Pentax 67 Lenses Q

[speywalker]

hello

Another question about the Pentax 67, this time the lenses.
The large majority of the Pentax 67 lenses are around F4 on the open side and the Pentax lenses are often said to be high quality lenses, "good glass".
If that is the case why do most of them start around F4 and not around F2.4, F1.8 etc.
Please bare with me on the nubbie questions, most of my limited camera knowledge is based on digital APS-C sensor sized gear.



PS- I am a nubbie but have a penchant for excellence, analogue devices and working with my hands that why I am here and with a medium format film camera.

 

[SLVR]

if it was possible to even have a p67 lens that fast it wouldn't be very usable. The DOF would simply be too shallow.

I'm sure there are better people to explain it on apug but I'll try.

You should wrap your head around the size of your capturing medium vs focal length and speed. I compare everything to 35mm in terms of FOV (field of view) and DOF (depth of field)

Dealing with a puny APS sensor the lenses have to be wider and faster to compensate for the smaller capturing medium. The lenses need to be wider to equal the same FOV as 35mm and would need to be faster to try to match the same DOF, though this really isn't possible I don't think. You can slap an F1.4 on aps and on 35mm and the 35 will still give shallower DOF because the capturing medium is bigger. Really for those formats F1.4 is sort of the limit in terms of price without going into specialty lenses.

With a 6x7 neg you have over 4 times the capturing medium of APS. With a larger capturing medium the opposite effect happens from APS. Lenses get longer and speed can drop because of many factors. The physical size of the lens and cost of the lens being one and the usable DOF of the lens being another.

I would encourage you to play with this online tool - http://www.dofmaster.com/dofjs.html

Now let me show you why you don't need blazing fast lenses on MF.

Looking at the pentax 67 SMC 55mm F4 This is a WIDE lens on 6x7, even though it has a 55mm focal length.
On 35mm the FOV equivalent is that of around a 25mm lens. On APS this would be the equivalent of a 19mm lens.

DOF of the 55mm at 3 meters @f/4 on 6x7 is 1.48m
The DOF equivalent on 35mm would require a 25mm F1.6
The DOF equivalent on APS would require a 19mm F1.2

Now these are approximations but the lens speeds required to match the 6x7 would be huge, expensive, and probably not perform well wide open.

Also these are all approximations because of what I could put into the online calculator but Im sure someone can correct me if Ive missed anything or made any mistakes.

 

[Alan9940]

SLVR has provided some very useful info, but IMO there's a very simple reason why we don't typically see fast glass on MF: SIZE! If a 1.8 max aperture lens for 6x7 was made, it would be HUGE and weigh about a 1/4 TON!! Heck, the lenses for P67 are already large enough.

As for the "good glass" question... Many years ago when I got my P67 system I directly compared the Pentax lenses to Zeiss lenses for my Hassy. For any typical enlargement I would make (up to about 16x20), I couldn't tell one from the other. So, yeah, I'd say...good 'nuff!

 

[Dan Fromm]

The fastest lens offered for the Pentax 6x7 is the 105/2.4. For a list, see http://www.ricoh-imaging.co.jp/english/products/filmcamera/lens/index672_list.html It includes a handful of lenses faster than f/4.

About size, weight and all that. I used to have a 6"/1.9 Dallmeyer Super Six. 3.5 pounds. I used to have a 200/2 S.F.O.M. ~ 14 pounds. I still have a 4"/2.0 TTH. Not quite so heavy, ~ 1.25 pounds.

 

[mweintraub]

DOF aside, Think about larger aperture lenses in the 35mm format. Larger, heavier, more expensive. The P6x7 lenses are monsters already.

BTW, there are f2.8 in the 90mm, 150mm, and 165mm.
Dead Link Removed

 

[bernard_L]

(...) high quality lenses, "good glass".
If that is the case why do most of them start around F4 and not around F2.4, F1.8

Why should one equate good quality with high aperture? except in certain bokeh-aficionado circles. Look for instance at the catalogue of Schneider Apo-Digitars, arguably among the better lenses of contemporary desig.
https://www.schneideroptics.com/ecommerce/CatalogSubCategoryDisplay.aspx?CID=1326

I'm very happy with the 45/5.6 Fujinon on my GS645W, on the other hand, the Radionar 80/2.9 (a triplet!!) on my Franka Solida is, wide open, a big joke.

 

[mweintraub]

Why should one equate good quality with high aperture? except in certain bokeh-aficionado circles. Look for instance at the catalogue of Schneider Apo-Digitars, arguably among the better lenses of contemporary desig.
https://www.schneideroptics.com/ecommerce/CatalogSubCategoryDisplay.aspx?CID=1326

I'm very happy with the 45/5.6 Fujinon on my GS645W, on the other hand, the Radionar 80/2.9 (a triplet!!) on my Franka Solida is, wide open, a big joke.

Pretty darn happy with my slow Pentax 67 75mm f/4.5 too!

 

[DREW WILEY]

There are also certain options to the same of similar focal length. For example, if you are hand-shooting a P67, it will obviously be easier to
focus in dim light using the fast 75/2.8 wide-angle lens. But if you're doing it on a tripod and have time for use a supplementary magnifier or the relatively bright "chimney" focus hood, the 75/4.5 is an optically superb alternative at a fraction of the price. Now lets go the opposite direction, to a relatively long telephoto. I have both 300mm lens in both a later regular version and the deluxe 300 EDIF. The latter is extraordinarily sharp even fully wide open, has extremely little color fringing, and is so damn good that I can put a Nikon on it using the
appropriate adapter, and it's probably sharper than anything equivalent Nikon itself offers, along with superb bokeh. But it's not anything I'd
leave behind in my truck when I'm out backpacking with a 4x5 instead. For that, the far less expensive regular 300 is more appropriate,
and it still gives good results with black and white film. The P67 system is a real bargain these days, though a few lenses remain rather
expensive due to their relative scarcity. Size and bulk are relative. To me, who considers an 8x10 normal, the P67 is a very portable system. I have no problem packing three lenses, two bodies, and even a tripod into an airline carry-on, or even into a shoulder bag.

 

[Poisson Du Jour]

The SMC Pentax 67 f4 lenses — there are a few, are a nuisance to focus in low light, or low light with a polariser. So many, many people will tell you this. Granted, a central-viewfinder magnifier is available, so too is the right-angle finder (I have both of these), but rather than fuss and fiddle, I switch from a 45mm f4 to the 75mm f2.8AL (I frequently shoot with this at 2.8) or the cute and almost cuddly 90mm f2.8 — if the scene and composition will allow it. Otherwise I hyperfocus or remove the polariser (98% of my work employs a polariser). I think the f4 standard of so many lenses harkens back to the dawning era of Distagon designs upon which these "slow" lenses are built — they're not lousy lenses by the way, just most often clunky, heavy and irksome to focus. They could have been made faster, but at probable increases in cost and weight that would have negated any benefit. Way back then, the MF systems still had to be accessible without being prohibitively expensive in the lens area (but the Pentax 67 was still mighty expensive in its hayday). Then came advances in optical engineering that made lenses faster and a bit lighter and much easier to use — with a price that we could all afford. And P67 lenses are still in high demand, with the aforementioned 75 f2.8AL commanding steep prices MINT or in excellent condition, and it's a beautiful lens to focus (light touch).

 

[DREW WILEY]

Often it doesn't matter, deep filter or not. Since most of these lenses have a hard stop at infinity, and the 75/4.5 has lots of depth of field,
aiming at some cloud shot off in the distance doesn't require visual focusing at all. On the other hand, this lens does have really lovely bokeh,
and often I use that fact very circumspectly - never blatantly - always needing some spot in the scene precisely in focus. Hence the separate
eyepiece magnifier for the prism. Sure, I'd also love to own the 75/2.8 too. But one has to prioritize their expenditures, and I certainly don't
regret spending it on that 300 EDIF.

 

[ColColt]

If I may go out on a limb a little I'd say the best fast glass for the 67 would be the 75 f2.8...not that large and from all I've read, a superb lens. I'm still on the hunt for one that won't break the bank.

 

[Poisson Du Jour]

If I may go out on a limb a little I'd say the best fast glass for the 67 would be the 75 f2.8...not that large and from all I've read, a superb lens. I'm still on the hunt for one that won't break the bank.

Very true. But there is also the 90mm f2.8 which is smaller than the 75 and gives the same bright focusing.
But the 75... well, that's a delightfully well-balanced and constructed lens. But it will break the bank. The value of this lens has increased a bit over the last 2 years, at least in Australia. Mine is in use all the time as a 'standard' prime and I love it's delicate focus and springy aperture selection, and I print BIG from it. The big plus though is how easy it is to focus in low light, even with a polariser. Was AUD$1,300 NIB. There heading toward AUD$1,500 now privately, probably more at retail level (try not to go that way!).

 

[ColColt]

I had the chance to buy that lens about three months ago and kept procrastinating till it was gone...won't do that again.

 

[mweintraub]

The 75mm 2.8 AL might be the best P67 lens, but it's only one FL. I've chosen to have a few lenses instead of just one lens (75mm 2.8), hence why I can't afford it right now.

 

[aoresteen]

I have bought the 45mm & 135mm 6x7 lenses. The next one will be either the 75 f/2.8 or the 600mm f/4. The 45mm & 135mm were inexpensive. The 75mm f/28 & 600mm are not. They will break the bank! The 75mm f/2.8 will cost between $800 to $900 and the 600mm run anywhere from $1000 to $2500. Beyond my budget right now.

 

[Poisson Du Jour]

There are a lot of P67 and later 67II photographers using the 75 f2.8AL prime. For a lot it is the one and only lens, understandable given its steep cost. For it, it was the last lens added to my 5-lens kit. And that's quite enough to carry!!