[Serkevan]

The Sony e-mount has a bunch of lightweight APS-C lenses that are a fair bit lighter than the FF FL equivalents. The 16-55/2.8 is 494g and the 24-70/2.8 is 890g, for example.

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I'm not sure how you found a Pentax kit that weighs 500g. Even if I used a plasticky K-70, in the comparison, the body with a battery weighs 688 g according to the PentaxForums database. That's not including a lens (which is kind of a necessity). You'd have to go down to a much inferior K-S1 or the like to even see 558g for a Pentax body. That still needs a lens.

I mean the *lens* kit. 150g for the FA43, 150g for the M20/4, 250g for the FA77. A bit over 500, but it was off the top of my head.
The camera weight is actually irrelevant, it's the heavy lenses that are a bother. Size of the camera is also largely irrelevant - and in fact Pentax cameras are smaller than Canikon equivalents (or than Panasonic FF MILCs).

An EVF is literally unusable for me, so MILCs are anyway a moot point in my case.

[mee]

The Sony e-mount has a bunch of lightweight APS-C lenses that are a fair bit lighter than the FF FL equivalents. The 16-55/2.8 is 494g and the 24-70/2.8 is 890g, for example.

Before you were referring to systems. So that is where my response was centered around. Now it's lenses? I'm still not sure how one of these dslrs is fitting in your pocket unless you have ridiculously large pockets. I don't think I've seen a single crop or FF camera fit in a jacket pocket. If I was going for carry around it would be a compact 1" sensor camera or a GR.


Anyways, f/2.8 on crop is not the same as f/2.8 on full frame when it comes to depth of field due to the differences in sensor size.


If we really want to compare apples to apples we need to use an f/2.8 lens for crop and an f/4 lens on full frame to get proper equivalence.

And when we do that, we'll see the lenses are much more similar in size and weight. One also has to consider lens construction. Not every lens is alike. Some are much sharper in the edges and corners with less CA than others (ultra pancakes).


So there is no free lunch I'm afraid.

Actually I just read a thread about someone who is moving from Fuji (crop) to Nikon Z (full frame), because they felt the newer lenses were getting too big and heavy so they might as well just use a FF system. One drop in the bucket, but I understand where he's coming from at least. And it plays into this discussion.

[Pål Jensen]

I think you missed my point by careful quote editing. The point was that very often APS-C lenses lose their size advantage if one insists on equivalent performance.

But nobody buy a format over another in order for them be equivalent. They choose them because they are not equivalent. There's not such thing as correct DOF for a certain aperture and angle of view. This is a matter of taste and shooting situation. Insistence on equivalence is frankly nonsense as two formats can never be totally equivalent anyway (you must choose which parameter to discriminate them by - all of them will never do simultaneously). You can take any format as reference point and proclaim that any properties of this format must be the same in another in order to compare them. It is a fruitless exercise and the one you use as reference will always "win".
The point is that if you want APS output you are best served with an APS system. Likewise if you want FF output you are best served by an FF system etc... This is the starting point. Decide what output you want. It is totally irrelevant for the happy APS user what DOF he woudl have gotten with his F:1.4 lens if he had use a same DOF wide open lens with the same angle of view on an FF system. A happy APS shooter may see it as an advantage not being hampered with FF style thin DOF at 1.4 - he may be able to get the whole subject in focus and still be able to shoot in low light.
APS though is smaller cheaper and lighter. Lenses are 50% shorter for same angle of view as for FF.

---------- Post added 07-07-21 at 12:34 AM ----------

If we really want to compare apples to apples we need to use an f/2.8 lens for crop and an f/4 lens on full frame to get proper equivalence..

'

Who says you need to shoot at the same DOF at the same aperture on two different formats at the same angle of view? There's no law about this. Different focal lengths will have different DOF characteristic. Which one of them are preferable is totally in the eye of the beholder. And whos says that the DOF at 2.8 on APS is not ideal? And why only minimum DOF? How about ISO and shutter speed? Should they too be the same?
The fact is is if you want the same DOF from FF as from APS (at the same angle of view) you need to shoot at one stop longer shutter speed or one stop higer ISO.

The lens aperture do not refer to DOF anyway. And there's no such thing as "proper equivalence". "Similar DOF wide open do not equivalent lenses make" (Yoda).

If you go out on a hypothetical photo trip with one format, and for argument sake pretend that you could relive this trip with another format. You will not have gotten the same images. And this is why some prefer some formats over others; they lens themselves to different shooting styles. Insisting on the same DOF at the same numerical wide open aperture at the same angle of viiew is petty nonsense....

BTW I shoot three different formats.....

[mee]

But nobody buy a format over another in order for them be equivalent. They choose them because they are not equivalent. There's not such thing as correct DOF for a certain aperture and angle of view. This is a matter of taste and shooting situation. Insistence on equivalence is frankly nonsense as two formats can never be totally equivalent anyway (you must choose which parameter to discriminate them by - all of them will never do simultaneously). You can take any format as reference point and proclaim that any properties of this format must be the same in another in order to compare them. It is a fruitless exercise and the one you use as reference will always "win".
The point is that if you want APS output you are best served with an APS system. Likewise if you want FF output you are best served by an FF system etc... This is the starting point. Decide what output you want. It is totally irrelevant for the happy APS user what DOF he woudl have gotten with his F:1.4 lens if he had use a same DOF wide open lens with the same angle of view on an FF system. A happy APS shooter may see it as an advantage not being hampered with FF style thin DOF at 1.4 - he may be able to get the whole subject in focus and still be able to shoot in low light.
APS though is smaller cheaper and lighter. Lenses are 50% shorter for same angle of view as for FF.

---------- Post added 07-07-21 at 12:34 AM ----------

'

Who says you need to shoot at the same DOF at the same aperture on two different formats at the same angle of view? There's no law about this. Different focal lengths will have different DOF characteristic. Which one of them are preferable is totally in the eye of the beholder. And whos says that the DOF at 2.8 on APS is not ideal? And why only minimum DOF? How about ISO and shutter speed? Should they too be the same?
The fact is is if you want the same DOF from FF as from APS (at the same angle of view) you need to shoot at one stop longer shutter speed or one stop higer ISO.

The lens aperture do not refer to DOF anyway. And there's no such thing as "proper equivalence". "Similar DOF wide open do not equivalent lenses make" (Yoda).

I'm not sure what you're disputing that I've stated. But it seems like you're grasping in order to disagree somehow.

[Wheatfield]

But nobody buy a format over another in order for them be equivalent. They choose them because they are not equivalent. ..

True, but when someone is deciding which format to purchase, they are either comparing them and figuring out what each format can do and what their requirements are in their expected shooting conditions, or they are throwing darts at a dartboard while blindfolded. That's not a great way to choose a camera system.

In the Pentax world, the reason why APS-C lenses are smaller, lighter and cheaper is because they are generally also at least a stop slower than their full frame equivalent lenses.
The problem with this is that if they are going to have the same capabilities, they need to be a stop faster than their full frame equivalents.
How much smaller than the D FA* 55/1.4 be if it was an f/1 lens and had the same outstanding optical performance? I bet not much.

---------- Post added Jul 6th, 2021 at 06:43 PM ----------

Insisting on the same DOF at the same numerical wide open aperture at the same angle of viiew is petty nonsense....

Actually, what you have written is what is called a strawman argument.

[Pål Jensen]

True, but when someone is deciding which format to purchase, they are either comparing them and figuring out what each format can do and what their requirements are in their expected shooting conditions, or they are throwing darts at a dartboard while blindfolded. That's not a great way to choose a camera system.

In the Pentax world, the reason why APS-C lenses are smaller, lighter and cheaper is because they are generally also at least a stop slower than their full frame equivalent lenses.
The problem with this is that if they are going to have the same capabilities, they need to be a stop faster than their full frame equivalents.
How much smaller than the D FA* 55/1.4 be if it was an f/1 lens and had the same outstanding optical performance? I bet not much.

APS lenses are the same speed as the FF equivalent when they have the same max aperture; ie F:2.8 = F:2.8 regardless of format the lens in intended for. APS lenses are 50% shorter for the same angle of view as FF lenses. That's why you can have a super telephoto APS lens at little more than 400g.
You can never get the same shutter speed, ISO, aperture and DOF (for the same angle of view) when comparing two formats. One (or more) of the parameters has to yield (no free lunch). Which one is purely subjective and will change from subject to subject. There's no objective equivalence to be found.....

[Jonathan Mac]

The lenses for my Fuji XT-1 are not especially small. The 56/1.2 is dwarfed by the DA* 85/1.4, but is larger than the 77/1.8. The 35/1.4 is close in size to the FA 50/1.4, and on and on. The Pentax DA Limited lenses are small because they are slow. They are nowhere near equivalent to the Fuji X mount lenses in speed or, frankly, quality.

That's strange because all of my Fujifilm lenses are nice and small - 18/2, 23/2, 35/1.4 and 18-55/2.8-4. Even the Viltrox 23mm and 56mm f/1.4s aren't that big and heavy, though more so than the Fujinons (but of course they're faster for the most part).

Depending on the person, those may only be supposed advantages. Generally, a full frame camera is going to have more pixels, lower pixel density and better IQ than a contemporaneous APS-C camera.
The Sony a1 is smaller and lighter than the Pentax K3III for example. So much for the size and weight advantage. Granted it is 3.5x more expensive, but for that one is also getting 50mp rather than 24.
The Sony A7C is smaller than the K3III, is full frame, is the same megapixel count, and costs about the same. So much for the price advantage, at least in the bodies. I'm not going to delve into lens pricing, I'm sure we could both cherry pick examples.

Maybe my post and comparison link were missed. Link to comparison --> here.

The Z5/Z6/Z7 are same size as a K-3 III and 20% lighter than the Pentax. But come with a Full Frame sensor.

I think the argument that full frame is bigger and heavier is not as convincing when we include mirrorless systems in the comparison. The weight from the mirrorbox and OVF are removed, which seems to free up some size and weight.

The Z5 is just under 1k USD right now. Used copies of course under that. Used Z6 go for just over 1K USD right now (but factor in the price of an XQD card).

It becomes more a personal choice on which system one values the most for whatever they want to do with it. An argument I care not to have -- thus I am just pointing out objective qualities for comparison (size, weight, price).

You obviously need to include lenses in the comparisons, not just bodies, and like with like: flagship with flagship, entry level with entry level. Nobody uses a camera body with no lens so it's a useless comparison. There are mirrorless APS-C and m4/3 systems and the lenses are much smaller and lighter than FF ones. Most people buying into those sensor sizes will know that they're losing out on equivalence in terms of depth of field when compared to FF so it makes no sense to say you need an f/1.4 APS-C lens to get equivalent to a FF f/2 lens.

Much of the extra size and weight comes from the modern designs which are huge, heavy and expensive because of the modern desire to have everything super sharp even wide open. That requires much bigger lenses for FF not just because the image circle needs to be bigger but because resolutions are higher and owners are more likely to be pixel-peepers.

It's only in the last couple of years that manufacturers have started to produce modern, sharp from corner to corner, FF lenses that are not super-fast. Sigma and Sony both now have a small range of FF f/2.0-3.5 primes in order to provide for those who don't need all their primes to be f/1.4 or faster but still want FF. If I had a FF mirrorless system I know I'd want to sacrifice some speed for size and weight and be able to take two or three primes with me instead of just one, for a similar size and weight. In the future this kind of lens might bring a FF system and set of lenses down to the size, weight and even price of something similar for APS-C, but we'll have to wait and see.

[Wheatfield]

APS lenses are the same speed as the FF equivalent when they have the same max aperture; ie F:2.8 = F:2.8 regardless of format the lens in intended for. APS lenses are 50% shorter for the same angle of view as FF lenses. That's why you can have a super telephoto APS lens at little more than 400g.
You can never get the same shutter speed, ISO, aperture and DOF (for the same angle of view) when comparing two formats. One (or more) of the parameters has to yield (no free lunch). Which one is purely subjective and will change from subject to subject. There's no objective equivalence to be found.....

APS-C lenses need to be a stop faster than their full frame equivalent lenses to be fully equivalent.
This is equivalency 101, and has been batted around as a talking point by the equivalency crowd for a decade.

---------- Post added Jul 7th, 2021 at 09:43 AM ----------

That's strange because all of my Fujifilm lenses are nice and small - 18/2, 23/2, 35/1.4 and 18-55/2.8-4. Even the Viltrox 23mm and 56mm f/1.4s aren't that big and heavy, though more so than the Fujinons (but of course they're faster for the most part).
.

I had a really quick look at a couple of manufacturer websites.

I have the Fuji 14/2.8. I didn't see a 21/4 full frame AF lens, so I'm not able to compare sizes, my 23/1.4 Fuji is larger than my FA35/2, the Fuji 35/1.4 is quite small, but whether it's significantly smaller than a 50/2 full frame lens is doubtful, the 56/1.2 is in the same size range as the Sony 85/1.8, the 60/2.4 is a bit smaller than the FA100/2.8, but I doubt if it would be any smaller than a 100/3.5.

[AgentL]

That's an apples versus oranges comparison in most cases. Look at Samyang fast manual focus primes sold today vs. OEM glass with AF; I don't believe you can say there's much if any size difference at this point. Ring AF motors are not physically large.

I'm curious what you're trying to suss out with this line of discussion.

I feel like this is a more commonly accepted concept maybe elsewhere than Pentax system, because I haven't heard too many people question this elsewhere. Never knew it was really much of a matter for debate, however I'm not getting anything out of continuing to debate it, so I think I'm all done.

[Wasp]

To me, something like a 50/1.4 is what it is. When I have it on my K200D and look through the viewfinder, I frame the shot, choose the aperture and fire away. Equivalence to full frame whatever? Meh.

[Wheatfield]

To me, something like a 50/1.4 is what it is. When I have it on my K200D and look through the viewfinder, I frame the shot, choose the aperture and fire away. Equivalence to full frame whatever? Meh.

That’s a different discussion. This one has morphed into an equivalence discussion regarding system sizes.

[Mbaez]

Nikon Zfc release date, price, specs and features | TechRadar
Is this a good compromise instead of reviving the DF, to me people are buying it for looks only according to the specs.
I wish there would be a SLR model with full frame, much like the old DF but updated.

It looks really nice, but it's not for me. Hopefully they will deliver a full frame version, then it will be a different story.

[Ian Stuart Forsyth]

But not DSLR lenses.

The FF DSLR 40 2.8 is only 7mm deeper than the pentax 40 2.8

[Ian Stuart Forsyth]

I'm not going to go into an equivalence debate here, but to make a fair comparison between APS-C lenses and full frame lenses, the APS-C lens needs to be about a stop faster than the full frame lens to account for the depth of field difference.

Mine was not really an equivalence debate also, It was put out there that if Nikon wanted to only produce primes for both cropped and FF cameras that building a cropped specific lens really does not reduce the size of the lens so running 2 different lenses for the same FL across 2 different formats really is not that helpful. Where we see some benefit is in the zooms to help cover some of the odd ball ranges like the 16-50 and 12-24 and if we look at the past history this is what Nikon has done in the past and is doing with the Z lines right now

It also help with the ecosystem of a lens range when I can use my 28 (40mm equivalent) 2.8 on a cropped body as a travel lens but when used on a FF camera I have a 1 stop faster 28 mm wide angle lens

---------- Post added 07-07-2021 at 10:32 PM ----------

But nobody buy a format over another in order for them be equivalent.

But they may buy a lens to get equivalent performance so that there is no need in buying a cropped body to reduce the size of their format while retaining the DR and lower noise when they are not shutterspeed limited . This is the very reason why many manufactures produce lenses in varying entrance pupil sizes take the 24-70 2.8 and the 24-70 F4 this is so we have the selection to use lenses based on their size, performance and our intended use. If I am going out and hiking I may decided to use a 70-200 F4 and 24-85 over the 70-200 f2.8 and the 24-70 2.8 and cut the size and weight of what I have to carry down to what a 16-50 2.8 and 50-135 2.8 would be on cropped. with a combined weight that is vary similar and a foot print that take up almost the same size in my bag.

---------- Post added 07-07-2021 at 10:47 PM ----------

APS lenses are the same speed as the FF equivalent when they have the same max aperture; ie F:2.8 = F:2.8 regardless of format the lens in intended for.

Depends on what you mean as for speed. If your intended determination of speed is your shutter speed and noise performance then no ƒ 2.8 is not equal to ƒ 2.8 because for the same ƒ stop you can increase the speed of your shutter by over a stop for FF
There is also the max aperture the size of the opening letting the light into your image. If we look at the size of the iris of the lens thru the opening that is letting in the light so that we can capture an image, that ƒ/ 2.8 on FF is wider that than that of the cropped lens by 1 stop. If it is just as fast why is it that lens is using a smaller opening ?
And if you look at what that ƒ/2.8 really means you focal length/2.8 this would become very evident as to why they don't let the same amount of light in

[Rondec]

Aren't equivalence discussions fun?

The only thing I would say is that if your mount stays really big (like the z mount), even if the sensor size is smaller, the lenses for APS-C probably aren't going to be that much different in size. Full frame works better for some folks and APS-C works better for others. The fact that you connect with one or the other doesn't mean that everyone is the same as you. I would say, at this point, that Fuji has a much more developed APS-C oriented line up, but you could certainly put something together for Nikon too -- particularly when you consider the flexibility you have with using adapters and lenses from other mounts.