Two quick questions.

1. Is there a benefit to setting the flange back settings if AF already appears to be good (tested at 1.5 meters, wide aperture, both tele and wide angle, with peaking and magnification)?

2. What is the purpose of setting the flange back for both AF and MF?

Best,
Christopher

You shouldn't even have to bother with FB unless you're noticing that the lens isn't holding critical focus. If you switch to MF, zoom in all the way, set focus, and zoom back out, then the focus should not change at all and it should be just as crisp at either end of the zoom range (provided it was properly set at full telephoto to begin with). Same thing for AF. If there's no change in critical focus then you should not need to do the FB operation.

Any time you change lenses, though, you should go ahead and calibrate FB. Really you only need to do this once with each lens you have, because there are FB memory presets available which you can assign to each lens. I think there are thirteen FB presets, more than you'll ever need in your XL H1 career.

The other useful thing about FB is just the coolness factor. If you want to impress your friends and show them how sophisticated your new H1 is, just show them the Auto Flange Back calibration feature. They might not have any idea what it is that you just showed them, but they'll probably think it's pretty cool anyway.

If it's necessary to adjust the flange depth when changing lenses, is it also necessary to do so when adding or taking off the wide angle adapter? I will be using the Cent. Precision .8x Universal wide angle adapter.

And while we're on the subject, we got the .8x because we heard that the .7x wide angle adapter goes soft in the corners. Any comments? I was at Samys camera the other day and they hadn't even heard of that problem (even though I was told the info by people at Canon and Century). I guess they were just trying to make a sale.

Denise,
It is not necessary to adjust the FB with zoom thru adapters. They are designed to pop on the front of a properly back focused lens without creating back focusing issues. Some fixed focus or Non zoom thru wide angle adapters use the FB or Macro for focus so it might be necessary to readjust it after using one of those.
As for the qualities of the .7x and focus in the corners I have seen it with my own eyes.It wasn't just the corners by the way. Most camera stores don't test every combination of gear they have so it doesn't surprise me that they haven't heard of it. Buyer beware

The .7x Century lens is very soft at the edges and suffers from Chroma issues too. This was on my XL2 and it was obvious there. It would only be worse on the XL-H1. I used the .8x for a week on the H1 and it blows the doors off of the .7x in my opinion. Sure it isn't quite as wide but it has just about zero problems as far as softness and chroma abberations. Plus it is light as a feather compared to the .7x. And it includes a free sunshade where you had to buy it extra with the old lens.

For what it is worth when I used the .7x WA on the front of my 16x manual lens I always set the backfocus with the adapter on. It made a huge difference the the sharpness of the image. Without setting this I would have issues with backfocus. The lens would not hold sharp focus as well without doing this.

I cannot confirm this with the .8x as I didn't have ample time to test it. If what you are shooting is critical and you have the time I would suggest checking the backfocus with the adapter on the lens to be 100% safe.

Peace!

While I was posting Daniel also posted the one just before me. While I respect that you shouldn't have to adjust the flange back I found in my real world applications that is was indeed necessary. Your mileage may vary but I would check it to be sure.

The other useful thing about FB is just the coolness factor. If you want to impress your friends and show them how sophisticated your new H1 is, just show them the Auto Flange Back calibration feature. They might not have any idea what it is that you just showed them, but they'll probably think it's pretty cool anyway.

Hey, thanks for the tip. I have since impressed many people who are not only amazed at the camera, but they are amazed at my ability to use the word "flange" in a sentence and not laugh.

Marty,
I always respect real world experience and I agree that back focus should be checked as part of checking the lens after putting on the adapter as well as any other lens functions one plans on using.
Most of my real world experience has been that improperly set back focus may be more noticeable with the wide angle adapter since that is where the adjustment makes the most difference in the focus. I can't blame it on the adapter being put on though. Sometimes the weight of the adapter put enough of a strain on the lens it is attached to that it shifts the lens at the mount. I don't think that will be the case with the XLH1 and the Century Adapter

I agree with you Daniel. When I had my XL2 and the 20x servo lens that came with it I would check the backfocus of the lens. It would remain sharp all the way through the zoom range to full wide. When putting the .7x WA on this unit I would experience focus shifts. Zoom in all the way, set focus and pull out and halfway through the range you would see it go soft.

Of course the XL2 had no provision for adjusting the backfocus yourself...you had to send it to canon for this. So there was no way to compensate or test it.

So I tried the manual 16x lens and found the same exact results. However if I manual set the backfocus with the WA adapter attached the problem went away completely.

So the moral to the story is that WA adapter could exploit minor backfocus issues that you do not see normally. IMHO that is.

Any time you change lenses, though, you should go ahead and calibrate FB. Really you only need to do this once with each lens you have, because there are FB memory presets available which you can assign to each lens. I think there are thirteen FB presets, more than you'll ever need in your XL H1 career.

Hi Chris,

I've looked everywhere and don't see how you save an FB setting to memory (or card). Can you explain further? Thanks... and thanks for the great site!

Hi Patricia,

When I wrote that post, I didn't have the operator's manual with me. Looks like I made two mistakes which need to be corrected. Thanks for catching this.

First, there are ten FB memory presets, not thirteen (see page 26 of the manual).

Second, I said "presets... which you can assign to each lens." That's wrong. You don't assign FB presets, the camera does this by itself automatically. Sorry about the earlier confusion,

Thanks, Chris. But I'm still confused. So if the camera saves a preset for each lens I attach to it, then why do I need to adjust FB every time I change the lens?

Hi Patricia,

I think the whole point is that you don't have to set FB every time you change lenses. Just one time only for each lens should be all you need to do. I'm swapping between the 20x HD and a 3x SD over here and I'm not seeing any difference in back focus. Are you finding that you need to re-adjust FB every time you change lenses?

Are you finding that you need to re-adjust FB every time you change lenses?

No, I'm not. I was confused by an earlier post in this thread but now it's starting to make sense to me. I just set FB once for the 20X and the 3X SD (which I also use) and then leave it that way unless I start to see focus problems.

Thanks again...

The confusion was most likely my fault due to a poor choice of words. I had said "Any time you change lenses, though, you should go ahead and calibrate FB. Really you only need to do this once with each lens you have..." -- that probably could have been better stated.

I am assuming this does not apply to the manual lens in any way since it has a physical flangeback adjustment. Right?

It has always driven me crazy that you have to adjust for back focus with video cameras.. you don't have to with film cameras.. but, because I've been "warned" I do it regularly and with precision...

To tell the truth, I've never tried just putting the lens back on the camera, as I would do with my 16mm camera (for which I have 7 zoom lenses and 5 primes)...

Could someone explain what changes when you remove and then re-mount a lens on a video camera?

It has always driven me crazy that you have to adjust for back focus with video cameras.. you don't have to with film cameras.

Isn't it the reverse? Digicam owners are driven crazy each time they have to send their camera to a repair center to match a body to a new lens. Video camera owners should coun't their blessings they have the ability to match a camera and lens in the field.

Best,
Christopher

I'm not sure I understand your response, Christopher -

Let me just say, rather than argue "abstract concepts", that I personally bought my first 16mm camera, a Bolex, in 1962 not far from where you are - Los Altos Rancho Camera Shop - I bought it off the shelf with an early Pan-Cinor zoom. By 1973 I had owned 3 other Bolexes and an Arri 16s and and Arri II (35mm).

For example, I shot a feature length documentary (ACAPULCO GOLD) during that time with a 400' Bolex and an Angenieux 12-120 and a Switar 10mm - it was blown up to 35 and distributed nationally - and it's currently available on DVD (although I don't get a dime from it).

During the 70's I owned a super16 Eclair NPR, an Eclair Camerette and a CP16. During the 80s I owned a total of five Eclair ACLs (one super16) and in 1990 bought a used super16 Aaton LTR7, which I still own.

As a result, I have owned nearly 20 zoom lenses made by Angeniux, Cooke, Century Optics, Zeis and Canon, as well as numerous primes.

Except for having the back focus CHECKED (just to be sure) when buying a new lens, I have never had any camera or lens ADJUSTED for back focus - You buy them, put them on, and shoot... That has been my experience..

So, what I'm asking is, simple question that has never been answered to my satisfaction - "why do they advise that you redo backfocus adjustment every time you change a lens on a video camera? - what changes?"

I do it because I'm careful, and because it says to do it, but "why?"

why do they advise that you redo backfocus adjustment every time you change a lens on a video camera?I'm not sure if I'm the culprit here or not... please see my post a couple of replies above. What I meant was that an XL H1 owner should only have to adjust FB one time only with each lens they have, just so the FB memory presets are in the camera. I certainly did not mean to imply that it should be done each and every time an XL lens is changed. This is my second apology for the miswording of that statement; I have a feeling that several more will be called for before this non-issue is finally buried for good.

Except for having the back focus CHECKED (just to be sure) when buying a new lens, I have never had any camera or lens ADJUSTED for back focus - You buy them, put them on, and shoot... That has been my experience.

So, you agree the lens and digicam body should be CHECKED for focus. What if the lens does not match the body and you purchased the lens mail order? A search of dpreview.com will show that it is not uncommom practice for owners to send their body and collection of lenses to a repair center for calibration.

The only point I was making is how nice it is that you can do this calibration yourself with the XL H1.

Best,
Christopher

::edit::: clicked on dpreview and realized by digicam's christopher was talking about digital still camera's not digibeta cameras (which also go in for lens matching) so my post was a waste of space....

Please understand, my comment was meant as a general question about video cameras, not a comment on the H1 itself.. the flange back memory function is a terrific tool..

Also, yes I always check a 16mm lens when I buy it, but I only check it when I buy it, not every time I remove then replace the lens... And I've never had to have one modified or adjusted, even wide angle zooms, because I always buy lenses that are in pristine condition, or new ...

It just suddenly struck me as curious that I have always accepted (and, I admit, recommended, as on this forum) doing it on video cameras - but I have never questioned why, that's all... My guess is that it needs to be done because the lenses ARE adjustable, and therefore can inadvertably be changed... but I just don't get why they have to be adjustable in the first place with modern non-tube cameras..

but I only check it when I buy it, not every time I remove then replace the lens.

Somewhere I think you may have misunderstood this "every time" requirement. You don't need to calibrate SLR digicams OR the XLH1 every time a lens is changed. I'm not sure where you picked up this "every time", but it just isn't needed. In addition, the nice thing about the XLH1 is that you can do the lens calibration yourself. Not so with the Canon SLR digicams. If one or more lenses need calibration, you have to box them all up and send them to Canon repair service. That's why, when you said you were "driven crazy" with the XLH1 and then went on to compare it to still cameras, I thought perhaps, just perhaps, you had misunderstood the benefits of the XLH1. Perhaps I'm wrong, and perhaps someone else can step in and assist, but when you continue to use phrases liike "every time", I think you may still be misunderstanding this issue. Hoping that helps.

Best,
Christopher

Hi, I'm just curious, what is actually changed and how when the back focus of the XL H1 is changed? (I know Hasselblad adjusted the length of their still camera bodys with a big hammer (!) if the body was too long. First they replaced the lens with a metal cylinder. Then they adjusted the length by banging with the hammer until the length was correct!)

Christopher: Every manual I've ever read recommends readjusting back focus every time you remove or change a lens on a video camera... And, as I said, I do it because I'm careful, and recommend the same procedure to others... Better safe than sorry, but still, seems unnecessary somehow...

Hi, I'm just curious, what is actually changed and how when the back focus of the XL H1 is changed? (I know Hasselblad adjusted the length of their still camera bodys with a big hammer (!) if the body was too long. First they replaced the lens with a metal cylinder. Then they adjusted the length by banging with the hammer until the length was correct!)

I'm pretty sure you are micro adjusting the distance from the back element of the lens to the CCD. If for example it is supposed to be 6.5mm but in reality, because of tolerances in manufacturing process, it is 6.4mm, you can adjust it back to 6.5mm. On the manual lens you actually mechanically move the back element of the lens. With the servo lenses I think you are moving the CCD to compensate (controlled electronically inside the XL-H1 when you do FB adjustment). I am not sure. But somehow you need to get them to the proper distance.

As a note, I randomly picked 6.5 mm......I have no idea what realistic measurements are.....this is just theoretical.

Peace!

Christopher: Every manual I've ever read recommends readjusting back focus every time you remove or change a lens on a video camera.

Video cameras that do not have the ability to remember the FB setting for each lens may require a readjustment with each lens change. The XLH1 stores the FB settings for each lens to memory, so in theory (and in practice according to some XLH1 owners), a readjustment is not necessary with each lens change, but only the first time each lens is attached.

If you see an actual difference in your XLH1 FB setting each time you reattach a lens that has already been FB set, let us know.

Best,
Christopher

Well there are several reasons to backfocus video lenes. For one thing remember your COC charts for film. larger circles for larger film formats. Also take into account that when light hits a frame of film it penetrates all the way to the back of the film.causing a chemical reaction. light must hit the front of a pixel for the image to be in focus> film thickness is massive compared to the surface of a pixel. video mounts are made of soft medals that actually expand and contract with temp changes. We will backfocus HD cams several times a day if the temps change. Film cameras do have shims placed behind the mount to correct for manufacturing tolerances being off. PL mounts are often reset or changed out as they wear on film cameras.

Adding to what craig said, not only do the temperature changes externally come into play but internally as well, I'm pretty sure there aren't too many film cameras with internal fans to regulate the temperature, this is common in the video counterparts.

...The XLH1 stores the FB settings for each lens to memory...

Is this done automatically each time you check FB or do you have to take some action to store/recall the data? Darned if I can find the answer in the manual.