, but remember to keep stray light from the front lens. A matte box is the best investment you can make when shooting with these anamorphics, Rafcamera should have one for you. They also turn up on eBay frequently.

Do some tests so you know what your lenses can do, checking and doing tests is essential with all Konvas equipment.
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#10 Freya Black

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Posted 21 September 2007 - 03:44 PM

I'm sorry to hear you're having a rough time but as my dad always says, "They can't eat you!" so try and not let it get you down. It's probably money or a guy and either of these are NEVER gonna last forever so just hang tough and you'll get through it.


They are welcome to eat me! I'm not afraid of that! :)
It's more to do with a paticular society or a couple of paticular societys.
I just ran into a very messed up girl who bullied me a lot, spread all kinds of fictions about me, destroyed the vast majority of my friendships, damaged me badly psychologically and managed to make me very disillusioned with art. I wish I could help her overcome the monsters in her head but she is just really destructive and eventually you have to say enoughs enough to protect yourself and your own sanity. I've learnt an awful lot from the whole experience and I'm hoping to manage to get away from the town where I'm living and to try and start again. At least that's what I hope when I'm in a good mood. Anyway I don't want to dwell on bad stuff, I'm trying to put it in the past now, and I'm just dealing with the effects of it all.

Better to think positive thoughts no matter how fantastical.
Good thoughts lead to good things, at least some of the time.

NOW on to GOOD things!

also for another $75 plus shipping US you MIGHT just run across a few rocking horse road apples (very funny BTW, I've never heard that expression before):

rafcamera.com/universal-dovetail-support-p-59.html

The dovetail plates that these supports slide on come up fairly regularly on ebay and sense I check it everyday, I'll give you a heads-up when one is listed.


Ah! I didn't know what road apples were either. I've heard bad models of macs described as road apples but I always assumed it came from the expression "one for the road!". Now I know better!

Well I've not seen the dovetail support before! I guess that could be useful on one of my really long lenses! :)
However I actually have the front bit of the lens support but not the base plate bit or whatever and I'm not even sure what goes between. It looks like there might be rods but there also seems a bit for a flat bit to attach to. Actually it seems like the rods are the most important bit as there is a little screw thing to tighten the rods in place. I don't even really have a clear idea what I need!

I actually want to get a set for the older Lomo mouse eared OCT-18 mount anamorphic lenses for my KSR-1 turret Konvas because I wanted to possibly do some MOS shakycam, steadicam and hand-held work on Blood Moon as the Werewolf's POV if the footage will cut together with the Lomo round-front stuff I'll be using for the rest of the picture which will be shot on a Kinor 35C. The only ones I've found however are anamorphic square front attachments for the 35mm which makes me wonder if they ever made another focal length for the mouse ear Lomos. If that's all I can find, and they will cut together, that's what I'll use, barrel distortion be damned!


I'm all OCT-18 here and I have the 3 focal lengths which I think is the complete set. However theres only 2 square fronts because for the longer lenses there are two different primes. I've often thought about trying to attach some other ordinary primes behined the anamorphic glass to get more focal lengths. Obviously the primes for anamorphic use have a different casing tho.

I think you wil have no problems intercutting the different lenses just as long as they are in different scenes.
People inercut different stocks in different scenes and most of the time when you are running around doing chase scenes and stuff theres going to be no dialogue probably just screaming and growling, or that's what I imagine anyway, so it can all be shot with the Konvas. I guess it depends what you have in mind but I'm betting it won't even ever be an issue.

I'd be much more careful about rack focusing and wild flares that may distract from what you're trying to accomplish in any given shot. At SOME point, you should probably get a de-anamorphic veiwfinder, down the road, just to check your composition. David recommended this in a thread I had about anamorphics a while back. What I have to do (aside from FINDING a Kinor gate and having it machined to anamorphic, thank you very much, because I will probably NEVER find an original Kinor anamorphic gate) is send Steve Morton a Konvas de-squeezer and a Kinor 35C standard viewfinder and have him BUILD me a Kinor 35C desqueezer which is going to cost the equivalent of a small nation's GNP, BUT then I should be able to change the viewfinder over to check composition then put the standard back to check what's actually in the frame in a larger image to look for mistakes before I roll the camera. I'll probably have to throw a blanket over the camera during the operation so as not to flash the film but it should work and do the same thing a Panavision switchable viewfinder can do with a little more effort.


I was going to suggest for a second that you could get a videotap with a flatpanel display that can unsquueze the image and then I remembered that it's not a 16:9 aspect ratio so it wouldn't solve the problem! :(

So far I've been totally having no problems composing with images squished on my dv camera, however the dv camera has a nice big bright display compared to a viewfinder so we shall see.

I guess what I'm saying is don't worry about it until you SEE there actually IS a problem. EVERYONE is going to find fault so wait and see if THEY'RE the one's with a problem and not you lenses. Anamorphic is a WONDERFUL option to have as a filmmaker so don't start building up a wall of doubt around one of the absolutely COOLEST tools you have in your arsenal! B)


I definitely want to shoot something in scope I'm just wondering if it's appropriate for the stuff I'm likely to do next.

love

Freya

Edited by Freya Black, 21 September 2007 - 03:46 PM.

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#11 Freya Black

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Posted 21 September 2007 - 04:07 PM

Freya,

the only lens in your set that will show some barrel distortion that actually matters in real-life conditions is the f=35mm square front lens.

So if you are shooting geometric patterns like the window front of a building or a wide fence with this wide angle lens, don't expect the lines to be straight. If you use an 18mm lens in spherical format, the problem will be the same.

Just yesterday I telecined some Konvas footage shot with f=35, 50 and 80mm square front anamorphics only, and it looked slightly better than the Foton-A zoom footage I shot before under same lighting conditions. In wide position which is f=37mm the distortions are not very different from the f=35mm fixed lens.

I recommend doing some test shots, then you get a feeling for the rendition of space these lenses will give you. Both the 35&50mm lenses have very good sharpness, but remember to keep stray light from the front lens. A matte box is the best investment you can make when shooting with these anamorphics, Rafcamera should have one for you. They also turn up on eBay frequently.

Do some tests so you know what your lenses can do, checking and doing tests is essential with all Konvas equipment.


I'm intrested that you have an 80mm lens. Is this in OCT-19? Mine is 75mm as I said before, seems curious that they had such similar focal lengths.

Yes flares! I shot a video in anamorphic DV, and it was the first time I had shot with an anamorphic lens. No mattebox, it was flaring all over the place, strange reflections everything. I was a bit horrified but then people saw me editing it and kept saying how they loved the flares, and one person even said it reminded them of blade runner! Riddley Scott would be turning in his grave I thought, except he isn't dead yet of course. At least I learnt the importance of a matte box! I have one which I think was for the 16mm kinor. Not sure if it will fit my Konvas 1m sadly, Not tried yet tho.

You are right about doing tests. I just noticed that the apeture is jammed on the 75mm lens. Luckily it's jammed at about 5 which is a usable apeture and I could always add ND filters I guess but it's still annoying.

Most of the Konvas stuff left out there is in a bit of a state.

Ah well.

love

Freya
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#12 dancordle

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Posted 21 September 2007 - 06:18 PM

Hi Freya,
Long time no type. I have a fantastic 50mm square front which I lent to a friend this year who's been shooting. He's actually a member here (Ian Dudley) and used it while shooting a scene of his excellent project for the Patrick O'brian foundation. The footage he shot with the lens is quite nice.

Best Regards,
Dan Cordle
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Aerial Filmworks

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Wooden Camera

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FJS International, LLC

Broadcast Solutions Inc

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