RB67 vs Pentax 6x7

[David H. Bebbington]

David, I crawl in the dust before you since youre able to detect the shutter induced vibration through the mirror induced vibration when firing the P67.

Soeren, as I have made clear several times on this thread, my experience of Pentax 67 is limited to using a borrowed example for a relatively short time quite a few years ago, and I certainly never had time to do a lab test.

My remarks were based on the Reichmann website, in particular this part:
QUOTE< Here's another example. With a 300mm lens and 1.4X extender, a shutter speed of 1/10th of a second, and with the camera mounted on a light weight Gitzo 1228 carbon fiber hiking tripod with an Acratech ball head, there is so much shutter-induced vibration that the shot is blurred. This is shown in the frame below and its accompanying enlargement. Please note that this photograph was taken with the mirror locked up and with the use of a cable release! The sharpness destroying vibration is from the large focal plane shutter. A light weight tripod just doesn't cut it with this camera.

By way of explanation, what's happened here is that the shutter has bounced, as all shutters do. So, there have effectively been two exposures. One during the opening of the shutter and the second during the closing, at which point the camera had essentially rung like a bell thus causing the second image.>UNQUOTE

The picture accompanying this text has a double image, both parts of which are of equal intensity and which must therefore have been caused by exposures of roughly equal length. Reichmann talks about shutter bounce, which as far as I am concerned happens only with leaf shutters at high speeds when they open and close correctly and then open again.

Based ONLY on this pictorial evidence (let's be clear, this was obtained with the mirror locked up) and my general experience with many different types of camera, I conclude that this double image was caused by a vibration which was set off when the shutter was released and which lasted around half of the total exposure time (if the shutter had really bounced, which I have never heard of with a focal-plane shutter, the result would have been a normal single image with extra density in a band at one end where the shutter had bounced and the shutter slit had moved back out part-way over the film).

My conclusion about shutter vibration is based on this and this alone - I really cannot imagine any other cause. Purely from an engineering point of view, it is very hard to make a large fp shutter which can approach the vibration level of a leaf shutter, since all the moving parts of a leaf shutter are symmetrical, which means theoretically that any vibration should be self-cancelling. Furthermore, adding a leaf-shutter lens to a camera like a Pentax 67 will give greatly enhanced flash-sync capability but won't cut vibration unless it is possible to close the leaf shutter, fire the fp shutter on T, wait for vibration to die down and then take the picture with the leaf shutter only.

In general, it appears that the vibration characteristics of the Pentax 67 have improved over the years - as I understand it, the original model had no mirror lock-up, this feature was then added, and then a Mark II eventually appeared. If somebody with extensive hands-on experience of Pentax 67 is telling me they get sharp pictures, I of course believe them without question - if on the other hand, I see evidence such as that on the Michael Reichmann site, my explanation is as stated above. I hope it is clear that this is all I am saying!

Regards,

David

 

[Charles Webb]

I have owned and used both extensively. I have had very little problems with either the RB's or the Pentax's. I personally prefer the Pentax, but either camera will do a fine job.

I have over come any need for interchangable backs as I normally use three cameras set up with different lenses or film. Works for me!

A short time back I purchased a minty Pentax simply for a spare body, now have four that can go to work at any time. I have never seen better lenses than those available for the Pentax therefor I recomend it very highly.

The RB's simply are not designed to fit me or my hands, so I suggest
handeling both before making a decision.


Charlie......................................

 

[wirehead]

RB's are designed to fit my hands. I hold it in the palm, put one finger on the shutter release and put my thumb on the focusing knob.

But, then again, I have big hands.

 

[ineffablething]

I vote for the Pentax 67. I have had two of them and they have performed flawlessly for years. The lenses I have 75mm 2.8, 105mm,165mm,150mm soft, and the 300 are all top performers and have better "bokeh" than my SL66 lenses. I tested the Pentax lenses against Hasselblad and Mamiya RZ/RB lenses before I chose the Pentax. I really just preferred the way the Pentax lenses rendered my subjects. Plus, the Pentax fits the way I shoot. I basically use the camera as a glorified 35mm for portraiture and landscapes. I shoot handheld 80% of the time. If I am concerned about sharpness when shooting at 1/60 or lower, I bring out the tripod. I never cared too much about separate film backs because I typically shoot a whole roll of 220 in about 5 minutes anyway.

 

[temujin]

have you also considered the bronica gs-1? i researched 6x7 cameras a bit before buying my bronica, and have been extremely happy with it. everything i heard about shutter vibration on the pentax turned me off to that. the bronica has leaf shutter and excellent lenses, and is a bit smaller than the mamiya. and alot of the bronica gear goes cheap nowadays. however, it doesnt have rotating backs.

 

[Steve Smith]

RB67 Pro SD - Christmas present to myself!

I can't comment on the Pentax 6x7 having never been anywhere near one but yesterday I received a Mamiya RB67 Pro SD in the post. (My christmas present to myself!).

From my limited playing around with it in the house, I was quite surprised at how easily I could hand hold it. It may get a bit tiring over time though.
I was also surprised at how quiet the mirror mechanism was compared to the noise my Bronica ETRS makes.

Hopefully the RB67 will eliminate some of the dilemnas I have with tye ETRS i.e. I prefer using the waist level finder to the prism but I find that 75% of the pictures I take are in the vertical format. The rotating back makes this easy.

The camera has come from the West Yorkshire Police photographic department and has not seen the heavy use that a camera in a pro portrait studio would. In fact, the second film back does not appear to have been used. It still has the manufacturer's label in the film label holder on the back.

It came with two backs, 50mm and 90mm lenses, UV filters on both and rubber lens hoods for both lenses and they put in twenty rolls of Fuji 160 ISO negative film for free.

If anyone is interested, they may still have a couple left. Details here: http://www.therightimage.biz/specials.html

Steve

 

[max_ebb]

<<4. I've shot with 67s for many years and never had one fail.>>

Either you're very lucky or I'm very unlucky. I've owned three of the 67s and each has suffered the dreaded fozen advance-lever problem ...including a P67II bought brand new ($350 repair bill). Yes, the lenses are sharp and the vibration issues are over-stated (and easily gotten around) but in my opinion the cameras are an engineering disaster. I'd recommend anyone staying away from them.

Sorry, but that's from my own expensive, unfortunate and truly miserable experience with them...

What was the specific cause of this 'dreaded fozen advance-lever problem' you're referring? On any of the times you had the problem, did you try taking the battery out? To my knowledge (and in my experience), what causes the advance lever to freeze up is that the mirror hangs and doesn't drop back down all the way. I've only had it happen a couple times out of thousands of shots (both times it was when I was doing multiple exposures with the 90mm LS lense in cool weather with a battery that was getting low). When this happens, all you have to do is take the battery out and the mirror will drop down the rest of the way (fixing the problem). I have since found out that there is a tiny little reset button on the front of the camera that does the same thing as taking the battery out. If this is the problem you had, you got ripped off big time paying $350 (or any amount for that matter) for a repair that you could have easily done yourself by taking the battery out or using the reset button.

As far as shutter vibration goes, I have never had any problems with it. I use a heavy duty tripod, and always use MLU for slow shutter speeds (and/or when using macro tubes). I don't have any lenses longer than 165, but I do a lot of macro work (using all three tubes together giving magnification higher than 1:1) where camera stability is just as much of an issue as it is with long lenses.

I also used an RB for a about a year and a half. IMO, pentax lenses are sharper than mamiya lenses, and they're also substantially faster than comparitively priced mamiya lenses. Everybody's requirements are different. I have no need for multiple or revolving film backs. For me, P67 beats RB67 hands down (because of lens quality). I also considered (briefly) the Bronica GS, but I had a Bronica SQA for a while, and I was less than impressed with the sharpness of Bronica lenses.

Also, leaf shutters give slightly more exposure to the center than they do to the outside. FP shutters insure that every part of the frame gets the exact same exposure.

 

[paul ewins]

Max, the usual point of failure on the older (non MLU) bodies is a stripped gear in the winding mechanism. This was beefed up when MLU was added and possibly again when the 67II was introduced. Because of these changes you can't get spares for the non MLU models and anyone of those with a winding issue is unrepairable. I know, I've tried, and ended up with a couple of nice bookends.

I've got a MLU 6x7 and a 67 and both of these are just fine. The 6x7 is heavily scarred and most of the MLU 6x7s and even 67s you see on eBay have had a lot of use yet are still working. Most of these are more than 20 years old and have been used profesionally for most of that time so there doesn't seem to be any inherent weakness in them.

One tip I have read is that your winding action should be smooth, not jerky. Putting a lot of torque through the mechanism with a 5fps thumb is not a good idea. When you are working hand held it is tempting to treat it like a 35mm SLR, but you are trying to move four times as much film for each frame, plus paper backing, so there is a lot more force involved.

 

[max_ebb]

Max, the usual point of failure on the older (non MLU) bodies is a stripped gear in the winding mechanism. This was beefed up when MLU was added and possibly again when the 67II was introduced. Because of these changes you can't get spares for the non MLU models and anyone of those with a winding issue is unrepairable. I know, I've tried, and ended up with a couple of nice bookends.

Yeah, I've heard about the winding mechanism problem (stripped gear). It's my understanding that it was fairly common with the pre-MLU models that were heavily used. It's also my understanding that it's very rare for the MLU models, and is caused by people being overly forceful with the winding lever (combined with heavy use).

The much more common cause of the winding lever locking up is the mirror not dropping back down all the way (hangs about half way in between). As I said, it's happened to me twice. It ruins one frame, but it's easily fixed by removing the battery or pressing the reset button (I haven't had it happen since I learned about the reset button, but from what I read, pressing the reset button does the same thing as taking the battery out).

When you are working hand held it is tempting to treat it like a 35mm SLR, but you are trying to move four times as much film for each frame, plus paper backing, so there is a lot more force involved.

Well, when you think about it, there really isn't much load on the winding lever to advance the film (consider the first 4 lever movements when you first load new film before the shutter cocks). The real load comes from cocking the shutter. The sutter spring mechanism is much stiffer than with 35mm shutters. My guess is that the load of cocking the shutter is what caused gears to strip in the older models. I agree with using a smooth motion though. I always use a smooth motion (not slamming it) when cocking the shutter/advancing the film.

 

[max_ebb]

After thinking about it, I wonder how many of the stripped gear problems with the film advance mechanisms happened because the mirror hung up (not dropping down all the way), and the user tried to force the advance lever out of frustration/desperation, and stripped the gear in the process.

Hmm, ya gotta wonder.