Pentax 67 55mm f/4 latest - floating element?

rdeloe · 08-04-2019, 11:02 AM

Does the Pentax 67 55mm f/4 (latest version) incorporate a floating element in its design?

torashi · 08-04-2019, 12:38 PM

No.

rdeloe · 08-04-2019, 01:30 PM

Thanks Torashi. For the way I'm going to use it, that's actually good news.
Rob

Originally posted by torashi

No.

**gofour3** · 08-04-2019, 02:15 PM - **1 Like**

This is a lens diagram of the 67 55/4:

Phil.

Attached Images

desertscape · 08-04-2019, 04:28 PM - **1 Like**

The 45mm does. The latest 55mm is Distagon-like in design.

rdeloe · 08-04-2019, 04:53 PM

I'm planning to get both. How I use them will be a bit different. I have a Fuji GFX 50R on the back of a Toyo VX23D technical camera. Technical camera lenses work fine in 80mm and longer, but wider either won't fit because there isn't enough room for the rear element, or barely fits but produces horrendous lens cast when shifting. Case in point is the Rodenstock Apo-Rodagon 55mm which is just a lovely lens, but produces loads of lens cast. So for wider I'm using these great Pentax lenses. I have a Pentax-A 645 35mm f/3.5 up and running already. Shift range is limited; it will shift to 10mm, but the edges are not great. Smaller shifts are very good, and unshifted it's great. I tried someone else's P67 55/4 on my GFX 50R with a shift adapter (not my Toyo); it was excellent and shifts well to 12mm with very little reduction in image quality.

The catch with lenses that have floating elements is at close distances I have to focus with the lens, which is slightly more awkward than focusing with the camera. But it's not a big deal. For example, up to 4' the P645 35mm needs to be focused with the lens to get the floating elements doing their job. Beyond 4' I can focus with the camera. I'll have to use the P67 45 the same way. It will be nice to not have to worry about this with the P67 55.

Anyway, thanks for helping me answer these questions folks.

Rob

torashi · 08-04-2019, 04:54 PM

Originally posted by desertscape

The 45mm does. The latest 55mm is Distagon-like in design.

Where did you get that idea? Both move as a single unit.

Silent Street · 08-04-2019, 05:41 PM

This is the first time I have read of a P67 55mm being used in this somewhat unconventional application.
I hope you get a 54mm f4 without the dreaded rattle that seems to plague this particular lens.

rdeloe · 08-04-2019, 05:53 PM

Originally posted by Silent Street

This is the first time I have read of a P67 55mm being used in this somewhat unconventional application.
I hope you get a 54mm f4 without the dreaded rattle that seems to plague this particular lens.

It is unconventional for sure. Perhaps the trickiest bit has been the mounting. To get the P645 35 working I had to get a machine shop to cut a Fotodiox adapter to the needed length and bolt it to a Toyo 24mm recessed lens board. It's awkward as can be to reach the aperture, but having spent time in the large format world I'm used to working with awkward gear. I'll be doing the same thing to mount the P67 lenses. Sadly they can't share the mounting board for my P645 lens because the deeply-recessed board doesn't have space to fit my P67 to P645 adapter.

I'll keep an ear out for the dreaded rattle! The copy I borrowed was fine, and the person I'm buying one from now offers free returns if there are any issues. It's a beast of a lens size-wise, but more than capable on the Fuji GFX 50R sensor. So it's worth the effort.

Silent Street · 08-04-2019, 07:27 PM

I'll keep an ear out for the dreaded rattle! The copy I borrowed was fine, and the person I'm buying one from now offers free returns if there are any issues. It's a beast of a lens size-wise, but more than capable on the Fuji GFX 50R sensor. So it's worth the effort.

The rattle in the 55mm may not show up if it is a near-new lens with very little, if any use, as mine was. The rattle turned up about 12 months after purchase, and it set me off, to the point of almost losing my carrot! It is a great lens, and even with a rattle as you roll, probably not justification in returning it on the assumption it is a once-off fault.

The 45mm is a different beast, physically wider, a bit of a heavyweight, and squatter. Be it known that it has a filter clasp at its rear element which may be of interest if you are using gelatin filters. Incredibly, very few owners know of the clasp, such is its nondescript appearance, with nowt but a slight 'lip' on the edge to give it away. No rattles with this lens! So I won't go off my carrot...

tuco · 08-05-2019, 08:58 AM

Originally posted by rdeloe

...Shift range is limited; it will shift to 10mm, but the edges are not great. Smaller shifts are very good, and unshifted it's great. I tried someone else's P67 55/4 on my GFX 50R with a shift adapter (not my Toyo); it was excellent and shifts well to 12mm with very little reduction in image quality.
...

Cool. I have a couple of view cameras and still use them. And I can correct for more convergence/divergence by aiming the camera up/down and tilting both the front and rear standard than a level camera with just front rise/shift alone. Front shift is a special case where adjusting the rear standard parallel to the subject plane handles all cases.

desertscape · 08-05-2019, 03:35 PM

Originally posted by torashi

Where did you get that idea? Both move as a single unit.

Pentax had a sales booklet that came out in the mid 1980's that covered most of the lenses for this camera system at that time. On page 16 it talks about the 45mm and mentions that it uses a floating element.

torashi · 08-05-2019, 06:59 PM

Originally posted by desertscape

Pentax had a sales booklet that came out in the mid 1980's that covered most of the lenses for this camera system at that time. On page 16 it talks about the 45mm and mentions that it uses a floating element.

Can you get a hold of a copy? I'd like to see it. The ones I've disassembled work as a single unit. Not even the more modern 75/2.8 AL has a floating element. I've only seen such design in lenses like the P645 120/4 Macro.

desertscape · 08-06-2019, 12:55 PM

It is quite possible that the floating element moves within the whole group, so that it is not seen moving as a separate piece. The booklet I have is shown below and mine was acquired around 1987-88 time frame. I have seen them for sale on ebay in the past.

**gofour3** · 08-06-2019, 01:54 PM - **1 Like**

I have a Pentax 6x7 booklet with a different cover and it also mentions that the 45/4 has a floating lens element.

Phil.

08-04-2019, 11:02 AM	#1
rdeloe Forum Member Join Date: Aug 2015 Posts: 62	Pentax 67 55mm f/4 latest - floating element? Does the Pentax 67 55mm f/4 (latest version) incorporate a floating element in its design?

08-06-2019, 12:55 PM	#14
desertscape Pentaxian Join Date: Feb 2009 Location: Arizona Posts: 1,272	Booklet P 6x7 It is quite possible that the floating element moves within the whole group, so that it is not seen moving as a separate piece. The booklet I have is shown below and mine was acquired around 1987-88 time frame. I have seen them for sale on ebay in the past. Last edited by desertscape; 05-15-2020 at 04:51 PM.

08-06-2019, 01:54 PM - 1 Like	#15
gofour3 Site Supporter Join Date: Oct 2008 Location: Vancouver, Canada Posts: 8,092	I have a Pentax 6x7 booklet with a different cover and it also mentions that the 45/4 has a floating lens element. Phil. Attached Images

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08-04-2019, 12:38 PM	#2
torashi Veteran Member Join Date: Sep 2017 Location: Medellín Posts: 1,322	No.

08-04-2019, 01:30 PM	#3
rdeloe Forum Member Join Date: Aug 2015 Posts: 62 Original Poster	Thanks Torashi. For the way I'm going to use it, that's actually good news. Rob Originally posted by torashi No.

08-04-2019, 02:15 PM - 1 Like	#4
gofour3 Site Supporter Join Date: Oct 2008 Location: Vancouver, Canada Posts: 8,092	This is a lens diagram of the 67 55/4: Phil. Attached Images

08-04-2019, 04:28 PM - 1 Like	#5
desertscape Pentaxian Join Date: Feb 2009 Location: Arizona Posts: 1,272	The 45mm does. The latest 55mm is Distagon-like in design.

08-04-2019, 04:53 PM	#6
rdeloe Forum Member Join Date: Aug 2015 Posts: 62 Original Poster	I'm planning to get both. How I use them will be a bit different. I have a Fuji GFX 50R on the back of a Toyo VX23D technical camera. Technical camera lenses work fine in 80mm and longer, but wider either won't fit because there isn't enough room for the rear element, or barely fits but produces horrendous lens cast when shifting. Case in point is the Rodenstock Apo-Rodagon 55mm which is just a lovely lens, but produces loads of lens cast. So for wider I'm using these great Pentax lenses. I have a Pentax-A 645 35mm f/3.5 up and running already. Shift range is limited; it will shift to 10mm, but the edges are not great. Smaller shifts are very good, and unshifted it's great. I tried someone else's P67 55/4 on my GFX 50R with a shift adapter (not my Toyo); it was excellent and shifts well to 12mm with very little reduction in image quality. The catch with lenses that have floating elements is at close distances I have to focus with the lens, which is slightly more awkward than focusing with the camera. But it's not a big deal. For example, up to 4' the P645 35mm needs to be focused with the lens to get the floating elements doing their job. Beyond 4' I can focus with the camera. I'll have to use the P67 45 the same way. It will be nice to not have to worry about this with the P67 55. Anyway, thanks for helping me answer these questions folks. Rob

08-04-2019, 04:54 PM	#7
torashi Veteran Member Join Date: Sep 2017 Location: Medellín Posts: 1,322	Originally posted by desertscape The 45mm does. The latest 55mm is Distagon-like in design. Where did you get that idea? Both move as a single unit.

08-04-2019, 05:41 PM	#8
Silent Street Veteran Member Join Date: Nov 2011 Location: Castlemaine, Victoria, AUS Photos: Albums Posts: 1,151	This is the first time I have read of a P67 55mm being used in this somewhat unconventional application. I hope you get a 54mm f4 without the dreaded rattle that seems to plague this particular lens.

08-04-2019, 05:53 PM	#9
rdeloe Forum Member Join Date: Aug 2015 Posts: 62 Original Poster	Originally posted by Silent Street This is the first time I have read of a P67 55mm being used in this somewhat unconventional application. I hope you get a 54mm f4 without the dreaded rattle that seems to plague this particular lens. It is unconventional for sure. Perhaps the trickiest bit has been the mounting. To get the P645 35 working I had to get a machine shop to cut a Fotodiox adapter to the needed length and bolt it to a Toyo 24mm recessed lens board. It's awkward as can be to reach the aperture, but having spent time in the large format world I'm used to working with awkward gear. I'll be doing the same thing to mount the P67 lenses. Sadly they can't share the mounting board for my P645 lens because the deeply-recessed board doesn't have space to fit my P67 to P645 adapter. I'll keep an ear out for the dreaded rattle! The copy I borrowed was fine, and the person I'm buying one from now offers free returns if there are any issues. It's a beast of a lens size-wise, but more than capable on the Fuji GFX 50R sensor. So it's worth the effort.

08-04-2019, 07:27 PM	#10
Silent Street Veteran Member Join Date: Nov 2011 Location: Castlemaine, Victoria, AUS Photos: Albums Posts: 1,151	I'll keep an ear out for the dreaded rattle! The copy I borrowed was fine, and the person I'm buying one from now offers free returns if there are any issues. It's a beast of a lens size-wise, but more than capable on the Fuji GFX 50R sensor. So it's worth the effort. The rattle in the 55mm may not show up if it is a near-new lens with very little, if any use, as mine was. The rattle turned up about 12 months after purchase, and it set me off, to the point of almost losing my carrot! It is a great lens, and even with a rattle as you roll, probably not justification in returning it on the assumption it is a once-off fault. The 45mm is a different beast, physically wider, a bit of a heavyweight, and squatter. Be it known that it has a filter clasp at its rear element which may be of interest if you are using gelatin filters. Incredibly, very few owners know of the clasp, such is its nondescript appearance, with nowt but a slight 'lip' on the edge to give it away. No rattles with this lens! So I won't go off my carrot...

08-05-2019, 08:58 AM	#11
tuco Pentaxian Join Date: Jul 2009 Location: Pugetopolis Posts: 11,030	Originally posted by rdeloe ...Shift range is limited; it will shift to 10mm, but the edges are not great. Smaller shifts are very good, and unshifted it's great. I tried someone else's P67 55/4 on my GFX 50R with a shift adapter (not my Toyo); it was excellent and shifts well to 12mm with very little reduction in image quality. ... Cool. I have a couple of view cameras and still use them. And I can correct for more convergence/divergence by aiming the camera up/down and tilting both the front and rear standard than a level camera with just front rise/shift alone. Front shift is a special case where adjusting the rear standard parallel to the subject plane handles all cases.

08-05-2019, 03:35 PM	#12
desertscape Pentaxian Join Date: Feb 2009 Location: Arizona Posts: 1,272	Originally posted by torashi Where did you get that idea? Both move as a single unit. Pentax had a sales booklet that came out in the mid 1980's that covered most of the lenses for this camera system at that time. On page 16 it talks about the 45mm and mentions that it uses a floating element.

08-05-2019, 06:59 PM	#13
torashi Veteran Member Join Date: Sep 2017 Location: Medellín Posts: 1,322	Originally posted by desertscape Pentax had a sales booklet that came out in the mid 1980's that covered most of the lenses for this camera system at that time. On page 16 it talks about the 45mm and mentions that it uses a floating element. Can you get a hold of a copy? I'd like to see it. The ones I've disassembled work as a single unit. Not even the more modern 75/2.8 AL has a floating element. I've only seen such design in lenses like the P645 120/4 Macro.