AF Confirm - is this as essential on an SLR as some suggest?

I have read around on whether to get an AF confirm adapter for M42-EF lenses (I imagine arguments are similar for others). I will be using an EF DSLR and an EF film SLR, and not using live mode. Are people exaggerating the inability to focus through the viewfinder? I have other EF-native manual lenses and don't have any problems with this. Is there some crucial aspect to non-native mounts that make it crucial, or is this just people being unable or unwilling to live without a little beep or light to quell their insecurities?

mapachebasura said:

I have read around on whether to get an AF confirm adapter for M42-EF lenses (I imagine arguments are similar for others). I will be using an EF DSLR and an EF film SLR, and not using live mode. Are people exaggerating the inability to focus through the viewfinder? I have other EF-native manual lenses and don't have any problems with this. Is there some crucial aspect to non-native mounts that make it crucial, or is this just people being unable or unwilling to live without a little beep or light to quell their insecurities?

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Cant speak to Canon but I have used manual focus ( nikkors and zeiss non cpu ) on my Nikon DSLR’s and purely through the viewfinder. Never used or needed af confirm even when it was available.

I am not sure focus confirm is particularly accurate or useful, at least on Nikon’s. A split screen microprism would be more useful however.

I've never used a Canon-SLR, but on my Pentaxes, with a lens in the range of (roughly) 40 to 80mm, manual focus with the OVF is doable. When in doubt, there's the setting to have the camera fire when it confirms focus; this is a standard menu-item, which is not depending on the adapter used. Again, no idea how this works on Canon.

A lot will depend on how bright the viewfinder is; generally speaking, DSLR OVFs (especially APSC) are quite crippled compared to film-SLR-OVFs.

mapachebasura said:

I have read around on whether to get an AF confirm adapter for M42-EF lenses (I imagine arguments are similar for others). I will be using an EF DSLR and an EF film SLR, and not using live mode. Are people exaggerating the inability to focus through the viewfinder? I have other EF-native manual lenses and don't have any problems with this. Is there some crucial aspect to non-native mounts that make it crucial, or is this just people being unable or unwilling to live without a little beep or light to quell their insecurities?

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I guess it depends. Most modern DSLR's are not meant to be used for manual focus and don't have manual focusing aids such as a microprism. That problem gets worse if you use a smaller APS-C viewfinder, and even worse if it's a dim pentamirror viewfinder that is found in the lower grade cameras. I found that my focus accuracy is much better with telephoto lenses. This is probably because it is similar to using digital magnification in liveview. It is much more difficult for me to get precise focus with wide angle lenses at infinity. Most of my lenses focus slightly past infinity at the infinity stop so that doesn't help. And then there is the issue with fast aperture lenses. The shallow depth of field means that if focus is off by a hair, the subject will be out of focus. Stopping down has its benefits, but also decreasing light entering the viewfinder since most adapted lenses will use stop down metering. Every issue is multiplied when the cameras megapixel count is enlarged, since there is more detail to see the imperfections or slight misfocuses.

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Formally Evogt500

None of my cameras SLR or mirrorless need special adapters to give AF confirm. I find the focusing aids on my mirrorless models more reliable than the AF confirm on the SLRs but even when it's just a green light for focus it's better than nothing.

I do have quite a number of EF adapters as I use that mount as an intermediate for some of my more exotic adapters. When buying them I usually found there was negligible difference in cost from the chipped versions above the standard models - so around half my EF adapters are chipped even though my cameras will ignore the chip.

mapachebasura said:

I have read around on whether to get an AF confirm adapter for M42-EF lenses (I imagine arguments are similar for others). I will be using an EF DSLR and an EF film SLR, and not using live mode. Are people exaggerating the inability to focus through the viewfinder? I have other EF-native manual lenses and don't have any problems with this. Is there some crucial aspect to non-native mounts that make it crucial, or is this just people being unable or unwilling to live without a little beep or light to quell their insecurities?

Click to expand...

It's easier to focus through the viewfinder without microprism or split image aids if you can see the texture of the screen, but that inevitably darkens the viewfinder. With autofocus cameras becoming the norm, the screen textures have been getting finer and finer, but that makes it easier to look past the screen texture, so I have to concentrate harder on getting the focus exact. My vision is quite a bit better than 6/6, but I still can't quickly focus using a Canon DSLR screen quite as precisely as the AF confirm light.

Canon cameras only sense that a lens is attached by getting an electronic response from it. That response switches the focus system on, whether it's the lights in the viewfinder or the match-triangles aid in the EOS R, R5 or R6. (That anti-social beep is the first thing I switch off when I get a new camera.) The other advantage of a chipped adapter is that the chips are programmable, which makes it easier to keep track of which adapted lens took which picture.

mapachebasura said:

I have read around on whether to get an AF confirm adapter for M42-EF lenses (I imagine arguments are similar for others). I will be using an EF DSLR and an EF film SLR, and not using live mode. Are people exaggerating the inability to focus through the viewfinder? I have other EF-native manual lenses and don't have any problems with this. Is there some crucial aspect to non-native mounts that make it crucial, or is this just people being unable or unwilling to live without a little beep or light to quell their insecurities?

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Canon is just about the worst offender in terms of using screens that don't produce a focus plane... and are a little brighter for it. After all, unlike Nikon, Canon has barely made any manual focus lenses in their autofocus mount.

Do you need the AF beep? NO!

You do NEED something. However, replacing the OVF screen can be a good answer. There are plenty of 3rd-party screens you can install easily for under $25 (although I've never gotten one in without getting a spec of dust or two in the finder).

rich_cx139 said:

mapachebasura said:

I have read around on whether to get an AF confirm adapter for M42-EF lenses (I imagine arguments are similar for others). I will be using an EF DSLR and an EF film SLR, and not using live mode. Are people exaggerating the inability to focus through the viewfinder? I have other EF-native manual lenses and don't have any problems with this. Is there some crucial aspect to non-native mounts that make it crucial, or is this just people being unable or unwilling to live without a little beep or light to quell their insecurities?

Click to expand...

Cant speak to Canon but I have used manual focus ( nikkors and zeiss non cpu ) on my Nikon DSLR’s and purely through the viewfinder. Never used or needed af confirm even when it was available.

I am not sure focus confirm is particularly accurate or useful, at least on Nikon’s. A split screen microprism would be more useful however.

Click to expand...

For manual focus with EF lenses on film there was the Canon EF-M, with a conventional split image and microprism screen:

https://global.canon/en/c-museum/product/film149.html

https://www.photo.net/discuss/threa...a-that-takes-only-canon-eos-ef-lenses.458448/

"Are people exaggerating the inability to focus through the viewfinder?"

Yes.

Why do you think that digital OVF is so much worse? The APSC part makes sense, just literally smaller in all respects, but as for a full frame also?

I've looked at this before actually! I'm pretty into the idea of getting a split prism viewfinder but haven't really found much justification... but maybe it can just be that it's fun. Is this a 'I can do it at hope, I'm pretty handy and have an air rocket and some pc repair tools' type deal or is it a "you need a clean room and a full kit' type deal?

mapachebasura said:

Why do you think that digital OVF is so much worse? The APSC part makes sense, just literally smaller in all respects, but as for a full frame also?

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It's simply my experience, using the same brand of digital and analog SLRs in small-format (which is ironically called "full frame" in digital )

The most obvious difference is the focusing screen, but brightness and magnification may also differ. Of course OVF-brightness of a 40+ year old camera can be affected by age or neglect related issues

Keep in mind that changing the focusing screen will affect the exposure meter. The Canon DLSR's with interchangeable focus screens had settings in the menu to alter the exposure meter algorithm. And unfortunately, its not as easy as changing EV compensation.

I'll make a note of that, at least in my head-math if I go this route - tbh I kind of forget to even look at my meter half the time. I kinda just exposure-math-vibe, which I guess is a benefit of never upgrading equipment. I've just learned what's gonna come out. But yeah, for the critical 'gotta get this shot perfectly' I should take what you're saying under advisement.

mapachebasura said:

I kinda just exposure-math-vibe, which I guess is a benefit of never upgrading equipment. I've just learned what's gonna come out. But yeah, for the critical 'gotta get this shot perfectly' I should take what you're saying under advisement.

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I think you will be fine. Remember the days when we had to focus with a distance scale on the lens

For shots where you want perfect focus and/or exposure, you can always use live-view, or check your images, and redo as desired.

The main issuees with a DSLR and manual focusing is that there are 3 different optical paths, the sensor, the AF sensor, and the focus screen, ideally they should be an identical distance from the lens including the reflections off the mirrors(main and sub).

In reality, since AF has become so dominant the viewfinder has been mostly transformed into a framing system from a focus & framing system due to cost savings, why make the viewfinder super accurate when 95% of users will use AF only, 4% may use both and maybe 1% uses manual only vs 100% manual use back in the manual only days.

So accuracy was the first casualty, then the focus screen texture was altered to increase brightness at the expense of DOF representation in the viewfinder, so you don't actually see the actual DOF of the lens, only an approximation.

I owned the 30D, 40D, and 1DIII before moving to mirrorless(NEX-7 & A7r), I did little manual focusing with the 30 & 40D, I did a lot of manual focusing with the 1DIII with various focus screens, while manual focusing was possible, it wasn't ideal nailing the plane of focus was near impossible if the focus screen wasn't calibrated to the sensor(optical path length), you could buy shims for the 1D series focus screen to adjust the path length(which should have been done at the factory, but that costs $).

When I jumped to mirrorless, it was a whole different experience, the plane of focus and DOF in the file was always exactly the same as what I saw in the EVF(WYSIWYG), there was no trial and error, I didn't have to check my shots to see if I missed focus , I could usually tell if I nailed it or missed it, and I could see the actual captured DOF before I tripped the shutter.

For example if I wanted the plane of focus on a flowers stamen, I could generally get it quite close with the DSLR, but with the mirrorless, I could choose to place the plane of focus on the front or rear half of the stamen, or the very tip if I choose to, then add as much DOF to get the effect I wanted, it was a completely different experience I wasn't expecting, EVF was the future, and I was living it.

Focus confirmation wasn't really talked about all that much when I started shooting manual lenses, so I already bought a bunch of non chipped adapters and I didn't see any advantage in going back to relying on the AF sensor to nail the plane of focus when I had moved to manual focus because I couldn't nail it with AF in the first place, although AF micro adjustment did help immensely with AF accuracy I still couldn't nail focus like I wanted with all subjects, low contrast subjects remained near impossible with AF.

mapachebasura said:

I've looked at this before actually! I'm pretty into the idea of getting a split prism viewfinder but haven't really found much justification... but maybe it can just be that it's fun. Is this a 'I can do it at hope, I'm pretty handy and have an air rocket and some pc repair tools' type deal or is it a "you need a clean room and a full kit' type deal?

Click to expand...

It's an easy swap on most cameras. For example, I did this to my Sony A350 years ago, and that's a model that Sony never intended to have an interchangeable screen.

The catch is that real focus screens are dust magnets -- basically, a finely-textured-thing that you end-up viewing through a magnifying glass -- so don't get upset if you see a speck or two when done. The screen kits come with tweezers and such for doing the install, and I recommend doing it in a low-dust environment (e.g., bathrooms tend to have less airborne dust because the humidity from showering settles many dust particles, but don't do the swap in high humidity), and it's really easy despite being done in a cramped little space with limited access (the camera generally does NOT get disassembled for a screen swap). The only complication is that some DSLRs need shimming to perfectly align the focus screen with the sensor plane and it's awkward trial-and-error inserting/removing shims... but most DSLR screen swaps don't need shimming if the screen kit is designed for your camera model in particular.

Does changing the screen change the exposure metering? That depends. On a DSLR that meters off the screen, yes. For a matte focus screen without focus aids, it should be a roughly constant exposure offset, but microprisms and splits can throw that off a bit in metering modes that weight the central region differently (e.g., center spot metering). In truth, that happened on film SLRs with focus screens too, but it was rarely a big deal -- in fact, stray light coming in from the OVF eyepiece tends to be a bigger problem (this is why you generally shouldn't use a DSLR on a tripod without your eye against the OVF or the OVF otherwise blocked). Also be aware that not all DSLRs meter in the OVF, so there are some DSLRs for which a screen change would not alter metering at all.

Changing the screen definitely makes a DSLR feel much more like a manual-focus film SLR, and that's not a bad thing. On the other hand, it's still not as effective as using a mirrorless with an EVF... but if you've already got the DSLR.... ;-)

In addition, if you're using a digital SLR with an interchangeable, rechargeable battery, then the risk of battery drain is going to live less on your mind than if you're using CR-2s on a film camera and have to half press for extended periods of time as you fiddle.

Don't take this as gospel- I haven't tested extensively enough to know whether this is an issue, but what I do know is you could end up running the AF 'circuits' alot more than usual. At the same time, you might be draining the battery as much as you ever would during a session of continuous autofocus.

If you are going to be shooting Canon film EF mount SLRs you might think about picking up a 650/630/600/RT (using EU naming for it here) as they are plentiful, cheap and support interchangeable focusing screens with a number of manual focus options. I have a four way split image one for mine, but there is microprism, horizontal split, parallax etc...

Do bear in mind that the ones I listed have their own specific line of screens that aren't compatible with EOS 1/3/50E, and vice versa.

And sure, you might lose out on AF points, but outside of the expensive flagships these will have the largest magnification finders you'll find on a Canon EF film body. It's all downhill from here (but at the very least they never went any lower than 0.7x magnification, unlike Nikon).

I can't speak for digital, but you're not going to find any easy third party options growing on trees for manual focusing screens, particularly as some manufacturers seem to have disappeared.