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08-13-2011, 01:36 AM   #16
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Only downside of course is it's the same size as a Tele!

08-13-2011, 03:09 AM   #17
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QuoteOriginally posted by axl Quote
I thin I would use 24/1.4 quite a lot but I have to say that focus f1.4 @ 24mm behind 5m distance would be a b*?!h... at least for me anyway.. I'm very happy with AF.
DOF of a 24/1.4 is thicker than of a 50/2.8 -- if you'd have a hard time focusing THAT then yes, you'd better stick to AF.
08-13-2011, 10:15 AM   #18
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QuoteOriginally posted by RioRico Quote
DOF of a 24/1.4 is thicker than of a 50/2.8 -- if you'd have a hard time focusing THAT then yes, you'd better stick to AF.
I think you would still have a problem with the 24/1.4 because the details you would want to focus on would be smaller in the viewfinder. At least, this is the trouble I have when trying to focus wide angles - I don't see fine detail because of the wide FOV.

But this looks like a very interesting lens - great next entry from Samyang.
08-13-2011, 11:24 AM   #19
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QuoteOriginally posted by RioRico Quote
DOF of a 24/1.4 is thicker than of a 50/2.8 -- if you'd have a hard time focusing THAT then yes, you'd better stick to AF.
That's simply not true.

Read this: DOF2

08-13-2011, 01:23 PM   #20
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QuoteOriginally posted by kevinschoenmakers Quote
QuoteOriginally posted by RioRico:
DOF of a 24/1.4 is thicker than of a 50/2.8 -- if you'd have a hard time focusing THAT then yes, you'd better stick to AF.
That's simply not true.

Read this: DOF2
The examples there posit KEEPING THE SUBJECT THE SAME SIZE IN THE VIEWFINDER which is not how we approach comparative DOF, which requires STAYING THE SAME DISTANCE FROM THE SUBJECT. Let's plug numbers into an online DOF calculator -- distance= 5m (chosen arbitrarily), focal lengths and apertures as above.
FL=24, f/1.4, D= 5m, DOF --> 2.6m (4.02-6.62m)
FL=50, f/2.8, D= 5m, DOF --> 1.13m (4.5-5.63m)
The 24/1.4 has DOF over twice as thick as the 50/2.8 when used at the same distance.

Where are their DOF's the same thickness? Either stop the 50 'WAY down:
FL=50, f/6.4, D= 5m, DOF --> 2.68m (4-6.68m)
Or move the 50, to 50% further away:
FL=50, f/2.8, D= 7.5m, DOF --> 2.6m (6.42-9.02m)
Or else move the 24, to 33% closer in:
FL=24, f/1.4, D= 3.36m, DOF --> 1.13m (2.89-4.02m)
If we FILL THE VIEWFINDER with different focal-length lenses at different distances, we may indeed see similarly-thick DOF's, but with rather different perspectives -- get too close, and perspective distortion raises its ugly head. (Perspective is determined SOLELY by lens-to-subject distance.) Ain't numbers fun?

Last edited by RioRico; 08-13-2011 at 01:30 PM.
08-13-2011, 03:29 PM   #21
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You could've just mentioned you were talking about keeping the same distance to the subject...
08-13-2011, 05:28 PM - 1 Like   #22
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QuoteOriginally posted by kevinschoenmakers Quote
You could've just mentioned you were talking about keeping the same distance to the subject...
To compare stuff, some standard is needed. Otherwise we're in apples-n-oranges land. I can easily prove that (say) 30/2 and 30/6 have the same DOF, or that 30/2 and 30/2 have very different DOF -- all I have to do is radically change distances. Sort of like 1+1=3, for large enough values of 1.

[/me dons Cloak Of Authority...] So, shorter focal lengths have thicker DOF than do longer focal lengths, unless we move stuff around till the numbers fit. Or think of it as, ALL ELSE BEING KEPT THE SAME, here's how factors affect DOF:

* Thicker DOF: Shorter focal length AND/OR tighter aperture AND/OR further subject-lens distance
* Thinner DOF: Longer focal length AND/OR wider aperture AND/OR closer subject-lens distance

The ALL ELSE includes angles, lighting, display size and type, viewing distance, viewer vision and consciousness, etc. Do I have enough epoxy to glue-down all of those? [/me hate epoxy and epoxy hates /me]

Once we skip around the ALL ELSE BEING KEPT THE SAME part, anything can happen. That Primogon's 35/4.5 DOF becomes razor-thin. My 135/2.5's DOF becomes thick as a brick. French poodles start talking. Economic crises are fixed. My old 1996 Ford Exploder gets 255 mpg. Miracles!! Yah, numbers are fun!
08-14-2011, 03:00 AM   #23
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QuoteOriginally posted by RioRico Quote
DOF of a 24/1.4 is thicker than of a 50/2.8 -- if you'd have a hard time focusing THAT then yes, you'd better stick to AF.
DoF might be thicker but magnification and visible detail much worse and THAT is the reason I would have trouble focusing it. I used to have 50/1.2 and now have 55/1.4 and I'm capable of focusing those (although since started to use glasses it's harder) but have styruggled with K24/2.8 at distances between 3 and 10 meters...

08-14-2011, 05:31 AM   #24
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24mm F1.4 would be interesting on a 35mm Pentax SLR or if Pentax had a FF DSLR but not so much with APS-C sensor as a 36mm FF eqiv. I have a Voigtländer Nokton 25mm f/0.95 that some people use wide open @F0.95 full time like in this video:

08-14-2011, 05:40 AM   #25
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QuoteOriginally posted by jogiba Quote
24mm F1.4 would be interesting on a 35mm Pentax SLR or if Pentax had a FF DSLR but not so much with APS-C sensor as a 36mm FF eqiv. I have a Voigtländer Nokton 25mm f/0.95 that some people use wide open @F0.95 full time like in this video:

I strongly disagree.
24/1.4 on APSC gives you near exact replication of 35/2 on FF. And if I'm not mistaken 35s were rather popular on film...
08-14-2011, 07:00 AM   #26
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QuoteOriginally posted by axl Quote
And if I'm not mistaken 35s were rather popular on film
That is correct - you can get a ton of great usage out of the 35mm focal length.
08-14-2011, 07:57 AM - 1 Like   #27
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I've been looking forward to this lens for several months. The rumor broke out from a twitter post back when the 35mm was released. This will likely fill the 24/1.4 niche well for Pentax, the closest to which is the Sigma 24/1.8. It would be good to see a comparison of the two once this comes out.

I am stoked that Samyang is keeping K-mount in the loop. With the loss of Zeiss and Voigtlander, new quality MF glass is becoming quite rare. I expect to buy this lens if priced around $600, gotta support companies like this...they're giving the classic lens makers quite the healthy competition.

P.S. I for one am glad that these lenses are FF, as I'm still holding out for the mythical Pentax FF DSLR.
08-14-2011, 08:29 AM   #28
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QuoteOriginally posted by jeffshaddix Quote
I am stoked that Samyang is keeping K-mount in the loop. With the loss of Zeiss and Voigtlander, new quality MF glass is becoming quite rare. I expect to buy this lens if priced around $600, gotta support companies like this...they're giving the classic lens makers quite the healthy competition.
Since the 85/1.4 is only $400 and the 35/1.4 ca. $500 I would be surprised if it was not around those figures.
08-14-2011, 11:08 AM   #29
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QuoteOriginally posted by joe.penn Quote
That is correct - you can get a ton of great usage out of the 35mm focal length.
I don't need to be reminded. My 24 takes around 48% of my shots, 55 takes care of 51% and 100mm has the remaining 1%. 31 is never on my camera...
08-14-2011, 11:10 AM   #30
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QuoteOriginally posted by jeffshaddix Quote
I've been looking forward to this lens for several months. The rumor broke out from a twitter post back when the 35mm was released. This will likely fill the 24/1.4 niche well for Pentax, the closest to which is the Sigma 24/1.8. It would be good to see a comparison of the two once this comes out.

I am stoked that Samyang is keeping K-mount in the loop. With the loss of Zeiss and Voigtlander, new quality MF glass is becoming quite rare. I expect to buy this lens if priced around $600, gotta support companies like this...they're giving the classic lens makers quite the healthy competition.

P.S. I for one am glad that these lenses are FF, as I'm still holding out for the mythical Pentax FF DSLR.
Me too. Plus if you still shoot film, you need FF. Very excited about this lens.
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