Why bother?


Horst

Link Posted 30/06/2014 - 06:27
K10D wrote:
Quote:
The pubs in Perth sell pints but charge in Fahrenheit figures as they are numerically larger, especially that 100/212 version where a 100% of cost outside of Australia means 212% in Perth.

This is only because you are all rich in WA.

Then he wrote:

Quote:
To Mark:
I still use FF K-mount lenses, 28mm, 31mm, 43mm, 50mm and every M & A series lens I own. I specifically avoid buying cropped glass where possible.

So do I. The only DA lens I have left is the Kit lems I bought with my K5.

Now Back to the original conversation:

I agree with all you who said that you need a reference.

If you buy or use a FA or similar lens designed for FF, then the markings eg. 50mm then we all know, what it looks like with the FF camera and we have to convert it to 75mm. most of you seem to be happy about this, because again you know what 75mm looked like on your FF camera and now on your APS-C camera.

But if you have a lens (DA) made specifically for APS-C, then why convert?
Just call or mark it 75mm and again you know all what 75mm looked on your old film camera and that's what it looks on your K5 or whatever It does not make sense to mark it 50mm and then to convert it. Safe your Braincells.

Just think, you want a 35mm view on your APS-C camera, Why look for a 23mm or similar lens. you should be able to buy a DA 35mm and that it.

After all if it now says DA23mm it still doesn't work on your FF camera.

Regards, Horst

Horst

Link Posted 30/06/2014 - 06:32
Pirate wrote:

Quote:
That being said, with a zoom lens is where things do change as say a Tamron 17-35mm on an APS-C body cannot see the full width, so you lose the effective width which is why it's best to use a cropped WA zoom on an APS-C body so you get the whole picture and not just a portion of it.

Your partly right, but as things are at the moment, A DA 17-35mm lens also
shows your only a cropped image of the 17-35 mm marking it should be marked:
25 - 52mm and all would be correct.

Regards, Horst

johnriley

Link Posted 30/06/2014 - 08:11
Quote:
Just call or mark it 75mm and again you know all what 75mm looked on your old film camera

Simply because it's a 50mm lens, not a 75mm. It behaves just like any other 50mm lens. If it were on a 645 camera it would be a wide angle. If it is on an APS-C then it's a telephoto. On 35mm film format it's a standard lens. But in all cases it has the DOF and other characteristics of a 50mm lens, regardless of what you put behind it.

Marking it 75mm is saying it's something it's not and basically dumbing down the information. Anyone who has only used APS-C will know their standard lens is 35mm and a portrait telephoto lens is 50 or 55mm. No conversion will be necessary for them.
Best regards, John

K10D

Link Posted 30/06/2014 - 08:18
Horst.

The logic is sensible but a 50mm lens is a 50mm lens regardless of what it's attached to. Better the angle of view be marked but no one would relate to that.

If you say I have a 50mm portrait lens on my K5 for example, people will relate to that.

ps. rich in WA.......not after buying a pint mate.

Best regards

tyronet2000

Link Posted 30/06/2014 - 11:01
I just look through the viewfinder and zoom in or out to leave out or capture what I want. For proper photographers there's always an alternative of course
Regards
Stan

PPG

Russ

Link Posted 30/06/2014 - 11:17
MrB wrote:
I do find the 35 mm equivalents helpful, and particularly on the small sensor compact cameras, e.g. MX-1.

(Off topic - the one I can't get used to is 'litres per 100 kilometres'. 'Miles per gallon' - now that's meaningful.)

Cheers.
Philip

I agree there. The lens sizes on compacts mean nothing without the 35mm equivalent conversion. Not against them quoting it for APS-C and Micro 4/3. I know a lot poeple who cannot get their heads around the sizes until they are stated in 35mm terms.

Horst

Link Posted 02/07/2014 - 14:45
Johnriley wrote

The lenses I am talking about are of course the DA lenses.

In a previous forum I was told, that the DA lenses are different to the FA F A etc lenses .In the DA lenses the light beams are different directed towards the sensor. More right angle directed to the Sensor.

This being the case, how do you know, that a DA lens marked as 50mm behaves itself the same as a non-DA 50mm lens?

Quote:
Marking it 75mm is saying it's something it's not and basically dumping down the information. Anyone who has only used APS-C will know their standard lens is 35mm and a portrait telephoto lens is 50 or 55mm. No conversion will be necessary for them.

You see,it seems a contradiction.

You say with APS-C: "Your standard lens is 35mm." I may have near the same angle of view, But it behaves itself differently. EG. more Barrel distortion than a 50mm lens for FF.

The same holds for the 50mm lens. It is never the same in its performance as a FF 75mm lens.

Further more, to say every APS-c user knows that a 50mm lens is now his portrait lens does not make sense to me. If every DA lens would be marked to its angle of view, then if it was marked DA75 (reflecting the angle of view) then also every APS-c User would know it is a portrait lens.

Regards, Horst

johnriley

Link Posted 02/07/2014 - 14:56
The design of digital lenses is telecentric, or at least more so than film lenses were, but not in every case. It's less of an issue with telephoto lenses. With wide angles it's important, but basically to ensure there isn't too much colour fringing and darkening at the edges of the field.

However, this is a different issue to the focal length and field of view. A 50mm lens is still a 50mm lens.

Now you say a 35mm lens behaves differently as a standard lens, and that's right in some ways. There's more depth of field, for example, being a 35mm lens. On film it would be a wide standard or moderate wide-angle, depending on your point of view. The distortion would not necessarily be greater or less, that would depend on the design parameters of that particular lens. There's no reason why a 35mm lens can't be built to have very low distortion, apart from design choices and cost.

The call for angles of view to be shown on lenses has been around for decades, but unfortunately such figures mean less to people than the marked focal length does. If some cameras showed the correct focal length and some the 35mm-equivalent, total chaos would ensue.

What we have may be imperfect, but it's easily understood with a bit of explanation and practice.
Best regards, John

Horst

Link Posted 02/07/2014 - 15:05
Well, John, after all this, why not compromise.

A lens build purely for The APS-C sensor could be marked for example 50mm/75mm, or 70mm/105mm the you would really know whats going on.

This could be done by all Manufacturers. just one needs to have the carriage of doing it.

Regards, Horst

johnriley

Link Posted 02/07/2014 - 15:14
Some bridge cameras do that already. Does it help? Does it confuse people who wonder how a lens can have two focal lengths? Should we expect people to be willing to learn a bit about their cameras so it isn't necessary?

Questions, questions.....I don't know the answer, although I do think it's necessary to put a bit of effort into our photography. Without that how can we hope to understand how to fully exploit the medium?
Best regards, John

Horst

Link Posted 02/07/2014 - 16:16
John,

Just before my previous post, you explained to me, how smart all the APS=C camera owners are. Now if it suit the argument, you tell me that they are easily confused.

It seems If I say white , you say black, if I say blue , you say red.

You really don't try and create a full discussion. it is always a quick return comment and with the idea: lets forget about it, I know better anyway.

Regards, Horst

Algernon

Link Posted 02/07/2014 - 16:24
A similar argument has gone on for years about whether shoes
should be marked L & R Me I enjoy working it all out
myself as I'm sobering up

--
Half Man... Half Pentax ... Half Cucumber

Pentax K-1 + K-5 and some other stuff

Algi

tyronet2000

Link Posted 02/07/2014 - 16:32
Algernon wrote:
A similar argument has gone on for years about whether shoes
should be marked L & R Me I enjoy working it all out
myself as I'm sobering up

--

I've seen wellies and seaboots marked L and R a hark back to the days when a lot of jolly jack tars were thick. Wasn't there a shop which sold panties marked C&A
Regards
Stan

PPG
Last Edited by tyronet2000 on 02/07/2014 - 16:33

johnriley

Link Posted 02/07/2014 - 16:39
I thought you wanted a discussion Horst, and I thought we were having one.
Best regards, John

gwing

Link Posted 03/07/2014 - 14:26
Horst wrote:
Well, John, after all this, why not compromise.

A lens build purely for The APS-C sensor could be marked for example 50mm/75mm, or 70mm/105mm the you would really know whats going on.

This could be done by all Manufacturers. just one needs to have the carriage of doing it.

Regards, Horst

Sorry Horst but I think that idea's plain daft and an unnecessary recipe for confusion. There's nothing special about the 35mm format that makes it the yardstick by which other formats should be judged and neither is there usually such a thing as a lens only for APSC. Any DA or APSC lens is likely to be usable on 35mm or even larger if you are prepared top accept some vignetting as well as being usable on smaller sensors such as the Q or 4/3 series.

Now it would be helpful if manufacturers, as now, just gave the proper focal length for their lenses but on each camera body put a stamp saying '47 degrees at 50mm' for whatever they consider their standard length lens. That would help anyone picking up a camera with odd sensor sizes, especially if there was standardisation on whether the width, height or diagonal AOV was to be used
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