Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
08-07-2015, 08:01 AM   #1
Site Supporter
Loyal Site Supporter




Join Date: Mar 2015
Photos: Gallery | Albums
Posts: 6,291
Just what is a "stack of primes"? (Philosophical discussion)

You hear the phrase used, but what does it mean?

Back in the day, it was accepted that a prime lens was better than a zoom lens - that gap has now closed significantly, and if you're willing to pay enough then I'm sure you can find zooms which are better at any FL than a competently built consumer prime at that same FL.

Back in the day, a K mount prime typically carried a wider maximum aperture than a zoom. Some of the Takumars were relatively slow, e.g. the 28mm f/3.5 and the 135mm f/3.5 version) while these days, some of the limiteds (especially the DA15/4.0) are also on the sluggish side, although it has to be acknowledged that their slower apertures are a deliberate sacrifice in the interest of compactness on the APS-C format.

SO it seems to me that a good rule-of-thumb definition of a "stack of primes" zoom is one which...

a) Has image quality at least equal to a consumer-level prime of approximately equal vintage from the same manufacturer (e.g. no-one's asking it to outdo an FA Limited or * prime, although it's a bonus if it does, and it's not fair to pit yesterday's lens formulae and coatings against today's). IQ to be judged on the basis of sharpness, resolution, resistance to CA and flare, minimal or easily correctable distortion, but NOT Bokeh, as this is IMO more a matter of individual taste.

b) Has a relatively fast maximum aperture, which it retains throughout the zoom range (f/2.8 seems a reasonable yardstick here, although f/3.5 might be acceptable if IQ is particularly good).

What are the thoughts of others? I'm not necessarily asking for candidate lenses (that's a direct road to the hell of heated arguments); I'm more interested in your views on criteria.

08-07-2015, 08:08 AM - 1 Like   #2
Pentaxian




Join Date: Oct 2011
Location: Savannah, GA
Posts: 5,270
IMO, when people use that phrase, it means nothing more than "this lens is very sharp and high-quality for a zoom" (i.e. why buy all those primes to cover the range, just use this), but it doesn't refer to anything in terms of distortion, bokeh, or flare. It *might* connotate having a relatively large max aperture (probably constant) for a zoom, but not sure about that. But then I've only ever heard the phrase applied to the Pentax-A 35-105/3.5, so maybe it just means that specific lens!
08-07-2015, 08:16 AM   #3
Site Supporter
Loyal Site Supporter




Join Date: Mar 2015
Photos: Gallery | Albums
Posts: 6,291
Original Poster
I've heard it applied to the Sigma 18-35/1.8, with good reason, and if only the AF didn't suck so much for some owners and for our forum testers it might have gone on to supplant the 35-105 in that regard.
08-07-2015, 08:18 AM   #4
Loyal Site Supporter
Loyal Site Supporter
blackcloudbrew's Avatar

Join Date: Mar 2009
Location: Cotati, California USA
Photos: Gallery | Albums
Posts: 3,969
Yes, the A 35-105 comes immediately to mind with this phrase. I've owned two of them and it really is kinda like that. Given the age of the A35-105 primes were really much better in comparison to zooms, but the A 35-105 was different (and still is IMHO) and behaved...like a stack of primes. I think modern zooms have rendered this notation moot but the moniker remains for the A 35-105.

08-07-2015, 08:45 AM   #5
Site Supporter
Site Supporter
jatrax's Avatar

Join Date: May 2010
Location: Washington Cascades
Photos: Gallery | Albums
Posts: 11,798
I think the phrase originated back in the day, when primes were king. A zoom that was even close to prime quality was a surprise and notable. The F 35-70 has often been described that way. And using it there is a distinct difference between it and other zooms of that era. How much of that was marketing and how much truth is a different question.

But as you say a good high quality zoom is very comparable to a good prime these days, or at least the difference has shrunk so as to be almost unnoticeable for most.
08-07-2015, 09:19 AM   #6
Loyal Site Supporter
Loyal Site Supporter
clackers's Avatar

Join Date: Jul 2013
Location: Melbourne
Photos: Albums
Posts: 12,756
The Canon 70-200 was a game-changer.
08-07-2015, 09:21 AM   #7
Site Supporter
Site Supporter




Join Date: Mar 2009
Location: Gladys, Virginia
Photos: Gallery
Posts: 19,743
I think people talk about a zoom that is decent wide open at a lot of different focal lengths. The DA *50-135 is described that way, but it is no where near as good at 77mm as the FA 77, for example.
08-07-2015, 10:00 AM   #8
Pentaxian
Site Supporter
normhead's Avatar

Join Date: Jun 2007
Location: Near Algonquin Park
Photos: Gallery | Albums
Posts: 32,638
You guys are completely missing the point.

The stack of primes is a zoom lens that exceeds primes through it's range....




There are just very few lenses with this type of centre and edge sharpness, zoom or prime in the 60-250 range and the little difference there is makes no practical difference, unless you want a faster lens. They and find any other pentax lens this close to excellent on the charts both centre and edge, all through it's range.

For example, compare the 60-250 at 135mm to the 70 macro... it's not too much of a stretch to speculate the 60-250 is probably better.


You could argue, the Canon 70-200 isn't any better over all, although the control of CA on the Canon is stellar for a zoom.


Last edited by normhead; 08-07-2015 at 10:13 AM.
08-07-2015, 10:36 AM   #9
Site Supporter
Loyal Site Supporter




Join Date: Mar 2015
Photos: Gallery | Albums
Posts: 6,291
Original Poster
Sorry to seem ignorant, but can you please explain what the abbreviations MTF50 and LW/PH mean?

In the last chart/table, you compare the 60-250 at 135mm to the "70 Macro" (which company? I didn't think Pentax made one) and then there is a table listed at 100mm. Did you in fact mean the 100 WR Macro?

By your own definition, it seems that if you're going to compare a zoom to a prime, surely you need to at least make the comparison at the same focal length (and apertures where these are common), NOT the focal length and aperture which is most advantageous to the zoom.

In the end, the issue is which primes you are exceeding. There is a difference between being better than a DA50/1.8 and being better than the DA*55/1.4, isn't there? And it's probably not hard for even a run of the mill zoom lens of today to be better than a third-rate, third-party prime of yesteryear. There has to be some sort of yardstick, otherwise you're comparing apples and oranges.

One thing I will accept from your argument, and that is that it's probably only objective indices like this which enable any sort of comparison. Also, standardisation of testing is important, and it seems to me that not all testing authorities out there agree on the metrics!!

Ultimately there is that mysterious quality called "rendering", which I'm not sure we will ever be able to quantify, any more than we can hope to quantify any aspect of human art. And that's what stops us all from ending up with the same basic lens (or set thereof) on the same basic system. Which is no help at all for LBA sufferers, but it does keep things interesting.
08-07-2015, 10:49 AM   #10
Site Supporter
Site Supporter
boriscleto's Avatar

Join Date: Dec 2009
Location: North Syracuse, NY
Photos: Gallery
Posts: 14,211
QuoteOriginally posted by pathdoc Quote
In the last chart/table, you compare the 60-250 at 135mm to the "70 Macro" (which company?
Norm owns a Sigma 70mm macro. It is one of his go to lenses for comparison...

Sharpness: What is it and how is it measured? | imatest

QuoteQuote:
Line pairs per millimeter (lp/mm) was the most common spatial frequency unit for film, but cycles/pixel (C/P) and line widths/picture height (LW/PH) are more convenient for digital sensors.
QuoteQuote:
Experience has shown that the best indicators of image sharpness are the spatial frequencies where MTF is 50% of its low frequency value (MTF50) or 50% of its peak value (MTF50P).

Last edited by boriscleto; 08-07-2015 at 10:55 AM.
08-07-2015, 10:50 AM   #11
amateur dirt farmer / mod
Loyal Site Supporter
pepperberry farm's Avatar

Join Date: Dec 2014
Location: probably out in a field somewhere...
Photos: Gallery | Albums
Posts: 14,325
in my short time on this forum, I've only seen two zooms referred to as 'stack of primes': the SMC A 35-105mm f3.5 and the SMC A 35-70mm (but which version, I'm not sure)...

I have a 35-105mm and it takes very nice pictures; while I agree that 'rendering' can be more subjective, especially since our idea of 'rendering' doesn't seem to jive with the standard definitions of the word...

I've always taken that a true rendering of color was essentially that the colors you see through the lense or in the image or on the print are the same colors that you would see if you saw the object in real life...
08-07-2015, 11:03 AM   #12
Loyal Site Supporter
Loyal Site Supporter
UncleVanya's Avatar

Join Date: Jul 2014
Photos: Gallery | Albums
Posts: 15,157
My DA* 50-135 and my DA* 60-250 were very close to my A*85 - so close I couldn't tell you which one made each picture when shot at 85 f/8. At f/4 the 60-250 was a little easier to pick out despite excellent results.
08-07-2015, 11:05 AM   #13
Site Supporter
Loyal Site Supporter




Join Date: Mar 2015
Photos: Gallery | Albums
Posts: 6,291
Original Poster
Thanks for the clarification, boriscleto.
08-07-2015, 11:55 AM   #14
Site Supporter
Site Supporter
.a.t.'s Avatar

Join Date: Mar 2011
Posts: 955
QuoteOriginally posted by clackers Quote
The Canon 70-200 was a game-changer.

Which model?
08-07-2015, 11:58 AM   #15
Pentaxian
ZombieArmy's Avatar

Join Date: Jun 2014
Location: Florida
Posts: 1,497
I've also seen "stack of primes" used for the 75-150mm M zoom, albeit not as much.
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
aperture, da, day, e.g, f/3.5, fl, glass, iq, k-mount, lens, lenses, ltd, normhead, pentax lens, people, primes, slr lens, stack
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
For Sale - Sold: Pentax SMC-A 35-105 f/3.5 "Stack of Primes" Zoom Lens Fat Albert Sold Items 7 04-15-2014 06:21 PM
Good hood for A 35-105 "Stack of Primes"? Fat Albert Pentax Camera and Field Accessories 10 02-06-2014 08:22 AM
For Sale - Sold: "Stack o' Primes" Pentax-A 35-105mm f3.5 Macro (WORLDWIDE) cheekygeek Sold Items 3 10-27-2013 12:24 PM
For Sale - Sold: "Stack o' Primes" Pentax-A 35-105mm f3.5 Macro (WORLDWIDE) cheekygeek Sold Items 5 08-09-2013 01:41 PM



All times are GMT -7. The time now is 10:06 AM. | See also: NikonForums.com, CanonForums.com part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top