Focus marks off ?

[Joseph S.]

I've only been around cine lenses for 3 years, but is it normal to have the infinity mark off by so much? I've never seen it before on regular canon/nikon lenses.

This is an RPP 100MM. When it's exactly on the infinity mark, it's not in focus (over 250 feet away).

This was brand new directly from RED two years ago, but I just opened it now and noticed this on a few lenses. I remember it was the same on the R1 as well as the Epic now.

 

[Matt Ryan]

I've only been around cine lenses for 3 years, but is it normal to have the infinity mark off by so much? I've never seen it before on regular canon/nikon lenses.

This is an RPP 100MM. When it's exactly on the infinity mark, it's not in focus (over 250 feet away).

This was brand new directly from RED two years ago, but I just opened it now and noticed this on a few lenses. I remember it was the same on the R1 as well as the Epic now.

The lens may need to be shimmed or your back focus is slightly off (Flange Focal Distance to be correct). That isn't normal if everything is correctly set up. The marks should be dead on.

Are the other marks correct?

 

[Nate Clapp]

if only one lens doesn't line up (tape out distances and check with focus chart) then the lens is out and needs to be shimmed. I have done this myself, but it is not a normal user serviceable thing, think of changing your own brake pads. If you feel at all uncomfortable, send it to a lens tech. If you do it yourself, you'll need at the very least get ahold of proper shims.
If all your lenses are not coming up right- problem is easier to fix. Your back-focus is out on camera body. On epic and scarlet it is pretty easy to calibrate so witness marks come up right.

 

[Cam Crowley]

The witness marks on RPPs are not exactly the best. Did you have a look at the opposite side of the lens to see if that lines up with infinity? My experience with RPPs is that while one side will be accurate, the other side wont match up (at any distance). Fairly simple fix - bit of tape, a sharpie, and a tape measure will give you new (accurate) marks. RPPs are good value for money optically - but the witness marks are basically shit. Forget them. Mark your own and you'll find life focus pulling a lot more manageable. Having said that - if you are finding that all your lenses are out at various distances than the most likely culprit is the cameras back focus (as already suggested).

 

[Joseph S.]

As I assumed, it was only a few lenses and not the camera. So I did the test with the same 100mm and found the 3'-6" and 30" marks to be off the exact amount that the infinity mark was off.

However, the 50mm RPP was spot on.

Since I do a lot of outdoor shoots and most of the time I'm on infinity, it tends to get a bit annoying. I guess I can have the lenses serviced.

Thanks for your advice folks.

 

[Glen Powell]

The witness marks on RPPs are not exactly the best. Did you have a look at the opposite side of the lens to see if that lines up with infinity? My experience with RPPs is that while one side will be accurate, the other side wont match up (at any distance).

This is an often repeated bit 'o' information - that I've found to be inaccurate in my experience. Any RPP's that I've rented, and the set that I own, have accurate witness marks on both sides of the barrel. Perhaps early versions were out?

 

[Cam Crowley]

I pull focus for a living. And I stand by what I said about MY experience with the RPPs. Make your own witness marks - it will make your life a whole lot less frustrating.

 

[Björn Benckert]

First calibrate camera then lens.

 

[Glen Powell]

I pull focus for a living. And I stand by what I said about MY experience with the RPPs. Make your own witness marks - it will make your life a whole lot less frustrating.

My 20++ years shooting probably don't count - but I stand stand by MY experience with the RPP's that I've rented and own… So there you have it different opinions from different guys who apparently know what they are talking about.

If you really want to set-up your RPP's - give Duclos a call, he'll add witness marks and collimate if that's what's needed. I do agree with Björn; get the camera checked first.

 

[Jeff Kilgroe]

+1 to what Glen is saying. I have yet to encounter a set of RPP's where the marks are off, assuming both the lenses are properly collimated and the FFD on the camera is properly set.

 

[Joseph S.]

Great info from you guys. I'm just surprised that half the lenses are accurate, and half are not. These lenses were new from RED (although from a couple years ago and just opened now).

And wouldn't a two day old Epic be accurate already?

I read how happy Ketch was with the added markings from Duclos. I'll give Duclos a call.

 

[Cam Crowley]

Wasn't trying to turn this into a pissing contest Greg. Was just trying to offer some advice to the OP so they didn't end up beating their head against a brick wall or unnecessarily fucking around with the camera backfocus. And I have experience with more than one RPP set where the focus marks were not accurate on both sides of the barrel.