Power to resolve

[rjlhughes]

The Canon experts say that there are only about 10 lenses that you can use with their top of the line cameras, simply because most of the glass doesn't have the power to resolve equal to the sensor.

It's starting to feel like the escalation in hardware that our friends at Microsoft have put us through, isn't it?

[Wacky]

No body ever replied (how rude!) and I can see you're trying to make conversation, so I'll make a completely ill-informed comment, if I may be so bold.

If I am understading what they are saying, then it does make sense...that to get the most out of the sensor's capabilities that you need to use the best lenses...as in, using a $200 lens on a 1DsMkII wouldn't use the sensor to it fullest capabilities...

Would it be the same in reverse? Like if I threw a $15,000 lens on my 350D, would that be a waste as my sensor would match the resolving power of the lens? Meaning, that there is a limit to the best lens I should use, because I'm not getting any benefit from a better lens?

When you think about it, if the sensor is THAT good that only the top 10 lenses make the most of it, it is impressive, considering everyone knows how good the top lenses are...

Surely this would be a similar situation with other manufacturers?

[Glen]

I have read the same about the D2X but with a larger number of lenses. Frustrating because in the old days you could borrow your mates best lens, throw your cheap film body on the back loaded with ISO 25 and get full use of the lens. But developing used to cost an arm and a leg and one couldn't afford to experiment

[leek]

I must admit that I don't really understand the argument that you need extremely good lenses with the top 'o' the range Digital cameras...

I read somewhere that when digital reaches 24 megapixels it will more or less match the resolving power of good film... If that is the case, why would you need better lenses for digital at the moment???

[Wacky]

For fear of this being taken the wrong way, dare I say it, maybe Canon only make 10 really good lenses that make the most of their top sensors? (that was a serious comment too)

Do a test with any manufacturer's camera, eg, a 20D. Take the same image under the same conditions, but with different lenses, ranging from what is considered bottom of the line, through to top of the line.

Surely (I don't know, so would love comment on my theory), as you go up in the lens range, the images would get better/clearer/sharper, and then surely there would be a point, where the images stop getting better...maybe for a 350D that's a $2000 lens...and 20D, a $4000 lens, and a 1DsMkII, a $8000 lens (figures pulled from my fat arse)?

As for 24MP/Film, does this mean that only THE top lens has the resolving power good enough to match film, therefore nothing less that the best lens is worth using? lol...too bloddy confusing!

[rjlhughes]

Wacky,

thanks for getting the conversation rolling again.

To answer all your questions: I don't know. It was a group of pro photographers and I assume they didn't need to be told.

I suspect it's something to do with the size of the individual sensors, and the fact that they are discrete units.

I suspect someone who does know will tell us. I doubt Canon would want to in an open forum

I don't think it's a criticism of the best Canon glass - it may be more a consequence of how these top sensors now are.

I don't think we're talking about a3 size prints either.

[Glen]

Not much interest to Canon glass users but have a look at the reviews on Nikon glass from Bjorn. He rates lenses, then rates them on the D2X (the top nikon) as this shows faults which aren't evident on other bodies. Some lenses have quite some difference http://www.naturfotograf.com/lens_surv.html

[gstark]

Good question.

I think that a part of the answer lies in our habits, as the photographer, and this will be especially true for those of us who have come from a film background.

With film imaging, how often did we find ourselves pixel peeping? Examining the full size image to the nth degree? It was neither practical, nor easy.

Contrast that with the digitial processes we're now working within, whereby it's incredibly easy and practical.

So we do, and we look for ... what ?

Ultimate resolution?

Sharpness ???

I certainly found that my standards had shifted, which is why I've gone to higher end glass.

Thoughts, y'all?

[Oneputt]

Gary I think that you have hit the nail on the head. Because of the powerful software we all use now, we are examing our images in much more detail than we ever did with film, particularly with regard to magnification.

I rarely printed much beyond the old 6x4 but now on my screen I magnify parts of the image to examine microscopic detail. hardly a fair comparison.

The expensive lenses are better in much the same way as a rolls is better than a mini, and for much the same reasons. The same with sensors.

Me at this stage I will still spend my money on glass until the bodies like the 2x come down in price. A lens looked after will last for life, a body may not.

[gstark]

I rarely printed much beyond the old 6x4 but now on my screen I magnify parts of the image to examine microscopic detail. hardly a fair comparison.

That's pretty much my point. Even with my own darkroom, I would rarely print beyond 14 x 11, colour or B&W, because it was (a) too expensive, (b) too much trouble, and (c) you'd need to probably make two or three prints to get one that was truly acceptable.

And even at that modest size, you're still working well within the capabilities of most lenses and certainly any film stock you'd care to mention.

Working digitally these days, it's just too easy, too convenient, and it costs nothing to look at the most minute detail of any image.

And we do!

Now consider this point - how many of us bought into the digital system we're in because we were using the same brand's film system? Yep, my hand's up here.

I figured that I could make good use of my existing glass with the new, digital body. Sound familiar?

Having bought the D70, I've also subsequently purchased 3 new lenses, simply because I've become more demanding in the results I expect of myself, and the realisation that the older, pre-existing glass that I previously thought was good enough .... wasn't!

Me at this stage I will still spend my money on glass until the bodies like the 2x come down in price. A lens looked after will last for life, a body may not.

The only caveat here is whether to buy a lens in the APS size, or go for a full frame. This is especially true with Canon, whereas Nikon haven't yet announced any FF digital cameras - and to my mind, that's not likely to happen anytime soon, either.

But once you have your lens collection, it will stand you in good stead beyond just the one body. FWIW, all of the lenses I have will fit most of my Nikon bodies (film and digital) although that will change with my next lens purchase, which will be the 12-24DX.

[Glen]

Gary, the Sigma 12-24 works on FF and APS bodies Don't shortchange yourself with only half the tool (and half the weight)

[gstark]

Glen,

Yep, I'm fully aware of that, but I don't see it as being all that great value, in the same way as I won't be putting Kia parts on my Benz, either.

[Glen]

Glen,

I won't be putting Kia parts on my Benz, either.

[sirhc55]

Ah! But does Mercedes make every single part of the SLK - the answer is NO

[gstark]

That's not the point.

The question is more a matter of which parts are geniune "factory" vs ...

[Wacky]

Having bought the D70, I've also subsequently purchased 3 new lenses, simply because I've become more demanding in the results I expect of myself, and the realisation that the older, pre-existing glass that I previously thought was good enough .... wasn't!

Gary, sort of relating to the topic I guess, and whoever brought film into it, as you say, you old lenses that were fine for film, just aren't cutting it for digital. Now, what if you were to use those new, better lenses you have since aquired, on your film body...do you think you would notice the difference in the quality of the images, or only if you were to study the film output excessively closely?

[gstark]

Having bought the D70, I've also subsequently purchased 3 new lenses, simply because I've become more demanding in the results I expect of myself, and the realisation that the older, pre-existing glass that I previously thought was good enough .... wasn't!

Gary, sort of relating to the topic I guess, and whoever brought film into it, as you say, you old lenses that were fine for film, just aren't cutting it for digital. Now, what if you were to use those new, better lenses you have since aquired, on your film body...do you think you would notice the difference in the quality of the images, or only if you were to study the film output excessively closely?

Another bloody good question!

I suspect it might depend upon the film stock I was using. Were I using AP100, K64 or perhaps E125/FC100, I think I would probably see a difference in my output, because of the fineness of those media and the way in which the output is treated.

Were I just using some colour print film though, I highly doubt I'd notice any difference.

I think it'd be fun to do a wetbench at a minimeet (or a group activity) at some time in the future.

We could set several goals :

1: For those with film experience but no darkroom experience, we could show them how it all used to be done.

2: For those with only digital experience, ditto!

3: We could, as a part of the exercise, do exactly this sort of test.

4: We could even compare outcomes using film + high-end optics Vs Digital + high-end optics.

First thing we need is the resources: who still has a working darkroom?

Second thing we need are the consumables. Before they become a relic of days gone by!

[Sheetshooter]

I'll offer an explanation which will address both the initial query and the subsequent twist of DX lenses on film:

ALL digital capture rquires lens systems of higher resolution than sensitised film emulasion. To this end, in the high-end part of the market with view cameras and MF capture devices (Sinar, Phase-One, Imacon, etc.) lens manufacturers such as Schneider and Rodenstock produce ranges of lenses of higher resolution specifically for digital capture. These 'DIGITAR lenses invariably have smaller image circles also because the chips are not as expansive as a four inch by 5 inch sheet of film - PLUS it is far more facile to produce higher resolving power with a smaller image circle.

Now - the need for higher resolution: an area of film has a random array of light sensitive particles that will capture all of what is projected onto any part of its surface. A digital chip, on the other hand, has a formal and geometric array of sensitised pixels and between each of these pixels is a gap which generates NO IMAGE at all. The frequency of these gaps (the pitch) as it relates to the spatial frequency of the lens resolution (line pairs per millimetre) creates the need for higher resolution lenses.

With the Canon system, however, (and possibly the Nikon) this is a bit academic because between the lens and the chip is a low-pass filter which obliterates resolution BEFORE the inmage is formed on the sensor and the sharpness is subsequently reconstructed. Nothing's simple any more, is it?

Can you see the difference between lenses on film? Probably not. In the case of most emulsions the resolving power of the lens exceeds the resolving power of the film. Sharp is sharp and there is no sharp sharper than that, if you get my drift.

I recently used a device called a PUTORA SHARPNESS INDICATOR to evaluate a number of lenses I owned. I shot the target as instructed and used T-Max 100 film which has a resoulution of 63lpm (T-Max 400 is 50lpm). All of the lenses rated excellent but one did even better - but how much better? A mystery because the film is unable to differentiate.

Cheers,

[kipper]

Gary, I totally agree both on examining images and buying based on using past systems.

I've printed a few images that looked blurred on my screen, and at 6x4 they look perfectly fine. Granted if I try and print at 12x6 they'll be blurred.

[rog]

FWIW, I think the expert statement is probably just saying that anything other than the 10 best lenses are going to be noticeable on an image from these top end cameras. It's already true of the lesser cameras to some extent. The resolving power of a lens can be measured and that can be compared with the ability of a camera body to determine what will give the result.

I'll ask my Dad for his thoughts, he's a programmer, but I understand that his work is quite close to this sort of stuff.

- Rog