Lens categories?

deudeu · 07-19-2008, 05:12 PM

Hello,

I was thinking that it would be useful to start threads where the members could post sample pictures according to the lens categorie. This would help people searching a specific type of lens out by giving them a database of pictures from all the competing lenses within a specific range.

But, I am not sure that my categories are appropriate.

Here is how I would make my subdivisions:

Super Wide: 8mm to 21mm.
Wide Angle: 22mm to 35mm.
Standard: 36mm to 65mm
Moderate telephoto: 66mm to 105mm.
Telephoto: 106mm to infinity.
Fisheye: I think that those should have their own section as well as the other speciality lenses like:
Macro:

Anyways, Let me know what you think about those categories. Should I subdivide the standard categorie in standard wide and standard tele? Are the focal length appropriate?

Thank you for your help and input!

RioRico · 07-19-2008, 09:22 PM

Categories are wonderful. Parameters (boundaries) are tricky. What category any lens fits into depends on the camera. An 8mm lens is a "fisheye" (producing a completely circular image on the film or sensor) for a camera using 24x36mm film or sensor. But on my K20D with its (roughly) 16x24mm APS-C sensor, I'd need a 5mm lens. And those using 645 and 6X7 big-brother MF cameras probably need around a 16mm lens, right?

Let's look at the proposed categories, applied to a 24x36mm target with a diagonal of around 44mm, and try to generalize:

Super Wide: 8mm to 21mm - less than 1/2 the diagonal.
Wide Angle: 22mm to 35mm - 0.5x to 0.8x the diagonal.
Standard: 36mm to 65mm - 0.8x to 1.5x the diagonal D.
Moderate telephoto: 66mm to 105mm - 1.5x to 2.4x of D.
Telephoto: 106mm to infinity - more than 2.4x the diagonal.
Fisheye: under 8mm - rather less than 0.2x the diagonal.
Macro: focusing to within 1.0x the diagonal, approximately.

I'll expect quibbling over my 'macro' definition, with savants pointing out that degree of magnification is what determines macro-tude. Whatever. But skipping the macro part, we can make a table of lens categories for different camera formats. I will leave out the much-beloved Pentax 110, and consider all MF boxes as being 60X60mm.

Category; Format: APS-C; 35mm; 60mm
==============================
Diagonal (roughly): 28mm; 44mm; 84mm

Fisheye: under 6mm; under 9mm; under 17mm
Super Wide: 6-15mm; 9-22mm; 17-42mm
Wide Angle: 16-22mm; 23-35mm; 43-66mm
Standard: 23-42mm; 36-66mm; 67-126mm
Moderate tele: 43-67mm; 67-105mm; 127-200mm
Long Tele: over 67mm; over 105mm; over 200mm

I eagerly await having my parms and math questioned and corrected. Note that the APS-C sensor size is pretty close to 16mm cine and 1/2-frame 35mm (like my late lamented Olympus Pen-FT).

SpecialK · 07-19-2008, 10:40 PM

I think it would work better to have pics from a specific lens. That way, people could compare the complete coverage of a particular lens, rather than dealing with overlapping focal lengths of a wide selection of lenses.

I have not looked in along time, but the lens datebase section would be the ideal location to post pictures from listed lenses.

JCSullivan · 07-20-2008, 05:53 AM

Breaking-down or categorising lenses would probably be as numerous as the number of lenses available for Pentax cameras.

I do however have a question. Are ALL lenses, including the new ones, still marked in 35mm focal lengths? I would like to see a list of relevant focal lengths without having to do the calculations.

In other words when I buy a 28mm I'm not really buying a 28m in today's digital world am I?

Lowell Goudge · 07-20-2008, 06:33 AM

I think the place to have any such images, i.e. images either by lens or focal length, would be in the knowledge base, afterall, that is really what you are discussing.

SpecialK · 07-20-2008, 01:01 PM

Are ALL lenses, including the new ones, still marked in 35mm focal lengths?

No.

I would like to see a list of relevant focal lengths without having to do the calculations.

Is adding 1/2 the value really difficult?

In other words when I buy a 28mm I'm not really buying a 28m in today's digital world am I?

Yes, in the digital world. In the film world, no.

The "35mm equivalent" number is normally provided as it is a common reference standard.

deudeu · 07-20-2008, 05:51 PM

Originally Posted by SpecialK

I think it would work better to have pics from a specific lens. That way, people could compare the complete coverage of a particular lens, rather than dealing with overlapping focal lengths of a wide selection of lenses.

I have not looked in along time, but the lens datebase section would be the ideal location to post pictures from listed lenses.

Good idea, I will just post my pictures there. I encourage the others to do the same!

RioRico · 07-21-2008, 12:11 AM

Are ALL lenses, including the new ones, still marked in 35mm focal lengths? I would like to see a list of relevant focal lengths without having to do the calculations.

Focal length is focal length, regardless of the frame size. What's 'normal' depends on the frame size. 35mm is 'normal' for 1/2-frame 35mm, for 16mm, and for APS-C sensors (like current consumer DSLRs). 50mm is 'normal' for full-frame 35mm film cams. 80mm is 'normal' for 6X6cm (or 6X7 or 6X9 or 645) medium-format cameras. I forget what's 'normal' for 4X5" and 8X10" large-format cameras. Whatever the number, a focal length is what it is.

Many of us with 35mm film experience think in terms of lenses for that format. 32mm and below is pretty wide, 75mm-150mm is mid-tele, etc. On your APS-C sensor'd DSLR, a 35mm lens is 'normal' so it's EQUIVALENT to a 50mm on your old Spotmatic, but it's still really a 35mm lens. Yeah, just multiply by 1.5 and you get the equivalences for the old mindset.

But don't get too hung-up on doing the mental math. The next generation of DSLRs (heralded by Canon) will have full-frame sensors, 24X36mm, just like that Spotmatic. All these DA* lenses we lust over now will be OBSOLETE, useful only for a soon-forgotten generation of once-hot cameras. Plan ahead; in a couple years you will NOT be doing those calculations. The good news: your wide-angles will be wide again. The bad news: your tele's will all get shorter. Live with it.

Classvino · 07-21-2008, 10:41 AM

Originally Posted by RioRico

Focal length is focal length, regardless of the frame size. What's 'normal' depends on the frame size. 35mm is 'normal' for 1/2-frame 35mm, for 16mm, and for APS-C sensors (like current consumer DSLRs). 50mm is 'normal' for full-frame 35mm film cams. 80mm is 'normal' for 6X6cm (or 6X7 or 6X9 or 645) medium-format cameras. I forget what's 'normal' for 4X5" and 8X10" large-format cameras. Whatever the number, a focal length is what it is.

Many of us with 35mm film experience think in terms of lenses for that format. 32mm and below is pretty wide, 75mm-150mm is mid-tele, etc. On your APS-C sensor'd DSLR, a 35mm lens is 'normal' so it's EQUIVALENT to a 50mm on your old Spotmatic, but it's still really a 35mm lens. Yeah, just multiply by 1.5 and you get the equivalences for the old mindset. But don't get too hung-up on doing the mental math.

Up to this point, were talking facts... A pretty concise summary.

But then this :

Originally Posted by RioRico

The next generation of DSLRs (heralded by Canon) will have full-frame sensors, 24X36mm, just like that Spotmatic. All these DA* lenses we lust over now will be OBSOLETE, useful only for a soon-forgotten generation of once-hot cameras. Plan ahead; in a couple years you will NOT be doing those calculations. The good news: your wide-angles will be wide again. The bad news: your tele's will all get shorter. Live with it

Unless you're planning on changing to a company not currently using APS-C sensors (are there any companies making DSLR's that don't have APS-C offferings? or equivalent sub 24X36mm sensor, like the 4/3rds) then the last paragraph need not apply. At this point it's just conjecture...

See The Sky Is Falling (fable - Wikipedia, the free encyclopedia) for more info...

*ChrisPlatt* · 07-21-2008, 01:15 PM

Sometimes it seems all we film users and you digital users have in common is the lens mount...

Chris

*roentarre* · 07-21-2008, 03:43 PM

We already got lens reviws section rated by users. I thought that was more than enough ...

deudeu · 07-21-2008, 03:57 PM

Originally Posted by roentarre

We already got lens reviws section rated by users. I thought that was more than enough ...

It can be, if people actually review their lenses and post pictures. Though a lot of lenses are reviewed, few pictures are posted.

Classvino · 07-21-2008, 04:07 PM

Originally Posted by ChrisPlatt

Sometimes it seems all we film users and you digital users have in common is the lens mount...Chris

Actually, though it may appear to be inconsistent on my part, I do like FF lenses, and have a couple film bodies I use (and will continue to use) them on. Given the same parameters and quality (and perhaps not too big a price gap) I would certainly buy the FF glass over the APS-C glass.

My post was aimed more at the whole idea that Pentax (and many other manufacturers) would be abandoning the APS-C format to go back to FF anytime in the foreseeable future. For a company that went to greater lengths than any of the other Big 3 (or 4 or 5 or whatever) camera companies to ensure backwards lens computability, it's rather presumptuous for someone to say the format that Pentax, and many of these other companies have invested so much money and time into "will be OBSOLETE, useful only for a soon-forgotten generation of once-hot cameras."

Wishful thinking, perhaps, with the accent on wishful...

deudeu · 07-21-2008, 05:00 PM

Originally Posted by Classvino

My post was aimed more at the whole idea that Pentax (and many other manufacturers) would be abandoning the APS-C format to go back to FF anytime in the foreseeable future. For a company that went to greater lengths than any of the other Big 3 (or 4 or 5 or whatever) camera companies to ensure backwards lens computability, it's rather presumptuous for someone to say the format that Pentax, and many of these other companies have invested so much money and time into "will be OBSOLETE, useful only for a soon-forgotten generation of once-hot cameras."

Wishful thinking, perhaps, with the accent on wishful...

I agree 100%. The APS-C sensors are here to stay. They will ALWAYS be cheaper to manufacture so the entry level Bodies will always have APS-C. Plus the advantage that those have on the long end over the FF bodies is quite nice if you are into this kind of stuff.
FF bodies are not going to be the norm, ever. They are just going to be another option.

RioRico · 07-21-2008, 07:27 PM

APS-C sensors are here to stay. They will ALWAYS be cheaper to manufacture so the entry level Bodies will always have APS-C.

I'm sure the makers of 1/2-frame 35mm film cameras (like my old Canon VFs and my late lamented Olympus Pen-FT system) also thought the format would last. Half-frames thrived under specific economic conditions, then died when domestic (Japanese) consumers wanted (and could afford) MORE. APS-C is basically 1/2 of full-frame. How long will it be sufficient for 1st-world consumers?

Digital sensors, being IC chips, are subject to Moore's Law, where semiconductor costs per capacity drop roughly 50% every 18 months. We've seen that with PNS digicams, where US$150 bought a 1mpx cam in 2003 and a 10+mpx cam in 2008. The equivalent to the 14+mpx sensor on my US$1100 K20D body would have cost US$14K a couple years ago. And a couple years ago, entry-level DSLRs were 5mpx and expensive; now they're 10-12mpx and rather less costly.

The trends are clear. By 2010, the entry-level DSLR will have a 20-25mpx FF sensor, and the body will retail for well under US$1K. Will there still be a market for APS-C DSLRs? Yeah, but it'll shrink into improfitability. Lenses aren't semiconductors (yet) so their prices will stay relatively high, which means that a APS-C half-frame (HF) system won't be price/performance competitive with a FF system. By 2015, HF DSLRs will be a small fringe market for those unwilling to give up their pricey DA* lenses.

And I expect in around 10 years to see glass lenses start to go away, replaced by adaptive-optics chips. Every photosensitive CMOS junction (or maybe small clusters of junctions) will be individually frequency-tuneable and aimable. Every 'lens' will be a pancake, upgradeable with new firmware. I SEE IT ALL NOW! Then of course we'll eventually just have digital taps placed in our optic nerves... but that's another discussion.