Yes, that's very true - but I understand the origin of the short hand. A lens, if focused at infinity, is effectively creating a focused image from parallel (collimated) light rays (so to speak). This is the reference state for the lens, ie. the state in which you want it to be when establishing the distance it needs to be from the film plane. One speaks of "collimating" the lens, but really one is collimating the light (or the image) - not the lens - but a byproduct of which then allows the lens focus plane to be found.

Yes, under most lighting conditions, you can still frame the subject without having to take the filter off of your lens. The trick is to switch to ‘live view’ mode and use your LCD screen if your optical viewfinder is too dark. In bright light, the optical viewfinder may be barely sufficient for framing.

And considerig that you have two Optivarons, both of which just happen to conform to the C-mount standard, I reckon that makes it a pretty safe bet that such was the idea.

The rear C-mount assembly screws on, so you could potentially undo the grub screw(s) locking it in place and unscrew it while checking collimation, to get a sense of where correct back-focus might be, but you can only do this adjustment in the one direction (adding distance), because the assembly is screwed down to a flat surface.

My old article on DIY optical adjustments describes completely different methods from Mr. Elek's, but there is one point of disagreement: there are reasons not to use maximum aperture.

I can totally recommend the Pro ND 1000. I wish its mount was a bit thinner, but keep in mind that this filter has to contain enough volume of dark glass to stop a serious amount of light.

The Hoya Pro ND 1000 filter can transform mundane shots into something magical, given the right subject (and given a tripod). Wind is your enemy; you might consider a shot with and without the filter to have options.

Hoya NDfilter 49mm

Thanks Dom - I don't think the camera will be here in the next two weeks. From what I understand they are testing the first batch as we speak, individually testing each one with a roll of film, before shipping them out. But if it does arrive in nthe next 2 weeks will certainly give you a call. However I may get the lens sooner, so perhaps I could come and see you and you could show me what sort of things I'll need to play with to adjust it. Pick your brains!

While Jean-Louis does say it was the camera flange depth that differed, I completely glossed over that. Indeed re-reading it now, I'm not sure I understand his reply at all. If it was the Beaulieu flange depth that was non-standard - to accomodate the filter, then the lens wouldn't have been "collimated" to this particular camera at all - since the non-standard flange depth + filter would have recorrected everything, ie. before the lens was brought into the picture..

I recently had someone bring in a Digital Bolex that had a very badly set flange depth, not only off but not even flat to the sensor! Hopefully the Logmar guys are more diligent.

The shot above is the histogram with the white balance measured right off of the grey card without any filter. I used the white balance as-recorded from the raw file.

The exif data indicated the no-filter shot was E.V. 10.3 and the Hoya ND filter shot was E.V. 0.3, so the filter is exactly 10 stops after all.

Anyway, will see what happens. Just got word from Logmar that they are getting their test back next week, after which they'll be FedExing the camera.

The rear C-mount assembly screws on, so you could potentially undo the grub screw(s) locking it in place and unscrew it while checking collimation, to get a sense of where correct back-focus might be, but you can only do this adjustment in the one direction (adding distance), because the assembly is screwed down to a flat surface.

Both of the Optivarons I own are perfectly collimated to the C- mount standard of 17.52mm, I believe the Beaulieu camera flange depth is what was (very slightly) adjusted to compensate for the gelatin filter rather than the back-focus of the stock zoom. This makes sense as the camera can then accept other C-mount lenses.

Well maybe I've been lucky that both my 4008 Optivarons were correctly set, from that thread it seems other people didn't have the same experience. Perhaps Beaulieu's quality control wasn't always the best and so lenses were adjusted to the camera without particular regard to the standard. But it would certainly have made sense for them to at least try and make the camera flange depth be adjusted for the permanent filters so it would work for other C-mount lenses.

Hoya ndfilter

My old article on DIY optical adjustments describes completely different methods from Mr. Elek's, but there is one point of disagreement: there are reasons not to use maximum aperture.

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HoyaVariableNDfilter

There are many characteristics of extremely dark ND filters that are difficult for manufacturers to get right. Many ND filters suffer from color shift, usually toward pink or orange. Other filters play havoc with lens resolution. Some filters have poor anti-reflection coatings that cause ghost images. Neutral density filters that avoid all of these pitfalls can get quite expensive.

You don’t necessarily want the longest possible exposure time for water; try a few different exposures to give yourself a selection.

Ah okay. So the Optivaron was made to the C mount standard and it was the Beaulieu flange depth that was adjusted to accomodate the filter - not the lens. So if the logmar flange depth is standard (and correct), and the lens is good, then nothing required.

From what I understand the Optivaron was calibrated (if that is a better term) for the Beaulieu Super8 camera (which used a gelatin filter). So in theory, one could use Dennis' geurilla method for "negative shimming" and just re-insert a clear gelatin filter back into the path to get it behaving on the Logmar - assuming of course that the Beaulieu otherwise had a standard C-mount flange to film plane distance. But of course, if it has shims already in there (to accomodate for a gelatin filter) can just remove those instead (for a clearer optical path).

For photographers who do landscapes or architecture, a strong neutral density filter should be a standard part of their gear. And, once again, don’t forget that tripod.

Yeah for sure. It makes complete sense that the body + filter would be intended as a complete correction. As you say, in that way a range of lenses could be used on the Beaulieu - not just the Optivaron.

I recently had someone bring in a Digital Bolex that had a very badly set flange depth, not only off but not even flat to the sensor! Hopefully the Logmar guys are more diligent.

Hoya NDfilter 77mm

The shot above is the histogram using the Hoya Pro ND 1000 filter and the same white balance created from the “no filter” shot. The color transmission isn’t identical to ‘no filter’, but it’s reasonably close.

Comparing the lens resolution results above (on a Nikon D850), there isn’t enough change to be able to visually tell the difference when using the filter. The MTF50 numbers show the barest hint of a resolution decrease with the filter.

Low magnification lenses typically have low NAs, meaning that they cannot capture the highest resolution information. To capture the widely diffracted ...

Please remember to cover that viewfinder eyepiece. Long exposures will cause eyepiece light leaks to ruin your shots. If you’re lucky enough to have an eyepiece shutter on your camera, this is the reason for its existence.

To correctly adjust a zoom, you start by setting focus at the telephoto end, then go to the wide end to adjust back-focus for best sharpness. You generally need to go back to the long end to re-adjust focus again, then back to the wide end to tweak the back-focus.

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Would everybody please express themselves as precisely as possible, always. Carl wants sharp pictures. A sharp mind is a prerequisite.

Exposure: 177s f/10.0 ISO 32. The outrageously long exposure didn’t totally get rid of the crowd around the pool, but it did make about 95% of them disappear. The heavy clouds combined with the ND filter allowed this long exposure time. A light breeze caused many palm fronds to smear; oh, well. The clouds unfortunately moved too much in this long exposure and became featureless. This shot then demonstrates the downside of wind during a long exposure.

This filter is fairly thick. It’s about as thick as a typical polarizer. Its (metal) mount is 2.0mm thick (not including threads), and happens to be exactly as thick as my Marumi DHG Super Circular Polarizer. This can cause some vignetting on super-wide lenses, so you may have to crop slightly if your lens only works with “thin” filters.

If you like, you're welcome to drop in to my workshop and I can check/adjust both camera and lens for you, I'd be curious to see the Logmar if you have it already. But you'll need to do it in the next 2 weeks as I'm about to go on a year-long sabbatical.

the proper way to adjust back-focus on the Schneider 6-66 Optiivaron is to undo the outer lock ring at the rear, lift out the rear optical group, and change the shims beneath. Without knowing exactly how many hundredths of a mm you need to add or remove, this would be something of a chore, particularly as you would need to cut your own shims and test them by trial and error.

Would everybody please express themselves as precisely as possible, always. Carl wants sharp pictures. A sharp mind is a prerequisite.

You might start finding excessive bright pixels in your shots with really long exposures. Remember to turn on ‘long exposure noise reduction’ to get rid of those speckles. It will take twice as long, but it may be worth it compared to the amount of time wasted post-processing trying to eliminate them at your computer.

The shot above is using the Hoya ND filter, with the same white balance as the no-filter preset white balance. It’s a hair different from the no-filter shot, but still quite neutral.

It may seem silly to have to verify such a thing, but does the Hoya Pro ND1000 filter really cut the light level by 10 stops? I’m notoriously skeptical about claims, and just because it’s advertised as 10-stop, that doesn’t make it so. A quick way to evaluate photos is via the “Exif Tool”. I took a pair of shots using auto-exposure in sunlight.

Collimation has nothing to do with the adjustment of focus. One cannot set a lens’ focus with a collimator. The (auto)collimator is an instrument for checking and adjusting deviating angles.

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The Hoya Pro ND1000 is a 10-stop neutral density filter. If you like those shots with rivers that look like mist, this is what you use to make them. Ocean breakers that transform into blankets of fog become possible with this filter. If you need to reduce crowds around popular landmarks, this filter is just the ticket.

Exposure: 30s f/9.0 ISO 32. Yes, my D850 “Lo” can go down to ISO 32. I used my Tokina 11-16 DX at 16mm. The Hoya needed a step-up ring to fit my 82mm filter onto my 77mm diameter Tokina. I had to crop a bit, because this combination causes some dark frame corners on my FX camera.

Anyway, so all that's left to consider is how precise the Logmar is in terms of it conforming to the C mount spec. And if the lens is still good.

With over 30 years of experience, not only in the field of light and color measurement but also in the field of imaging technology, we develop high-quality ...

I purchased an 82mm diameter filter, so it fits the largest lenses I want to use it with. For my smaller lenses, I have step-up rings to use this filter for anything down to 52mm. Step-up rings are really inexpensive and an ideal way to spread the cost of a single expensive filter over several lenses.

the proper way to adjust back-focus on the Schneider 6-66 Optiivaron is to undo the outer lock ring at the rear, lift out the rear optical group, and change the shims beneath. Without knowing exactly how many hundredths of a mm you need to add or remove, this would be something of a chore, particularly as you would need to cut your own shims and test them by trial and error.

Notch optical filters are an ideal choice for numerous illumination and detection applications. They block a preselected wavelength region while transmitting ...

Collimation has nothing to do with the adjustment of focus. One cannot set a lens’ focus with a collimator. The (auto)collimator is an instrument for checking and adjusting deviating angles.

Well maybe I've been lucky that both my 4008 Optivarons were correctly set, from that thread it seems other people didn't have the same experience. Perhaps Beaulieu's quality control wasn't always the best and so lenses were adjusted to the camera without particular regard to the standard. But it would certainly have made sense for them to at least try and make the camera flange depth be adjusted for the permanent filters so it would work for other C-mount lenses.

I don’t mean to imply that this is the most expensive neutral density filter, but it’s not the cheapest, either. What follows is how I evaluated this filter manufacturer’s claims. I own a couple of other Hoya filters, and I haven’t been disappointed.

Hoya ndchart

I made a white balance preset with no filter, using a grey card. After shooting the grey card, I then mounted the ND filter and re-shot the grey card using the same white balance preset. The only difference should be the longer exposure with the filter.

Can a camera still focus with a 10-stop filter on the lens? It’s a real pain to have to remove a filter to focus a lens, so of course I tested auto-focus. I used my D850 for testing, which can focus down to EV -4. Typical outdoor lighting with a low-angle sun is around EV +10. Since EV increments are in full stops, this means that a 10-stop filter will result in an EV around 0, or 4 stops brighter than the D850’s lower limit. Focus is no problem.

Both of the Optivarons I own are perfectly collimated to the C- mount standard of 17.52mm, I believe the Beaulieu camera flange depth is what was (very slightly) adjusted to compensate for the gelatin filter rather than the back-focus of the stock zoom. This makes sense as the camera can then accept other C-mount lenses.

Hoya ndfilter review

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I confess to using a bit of HDR to make this shot a little more dramatic. It’s the misty water that makes the shot, though. You just couldn’t do something like this without a really dark ND filter.

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If you like, you're welcome to drop in to my workshop and I can check/adjust both camera and lens for you, I'd be curious to see the Logmar if you have it already. But you'll need to do it in the next 2 weeks as I'm about to go on a year-long sabbatical.

Hoya NDFilter 82mm

I've never done this before but I completely understand the theory.So I want to collimate a lens and in particular a C-mount Optivaron (6-66mm), originally collimated for the Beaulieu, but for repurposing on a standard C mount camera (the Logmar).I can follow the theory of what's going on in the following guide - basically it's using a camera and lens already understood to be correctly collimated, and focused at infinity, to image the image plane on the other camera, with it's lens also set to infinity, but in an unknown collimated state:http://elekm.net/zeiss-ikon/repair/collimate/This I can manage quite well using a DSLR as the imaging camera - or rig up some alternative setup with diode lasers etc. Can do all the required levelling, making sure it's all parallel etc.What I don't know, but would love to know, is what I need to do with the Optivaron lens in order to modify it's collimation setting. I understand it will need to be partly disassembled. I'm perfectly fine with that. Just don't know what rings/notches/or whatever, inside the lens, need to be rotated/moved in order to tweak it's collimation setting. I can certainly open it up and experiment (and will eventually work it out) but if someone knows how to do it already, that will certainly save me some anxiety.Any advice much appreciated.Carl

Hoya NDFilter 67mm

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A good filter shouldn’t cause any significant change in lens resolution. Physics being real, all filters will have some impact on your lens, but that doesn’t mean that it has to be objectionable or even noticeable. I’ll use the MTFMapper program and a large resolution chart to see how much degradation in lens sharpness this filter causes.

I suppose you could stack this filter with a polarizer or another ND filter if you need yet more light reduction, but 10 stops is enough for most situations.

I’ll use a grey card to evaluate the color fidelity of the Pro ND1000 filter. For a completely neutral photo, the RGB peaks on a histogram should perfectly overlap.

To correctly adjust a zoom, you start by setting focus at the telephoto end, then go to the wide end to adjust back-focus for best sharpness. You generally need to go back to the long end to re-adjust focus again, then back to the wide end to tweak the back-focus.

Speaking of threads, this filter screws on and off very smoothly; the threads are precision. I also noticed that it has about a whole extra thread compared to most filters, which makes it very stable when attached.

No protest on that. If you'd read my 1991 article on DIY optical adjustment, you'd find no words "collimate" or "collimator" in that. Optical knowledge is to the point, and doesn't hide behind fancy words.