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Forum: Pentax Medium Format 4 Days Ago  
Adapting Rollei Planar HFT 80mm Rollei SLX to P67
Posted By desertscape
Replies: 4
Views: 381
Indeed! There is a reason why lenses for the 6x7, shorter than 90mm are reverse telephoto, retrofocus or Distagon-like designs.
Forum: Pentax Medium Format 11-08-2022, 11:24 AM  
67ii advance tension
Posted By desertscape
Replies: 2
Views: 246
The tension you speak of is necessary to keep the film flat on the backing plate. The winding lever pressure is not light on any of the 6x7, 67 or 67II models.
Forum: Pentax Medium Format 09-23-2022, 05:54 PM  
67 vs 67 ii
Posted By desertscape
Replies: 2
Views: 615
The 67II has had more problems than the 67 and this can be an issue when trying to get it fixed, as few places will work on this camera. The AE metereing system on the 67II is more accurate than the TTL prism on the older 67. The prisms on the 67II use silver surfaces and are brighter than the prisms on the 67.
Forum: Pentax Medium Format 09-23-2022, 04:35 PM  
Curved Field Lenses for 645
Posted By desertscape
Replies: 6
Views: 740
The depth of field in most lenses is curved and only specially made lenses have a flat depth of field ( projection lenses). Curvature of field is considered an aberration at the focal plane and has to be corrected out in the design phase to eliminate it. In most cases, only a slight amount remains. It is easily masked by stopping down slightly. Some macro lenses have a flat depth of field but not many. Projection lenses have both a flat DOF and a flat focal plane.
Forum: Pentax Medium Format 08-01-2022, 04:11 PM  
Pentax 67 with Stacked Converters vs 400mm with 1.4X/2X
Posted By desertscape
Replies: 16
Views: 1,099
The 400 Takumar is quite well corrected for color and other aberrations. It does well with the Pentax 1.4X grey converter. Using two 2x converters on the 200 is not only magnifying the image but also magnifying the aberrations. The 200 with the 1.4X works fine but going much beyond that, the image starts to degrade. The 400 Takumar at f'/11 without a converter is very sharp. It is a much better lens than the 300 Takumar.
Forum: Pentax Medium Format 06-20-2022, 10:01 AM  
Pentax 6x7 MLU Battery Drain
Posted By desertscape
Replies: 10
Views: 498
Is your mirror stuck, part way up?
Forum: Pentax Medium Format 06-18-2022, 01:44 PM  
Pentax 6x7 MLU Battery Drain
Posted By desertscape
Replies: 10
Views: 498
The battery check light is not an accurate indicator of battery power. Are you sure that the batteries are dead?
Forum: Pentax Medium Format 06-17-2022, 03:35 PM  
Pentax 6x7 MLU Battery Drain
Posted By desertscape
Replies: 10
Views: 498
Do you have the TTL prism on this body?
Forum: Pentax Medium Format 06-02-2022, 05:38 PM  
Stacking extension rings and teleconverters (P67II)
Posted By desertscape
Replies: 9
Views: 625
With some lenses, there is no choice in the configuration between TC and tube. For the 600 Takumar, the tube must be put on the lens and the converter on the camera body. The resulting shots turn our well, at least with the 1.4X converter.
Forum: Pentax Medium Format 04-03-2022, 05:21 PM  
Pentax 645 90mm f/2.8 and 67 105mm f/2.4
Posted By desertscape
Replies: 19
Views: 1,881
The original 105 used Thorium glass and was changed in design type to accommodate a non-radioactive high index glass. Also changed was the coating. The ones since circa 1975 are SCM, which is a 7 layer multi-coat. The improvements over this coating has been minimal over the years. The lens at f/8 can make prints of 24 X 30 inch size. It does well on the 67 for portraits. DOF can be a bit too thin at f/2.4.
Forum: Pentax Medium Format 03-16-2022, 11:58 AM  
Using Pentax 6x7 lens with Fujifilm gfx 50S II
Posted By desertscape
Replies: 7
Views: 1,785
Hi Ed-- The auto -manual toggle/slider is a bit fiddly on the 67 lenses. It needs to be lifted up, away from the lens body on the left side as you slide it to go from auto to manaul to lock it in place. Simply sliding it on the older 6x7 lenses is hit or miss. The newer lenses had a different slider that made it easier to lock into manual mode.
Forum: Pentax Medium Format 03-12-2022, 02:24 PM  
Pentax 6x7 - The Diopter of Despair
Posted By desertscape
Replies: 9
Views: 722
For future reference for anyone looking for similar lenses to what you want, there is always Edmund Optics. They have a huge supply of various lenses. I bought a few items from them many years ago.Optical Lenses | Achromatic Lenses | Edmund Optics
Forum: Pentax Medium Format 03-01-2022, 12:30 PM  
What are the advantages and disadvantages of a Double Gauss lens design
Posted By desertscape
Replies: 17
Views: 2,087
The 90 Takumar (leaf) and the 90 Pentax are both double gauss designs on the 6x7. Even though these two designs are not totally symmetrical, the fact that they are close to it, makes it much easier for the designer to correct three of the transverse aberrations.This design type also has very low spherochromatism.
Forum: Pentax Medium Format 02-16-2022, 11:52 AM  
Lens hood for 6x7 75mm Shift ?
Posted By desertscape
Replies: 2
Views: 503
Shifting moves the lens a bit further from the film plane, so the DOF scale is not as accurate as when the lens is unshifted. So, it's best to stop down a bit further than what the DOF scale would suggest. So if your DOF scale says 20 feet to infinity will be in focus when at f/8, it would be best to stop down another stop or 2 to be safe.
Forum: Pentax Medium Format 12-27-2021, 11:05 AM  
Pentax 6x7 non-MLU transport/last frame issue
Posted By desertscape
Replies: 2
Views: 437
Losing the last frame is usually caused by excess spacing between frames. This is fairly common on the non lock up bodies. There is a fix for this, I'm told.
Forum: Pentax Medium Format 11-16-2021, 04:35 PM  
6x7 35mm f/4.5 Fisheye -- Any good for color?
Posted By desertscape
Replies: 7
Views: 564
Yes; even though the 45 is an old design, it is still sharper in the corners than the 35.
Forum: Pentax Medium Format 11-16-2021, 10:43 AM  
6x7 35mm f/4.5 Fisheye -- Any good for color?
Posted By desertscape
Replies: 7
Views: 564
I used mine for color work only, for large expanses like the Grand Canyon. The edges of the frame were slightly soft, even at mid apertures, so I sold mine. It can be used successfully but really requires one to crop the frame down a bit when scanning the slide or neg.
Forum: Pentax Medium Format 11-06-2021, 03:24 PM  
Can Anyone Help Me Pick The Next Lens For My Pentax 67II?
Posted By desertscape
Replies: 22
Views: 2,349
The 75 Shift for architecture work is limited due to its angle of view. I own one for landscape work. I use it for when trees or tall cactus are the frame and I don't want them leaning. If you have a need for perspective control in landscape work, it's a good lens. If you are considering this lens for architectural work only, I would pass on it.
Forum: Pentax Medium Format 10-16-2021, 02:05 PM  
Could a 67 III be released in todays market?
Posted By desertscape
Replies: 21
Views: 1,475
The 105 was $470 at B&H in March of 1998.
Forum: Pentax Medium Format 10-09-2021, 04:48 PM  
Could a 67 III be released in todays market?
Posted By desertscape
Replies: 21
Views: 1,475
Considering the amount of people buying into the 67 system in the past six years, there is obviously a lot of demand. I don't believe that it would be a good idea for Pentax to extrapolate on the 67II design, as there seemed to be more weaknesses in that design than in the previous model. An upgraded 67 with an AE prism like the 67II had, would be a good start. They could keep the existing lenses with only a few upgarades necessary, on lenses like the 45mm, the fisheye and maybe the 600mm. Keeping the cost down would be paramount to selling these, as those who are buying the used 67s now, probably would not want to pay $5000 for for a 67III.
Forum: Pentax Medium Format 10-04-2021, 02:50 PM  
45mm and 55mm P67/645 Lenses on 645N Camera
Posted By desertscape
Replies: 5
Views: 752
Be aware that the 45mm for the 67 has some mustache distortion that gets worse as your get closer to the edge of the frame. Even though it is not the sharpest lens in the 67 lineup, it is not a dog either. The distortion becomes bothersome if shooting a seascape or any other subject with straight lines near the edge of the field. It may come down to price as to which 45 is for you.
Forum: Pentax Medium Format 08-31-2021, 08:09 PM  
Post your medium format photos!
Posted By desertscape
Replies: 19,024
Views: 2,995,068
Thanks Ed and Barondla! I've been shooting lightning for 27 years now with the 6x7 and I have some successes, with some being published.
Forum: Pentax Medium Format 08-31-2021, 04:48 PM  
Post your medium format photos!
Posted By desertscape
Replies: 19,024
Views: 2,995,068
From last July-- A monsoon storm over Tucson, Arizona. Pentax 6x7, 300 EDIF, Velvia 100.
Forum: Pentax Medium Format 08-28-2021, 04:33 PM  
Looking for Pentax 6x7 lens diagrams in a brochure
Posted By desertscape
Replies: 11
Views: 818
What you are looking for, looks like this. It is a user's manual. This one has the older lens cross sections, including the 800 f/4. This one is from the end of 1988. It came with my new camera.
Forum: Pentax Medium Format 07-26-2021, 12:28 PM  
Pentax 67 and extension tubes
Posted By desertscape
Replies: 4
Views: 875
Also, if you ever use the helicoid extension tube, remember that it is not an auto tube and has to be used in the fully manual mode, with metering and shooting stopped down. Using the auto tubes along with the helicoid tubes, one must treat it as if it were just like using the helicoid alone.
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