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06-04-2012, 06:42 AM   #571
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QuoteOriginally posted by beholder3 Quote
I put an Article and an Excel spreadsheet in the Forum here: https://www.pentaxforums.com/forums/photography-articles/186001-lens-potentia...lculator.html?

This allows you to compare lenses on different sensors regarding background blur and DoF.
It does also explain how DoF and background blur are NOT the same and differences can be surprising for those who only seek DoF.

The calculator always adjusts the distance to the subject so it is fully framed, regardless of focal length.

Go play with it and you will find some interesting results.
Changing the distance is what confuses people quite a bit initially, moving the camera. They don't realize one of the variables has changed.

06-04-2012, 07:17 AM   #572
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I know... Pentax tends to pride them selves in compactness. And I tend to like all there lenses too. Pentax had a 35mm f/1.4 prototype but it was never put into production.
Their 85mm f/1.4 is one of the best.
06-04-2012, 07:32 AM   #573
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Last edited by beholder3; 08-11-2013 at 07:30 AM. Reason: [deleted]
06-04-2012, 07:34 AM   #574
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QuoteOriginally posted by mikeossur Quote
I know... Pentax tends to pride them selves in compactness. And I tend to like all there lenses too. Pentax had a 35mm f/1.4 prototype but it was never put into production.
Their 85mm f/1.4 is one of the best.
The K 50/1.2 and A 50/1.2 weren't bad. The K 28/2 was a collaboration with Zeiss. They had several other K-mount 28/2 and 35/2, 24/2. They also had the A* 135/1.8. In the m42 era, they released the 8-element 50/1.4 (1964 to 1966) followed by the 6/7 versions. There were several m42 85/1.8 lenses including one in the 1950s as well as the Auto Tak 35/2.3 released in the 1950s.

06-04-2012, 07:59 AM   #575
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I had the K 28 f/2 at one time along with the 85 f/1.4 but I got rid of it all for a pittance back in the 90's when I bought all my 6x7 gear. I am still kicking myself for that.
I own about four 50mm f/1.4 lenses. two m42's one K and one M. Had even more of them but gave a couple away.

Shot with a Spotmatic SMC 50mm f/1.4 m42
06-04-2012, 10:01 AM   #576
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QuoteOriginally posted by mikeossur Quote
I am a little confused about this. As I understand it, the crop factor is just that. a cropping of the image. The lens is still the same distance from the film plane (err...digital plane ) The focus and DOF should be identical in both FF and 1.6x or 1.3x.... It is just matter of cropping down the visual area. Saying that a 50mm is a 62mm (or there abouts) when a crop factor is added is a little miss leading because there is no magnification involved as would be when you extend the focal length.

How do you like that Sigma 30mm f/1.4. It's too bad that Pentax has always been a little conservative about making fast lenses
If you're commenting on my comment then you misunderstood me.
I was not talking about the focal length but the physical size of the sensor and what kind of effect that has on the image.

If you want to print an enlargement of your photo the smaller sensor of the APS-C needs to be enlarged more then the image of the FF sensor.
That's it, forget about focal lengths, focus distance or anything else.
APS-C image needs to be enlarged 1.5 times more then FF image and this influence the photo as well, basically the APS-C need to capture 1.5 times more details to be equally sharp at the same print size.


ps. 1.5 times sounds a lot but you already have more DOF because of the way lenses are use differently.


It's indeed sad that Pentax has nothing beside the expensive FA 31mm, they had plans for DA*30 but that lens never came sadly and it isn't on the roadmap
So far i quite like the lens, i can't fault it for what i use it for. You shouldn't use it for architecture for example but for the rest, nothing wrong with it really.
06-04-2012, 10:05 AM   #577
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QuoteOriginally posted by beholder3 Quote
Choosing a variable automatic distance was one of the main reasons why I started the calculator, because none of the existing ones did. And in my small practical world of photography the subject and its framing come first. If it doesnt fit I walk or zoom. Doing the same shot using different focal lengths and not adjusting distance/frame to me is silly artificial stuff and completely irrelevant. If I want to do a Head portrait with a 50/1.4 I move. No way I settle for half a nose, One eye and an ear.
Actually with the first you also change the perspective of your photo as well so actually comparing FF with 50mm and APS-C with ~35mm is a better way if you ask me because that keeps the subject the same in the comparison.
06-04-2012, 10:46 AM   #578
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Last edited by beholder3; 08-11-2013 at 07:30 AM. Reason: [deleted]
06-04-2012, 11:56 AM   #579
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QuoteOriginally posted by Anvh Quote
If you want to print an enlargement of your photo the smaller sensor of the APS-C needs to be enlarged more then the image of the FF sensor.
Who prints?

Seriously, those who print will pay more for added sensor sizes, and the vast majority who no longer print, will not.

And the size of the print matters as APS-C is more than adequate for 5x7 which is, for example, a dominant size in photobooks (one area of growth in photo printing). And anything above 5x7 (or 6x6 square crop) usually requires substantial editing as well, as it did in the wet darkroom days.

Using print as a reference point when it is declining as the "normal" output for photos is disingenuous.

To be more accurate from a market perspective (check the thread title) one needs to match the sensor format to the normal intended use. Look at the camera package value as well (Q = epic fail).

Granted, the D800 and other FF's can do it all, but at a cost. The same for the FA 31mm Ltd. Heckuva lens, and for FF, but the price isn't going to make your Flickr photos much better.

The thing sis, camera snobs don't get it. The overall market averages do. It's about price (I have a budget), then value (budget compared to what the market offers), then intended use (this is what I need it for), leading to a purchase decision (what gives me the most bang for my $). People always aim high in talk, then buy within budget. (Not all, many go stoopid with the credit, to the benefit of those of us who buy used; but those are exceptions to the rule).
06-04-2012, 12:56 PM   #580
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@Anvh

I was, I think I need to click reply, not post. Lol. What you say makes sense. I think I was on another tangent regarding bouquet and crop factor.
06-04-2012, 12:58 PM   #581
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@Aristophanes
Hehe... well said.
06-04-2012, 03:32 PM   #582
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Last edited by beholder3; 08-11-2013 at 07:29 AM. Reason: [deleted]
06-04-2012, 03:40 PM   #583
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I agree that 10 megapixels is enough for many common print sizes and most viewing distances.

However the quality of those pixels - i.e. the smoothness/sharpness/whatever - has a great deal to do with the sensor size.
06-04-2012, 04:57 PM   #584
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QuoteOriginally posted by ElJamoquio Quote
I agree that 10 megapixels is enough for many common print sizes and most viewing distances.

However the quality of those pixels - i.e. the smoothness/sharpness/whatever - has a great deal to do with the sensor size.
Yes, especially in low-light/high-ISO situations where DR should be preserved at a a premium.

The other reason for higher resolutions is zoom cropping in PP. I do this a lot—crop to tighten the frame. It's a huge advantage of digital; that and cropping to square format.

Any editing of substance benefits from greater resolution and the larger sensor benefits that benefit (awkward logic applied).

So I don't dismiss the need or desire for FF, but that it's an expensive format in a world that prints a lot less, so using prints quality as a baseline standard to is not really a normative market measure. APS-C is pretty much perfect for web and up to 5x7 prints. Beyond 5x7 things get a little bleary, but again, the initial shot quality (low ISO helps a lot in digital) may make up that difference.

And I print a lot. I probably do at least 40 prints/month in 4x6/5x7. And I do photobooks on top of that, mostly annuals of family photos. If I do an 8x10 or higher, it's from a medium format negative scan!
06-04-2012, 08:58 PM   #585
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QuoteQuote:
es, especially in low-light/high-ISO situations where DR should be preserved at a a premium.

The other reason for higher resolutions is zoom cropping in PP. I do this a lot—crop to tighten the frame. It's a huge advantage of digital; that and cropping to square format.

Any editing of substance benefits from greater resolution and the larger sensor benefits that benefit (awkward logic applied).

So I don't dismiss the need or desire for FF, but that it's an expensive format in a world that prints a lot less, so using prints quality as a baseline standard to is not really a normative market measure. APS-C is pretty much perfect for web and up to 5x7 prints. Beyond 5x7 things get a little bleary, but again, the initial shot quality (low ISO helps a lot in digital) may make up that difference.
And I print a lot. I probably do at least 40 prints/month in 4x6/5x7. And I do photobooks on top of that, mostly annuals of family photos. If I do an 8x10 or higher, it's from a medium format negative scan!
Even a 6.1 mega pixel camera should be able to do a decent 5x7 print. I did a few prints with my old Pentax *stDs and got pretty nice results. It does not take a lot of megapixels to make a nice looking photo on Flickr or the Internet in general. If you plan on making big prints or even be taken serious these days you need at least 10 mega pixels.

FF does not hurt but it is hard to believe you cannot get reasonably nice images at 8x10 with APS-C. 35mm film can handle 8x10 with no issues so APS-C should be able to do the same. I am sure a really sharp lens does not hurt either.

Last edited by mikeossur; 06-04-2012 at 09:07 PM.
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