Luminous Landscape Forum
Equipment & Techniques => Medium Format / Film / Digital Backs – and Large Sensor Photography => Topic started by: awofinden on July 31, 2007, 10:32:05 am
-
Anyone know if you can use the microprism focusing screen for the mamiya 645 afd to aid in manual focusing the af lenses. I find the af to be virtually useless in this camera and would love to have a micro prism screen. Will it mess up the metering?
-
I use the microprism "Type C" focusing screen in my AFD with the AF lenses all the time. I usually manually focus shooting landscape with a P45, mostly. Works fine.
-
I'm using the Type C screen as well for my landscape either my AF or Mf lens. No problems.
-
When using the "type C" screen and a digital back, did you add frame lines (or a mask) for the smaller area, or just get used to it?
Stuart
-
I'll definitely try the type c screen, I really have a hard time focusing the af lenses manually.
-
When using the "type C" screen and a digital back, did you add frame lines (or a mask) for the smaller area, or just get used to it?
Stuart
[a href=\"index.php?act=findpost&pid=131020\"][{POST_SNAPBACK}][/a]
I use a Phase One back. Phase supplies a transparent underlay (i.e. it slips in under the Mamiya screen) which has the 49.1mmX36.8mm area outlined in black. I find it easy to see the outline and it is easy to use. Haven't miss framed yet, but maybe I'm just lucky.
-
I use a Phase One back. Phase supplies a transparent underlay (i.e. it slips in under the Mamiya screen) which has the 49.1mmX36.8mm area outlined in black. I find it easy to see the outline and it is easy to use. Haven't miss framed yet, but maybe I'm just lucky.
[a href=\"index.php?act=findpost&pid=131116\"][{POST_SNAPBACK}][/a]
I wish they had a full blackout of the area that wasn't in the frame, i hate looking at the black lines. When I look through the viewfinder I just want to see whats in my frame.
-
tried to get a custom screen for my afdII and spoke with a specialist...also asked him about the C screen (mamiya says the c screen is recommended for using manual lenses on afd)...he said all can be used, BUT all afd bodies have (more or less) custom screens in specific to their bodies..they all have a certain curvature to them (they are very slightly warped middle to corners) which is not a problem at all as long as the camera is calibrated to THAT screen....so if you are buying a afd, the screen is calibrated for that body....you can change the screen, but the camera has to go in for re-calibration....or you get lucky and it is not an issue....
-
I think that a blacked out area may have an effect on metering especially in averaging mode. The meter sensor is in the finder.
-
tried to get a custom screen for my afdII and spoke with a specialist...also asked him about the C screen (mamiya says the c screen is recommended for using manual lenses on afd)...he said all can be used, BUT all afd bodies have (more or less) custom screens in specific to their bodies..they all have a certain curvature to them (they are very slightly warped middle to corners) which is not a problem at all as long as the camera is calibrated to THAT screen....so if you are buying a afd, the screen is calibrated for that body....you can change the screen, but the camera has to go in for re-calibration....or you get lucky and it is not an issue....
[a href=\"index.php?act=findpost&pid=131280\"][{POST_SNAPBACK}][/a]
Hmm, so does that mean that you could have focus problems when you put in the C screen?
-
tried to get a custom screen for my afdII and spoke with a specialist...also asked him about the C screen (mamiya says the c screen is recommended for using manual lenses on afd)...he said all can be used, BUT all afd bodies have (more or less) custom screens in specific to their bodies..they all have a certain curvature to them (they are very slightly warped middle to corners) which is not a problem at all as long as the camera is calibrated to THAT screen....so if you are buying a afd, the screen is calibrated for that body....you can change the screen, but the camera has to go in for re-calibration....or you get lucky and it is not an issue....
[a href=\"index.php?act=findpost&pid=131280\"][{POST_SNAPBACK}][/a]
This seems strange since Mamiya has for years offered three screen types for AF, AFD, and AFD II. Of course anything can happen but if you look at the hinged screen holder any variations in screen shape could result in random movement by the screen in the holder which would cause out-of-focus conditions both within and between exposures. Furthermore, why woud some camera bodies focus the middle of the image in a different plane than the edges? A lens might (will) do this but how could the camera body?
If i get a chance I will contact the MAC Group to be sure.
-
i am just repeating what i was told.....if the center of one screen is closer to the lens (or further away) then the edges it (or a different screen that might be flatter) rests on, the focus will be off......again: this might be a problem, it might not be....but the slightest fraction would trow focus off by quite a bit....
this is from the guy who made my custom screen for the RZ....which is amazing..i wanted to get one made for the afd as well, but he warned me about this issue and told me that most likely the body would have to go in to have focus adjusted.....
-
i am just repeating what i was told.....if the center of one screen is closer to the lens (or further away) then the edges it (or a different screen that might be flatter) rests on, the focus will be off......again: this might be a problem, it might not be....but the slightest fraction would trow focus off by quite a bit....
this is from the guy who made my custom screen for the RZ....which is amazing..i wanted to get one made for the afd as well, but he warned me about this issue and told me that most likely the body would have to go in to have focus adjusted.....
[a href=\"index.php?act=findpost&pid=131406\"][{POST_SNAPBACK}][/a]
PSS, no chance I would question what you were told. I respect your professionalism and experience in photography. Your source may be correct but until I check this out I will consider it nonsense based on my long carrier in industry and in the business of manufacturing to tolerances.
I don't think there is any way that Mamiya can manufacture and calibrate specific cameras to specific focus screens at the prices at which these cameras sell. Furthermore I can't imagine the exposure to ridicule and disdain, amongst photographers, to which Mamiya would be subjected should the public find out that Mamiya is selling add-on focus screens for use on cameras for which the screens are not calibrated!
I don't know the source of your information and don't really care. he may be right. Or he may be like a friend of mine who for years made replacement parts for a very expensive high-end phonograph turntable. His replacement bearings and other parts were beyond compare. So was his "snake oil" line about the technology and its benefits.
Having said that, I must also say that I have used various after market focus screens for Rolleiflex as well as Mamiya 1000S and 645 Pro cameras with great success. Not because the stock screens were defective but because the after market ones were brighter, easier to focus or both.
Your source may be truthful, he may make great replacements, or none, one or both of these statements. Until I have heared from Mamiya on this topic, and I intend to do just that, I think this is nonsense.
-
jack....i understand your concerns....i have no way of explaining this or even really understanding...the info is straight from bill maxwell, who custom makes some of the best screens for any camera....
i would be interested as well what mamiya has to say about this, but i don't necessarily think they would be completely honest about this....
if you have a minute (or better 45minutes...) give bill a call and ask him about this.....
i don't think this really is an issue for mamiya anyway....they just calibrate every camera as it leaves the factory....and with that screen the calibration will be perfect....
hey maybe i just got it all wrong....but i remember not getting the custom screen for the afd because i did not want to send the camera in...which is what bill warned me i might have to do....
-
Paul,
I have an email request in to MAC Group for clarification. If I don't hear from them in a day or two I'll telephone. I have had good answers and response from them in the past but they have not been very attentive to email requests lately.
I've had calling Bill Maxwell on my to do list to see about a screen that includes a split image as well as microprism. A cataract in my left (dominant) eye has made me focus with my right. Not so easy to get used to, either. Maybe I can kill two birds with one call.
-
Point of information:
Usually AF on SLRs does not involve the screen, the sensor sits below the mirror. Hence a screen issue will create problems with the MF, not AF.
Edmund
Paul,
I have an email request in to MAC Group for clarification. If I don't hear from them in a day or two I'll telephone. I have had good answers and response from them in the past but they have not been very attentive to email requests lately.
I've had calling Bill Maxwell on my to do list to see about a screen that includes a split image as well as microprism. A cataract in my left (dominant) eye has made me focus with my right. Not so easy to get used to, either. Maybe I can kill two birds with one call.
[a href=\"index.php?act=findpost&pid=131537\"][{POST_SNAPBACK}][/a]
-
I agree with Edmund regarding the AF function being located in the body. However, I'm pretty sure the metering function is in the viewfinder housing. Thus, a partially blackened screen around the perimeter might affect metering.
-
I spoke to the U.S. Mamiya Distributor, The MAC Group, today. They confirmed that the focus screens are not made to match a particular body. They are interchangeable between bodies.
Regarding the viewfinder screens for digital backs that provide a border line showing the crop factor, I asked whether blacking-out the area outside the crop line would affect metering. They said that this is not likely to affect spot meterring and probably not average metering either, since the perimeter area is so thin relative to the total area. I would want to test this to determine what if exposure change might occur.
-
I spoke to the U.S. Mamiya Distributor, The MAC Group, today. They confirmed that the focus screens are not made to match a particular body. They are interchangeable between bodies.
Regarding the viewfinder screens for digital backs that provide a border line showing the crop factor, I asked whether blacking-out the area outside the crop line would affect metering. They said that this is not likely to affect spot meterring and probably not average metering either, since the perimeter area is so thin relative to the total area. I would want to test this to determine what if exposure change might occur.
[a href=\"index.php?act=findpost&pid=131943\"][{POST_SNAPBACK}][/a]
I actually have blacked out the outside of the crop lines with a sharpie, very fancy I know. Metering does not seem to be effected. I generally use the meter as a very rough guide at best, I rely on the histogram.
-
So I got a C type microprism and I'm happy to say that it doesn't mess up either the metering or the af and it makes manual focusing loads easier and at 50 dollars its as cheap as chips too.
-
jack....i understand your concerns....i have no way of explaining this or even really understanding...the info is straight from bill maxwell, who custom makes some of the best screens for any camera....
I also spoke to Bill Maxwell a few weeks ago, and he told me the same exact thing. That if you change the screen, you may throw of the AF a bit and you may need to send the body back in for AF recalibration. He indicated the reason was that Mamiya screens had a lot of variation in them (curvature variation). You might get lucky and not need to recalibrate. But then again, you might not be lucky.
To answer another poster, the screens themselves are interchangeable. But that doesn't mean the AF doesn't have to be recalibrated when you change the screen.
I personally don't know what the truth is, but Bill Maxwell is one of the most highly respected suppliers of custom screens, and he certainly knows his stuff.
-
I also spoke to Bill Maxwell a few weeks ago, and he told me the same exact thing. That if you change the screen, you may throw of the AF a bit and you may need to send the body back in for AF recalibration. He indicated the reason was that Mamiya screens had a lot of variation in them (curvature variation). You might get lucky and not need to recalibrate. But then again, you might not be lucky.
To answer another poster, the screens themselves are interchangeable. But that doesn't mean the AF doesn't have to be recalibrated when you change the screen.
I personally don't know what the truth is, but Bill Maxwell is one of the most highly respected suppliers of custom screens, and he certainly knows his stuff.
[a href=\"index.php?act=findpost&pid=0\"][{POST_SNAPBACK}][/a]
personally i trust bill more then what someone at mac or mamiya will say...they won't admit that there are variations in the manufacturing.....i understand that....the question is how often and how much (to which extent) does this actually manifest itself....bill is a stickler for quality and i am sure he can back all this up with data.....
bottom line: one MIGHT have to send the body in for calibration....not the worst thing in the world....i guess it should go in every year or so anyway.....
-
Bill Maxwell may be correct regarding unintended or random differences in the screens. Heat and handling can certainly have its affect on plastic which is what the screens are made from.
However, the original question was whether the screens are made for or tailored to a specfic body. They are not.
That said, after changing my AFD to a Type C screen I did a focus test, i.e. back/front focus and edges/center. I found the replacement screen to be within a mm or so on back/front focus. I wonder if the original screen was as good, as I did not test it!
-
I switched my focus screen shortly after I got the Hartblei and 300 f2.8 and have had no problems with focusing. Actually I’m glad I changed screens as it just appears to be easier whether I’m using AF or MF lens; I find that I’m switching my AF to MF more and more
I had thought about having a custom screen made but since finding the proper way to place the Phase One P30 focus overlay I’ve decided to place that on hold for now.
-
I switched my focus screen shortly after I got the Hartblei and 300 f2.8 and have had no problems with focusing. Actually I’m glad I changed screens as it just appears to be easier whether I’m using AF or MF lens; I find that I’m switching my AF to MF more and more
I had thought about having a custom screen made but since finding the proper way to place the Phase One P30 focus overlay I’ve decided to place that on hold for now.
[a href=\"index.php?act=findpost&pid=132256\"][{POST_SNAPBACK}][/a]
What is the proper way?
-
Place the overlay screen under the focusing screen, i.e. on the mirror side. Maybe it should be called an underlay screen.
-
Place the overlay screen under the focusing screen, i.e. on the mirror side. Maybe it should be called an underlay screen.
[a href=\"index.php?act=findpost&pid=132363\"][{POST_SNAPBACK}][/a]
Are you sure ? I would have thought this would the focusing screen up by one thickness, guaranteeing bad focus.
Edmund
-
During my first two attempts to get the little plastic in I too thought it needed to lay on top of the screen. I never could get everything to line up correctly and then decided what the heck just don’t use it. I posted a question here several weeks ago about getting a custom screen made and it was during that thread that I learned I had been attempting to mount the plastic screen all wrong, so disregarding the instruction I placed the bracket screen first on the metal holder then placed the focusing screen on top of that and closed it. No problems whatsoever this also includes close to 6 hours on a 19’ boat in very choppy waters last week in Lake Powell. If I had to find one gripe about Phase it would be the plastic bracket screen. I had a Kodak Pro Back that had a crop factor but Kodak had an actual focus screen replacement instead on stacking like I currently have to do. But as I said earlier no problems so far …..
don
-
Don is right. If you think about it the metal frame that holds the screen closes and locks, with the screen in place, to a fixed position above the screen holder. The plane of this position, at which the screen stops, is the plane of focus of the viewfinder system. The body is engineered so that this position is at the same focal distance as is the film or sensor plane. So, now when you change a screen and lock the frame into position it will consistently lock the screen against this reference point, i.e. assuming that the frame locks firmly, as it has for me.
Now, if you place the overlay above the focusing screen it will force the screen to a position below the focus point by the amount of the thickness of the overlay screen, i.e. about 1/000 inch. Thus, focus will be changed by 0.0007873 nanochrons. Or , somehthing nearby.
If you feel as I do that this should be termed an underlay screen my only suggestion would be to write your congressman to request that the name be changed.
Thank you for your intrest in this subject!