[jsherman999]

PK-NEX Lens Turbo to make full frame lenses work like full frame lenses on APS-C sensors with 1 stop gain .

I've heard it turns the edges to mush from my local camera-counter LBA enabler at National Camera. True or no?

[jogiba]

I've heard it turns the edges to mush from my local camera-counter LBA enabler at National Camera. True or no?

I should be getting my Lens Turbo this week but from the photos I have seen they are not that bad.
Gary Barnes | Photographer
https://www.pentaxforums.com/forums/pentax-price-watch/224280-199-focal-reduc...ml#post2396454

[Rondec]

Honestly, there are few to no wide angle lenses on full frame that match the landscape abilities of the DA 15 limited. Particularly when it comes to flare resistance. I don't really care that its full frame equivalent would be a 22.5mm f5.6 lens. I shoot it stopped down to f8 all of the time and it's perfect for me. The FA 31 limited is a nice lens, faster and sharper edge to edge, but I don't believe that it would match up against the DA 15, even on a full frame camera.

[rawr]

I should be getting my Lens Turbo this week but from the photos I have seen they are not that bad.

Why not look at Christine Tham's recent photos using the PK to NEX version here. It looks quite OK.

[normhead]

Oh, I've been trying that too. The concept of equivalence is still witchcraft to some.

That's because it's largely a useless concept... the concept that an image has to be exactly a certain way, and that one should try and emulate what one does with one system on another system suggests that photography is a technical medium in which it is important to exactly create a specific image and that images that aren't created exactly that way are somehow lacking. it's a very rigid way of looking at photographic systems. That is "techcraft". The assigning of non-existent technical requirements to artistic media. You can study your graphs and tables, any of which have the ability to be a complete mis-representation, and doesn't present any information you can't absorb more usefully or practically by looking through the viewfinder. Information is useless without context, and those who promote this concept of "equivalency" tend to focus on very narrow measurable criteria to the exclusion of all else, including the context in which those criteria need to be understood.

But the biggest fault of techcraft is it's fallacious belief that it can understand through mathematical formula etc. Like the social sciences, there are things you have formula for and things you don't. Being able to measure some things but not others, and some very important things, micro-contrast and it's effect on the appearance of sharpness, how the control of CA affects the appearance of sharpness etc. or deliberately leaving them out of the discussion creates a narrow discussion based on depth of field, or dynamic range etc. things that can be measured. And in DoF it's extremely problematic, because, extremely narrow DoF for most photographers is not a desirable characteristic, very often.

SO you have those for whom "equivalency" is not understood (in it's limited technical explanations) who look through a camera lens and examine the images and you understand perfectly without the mumbo-jumbo. Then you techies who have tried (like Psychologists) to turn a soft science into a hard science., and spend way to much time reading numbers and charts to prove things that present only part of the picture. And in between you have those who just understand intuitively the difference between different formats, because they've looked through a lot of cameras., and most of those absolutely do not need to understand a bunch of numbers. Their hand reaches out for the appropriate camera based on the shooting situation. No one looks at a bunch of charts to see what sensor will give them 6 inches of DoF at f 5.6 from the distance they are shooting. And if they did, they would still be choosing an APS-c camera much of the time, they would also be choosing FF cameras, micro 4/3 cameras, and view cameras with scanning backs. But most of us don't have a closet full of different format cameras. We want the best compromise. Every sensor is some kind of compromise.

APS_c is a very good compromise system, so are FF cameras. There is no equivalency because no one format presents a "standard" against which others should be measured. The key is to understand the strengths and weaknesses of each system, not in some bogus "equivalency" concept that ignores ease of use, versatility, carry weights, ergonomics, the different ages and light absorption properties of different sensors, the effects of CA and distortion, the internal processing engines of different cameras etc.

From my perspective equivalency is just too narrow a focus to be useful. It's not witchcraft. It's a microscopic look at one small part of camera systems, so myopic as to be next to useless from an artistic stand point. WHo has a better understanding of the laws of motion? The guy who can create a device to launch a basket ball through hoop 24 feet away using mathematical formula. Or the guy who just does it by practicing his 3 point shot? There are two ways to understand things. Throw in ability of the human brain to appreciate non-random characteristics that have never been completely defined, and what you have is pseudo science.

[Paul MaudDib]

That's an awful lot of words you're using to tell me why I don't need a wide angle lens if I don't want to spend as much as I did on my entire camera system on a single wide-angle zoom. For the price of that "cheap" lens I can almost go out and buy a used Canon 5D classic body. Or one of the non-AF Metabones Speed Boosters (brand name). Or one of the knockoffs and a nice evening out or something. I intend on buying one of the Speed Boosters depending on how well they compare.

People like playing with old lenses, and people want the field of view the lens can actually deliver, not a crop of it. It's kind of amusing to see you get so upset about people asking for the logical next step that pretty much every camera manufacturer besides Pentax has made or is making. Or even telecompressors which would provide similar fields of view.

[normhead]

That's an awful lot of words you used to tell me why I don't need a wide angle lens if I don't want to spend as much as I did on my entire camera system on a single wide-angle zoom lens (the "cheap" option you listed). People want the field of view the lens can actually deliver, not a crop of it, and it's kind of amusing to see you get so upset about people asking for the logical next step that pretty much every camera manufacturer besides Pentax has made. Stockholm syndrome much?

OK now that's just offensive, I didn't address wide angle lenses, nor specific cases, nor did I imply that there might not be reasons for wanting a specific lens or sensor, for a specific case. Unlike yourself, I do not assume I know what people want ("People want the field of view the lens can actually deliver, " and I've definitely left it open for people to choose what they wish with my blessing. I simply refuse to accept most of the reasons advanced for using a full frame camera.

By the way, The Nikon 14-24, a rough equivalent to my Sigma 8-16 capable of producing close to twice the resolution on a D800 as my 8-16 will produce (which is the kind of performance I'd be looking for if I were to buy an FF system ) is about $2000. That's three times the price of my Sigma 8-16.

So for me to "step up" I need a $3000 camera and a $2000 lens. I believe that would make a significant difference for my IQ on prints larger than 30inches by 40 inches. But I currently don't print that large.

If Pentax makes an FF, I'll need a $3000 camera and at minimum a 31 ltd. but I won't have anything like the Nikon 14-24. SO for me the FF system I'd go to next is already there. I just haven't got 5K lying around to go for it, or any other criteria that would make it attractive, like needing larger prints or narrower DoF or higher ISO functionality. There is nothing in a Pentax system that in anyway approaches the 4000+ lw/ph in the D800 14-24 combination. But there is also no guarantee that will change if Pentax releases an FF. Apart from the D800, everything else is inadequate as an upgrade path based on lw/ph, and many (but not all) other criteria. FF or not FF has little to do with it.

Does that address the wide angle thing sufficiently?

[jogiba]

Why not look at Christine Tham's recent photos using the PK to NEX version here. It looks quite OK.

See, I knew it's not that bad. My NEX-3N with Pentax 50mm F1.4 FA and Lens Turbo should make a nice combo that is not too big.

[ElJamoquio]

Seeing as we have just been spoon food I am going t o go further. How much better do the cameras before in low light? It sounds like nostalgia comes into play with people really wanting FF.

About 60% better.

[ElJamoquio]

Well, I would submit that if that's a real need, then Pentax does make a 645D that should be even better than a 35mm "FF", no?

Yes. It's also far more expensive.

[normhead]

About 60% better.

What does 60% better look like?

[ElJamoquio]

Same old suspects, same old conclusions...

So far a 24 MP FF increases MTF 13 % for a 50% increase in file size. Over a 24 MP APS-c camera, and that only in lab tests.

Could you please link to this lab test? I've asked repeatedly and politely. Thanks.

[ElJamoquio]

What does 60% better look like?

On a computer monitor, downsized to 400x600, starting with ISO 100 or so, no difference.
On a 30x20 print, at ISO 800, quite a bit.

I was pixel peeping some eagle shots a while back. I couldn't figure out why some were so much clearer than the others. Turns out the good ones were ISO 100 and the bad were ISO 200. See it on a computer monitor? Only at 1:1. See it on a 30x20 print? Maybe if you're picky.

[ElJamoquio]

...and, of course, the real reason for me to use FF is that it's cheaper to get the pictures I want.

[normhead]

Oh sorry.... I have noticed you ask for it, but I find as I get older, I forget things, not that my memory was ever all that great. Feel free to send me a PM to get my mind back on track.
Nikon D3200 2400-2500 lw/ph extinction at 3400 lines.

Nikon D600 24 MP Lw/ph = 2700 lw/ph total extinction at max 3800 lw/ph..

2700/2500 = 1.08. AN 8 % increase, I gave it too much.

For me, it's D800 or nothing. A d800 has exceeded 4000 lw/ph