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Dedicated Monochrome Cameras

Pradeep

Member
Sent my A7r3 to Life Pixel for conversion, Daniel Morrison couldn't do it in time for my trip to Africa next month (he's away for a while).

While waiting, I would like to get the IR cut filters. I will need both 77mm and 82mm sizes.

These large filters are not cheap of course. Given that there are variable IR wavelengths they cut off, what would be the most useful range or number to get? The options are 590nm, 665 or 650 nm, 770nm and similar numbers.

I am quite confused as to what to get.

Basically what I would like to do is

1. standard IR photography of African vistas and wildlife when the right composition or subject presents itself.
2. Improved B&W imaging of everything

Towards this end, I've asked for a 'full spectrum' IR conversion on the camera. This, from my understanding gives me the most flexibility. However, if I want to make really sharp monochrome (not IR) images, I will need to put a filter on the lens to cut off the IR part of the spectrum so as to not overload the sensor and also to allow better focusing of the light overall and enhance resolution. And this is where I am stuck, what part of the IR should I cut off? And is there a difference between the B&W type where the light (IR) is eliminated by interference, or the type (Kolari) where it is absorbed, thus eliminating issues with wide-angle lenses.

I am not very good with my hands in the field and definitely do not want to fiddle with internal (over the sensor) filters, so whatever I get will have to go over the lens in the front.

Requesting Vivek and others here to please 'shed some light' :D on this issue for me.

Finally, what brand to consider?

Thanks.
 

JoelM

Well-known member
Sent my A7r3 to Life Pixel for conversion, Daniel Morrison couldn't do it in time for my trip to Africa next month (he's away for a while).
Okay, this is where I messed up last time. I don't think he is from Life Pixel. If you sent your camera to Life Pixel, then perhaps you are getting a conversion for IR. Daniel Morrison is from Monochrome Imaging. Life Pixel is Daniel Malkin. Damn, why did they both have to be named Daniel and on top of that, the same last name initial. Life is hard enough as it is.

Joel
 

Pradeep

Member
Okay, this is where I messed up last time. I don't think he is from Life Pixel. If you sent your camera to Life Pixel, then perhaps you are getting a conversion for IR. Daniel Morrison is from Monochrome Imaging. Life Pixel is Daniel Malkin. Damn, why did they both have to be named Daniel and on top of that, the same last name initial. Life is hard enough as it is.

Joel
Yes, you are correct, Daniel Morrison is from Monchrome Imaging whereas Daniel Malkin is from Life Pixel. I've been talking to the former for a month about my conversion while waiting to get the camera in. Last week he told me he is now gone for several weeks on a much needed vacation so I am getting the conversion by Life Pixel. The latter also comes in at almost half the cost, I just hope he is equally good.
 

Pradeep

Member
I am now trying to understand the various filters on Kolari Vision's website, they do seem to have good explanation for different wave lengths. Would love to hear the opinions from users though.
 
V

Vivek

Guest
Huh?!

I am pretty sure the full first name of the maxmax owner is also Daniel.

How difficult is it to check a website to find out what they do? :shocked:

Okay, this is where I messed up last time. I don't think he is from Life Pixel. If you sent your camera to Life Pixel, then perhaps you are getting a conversion for IR. Daniel Morrison is from Monochrome Imaging. Life Pixel is Daniel Malkin. Damn, why did they both have to be named Daniel and on top of that, the same last name initial. Life is hard enough as it is.

Joel
 
V

Vivek

Guest
Pradeep, I have various filters (of different strength and make) from over the years.

Your problem might be with the use of the Sony lenses for IR. Many of them are not useful.

The FE 55/1.8 is OK (not great though) but not the FE 35/2.8. The Samyang 24/2.8 is superb!

I am afraid that most zooms are not good for IR.

Sent my A7r3 to Life Pixel for conversion, Daniel Morrison couldn't do it in time for my trip to Africa next month (he's away for a while).

While waiting, I would like to get the IR cut filters. I will need both 77mm and 82mm sizes.

These large filters are not cheap of course. Given that there are variable IR wavelengths they cut off, what would be the most useful range or number to get? The options are 590nm, 665 or 650 nm, 770nm and similar numbers.

I am quite confused as to what to get.

Basically what I would like to do is

1. standard IR photography of African vistas and wildlife when the right composition or subject presents itself.
2. Improved B&W imaging of everything

Towards this end, I've asked for a 'full spectrum' IR conversion on the camera. This, from my understanding gives me the most flexibility. However, if I want to make really sharp monochrome (not IR) images, I will need to put a filter on the lens to cut off the IR part of the spectrum so as to not overload the sensor and also to allow better focusing of the light overall and enhance resolution. And this is where I am stuck, what part of the IR should I cut off? And is there a difference between the B&W type where the light (IR) is eliminated by interference, or the type (Kolari) where it is absorbed, thus eliminating issues with wide-angle lenses.

I am not very good with my hands in the field and definitely do not want to fiddle with internal (over the sensor) filters, so whatever I get will have to go over the lens in the front.

Requesting Vivek and others here to please 'shed some light' :D on this issue for me.

Finally, what brand to consider?

Thanks.
 

Pradeep

Member
Pradeep, I have various filters (of different strength and make) from over the years.

Your problem might be with the use of the Sony lenses for IR. Many of them are not useful.

The FE 55/1.8 is OK (not great though) but not the FE 35/2.8. The Samyang 24/2.8 is superb!

I am afraid that most zooms are not good for IR.
Thanks Vivek.

I am afraid I only have one prime lens left, the Batis 18mm f2.8. All the others are zooms. I was thinking of keeping the 24-70 f2.8 on the A7r3(m) for IR photography (or for dedicated B&W). This is a very sharp lens otherwise and gives me the range I am most likely to use in Africa. I also have other WA zooms (12-24 and the 16-35) but this would be the most versatile.

What is the problem with zooms? I know the camera becomes manual focus with IR conversion, but is there another reason why the zooms don't do well? If I wanted to do simply B&W and not IR in a given scenario, would the zoom still not perform well?

I could get the Samyang 24mm, or now that the AF is gone, even the Loxia lenses (smaller is better for me). What do you think about those? I will also need something longer than 24mm, perhaps something in the 70-100 range, especially if the animals are going to be a bit farther away.

Any other recommendations? What about the filters themselves?

Thanks.
 
V

Vivek

Guest
I know the camera becomes manual focus with IR conversion
On the contrary, they may focus better! This depends on the lens transmission, filter used and the light. Remember that the focus is off of the sensor itself. You still have the micro lenses and the PDAF (this is not the case when there is a monochrome conversion is involved).

The issue with many zooms (again, it depends, you may luck out with your 12-24, and the 100-400) is the coatings on the multitude of elements. You need to check them out. To do this quickly, a clip filter that goes into the camera body is quite favourable. I can lend you one if you wish. Drop me a line.

The Samyang 24/2.8 is highly recommended for IR. You can use this as a standard to check the IR performances of your other lenses.

Since most filters are uncoated, lately, I like and favour filters from China. They are cheap as well. Same material as the pricier ones from Germany.
 

Pradeep

Member
Got my A7r3 after a full spectrum conversion. Being a total noob in this area I have a few observations, not sure they are peculiar to me/my set up and if anything needs to be done.

I did get the Samyang 24mm f2.8 lens to try out with this combo, it is indeed an amazingly light lens. However, my 24-70 GM seems to be sharper wide open esp. at the edges. I will continue testing.

Vivek, you are correct, the AF works beautifully, so no need to struggle with MF.


Shooting without an IR cut filter: creates a colored image, but interesting look.

Shooting with the 850mm IR cut filter from ZoMei:

I am using AWB while shooting, which creates a blue cast in the RAW files, but with the monochrome2DNG converter, this is gone. What an amazing program this is.

The only problem I have noticed is that at anything over f2.8, there is a bright spot in the center of the image, gets worse at smaller apertures. Is this normal? I seem to have read somewhere that this may be normal behavior. It is very annoying because now it becomes a DOF issue with longer lenses or even with the 24mm. I suppose I could manage it in post, but is there another remedy?
 

Pradeep

Member
So the bright central area I am seeing is a lens generated hot spot I believe.

I just went through the Kolari Vision lens hot spot database. The Sony 24-70 2.8GM is listed as a 'poor performer'. I guess this is what I am seeing. The Samyang 24mm is not listed on their website, but I suppose it is also a 'poor performer' in this regard.

I am going to test my other lenses now.
 

GrahamWelland

Subscriber & Workshop Member
Hot spots are the challenge. Typically T* and other coatings found on a lot of modern corrected lenses suffer this as you stop down.
 

Pradeep

Member
I just tested my Sony lenses, almost all suffer from the hotspot issue. The only one so far that does not have it at all is the 70-200 2.8GM, not tested the 100-400 yet, unlikely I would ever use it for IR work.

I wonder if the Kolari filters with the AR coating would make a significant difference.
 
V

Vivek

Guest
I have tested the Samyang 24/2.8 on my A7rII(m) and an 720nm IR converted NEX-5N and reported that it exhibits no hot spot issue.

Another gem for IR is the FE 28/2. No hot spot issues.


I am not surprised that the Sony zooms fare poorly (i said so earlier).

So the bright central area I am seeing is a lens generated hot spot I believe.

I just went through the Kolari Vision lens hot spot database. The Sony 24-70 2.8GM is listed as a 'poor performer'. I guess this is what I am seeing. The Samyang 24mm is not listed on their website, but I suppose it is also a 'poor performer' in this regard.

I am going to test my other lenses now.
Untitled by Vivek Iyer, on Flickr
Sony A7rII(m), Samyang 24/2.8, f11, 850nm

Untitled by Vivek Iyer, on Flickr

Sony NEX-5N(IR), Samyang 24/2.8

Untitled by Vivek Iyer, on Flickr

Sony A7rIIm, Sony FE 28/2, Hoya 720nm
 
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Pradeep

Member
I have tested the Samyang 24/2.8 on my A7rII(m) and an 720nm IR converted NEX-5N and reported that it exhibits no hot spot issue.

Another gem for IR is the FE 28/2. No hot spot issues.


I am not surprised that the Sony zooms fare poorly (i said so earlier).
Thanks Vivek, great pictures.

My Samyang must be off, or it could be the A7r3, or it could be that the conversion I had done was 'bare' i.e. they did not put in an AR filter over the sensor, simply a clear glass one.

Kolari vision does (and I am sure some others too) put an additional AR coated filter over the sensor when you do the conversion with them, apparently this reduces hot spots. It is an optional extra but not too much. They also offer an external AR coated IR Cut filter, not sure it does the same job.

Here is a review of the product after this additional filter is put on the sensor during the conversion process.
 
V

Vivek

Guest
Pradeep, My A7rII(m) has an uncoated coverglass. I shot with an uncoated ZoMei 850nm filter on the 24/2.8.

My IR filter inside the NEX-5N is also uncoated.

Did you see a central hotspot from the 24/2.8 or was it a flare? Can you post a sample?
 

Pradeep

Member
Pradeep, My A7rII(m) has an uncoated coverglass. I shot with an uncoated ZoMei 850nm filter on the 24/2.8.

My IR filter inside the NEX-5N is also uncoated.

Did you see a central hotspot from the 24/2.8 or was it a flare? Can you post a sample?
Vivek, I was doing some testing comparing the Samyang 24mm with the Sony 24-70GM set at 24mm. The moment I closed down the aperture, I started seeing a bright white spot within the focus rectangle, almost the same size. I thought it was the angle of the sun or something since the sun was just outside the frame. Later even with the sun on my back, I saw the hotspot at anything smaller than f2.8. At the time I thought it was the ZoMei filter (850nm). Then last night (indoors with all the lights on) I just looked through the camera with different lenses on, without the ZoMei filter, i.e. allowing all visible light to enter the camera. No need to take pictures, just dialing down the aperture creates a hot spot with almost all the lenses.

This is not a good way to look at the problem, so tomorrow I am going to test it out outdoors, somebody suggested the best way is to look at the cloudless sky just above a tree (don't know why the tree should be important).

I am going to call the Kolari Vision guys today.
 

Pradeep

Member
The 24-70 f4 Sony lens has worked well for me without hotspot.

Joel

Yes, apparently some of the lenses that are f4 at widest do better, don't know why. Here is the lens hotspot database on Kolari Vision. It does not list too many Sony FE lenses and unfortunately I have none of the 'good performers'. Going by this list it seems that zooms are no better or worse than primes. I suspect there are many more 'poor performers' out there.

The other thing that seems highly variable is a lens may perform better on a given system (Vivek's for example) and not do so well on another - mine for instance.

I spoke with the Tech person at Kolari Vision. He says that the AR coated glass makes a difference ONLY If placed internally on the sensor, not in front of the lens, so I am out of luck in this regard. However, they do swap out the clear glass from other conversions for the AR coated one, so I will probably have to go this route. And according to him, it will make the hotspot issue less of a problem, though it still has to do with what kind of lens you put in front of the camera.

It is painful to have to restrict myself to one or two lenses only (or, so far, just the one) after having spent so much money on an IR body, it makes sense to get it right in the end. 'In for a penny, in for a pound' as they say :cry:
 
V

Vivek

Guest
Does the bright “spot” flicker? I suspect what you are describing is not an IR hotspot but the built in IR LED in the shutter mechanism that is acting up.

The original UV/Ir cut filter in a stock camera takes care of it.

Since yours is “full spectrum” the IR from the LED (it is there to do quality control of the shutter) lighting up the sensor.

My A7rII is also supposed to have this but the way Daniel @monochromeimaging converted it poses absolutely no problems.

Lifepixel did not consider this and did not mitigate the issue.

I ask again for sample pictures for this very reason.

Vivek, I was doing some testing comparing the Samyang 24mm with the Sony 24-70GM set at 24mm. The moment I closed down the aperture, I started seeing a bright white spot within the focus rectangle, almost the same size. I thought it was the angle of the sun or something since the sun was just outside the frame. Later even with the sun on my back, I saw the hotspot at anything smaller than f2.8. At the time I thought it was the ZoMei filter (850nm). Then last night (indoors with all the lights on) I just looked through the camera with different lenses on, without the ZoMei filter, i.e. allowing all visible light to enter the camera. No need to take pictures, just dialing down the aperture creates a hot spot with almost all the lenses.
 

Pradeep

Member
Does the bright “spot” flicker? I suspect what you are describing is not an IR hotspot but the built in IR LED in the shutter mechanism that is acting up.

The original UV/Ir cut filter in a stock camera takes care of it.

Since yours is “full spectrum” the IR from the LED (it is there to do quality control of the shutter) lighting up the sensor.

My A7rII is also supposed to have this but the way Daniel @monochromeimaging converted it poses absolutely no problems.

Lifepixel did not consider this and did not mitigate the issue.

I ask again for sample pictures for this very reason.

Vivek, I don't see a flicker. It seems like the camera has a low-power flashlight that creates a bright spot in the center of the frame. This spot is bigger at bigger apertures and therefore not so noticeable. At smaller apertures it becomes smaller and more 'dense' if you like, resulting in an obvious bright central 'hot spot'. Even wide open you can see that the central part of the image is brighter. Here are four sample shots from yesterday, I've cropped them to save bandwidth and illustrate the problem. The text explains it all.

I am going to keep testing, it seems that depending upon the subject this may or may not be that big an issue.

I did read about the LED light, but I am not sure if it becomes smaller with smaller apertures. And I don't see it with my 70-200GM.

Would be interested in your thoughts on these samples. Forgot to mention, these are straight DNG conversions from RAW, no sharpening of any sort or white balance or other adjustments.











 
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