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Ryan Avery
April 28th, 2008, 09:36 AM
Piotr:

A double threaded version is hard to find - in fact of the B+W I don't think it exists, so this is what I did. I have a 77 to 100 step-up ring with a 95mm thread inside, to which I clamp my Cavision matte box (see my threads on that for interest). Inside this step-up ring I have a 95 to 77 step-down ring that holds the 77mm IR/UV filter on the inside so that the IR/UV filter is in fact in "backwards." This allows the use of the 77mm filter behind a matte box and is a lot cheaper than using the 100mm filter which is about $500 or wasteing a matte box slot. This arrangement works fine and there is no vignetting at any focal length by reversing the filter so it is as close as possible to the camera.

Mike


Mike,

Your solution seems to be a great option for EX1 users. For RED users it doesn't work because of the thread size. This is why we made the mattebox option as well which full explaination is in my previous post.

Thanks for the good idea and solution for a EX users.

Ryan Avery
Schneider Optics

Piotr Wozniacki
April 28th, 2008, 09:48 AM
Dear Ryan,

Thanks for your answers; however, sticking to the EX1 and Letus 35mm adapter applications, which filter I'd be better off: the existing 486, or the existing 489 one?

Ryan Avery
April 28th, 2008, 12:37 PM
Dear Ryan,

Thanks for your answers; however, sticking to the EX1 and Letus 35mm adapter applications, which filter I'd be better off: the existing 486, or the existing 489 one?

Based on the discussions here and my knowledge of both filters, I would think that the 486 would be the better choice. I do not have direct experience with the set up you are talking about but from a science aspect the 486 is the proper filter.

Ryan Avery
Schneider Optics

Piotr Wozniacki
April 28th, 2008, 01:35 PM
Based on the discussions here and my knowledge of both filters, I would think that the 486 would be the better choice. I do not have direct experience with the set up you are talking about but from a science aspect the 486 is the proper filter.

Ryan Avery
Schneider Optics

Thanks again Brian,

The specifics of the setup I mean is that with the 35mm adapter like the Letus, the 486 filter would be "closed" between the camera lens and the achromat lens of the said adapter. Reflected IR could bounce within this space (of course being partially absorbed), but wouldn't they contaminate the picture?

Conversely, with the 489 filter the IR would be absorbed by the filter, hence theoretically less reason for concern...

Is this theory right?

Sean Donnelly
April 28th, 2008, 07:11 PM
Piotr, earlier in this thread I suggested that perhaps that isn't so much of a concern. I still maintain that it doesn't really matter what happens to the IR light reflected by the 486, as long as it doesn't pass though to the sensor. It's not going to contaminate the image, and it's also not going to cook your Letus :)

Piotr Wozniacki
April 29th, 2008, 01:29 AM
Piotr, earlier in this thread I suggested that perhaps that isn't so much of a concern. I still maintain that it doesn't really matter what happens to the IR light reflected by the 486, as long as it doesn't pass though to the sensor. It's not going to contaminate the image, and it's also not going to cook your Letus :)

Sean,

Considering that even without the Letus I am getting the green tint in the picture extremities (because of the angle of incidence of the light), the multiple reflections of the IR could increase this effect.

On the other hand, with LEX the camera is zoomed in to some Z78, which should help avoiding this...

Unless the multiple reflections will cause considerable amount of IR to reach the lens at the "wrong" angle also in the middle, and this possibility is the reason for my concern!

Since I need to make up my mind which double-threaded filter model to pick, I'd be grateful for some more authoritative answer.

Mike Stevens
May 1st, 2008, 05:20 PM
Serena asked me does the 486 IR/UV work. It does - big time.

I just came back from three days in the desert (that was hot this trip) and I compared the 486 vs. the standard UV/Haze. The green foliage that looks brown with the UV/Haze is correctly green with the 486.

The 486 did mute the reds a tad and so I compensated with a matrix shift of G-R=15 and that seemed to work for me.

Mike

Leonard Levy
May 1st, 2008, 08:45 PM
This thread mystifies me. Is there any consensus about the green vignetting that Piotr documented?

The pictures he posted were extreme, far worse than any red problem I've seen, but it doesn't seem like anyone else has seen it, or if they have they aren't concerned.

I could live with an overall green cast that's correctable, but the vignetting was unacceptable to me.

Are you other guys with the filter having any of this problem at wide angle or anywhere else? Is there any consensus about when you will or won't have the problem. Other images would be appreciated. Thanks

Lenny Levy

Steven Thomas
May 1st, 2008, 11:50 PM
Yes, I'm wondering the same thing. Does the 486 IR/UV have the green cast issue on the edges?

I want to buy one, but I'm also confused on if its problems might out weight the IR contamination fix.

Piotr Wozniacki
May 2nd, 2008, 04:22 AM
Guys, the green cast at the extremities is due to IR light angle of incidence, and even Ryan Avery of Schneider Optics confirmed it's unavoidable with those screw-on, circular filters - so I guess you cannot avoid it completely.

As I said: in natural light, this is not a problem at all (even indoors).

It's most pronounced with incandescent / tungsten (warm) lighting, as my pics posted earlier show (they were deliberately chosen from the worst part of my recording, though).

With LED light it's not visible (have done some tests recently, but only in the mixed natural light at dusk, and some LED lamps - see the grabs attached); unfortunately couldn't wait for the sunset at that particular location, so cannot be sure how it works with LED light on its own. One of the grabs shows the scenery in natural light at dusk; the other with LEDs switched on (taken within just a couple of seconds time). As you can see, there is virtually no green cast even in the corners (even though I was at the widest in the right grab).

Bob Grant
May 2nd, 2008, 06:51 AM
Interesting tests by Adam Wilt:

http://provideocoalition.com/index.php/awilt/story/schneider_ir_filter_tests/P0/

This is not the first such tests I've read of, interestingly all camera seem to have these issues to varying degrees. The other not public tests found that cameras such as the Varicam can need an external IR cut filter.

Piotr Wozniacki
May 2nd, 2008, 07:21 AM
Thanks Bob for the link - what Adam is showing as the adverse effects of the 486 on EX1 at full wide, is nothing compared to the ugly cast in my grabs posted here earlier!

As I said - all depends on many variables, but having a filter like this handy is a must with the EX1.

Mike Stevens
May 2nd, 2008, 09:22 AM
This thread mystifies me. Is there any consensus about the green vignetting that Piotr documented?

The pictures he posted were extreme, far worse than any red problem I've seen, but it doesn't seem like anyone else has seen it, or if they have they aren't concerned.

I could live with an overall green cast that's correctable, but the vignetting was unacceptable to me.

Are you other guys with the filter having any of this problem at wide angle or anywhere else? Is there any consensus about when you will or won't have the problem. Other images would be appreciated. Thanks

Lenny Levy
The green casts and vignetting have nothing to do with the 486 filter. Piotr has something else going on or the filter is bad or is mounted wrong. As I said, the only down side is a slight muting of the reds that I somewhat corrected with a green to Red +15 in the matrix.

Piotr Wozniacki
May 2nd, 2008, 09:40 AM
The green casts and vignetting have nothing to do with the 486 filter. Piotr has something else going on or the filter is bad or is mounted wrong. As I said, the only down side is a slight muting of the reds that I somewhat corrected with a green to Red +15 in the matrix.

C'mon, Mike. While I picked those ugly pics on purpose, the green cast is a fact, confirmed by the filter manufacturer.

In 90% of my shooting scenarios, it's a non-issue at all - so it's possible you have just never noticed it. Especialy that - afaik - yours is not directly on the lense, is it? By increasing the distance (e.g. mounting it in the matte box), you're avoiding the critical incidence angle.

Ryan Avery
May 2nd, 2008, 09:43 AM
Thanks again Brian,

The specifics of the setup I mean is that with the 35mm adapter like the Letus, the 486 filter would be "closed" between the camera lens and the achromat lens of the said adapter. Reflected IR could bounce within this space (of course being partially absorbed), but wouldn't they contaminate the picture?

Conversely, with the 489 filter the IR would be absorbed by the filter, hence theoretically less reason for concern...

Is this theory right?

The 486 and 489 alter IR light differently. The 489 will absorb the IR light but only affects this end of the spectrum. The 486 reflects the IR light within the layers of the filter and therefore also controls the UV contamination which will affect blue and green casts to your image. The sensitivity of digital sensors to UV light is much less than the IR light. Therefore a 489 should be relatively as effective as the 486 but for the fact that UV sensitivity still exists with digital sensors and this could be what you are getting with your lens set up.

In mounting the filter, the sequence is very important. A 486 filter reflects the light and there for should be used in the front of all elements. If you are mounting the 486 internally then the issues you state could be happening. The 489 is a better application for internal use such as the situation you state. It is better to have no UV filtration in the 489 and aviod the internal reflection problems.

In short, for this application only, use the 489 internally OR put the 486 in front of the 35mm lens.

Ryan Avery
Schneider Optics

Ryan Avery
May 2nd, 2008, 09:46 AM
Based on the discussions here and my knowledge of both filters, I would think that the 486 would be the better choice. I do not have direct experience with the set up you are talking about but from a science aspect the 486 is the proper filter.

Ryan Avery
Schneider Optics

I obviously thought about this one a little more and the above post relates that the 486 is the best filter to use but not for the sequencing of filters used in this particular application.

Ryan Avery
Schneider Optics

Christopher Barry
May 2nd, 2008, 03:27 PM
Ryan,

A 486 filter available as a 4x4 for MB use?

Thanks.

Piotr Wozniacki
May 3rd, 2008, 02:44 AM
In mounting the filter, the sequence is very important. A 486 filter reflects the light and there for should be used in the front of all elements. If you are mounting the 486 internally then the issues you state could be happening. The 489 is a better application for internal use such as the situation you state. It is better to have no UV filtration in the 489 and avoid the internal reflection problems.

In short, for this application only, use the 489 internally OR put the 486 in front of the 35mm lens.

Ryan Avery
Schneider Optics

Dear Ryan,

What a pity you confirmed my concerns only after I have bought another 486 filter (this time, the one with double thread to replace my current 486 SLIM version) - should you have answered two days earlier, I'd go with the 489 as I currently am not using a matte box :(

But never mind; I'll replace it again should need be. However, the following afterthought crossed my mind when reading your answer:

If indeed the reflecting 486 filter type should always work as the outermost (i.e. the first in the stack) optical element, why does its double-threaded version exists in the first place? Having the thread at the front side, it suggests screwing some other optical element into it is conceivable, after all...

Or maybe this is just for some non-optical element, like a sunshade of some sort?

Michael Maier
May 3rd, 2008, 11:24 PM
Dear Ryan,

What a pity you confirmed my concerns only after I have bought another 486 filter (this time, the one with double thread to replace my current 486 SLIM version) - should you have answered two days earlier, I'd go with the 489 as I currently am not using a matte box :(

Nevermind that I said like a dozen times the 489 was the right one to use behind a 35mm adapter and that I got that info from somebody at Schneider and have bought the 489 and it is working great with 35mm adapters.
You can just figure that on your own just by reading how both filters handle incoming IR actually. But I tried.

Piotr Wozniacki
May 4th, 2008, 02:07 AM
Yes Michael - I know you said it, but a couple of persons using the 486 said it was also working OK, and Ryan of Schneider even mentioned the 486 is "a better choice for this application"... :)

But of course I'm far for blaming anybody but myself for this decision. Since my new 486 provider has the 489 as well, I'll be trying to swap them - he might go for it, if I pay the shipping costs. Before I do however, please answer my other question I also was asking earlier in this thread:

- does the double-threaded 489 filter fit under the stock lens hood, when Letus is not used?

Thanks in advance!

Mike Stevens
May 4th, 2008, 09:54 AM
Piotr:
ONLY slim-lines fit under the stock sunshade. That is why I needed to put together the adapter ring arrangements that Schneider complemented me on. See details above somewhere. Slim-lines do not have front threads so the answer to your question is NO

Piotr Wozniacki
May 4th, 2008, 12:30 PM
Wrong again, Mike:

http://www.dvinfo.net/conf/showpost.php?p=863084&postcount=122
http://www.dvinfo.net/conf/showpost.php?p=864020&postcount=132

- I have no reason not to believe Peter; anyway I will check it with mine which should arrive soon.

Mike Stevens
May 4th, 2008, 07:10 PM
Wrong again, Mike:

http://www.dvinfo.net/conf/showpost.php?p=863084&postcount=122
http://www.dvinfo.net/conf/showpost.php?p=864020&postcount=132

- I have no reason not to believe Peter; anyway I will check it with mine which should arrive soon.

Piotr: Maybe you are addressing MM, but if you are addressing me I assure you the B+W 486 IR/UV slimline does not have a front thread. (Don't be misled by the B&H site that says it does. They are wrong). Now some other fatter IR filters will have a front thread but I do not know of one that can fit under the Sony head. The link you referred to is addressing the slimline with no front thread.

Sean Donnelly
May 4th, 2008, 07:59 PM
I'm using a B+W 486 filter with front threads. It fits under the hood. I also have put a pola in front of that with no problems. I'll be doing thorough tests with a letus and this filter next weekend.


-Sean

Mike Stevens
May 4th, 2008, 09:53 PM
I'm using a B+W 486 filter with front threads. It fits under the hood. I also have put a pola in front of that with no problems. I'll be doing thorough tests with a letus and this filter next weekend.


-Sean

What is the model number? I could not find one and B+W told me not one in their catalog. Be interested to know. It's good though its all a bit academic as I would think with a camera of this sophistication you would have a matte box. Had to do what I did because I have the Cavision clamp on as I did no want the weight of rails.

Bob Grant
May 5th, 2008, 02:31 AM
Piotr: Maybe you are addressing MM, but if you are addressing me I assure you the B+W 486 IR/UV slimline does not have a front thread. (Don't be misled by the B&H site that says it does. They are wrong). Now some other fatter IR filters will have a front thread but I do not know of one that can fit under the Sony head. The link you referred to is addressing the slimline with no front thread.

It's likely that not all 486 filters are created equal. Some say the standard 486 will fit under the hood and no doubt they're correct. But the ones the local agent has in stock sure don't. I know, I tried, hard.

Sean Donnelly
May 5th, 2008, 05:24 AM
http://www.bhphotovideo.com/c/product/475095-REG/B_W_65031976_77mm_486_Digital_UV_IR.html

I actually got mine form a different supplier because I needed it quickly and B+H didn't have it in stock.

Sean Donnelly
May 5th, 2008, 05:45 AM
Hope this is okay to post, but this is Schneider's description of how the 486 works:

http://www.schneideroptics.com/ecommerce/CatalogItemDetail.aspx?CID=677&IID=4397

"This B+W Interference Filter has a completely colorless glass carrier coated with a number of extremely thin, partially reflecting layers with precisely computed thicknesses, similar to MC coating. The B+W Filter 486 does not block by means of absorption, but by interference of the unwanted UV and IR radiation that is repeatedly reflected between these layers, affecting the wavelengths on both sides of the visible spectrum with a steep cut-off..."

Just wanted to put that out there. It sounds to me like it's not reflecting IR back outward, but creating interference which stops it. The Phantom HD which I use quite often has a similar filter ("reflective" type) bonded to the sensor assembly, which now has a low pass filter in front of that and behind the lens. I have never seen any problems with that system, and have exposed it to some extreme amounts of IR (75,000 watts of tungsten light in a 4' area). The absorption filters I believe are more effective, however I don't like the light loss or color shift that needs to be balanced out.

-Sean

Mike Stevens
May 5th, 2008, 09:26 AM
A lot said about the 486 but screenshot comparisons so here is desert landscape taken on a moderatly hot day with and without the 486. Camera setting of course were exactly the same for both shots. The "greener" snapshot is with the 496.

Leonard Levy
May 5th, 2008, 11:13 AM
Sean (or anyone else for that matter) , does your B+W filter produce the green vignetting at wideangle under tungstun that Piotr showed?

I'm still trying to get a clear answer from people's experience as to how bad this is, and whether it is endemic to all of these filters.

Sure would like to see a few shots of a relatively flat grey scene, under tungstun, iris wide open (usually shows more problems) that shows how bad this is at full wide and when the problem disappears.

Mike,
Do you see a radical difference between the desert shots? Aside from the minor color balance issue, to me the 486 has more contrast but nothing I couldn't fix with a minor tweak in post. Am I missing something?

Lenny Levy

George Strother
May 5th, 2008, 12:05 PM
A lot said about the 486 but screenshot comparisons so here is desert landscape taken on a moderatly hot day with and without the 486. Camera setting of course were exactly the same for both shots. The "greener" snapshot is with the 496.

Mike

What Picture Profile are you using for those shots?

Mike Stevens
May 5th, 2008, 01:48 PM
Sean (or anyone else for that matter) , does your B+W filter produce the green vignetting at wideangle under tungstun that Piotr showed?

I'm still trying to get a clear answer from people's experience as to how bad this is, and whether it is endemic to all of these filters.

Sure would like to see a few shots of a relatively flat grey scene, under tungstun, iris wide open (usually shows more problems) that shows how bad this is at full wide and when the problem disappears.

Mike,
Do you see a radical difference between the desert shots? Aside from the minor color balance issue, to me the 486 has more contrast but nothing I couldn't fix with a minor tweak in post. Am I missing something?

Lenny Levy
Lenny:

From the two shots I posted you can see how the greens clean up. I did one panorama from a hill to over-looking a desert on a very hot day and all the green bushed were really brown and it was beyond what post could do. That's why i got the filter. If you are not in a very hot environment you wont see much difference. In fact, when it is not radiating great heat from the ground I take the filter of and use a UV/Haze.

Mike Stevens
May 5th, 2008, 02:00 PM
Mike

What Picture Profile are you using for those shots?

George:

I'm not 100% sure but I am 95% sure it was Cine1 with the cinema matrix and the master black level set to about -25.

Ryan Avery
May 5th, 2008, 03:36 PM
Check this out. We gave some of these in 4x5.65 size to Art Adams and he did some interesting tests.

http://provideocoalition.com/index.php/awilt/story/schneider_ir_filter_tests/

This indeed confirms the use of the new True-Cut IR filter (486 less the UV filtration) as a good use for RED cameras only when extra ND is applied as well as regular HDV cameras with no filtration at all.

Ryan Avery
Schneider Optics

Ryan Avery
May 5th, 2008, 03:43 PM
Yes Michael - I know you said it, but a couple of persons using the 486 said it was also working OK, and Ryan of Schneider even mentioned the 486 is "a better choice for this application"... :)

Thanks in advance!

Again, sorry about that comment. I neglected to look at your application carefully. The 486 is the proper filter if its the first optical element in the chain. If not, then use the 489.

The double threaded version exists for non-optical applications like lenshades. Our Industrial Optics division might have another application but I am not aware of it.

Ryan Avery
Schneider Optics

Mike Stevens
May 5th, 2008, 07:32 PM
Again, sorry about that comment. I neglected to look at your application carefully. The 486 is the proper filter if its the first optical element in the chain. If not, then use the 489.

The double threaded version exists for non-optical applications like lenshades. Our Industrial Optics division might have another application but I am not aware of it.

Ryan Avery
Schneider Optics

OK: This is my set-up with ND before and aft. Starting from the CDC I have:-

1. Internal ND
2. Camera Lens
3. 486
4. ND in Matte Box
5. Graduated Filter.

Is my 486 the right choice?

Piotr Wozniacki
May 6th, 2008, 10:05 AM
Again, sorry about that comment. I neglected to look at your application carefully. The 486 is the proper filter if its the first optical element in the chain. If not, then use the 489.

The double threaded version exists for non-optical applications like lenshades. Our Industrial Optics division might have another application but I am not aware of it.

Ryan Avery
Schneider Optics

Ryan,

Nevermind, everything is not lost yet :)

Tell me please one thing: does the 489 filter model create the green cast near the corners/edges due to the IR angle of incidence like the 486, or is this effect weaker, or stronger?

Piotr Wozniacki
May 10th, 2008, 10:01 AM
Since Ryan is not answering, I'd like to ask the 489 filter users for posting some grabs of their shooting in tungsten / incandescent light, and at the full wide EX1's zoom. Does it also produce the green cast near the edges, like the 486 does? I can still replace my new 486 filter (the double-threaded version this time, which indeed fits under the stock lens hood, and can accept the Letus without detaching) with its 489 version, but - before I go for it, and loose money again - I'd like to be certain it's worth it this time :)

BTW, my new 486 works exactly the same with and without the Letus over it - i.e. the adverse affects are there with Letus but only under conditions they would be there without it, as well. At least so far, I didn't notice any additional contamination resulting from closing the filter between my EX1's lens and the Letus' achromat...

Robert Musiello
May 16th, 2008, 06:39 AM
I have just the camera... no matt boxes
I would just put this on the lens...
486 or 489?

Piotr Wozniacki
May 16th, 2008, 07:13 AM
486 will be enough.

Robert Musiello
May 16th, 2008, 08:23 AM
Piotr
If yours fits under the stock shade do you want to sell yours I read your post about buying the other one...
if so email me
ramvideo!optonline.net

Leonard Levy
May 16th, 2008, 04:02 PM
Ryan, Is there any reason not to just go with a 489 as general purpose in front of other elements or in the middle?

- Lenny Levy

Leonard Levy
May 16th, 2008, 04:18 PM
Ryan, Is there any reason not to just go with a 489 as general purpose in front of other elements or in the middle?

- Lenny Levy

Ryan Avery
May 20th, 2008, 10:21 AM
Ryan, Is there any reason not to just go with a 489 as general purpose in front of other elements or in the middle?

- Lenny Levy

Lenny,

The 489 was designed for industrial optical applications where it would be placed in between optical elements; preferably nearest the sensor. The 486 has more coatings and is more efficient at blocking IR light. As a side benefit, the 486 also blocks UV light. The downside, as discussed, is that it should not be used in between elements due to the remote chance that the filter can reflect light in certain light angles and cause issues inside the lens. Hence we recommend that you place it on the first element of the lens so that reflections do not harm the image.

Use the 486 unless you are placing it between elements but keep in mind that using the 486 in between elements may not have an adverse effect on your image because of the remote chance of the reflection issue occurring.

Ryan Avery
Schneider Optics

Piotr Wozniacki
May 20th, 2008, 11:08 AM
Ryan,

Good to see you here again :)

Tell me please one thing: does the 489 filter model create the green cast near the corners/edges due to the IR angle of incidence like the 486, or is this effect weaker, or stronger?

Ryan Avery
May 22nd, 2008, 09:39 AM
Ryan,

Good to see you here again :)

Tell me please one thing: does the 489 filter model create the green cast near the corners/edges due to the IR angle of incidence like the 486, or is this effect weaker, or stronger?

Piotr,

I have been out travelling on business so I haven't had the chance to participate in the forums like I had hoped. But I'm back!

The 489 should create less green cast that is possible (remotely so) than the 486 at certain angles of incidence from light sources. The 486 is still a better application due to its efficiency when not directly next to a sensor. It seems in your application that it may make a difference but most users do not report these effects.

Ryan Avery
Schneider Optics

Ryan Avery
May 22nd, 2008, 09:42 AM
OK: This is my set-up with ND before and aft. Starting from the CDC I have:-

1. Internal ND
2. Camera Lens
3. 486
4. ND in Matte Box
5. Graduated Filter.

Is my 486 the right choice?

You are probably OK. If you don't expereince any green casts or other image anomoly then you are likely not to in the future. It all depends on the angle of light entering your lens. In this case, it seems to be working fine. If you can, I recommend you move the 486 to the front of the lens. If not, then don't sweat it if the results are good.

Its like my car, the manufacturer recommends I put premium fuel in it. I put regular and it runs fine. Should I put premium fuel just because the manufacturer says so? Probably but my results are satisfactory so I don't lose sleep over it. I probably just made some gear-head out there cringe but its the truth!

Ryan Avery
Schneider Optics

Jon Carlson
June 11th, 2008, 08:35 PM
So... is there an easy way to compensate for this in post? I shot a graduation with an EX1 and an XHA1. On the Canon, the caps and gowns look black... Not so much on the EX1.

I'm using Axio / PPro 3. Any suggestions to help them cut together more seemlessly.

Ryan Avery
June 16th, 2008, 11:21 AM
So... is there an easy way to compensate for this in post? I shot a graduation with an EX1 and an XHA1. On the Canon, the caps and gowns look black... Not so much on the EX1.

I'm using Axio / PPro 3. Any suggestions to help them cut together more seemlessly.

Once IR light has contaminated an image, it is in there for good. You would have to affect all of your black levels in post and everything would look oversaturated and no details. It would look like you took a black marker to everything.

The 486 filter or the new Schneider True-Cut filter (the 486 minus the UV for less internal lens reflections) would solve this problem.

Ryan Avery
Schneider Optics

Chuck Wall
June 16th, 2008, 11:48 AM
Ryan

If I understand you the 489 77mm filter would be used when using a DOF adaptor such as the Letus and the 486 true cut when just using the camera without any other adaptors.

What is the model of the 77mm 489 that has threads on both sides?
What is the model of the 77mm 486 trucut?

Thanks

Chuck