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Photo Forum / Film Photography / Medium format / July 2006auto focus mf camera
What cameras are there in the Medium Format that are auto focus.I was at camera store today and could not find one. Anyone have any suggestions for a auto focus MF camera? Don > What cameras are there in the Medium Format that are auto focus.I was at > camera store today and could not find one. Anyone have any suggestions for > a > auto focus MF camera? The Contax 645 has AF. Many of the rangefinders like the Fuji have AF.  SignatureTom Thackrey www.creative-light.com tom (at) creative (dash) light (dot) com do NOT send email to jamesbutler@willglen.net (it's reserved for spammers) > What cameras are there in the Medium Format that are auto focus.I was at > camera store today and could not find one. Anyone have any suggestions for a > auto focus MF camera? I can think of 5 off hand. The claim is that the Hasselblad H1 is the best/fastest. It's a tad pricey. I'd guess that it has the best glass. Other options include the Pentax, Mamiya, and Contax. The Pentax is probably the most reasonably priced. The Contax glass may be the best of the three, although the reviews I've seen say there isn't much difference. There's an AF version of the Rollei 6008, although AF lenses are in short supply. I don't know about the Pentax, but all the other cameras have limited choices for AF lenses. I'd personally lean towards the Pentax. Observing the landscape magazines in Japan, the Pentax is clearly the 645 camera of choice for landscape photography here. All are glacially slow compared to the cheapest Canon Rebel 35mm film camera. If you really need AF, you probably don't really need MF. Get the Canon 300D for your sports, kids, available light work, and a manual focus MF for quality work. David J. Littleboy Tokyo, Japan do a google on the words: autofocus camera 645 denny > What cameras are there in the Medium Format that are auto focus.I was at > camera store today and could not find one. Anyone have any suggestions for a > auto focus MF camera? > > Don I own a Fuji GA645Zi. This is a very nice AF/MFcamera w/zoom lens; it takes wonderful MF pictures. It is light weight and makes for a good walking around/travel/vacation camera. One drawback is it has a slow lens 4.5-6.9 at 55mm-90mm focal length. I use mine mostly outdoors but it does have a built in flash. The prices have been coming down on these in the used market. Regards, Gary I think the major benefit of AF for many of us using MF would be confirming focus, esp. for low constrast scenes and wide angle lenses? Rather than buying new AF bodies and all new AF lenses, I would like to find a means to modify a prism or chimney finder to indicate in-focus or not using LEDs or whatever. One of the pentax transitional 35mm SLRs ( ME-F, IIRC?) was an intermediate design with focus confirmation but w/o AF mount or lens control interface. The lights in the prism indicated in or out of focus. Has anyone experimented with a focus indication module to see if these can be reworked for standalone use (e.g., Nikon Multi-CAM530 autofocus module etc.)? Perhaps a simpler sensor from a low cost P&S unit could be used too? thanks for any ideas or pointers and tips ;-) bobm PS see http://medfmt.8k.com/third/af.html AF problems pages - to see many reasons why AF is not always a great solution to many photo problems ;-) Signature*********************************************************************** * Robert Monaghan POB 752182 Southern Methodist Univ. Dallas Tx 75275 * ********************Standard Disclaimers Apply************************* > I would like to > find a means to modify a prism or chimney finder to indicate in-focus or > not using LEDs or whatever. You mean that even with the chimney-finder, you can't (sometimes) focus correctly? Or is it just some technical experiment that you would like to do? A single AF-sensor would just use the center of the image, so what's wrong with good old split-image or microprisms? much simpler and it gives the same info... Your best bet could be to check out how the Nikon F3af works, it looks like a normal F3 but with a different finder. But I don't know if the body or the finder has the AF-sensor in it... both parts are different from a normal F3. Lourens yes, there are conditions where using ultrawides or in low contrast or lighting situations where focusing becomes more problematic ;-) The early ME-F and F3-AF you cited are probably examples of the simplest sensors and electronics, as they were for the early systems (but performance may not be as good as currently possible?). At worst, it might be feasible to take a P&S and use the electronics modules from them. Sadly, I don't have access to camera repair tech magazines, so I don't have the direct info I would need to scope out which modules would be the simplest to modify/use? You don't have to use on-axis light or the center point; the old vivitar AF lenses (200mm f/3.5 AF) provided autofocus using internal electronics and motors and batteries in the lens, not the camera body. They used off axis lighting to do the AF sensing. But yes, it would be interesting to see if there is a simple module such as those for Nikon I cited (not so simple, as they use multi-sensor points etc.), which could be easily adapted to a chimney finder or prism module. Just power and LEDs, ignore the motor control outputs etc.? Then again, if I wait a bit, perhaps Kiev folks will come out with this kind of prism too - they just delivered on the spotmeter variant ;-) grins bobm Signature*********************************************************************** * Robert Monaghan POB 752182 Southern Methodist Univ. Dallas Tx 75275 * ********************Standard Disclaimers Apply************************* > I think the major benefit of AF for many of us using MF would be > confirming focus, esp. for low constrast scenes and wide angle lenses? > Rather than buying new AF bodies and all new AF lenses, I would like to > find a means to modify a prism or chimney finder to indicate in-focus or > not using LEDs or whatever. The Rollei 6008AF does indicate focus confirmation on many of the manual focus lenses. I have not tried one, so I have no comments on how well that works (or not). > One of the pentax transitional 35mm SLRs ( ME-F, IIRC?) was an > intermediate design with focus confirmation but w/o AF mount or lens [quoted text clipped - 4 lines] > module etc.)? Perhaps a simpler sensor from a low cost P&S unit could be > used too? One weird idea is to use the module from a Polaroid SX70. These are sonar autofocus, but they have a simple mechanical drive to move the lens. Perhaps a rework of one could be rigged. The device is easy to remove from the SX70. Ciao! Gordon Moat Alliance Graphique Studio <http://www.allgstudio.com Hi Gordon, that's an idea; you can buy a stand-alone module for distance measuring, but the SX70 setup uses sound traveling time/2 to estimate the distance setting. Bit tricky if you wanted to focus on the middle person in a line, say, since the return would be from the first one? ;-) I do suspect that there are some modest cost replacement part AF sensor modules out there which could be remounted with simple power setup and diode LED readouts to provide in and out of focus signals using contrast differentials directly. Why bother, some ask? Because it would be a lot cheaper than investing in an AF kit in medium format just 'cuz our eyes are getting older and less flexible ;-) I guess I will try asking on the camera fix mailing list to see if any of the repair techs can suggest a likely candidate module, perhaps one with only one AF sensor point for simplicity to start. ;-) grins bobm Signature*********************************************************************** * Robert Monaghan POB 752182 Southern Methodist Univ. Dallas Tx 75275 * ********************Standard Disclaimers Apply************************* > Why bother, some ask? Well, wide angle lenses really are hard to focus... > Because it would be a lot cheaper than investing in > an AF kit in medium format just 'cuz our eyes are getting older and less > flexible ;-) You should be able to adjust your viewfinder diopter + glasses combination so that you can focus on the screen. YMMV, but I find that even with glasses, adjusting the diopter setting is both important and helps a lot, at least with faster longer lenses. I have varifocal glasses, so I have to be sure to always use the same section of the glasses for viewing. David J. Littleboy Tokyo, Japan Hi, Recently, Bob Monaghan <rmonagha@engr.smu.edu> posted: > Why bother, some ask? Because it would be a lot cheaper than > investing in an AF kit in medium format just 'cuz our eyes are > getting older and less flexible ;-) I must admit to eagerly awaiting the justification for such a device! ;-) None the less, I'm curious as to how you'll couple it to the focus mechanism in a meaningful way. I suspect that when the built-in loupe fails me, it's time to sell. 8-) Neil my goal isn't to create an autofocus system which somehow focuses manual lenses; I can do a good job of moving the lens focus ring myself, but it would be nice to have an "in-focus" indicator, esp. with some wide angle lenses which are harder to focus by eye. I use diopters now, including the adjustable ones in some prisms and chimney finders, but there are other issues (astig. etc.). A really accurate in-focus indicator with a good null indicator would be quite useful (more so than the In-focus lights in some some systems which are on over a very wide range of distances ;-) according to one source, the AF module splits light at two angles onto two contrast sensors which go to a comparator. As you bring the image into focus by manually focusing the lens, the differences become smaller until they are minimal and you get an in-focus indication. You could go to an LED set to detect the null point of "in-focus", or use a small analog meter or whatever you prefer ;-) Depending on the sensor size and design, you could mount it at/under the ground glass screen or prism and supply power and wiring to the indicator setup. They did something like this to the pentax ME-F. The trick is going to be getting info on the AF sensor and a repair parts source for it ;-) regards bobm Signature*********************************************************************** * Robert Monaghan POB 752182 Southern Methodist Univ. Dallas Tx 75275 * ********************Standard Disclaimers Apply************************* > according to one source, the AF module splits light at two angles onto two > contrast sensors which go to a comparator. As you bring the image into [quoted text clipped - 6 lines] > the pentax ME-F. The trick is going to be getting info on the AF sensor > and a repair parts source for it ;-) That would be pretty cool. I suppose an earphone jack would retrofit better than a meter. If you can express contrast as a frequency, the beat tones would probably be the most direct feedback you can get. Moving scenery would make pretty interesting music while you twiddle. :-) yes, that's a neat trick too ;-) You can use the null indicator output voltage to control a Voltage to Frequency converter chip and listen for the lowest frequency as the precise in-focus point ;-) Much more accurate than the go/no-go LED in-focus indicators in most cameras ;-) You can also make use of stereo headphones by using bipolar +/- output, so as you focus from far to in-focus to nearer points, the tone goes from hi to very low in say left headphone, then starts up from low to high on the right side headphone, so you always know which way to turn the focus. When the focus is exactly right, the frequency would be equally low in both ears ;-) Null devices are fun (I'm resurrecting an old heathkit LCR bridge using such a setup now in my garage, nifty ;-)... grins bobm Signature*********************************************************************** * Robert Monaghan POB 752182 Southern Methodist Univ. Dallas Tx 75275 * ********************Standard Disclaimers Apply************************* Recently, Bob Monaghan <rmonagha@engr.smu.edu> posted: > according to one source, the AF module splits light at two angles > onto two contrast sensors which go to a comparator. As you bring the [quoted text clipped - 7 lines] > trick is going to be getting info on the AF sensor and a repair parts > source for it ;-) This project would present some interesting challenges, anyway. I can imagine a finder with a hinged, angled sensor platform that would move in a similar way to the eye-level sports finder on Rollei TLRs. It would probably be cheaper to buy an AF camera than try to make this work right, but what fun would that be? ;-) Neil > Recently, Bob Monaghan <rmonagha@engr.smu.edu> posted: > > [quoted text clipped - 18 lines] > > Neil How about an accessory rangefinder? http://www.photoethnography.com/ClassicCameras/finders.html http://www.erikfiss.com/foto/cams/voigtrf/e.html Maybe the easiest way to get one would be to rip it off an old Polaroid pack camera, but then the scale would have to be calibrated somehow. -- Lassi Recently, Lassi Hippel?inen <lahippel@ieee.orgasm-research.invalid> posted: >> Recently, Bob Monaghan <rmonagha@engr.smu.edu> posted: >>> [quoted text clipped - 26 lines] > Polaroid pack camera, but then the scale would have to be calibrated > somehow. The problem that needs to be solved with that approach is that it is uncoupled from the focusing mechanism of the camera. You don't wind up with "focus confirmation", but with "focus information" that has to be manually transferred to the lens via rather ambiguous distance scales. It would make getting eyes in focus a matter of chance! Neil yes, that's very true. The reason for an in-focus indicator is that it eliminates the issues with transferring distance info to the lens. I did find some articles on a stand alone sound based distance measuring device run thru a PIC microcontroller in a Nuts and Volts magazine article from a few years back. But the problem is the range is limited and you still can't be sure that you have the lens properly focused or that the signal is bouncing off the desired subject point. Hence a thru the lens in-focus indicator is needed, which suggests a contrast based AF module grafted onto the finder (i.e., where a split rangefinder screen might be placed?). And most short range active IR AF units are limited to about 20 feet or so, not really useful with a long telephoto lens ;-) I was looking at a junk captiva polaroid SLR last night in the junque box; I picked it up as 6x9cm coverage AF setup (also possible polaroid hacked back for koni omega per one past poster..) with 107mm slow (f11-ish?) lens but it is AF, autoexposure, and an SLR. Hacking it onto a rollfilm back would provide a rather modern (if fixed lens) AF unit (use ND filters or hack the autoexposure module to vary ISO film speeds etc.). But in our case, this is a unit with an AF module that sells for under $50 with the whole camera (mine was $1 at a yard sale). Now if I could just get detailed info on some of these AF modules, this project might be a lot easier ;-) In the meantime, lots of other projects to do too ;-) grins bobm Signature*********************************************************************** * Robert Monaghan POB 752182 Southern Methodist Univ. 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