Jump to content


Photo

Eclair ACL focusing issues with 35mm lenses


  • Please log in to reply
5 replies to this topic

#1 Justin Richards

Justin Richards

    New

  • Basic Members
  • Pip
  • 2 posts
  • Student

Posted 30 December 2010 - 05:47 PM

I am new to posting here. I am shooting a film this upcoming week in winter conditions in South Dakota. I am using my own Eclair ACL camera with 400' magazine, a 10mm Switar lens and a set of Minolta MD mount lenses. I know this camera is very finicky. I have had to overcome light leak and flicker issues, problems that I believe I have solved in the latest test.

The test did have one major issue though. On the test, I used a cheapo MD to c-mount adapter and though we measured the focus in each shot (using measuring tape and focus pulling according to the markers on the lens barrel), the focus was often somewhat off (the focus often went in and out of correct focus on follow shots or was slightly off on non-moving shots). I was expecting a professionally made adapter from a camera tech, but it will not be ready in time for the shoot. My main question is, because the focus is not correct on the lens barrel, should I try focusing the shots by eye, that is through the viewfinder, or by the barrel on the lens somehow?

I've also done more testing to determine where the focusing could have gone wrong. I used the 10mm switar lens as a control (since it does not need an adapter) and compared the viewfinder image focus to the technically correct, measured focus. The focus that I was able to get by eye with this lens was almost exactly the same as the correct measured focus. (i.e. I measured a subject 1 meter in front of the lens, set the correct focus and turned the focus back in forth until it looked in focus in the viewfinder; the viewfinder focus was the same as the correct measured focus). I did this for a series of measurements with the lens and found that the viewfinder focus was always correct. I should also note that the diopter was locked down during the entirety of the test.

I then tried to determine to what degree the markings on the lens barrels was set off because of the adapter. Before testing the lenses on the adapter on the Eclair ACL, I tested that the focus markings were correct on my Minolta X-700 still camera. All of the lenses were correct except for the 24mm where the focus markings were set off before the measured focus (i.e. actual focus: 6 ft.; on lens barrel: 3 ft.). When testing the lenses on the Eclair ACL, the 24mm lens had the same incorrect variation that I had expected but the other lenses had unexpected results. The 35-70 mm zoom and the 75-210mm zoom had correct focus in viewfinder and on the focus markings, which seemed to indicate that the adapter did not set off the focus on the barrel. But the 50mm and 50-135mm zoom lenses' focus markings on the barrel were after the measured focus (i.e. actual focus: 30 ft; on lens barrel: 40 ft).

So from this test, I have a few questions: how could the adapter create different levels of variation in the correct focus on the barrel for different lenses? Is setting the viewfinder to the correct focus on the 10mm lens, not enough to determine if the focus is correct on the 35mm MD lenses? Is the viewfinder not reliable to determine the correct focus?

I am sorry for writing such a long-winded comment here but I also have a few more questions and concerns. I also have a Super 8 camera. If there is no way to determine the correct focus for the ACL should I use that camera instead? Also I have not loaded 400' cores on my camera before, only 100' daylight loads. Loading a practice roll in a changing bag was quite easy and it ran smoothly when I attached it to the camera. There is only one step in the loading process that I am concerned about. Should I gaffer tape up the feed side of the mag before taking it out of the changing bag or is it okay to tape up that side of the mag outside a changing bag or in a somewhat darkened room?
  • 0

#2 Evan Ferrario

Evan Ferrario
  • Basic Members
  • PipPipPip
  • 138 posts
  • Director

Posted 04 January 2011 - 03:31 PM

Justin


I have had similar problem with cheap c-mount lenses not matching the markings on the barrel. The way the ACL works, if you can see the ground glass markings clear and focused through the viewfinder, then it will be clear and focused on the film. You should always focus or check the focus by eye, if it is sharp through the viewfinder (properly set up of course), then it will be sharp on the film. The problem with this method for me began once i started running the camera. Once it is running, it is very hard to focus by eye with the flicker. I would suggest getting focus marks based on the viewfinder before trying to shoot a shot, it's almost impossible to maintain focus with the ACL running just by using the viewfinder. That being said, use your adapter, just make sure your shot is super sharp through the viewfinder and you will get nice images.

I would agree with you that the ACL is a finicky camera, but it is also extremely reliable and predictable. I had a few problems with my ACL when I first started shooting with it and every time there was a problem, the camera sounded different when running. Get to know the sound of your ACL and if it sounds like something is off, turn it off and examine the film path. Also you're flicker problem and light leaks are easily preventable with lots of gaff tape, go overboard covering possible leak positions and you should be covered. Also make sure the eye piece is always shut when not looking through it.

I shot with my ACL last winter in upstate New York in 10 below weather with no issues from the cold. Have a spare battery on hand as the cold will drain the battery faster. Also, watch out for condensation from going from hot to cold or cold to hot situations.

I've always loaded the feed side of my 400 in complete darkness and then loaded then take up side in a little light. If you have the practice to do the whole load in darkness, this would be best, I've always needed to double check everything so I light the one side, but I've never had any light leak issues from doing this.

I would highly suggest you use your ACL instead of super8, you will be much happier with the final product. I understand it can be nerve racking using an old camera system which can very easily render your footage useless. Get to know the sound of your camera, cover any possible light leaks and you're confidence in the system will grow. I have never gotten bad film from my eclair that didn't give off some sort of sign while shooting. And I'm sure you already know this, but I've found it to be the key to the ACL is perfectly measured loops, a little more on the bottom than the top.

I hope some of this was helpful, there is a learning curve to every film camera but the more you use it, the more you will understand the little nuances of your camera and have complete confidence that you're getting good pictures.
  • 0

#3 Gregg MacPherson

Gregg MacPherson
  • Basic Members
  • PipPipPipPip
  • 1880 posts
  • Other
  • New Zealand

Posted 05 January 2011 - 05:57 PM

Do you not have a lens technician you can use? A basic check of the lenses shouldn't cost nuch (untill he starts fixing things). Untill you have a reliable focus reference on the barrel you have no choice but to do all your focus by eye.

I don't think I agree with the other reply re the ground glass and frame markings. They are sharp if the eyepiece diopter is set, even if the lense is out of focus.

Re the magazine and loading. Normally, load the feed side in the dark, check the lid is closed properly, then in daylight thread the takeup side, then tape the mags. If finishing the take up side is slow or delayed then the feed lid gets taped as soon as you are out of the bag/tent.

If a feed side lid was damaged or warped so you were woried about the seal, it would be better to fix it. Or you could put a piece of B&W test film in there, wave the mag around in the sunshine and process it by hand to check the seal.

Cheers
Gregg
  • 0

#4 Evan Ferrario

Evan Ferrario
  • Basic Members
  • PipPipPip
  • 138 posts
  • Director

Posted 06 January 2011 - 07:08 PM

I don't think I agree with the other reply re the ground glass and frame markings. They are sharp if the eyepiece diopter is set, even if the lense is out of focus.


Read more: http://www.cinematog...9#ixzz1AIrJ5I6C


Sorry I wasn't very clear about this, we are talking about the same thing. I meant the ground glass markings need to be infocus to verify the viewfinder has been properly setup. Of course you need a focused image from the lens for the film image to be sharp. If you can clearly see the ground glass markings AND you're image appears sharp, then the image on the film will be sharp.
  • 0

#5 Jason Hinkle (RIP)

Jason Hinkle (RIP)
  • Basic Members
  • PipPipPip
  • 240 posts
  • Cinematographer
  • Chicago, IL

Posted 25 January 2011 - 12:33 AM

Hey Justin, are you able to focus to infinity? Meaning if you set the focus at infinity on the lens, is everything in the distance in focus, or do you notice that you cannot focus past 20 feet or so?

The reason is because if you cannot get infinity focus then it is likely that you have the wrong c-mount adapter. You might have one made for the Bolex RX camera which has a different focal length. That basically means, the distance of the rear lens is too far from the film because the specification for the Bolex RX is slightly different than for any other camera. A lot of eBay sellers have no idea what they are selling and they don't know the difference.

If you can get infinity focus then the adapter is just probably a little off. At the rear lens mount the tolerance is less than a millimeter so the thread on a cheap adapter only has to be a tiny bit off and it throws the focus out.

If you are the type who likes to focus by tape (which I do prefer myself) then you might want to consider forking out the dough for a professional adapter like one from Les Bosher. Unfortunately they are really expensive like $350.
  • 0

#6 Dimitrios Koukas

Dimitrios Koukas
  • Sustaining Members
  • 569 posts
  • Cinematographer
  • Athens, Greece, London UK

Posted 25 January 2011 - 04:51 AM

You need to go only with the lenses you are sure that are in focus and drop the others for this production, or use higher t-stops when possible.
And ok sometimes focusing thru the viewfinder is reliable, but what if you have to use a POLA and one 85N3?
You won't be able to see much of your image thru this...
  • 0


Paralinx LLC

Aerial Filmworks

CineTape

FJS International, LLC

Gamma Ray Digital Inc

Opal

Visual Products

Abel Cine

Glidecam

Technodolly

The Slider

Tai Audio

Willys Widgets

CineLab

Ritter Battery

Wooden Camera

Rig Wheels Passport

Metropolis Post

Media Blackout - Custom Cables and AKS

rebotnix Technologies

Broadcast Solutions Inc

Wooden Camera

Tai Audio

Technodolly

Broadcast Solutions Inc

Willys Widgets

The Slider

CineTape

Rig Wheels Passport

Visual Products

Abel Cine

Paralinx LLC

Glidecam

Ritter Battery

Opal

Gamma Ray Digital Inc

Metropolis Post

FJS International, LLC

Media Blackout - Custom Cables and AKS

rebotnix Technologies

CineLab

Aerial Filmworks