Disassembly of the Maxxum 35-70mm f/4 for Repair Photo Gallery by Pete Ganzel at pbase.com

Disassembly of the Maxxum 35-70mm f/4 for Repair

This unique little lens has a few tricks up it's sleeve. It was made as a companion to the excellent 70-210f/4 and at the time (1985)
must have been conceived as a zooming replacement for a 50mm normal lens.
The central zoom body is a machined metal die casting. The rear element of the front group is a hybrid aspheric, the first of it's kind in a production zoom lens.
The focus helicoid has a beautifully machined aluminum outer portion mated with a plastic lens cell.

The floating rear group houses the aperture which is occasionally contaminated with lubricant, requiring disassembly.

35-70-4_Page_01.jpg	35-70-4 7.jpg	Front Trim remove 001.jpg	Front Element Ring 0007.jpg
Front Tube Replace 0066.jpg	Front Tube align 0069.jpg	Marking Tube notch 0064.jpg	Front Tube Removed 0062.jpg
Front Element Group 0041.jpg	Contact Board 0060.jpg	Ground Spring 0058.jpg	ROMFlex 0054.jpg
Removing Mount 0052.jpg	Iris Actuator 0045.jpg	Aperture Actuator Train 0005.jpg	Trim Ring Screws 031.jpg
Trim Ring Removal 0028.jpg	Grip Removal 43.jpg	Encoder Wiper 0042.jpg	Macro Switch 0039.jpg
Macro Switch Spring 0033.jpg	Macro spring 032.jpg	Zoom Screw 0024.jpg	Zoom Ring Removal 0026.jpg
Marking Casting 0010.jpg	Zoom Body Removal 0023.jpg	Zoom Cam Screws 0021.jpg	Rear Group Remove-Insert 022.jpg
Iris Pin 0001.jpg	Rear Group Disassembly.jpg	Rear Group front half 0006.jpg	Iris Blade arrangement 036.jpg
Iris Reassembled 0037.jpg	AF Drive Gear 0044.jpg	Reglue Macro Switch 0035.jpg	Aperture Actuator 0051.jpg
Focus Ring Gear 0014.jpg	Front Trim Replace 0009.jpg

comment |

Guest		12-Apr-2024 17:21
Do you have to disassemble all the front to get at the pasture in the back I have slow blades but no sign of oil thanks

Nise		21-Jan-2018 13:58
A tricky lens indeed, thanks for the help.

Vincenzo		12-Jul-2017 23:36
Wonderful jib! Thank you very much!

Patrick		30-Nov-2014 22:17
Thank you very much for this step-by-step guide! My aged 35-70 4.0 suffered from a slowly closing automatic diaphragm without any lubricant visible on the blades. To find the problem and maybe fix it I tried the surgery. It came out that only the thin gap between the gear linkage disk and the apperture retainer was contaminated with oil, the blades themselves where dry. So I cleaned the outer edge of the disk and the outer rim of the retainer with a dry cloth, reassembled the lens and lo and behold: The apperture is as fast as in factory state again! Upon reassembly I activated AF in macro mode by covering with tesafilm the inner two circuit paths at the end near the ribbon cable (the parallel two of nearly equal length): Works perfectly except for the fact, that the focal length transmitted in macro mode is 60 instead of 70 mm. Greetings from Germany, Patrick P.S. By unscrewing the focus helicoid in the leftmost macro position to the maximum while being connected to the front tube it is possible to achieve a magnification of 1:3! But with the disadvantage in normal mode of not beeing able to focus on infinity and also limit the range of focal length to 45-70...

Tim		10-May-2011 14:55
Has anyone had a problem with re-installing the front tube? I lined up the knoches and it went in but, it is not locking in with the front element. Even after installing the front element ring. Hence not focusing at all. What is it that locks that tube in place after replacing it in the body?

Guest		31-Mar-2010 19:33
Purchased a faulty copy of this lens. Refunded in full and told to keep it. So... the fault appears to be the autofocus motor.. Camera is constantly showing MF. Cosmetically no sign of wear or abuse. I intend to disassemble as I have nothing to lose. Your pics and diagrams are a fantastic help. Waiting for a full day free from distraction. Any advice? Initial hook-up of the lens and the motor definately sounded for one picture but seems stuck on infinity. Manual zoom seems to work after a fashion! Thank you.

Neil		23-Mar-2010 04:22
Hello Pete, after purchasing this lens on line, found it had oily aperture blades. After a complete dis-assembly, I cleaned the blades and retainer as suggested. Re-assembled and found the aperture action still extremely dampened. Completely dis-assembled the lens again and removed the rear group and aperture assembly. This time, I discovered the small channel which runs the inside diameter of the front half of the rear group makes an excellent collection area for lubricant that has seeped into the aperture assembly. If this channel is not cleaned at the same time the blades are, when the blades and retainer are mated back to the front half of the rear group, the lubricant in the channel attaches with the outer diameter of the metal retainer which dampens the rotational action of it. I would suspect this to be the case for those folks who report slow aperture action but do not display the signs of oily blades. Thanks for your great site!

Gene		19-Feb-2010 19:59
Hi Pete, I have a MinO 35mm f1.4 which (sometimes) has a rough and/or stiff focus ring at some point during manual focusing-it's like catching on something. Same happens when auto focusing - it's a little bit hesitant to get in focus. Any word of wisdom on my plan to disassemble this lens to find what might causing the problem? Thanks Much - Gene

Michel Vos		14-Oct-2009 18:01
This works great. I had one with oily blades but now it works perfect. I cleaned the blades with terpentine and that worked very well. The thing is that you must realign the from part with the front tube correctly otherwise you might not be able to focus to infinity. This is a nice little lens for a full frame.

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