Flange Back at DVinfo.net

Christopher Glaeser · May 8th, 2006, 09:17 AM

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

Chris Hurd · May 8th, 2006, 09:26 AM

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.

Denise Brassard · July 5th, 2006, 05:29 AM

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.

Daniel Epstein · July 5th, 2006, 08:08 AM

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

Marty Hudzik · July 5th, 2006, 08:09 AM

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!

Marty Hudzik · July 5th, 2006, 08:11 AM

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.

Steven Dempsey · July 5th, 2006, 02:56 PM

Quote:

Originally Posted by Chris Hurd

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.

Daniel Epstein · July 5th, 2006, 03:18 PM

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

Marty Hudzik · July 6th, 2006, 06:39 AM

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.

Patricia Lamm · July 13th, 2006, 07:52 PM

Quote:

Originally Posted by Chris Hurd

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!

Chris Hurd · July 15th, 2006, 12:24 PM

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,

Patricia Lamm · July 15th, 2006, 12:27 PM

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?

Chris Hurd · July 15th, 2006, 12:41 PM

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?

Patricia Lamm · July 15th, 2006, 12:46 PM

Quote:

Originally Posted by Chris Hurd

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...

Chris Hurd · July 15th, 2006, 01:17 PM

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.

May 8th, 2006, 09:17 AM	#1
Christopher Glaeser Major Player Join Date: Sep 2005 Location: Pleasanton, CA Posts: 258	Flange Back 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

May 8th, 2006, 09:26 AM	#2
Chris Hurd Obstreperous Rex Join Date: Jan 2001 Location: San Marcos, TX Posts: 27,368 Images: 513	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. __________________ CH Search DV Info Net \| 20 years of DVi \| ...Tuesday is Soylent Green Day!

July 5th, 2006, 05:29 AM	#3
Denise Brassard Tourist Join Date: Jul 2006 Location: Los Angeles, CA Posts: 1	Change flange depth with wide angle adapter??? 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.

July 15th, 2006, 12:24 PM	#11
Chris Hurd Obstreperous Rex Join Date: Jan 2001 Location: San Marcos, TX Posts: 27,368 Images: 513	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, __________________ CH Search DV Info Net \| 20 years of DVi \| ...Tuesday is Soylent Green Day!

July 15th, 2006, 12:41 PM	#13
Chris Hurd Obstreperous Rex Join Date: Jan 2001 Location: San Marcos, TX Posts: 27,368 Images: 513	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? __________________ CH Search DV Info Net \| 20 years of DVi \| ...Tuesday is Soylent Green Day!

July 5th, 2006, 08:08 AM	#4
Daniel Epstein Trustee Join Date: Jan 2006 Location: New York, NY Posts: 1,267	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

July 5th, 2006, 08:09 AM	#5
Marty Hudzik Trustee Join Date: Jul 2004 Location: Canton, Ohio Posts: 1,771	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!

July 5th, 2006, 08:11 AM	#6
Marty Hudzik Trustee Join Date: Jul 2004 Location: Canton, Ohio Posts: 1,771	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.

July 5th, 2006, 03:18 PM	#8
Daniel Epstein Trustee Join Date: Jan 2006 Location: New York, NY Posts: 1,267	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

July 6th, 2006, 06:39 AM	#9
Marty Hudzik Trustee Join Date: Jul 2004 Location: Canton, Ohio Posts: 1,771	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.

July 15th, 2006, 12:27 PM	#12
Patricia Lamm Regular Crew Join Date: Nov 2005 Location: Okemos, MI Posts: 174	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?

July 15th, 2006, 01:17 PM	#15
Chris Hurd Obstreperous Rex Join Date: Jan 2001 Location: San Marcos, TX Posts: 27,368 Images: 513	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. __________________ CH Search DV Info Net \| 20 years of DVi \| ...Tuesday is Soylent Green Day!