benoit_sauzier1

<p>Well, maybe it does not work for wide angles, but my 55 f2.8 micro Nikkor front element measures approx 19mm, 105mm f2.5 measures 43mm, 180mm f 2.8 measures 66mm... Are you telling me that the front element of a 600 mm f4 does not measure 150mm? Or that the front element of a 300 f2.8 does not measure 107mm? </p>

<p>The question was: "I want to know is what is the initial max f-stop value on a reversed lens." So, the answer is the one I have provided in my previous post. Now, to figure out what the effective aperture is at a given working distance, magnification has to be taken into acount.</p>

<p>Let's start with the basics: f-stop = focal length/ D, where D is the diameter of the front element. So, for a Nikon 28mm f2.8, the front element diameter is 28/2.8=10mm. You can verify that for yourself. So, if you want to know what the initial max f-stop is when the lens is mounted in reverse, then just measure the diameter of the rear element, and divide the focal length by that number, in millimeters of course!</p>

<p>Ray,<br>

Even without the CC filter I think that you still need to compensate 1/3 stop. The 2.5G filter will absorb less than 1/3 of a stop. Also, take a look at velvia 100 compensation chart. You will notice that as the time increases, the recommended CC filter remains the same, but the film still needs a little bit of exposure compensation. Keep in mind that a 2.5 CC filter strength is the mildest of them all, and 1/3 of a stop is also a tiny amount. </p>

<p>I have two questions about exposing Ilford SFX 200 correctly:<br /> 1. Does anybody know if it is ok to apply Ilford's standard reciprocity curve to SFX 200? Ilford's spec sheet does not mention anything about reciprocity failure for this film, and if I contact them, I feel that I am likely to get a vague answer like "bracket + - 2 stops".<br /> 2. I am planning to use this film with a deep red 89B filter. From Ilford's spec sheet, the applicable filter factor is four stops. Fine! Elsewhere in the spec sheet they state that the correct exposure under bright sunshine is 1/30 s at f5.6 with the 89B filter. Now, if I "remove" the filter, and add four stops, I come up with an exposure of 1/250s at f8.0, and yet sunny 16 rule for a 200 iso film is 1/250 at f16. So basically the film would be over-exposed by two stops. What am I missing? Can someone enlighten me about this please? I intend to use an external meter and add the filter factor afterwards, no ttl metering involved here.<br /> Thank you!</p>

<p>Before wasting a film, try to fire the shutter by keeping the back open, and looking through the lens will of course confirm its operation.<br>

Best<br>

Benoit Sauzier</p>

If both patches in the viewfinder coincide exactly with each other when your 150mm lens is set at infinity as you describe, then it sounds

like your rangefinder is properly calibrated. The focusing ring displacement between the 30ft and 50ft marks is too short for you to obtain a

reliable reading with your test. If you want to perform that test, use a focusing screen on the film rails with the back open. Focus on an

object with the rangefinder, and then double check against the ground glass through the lens (wide open). If you need to refocus while you

are looking through the ground glass, then you will have a pretty good indication by how much you are off on the lens barrel. You can also

set the camera on a tripod, set the lens at its minimum focusing distance, and focus on a wall by moving the tripod in and out. Then

measure the distance between the wall and the film plane (which you can guess to within a mm), and hopefully you should read exactly

1.80m. Yes, all the lenses for the Mamiya 7 should focus at infinity, and not past infinity which is total nonsense.

Start by making yourself a focusing screen to fit on the film rail at the back of your M7. Cut a piece of clear plastic from a CD case for

example, and line it up with frosted tape on one side. Your target could be two pencils, placed vertically, one at approximately 1.2m from

the lens, and the second one just a bit further away. (2m for your 150mm lens). With your camera mounted on your pano rig, open the

back, set the shutter on B, and keep it open with a cable release when you are ready to do your measurements. Focus on your target

through the lens with your home made focusing screen, and then rotate the camera back and forth on its pano head and observe the

relative movement of your two objects as you do so. Adjust the camera either forward or backward, and repeat the exercise until there is

no relative movement between your two objects. A small loupe such as the ones use to view slides might help to look at the image on

your focusing screen. You will also discover that the exact pivot point can be off by one or two millimeters without any noticable effect.

Furthermore, your actual subject is likely to be at a much greater distance that the one or two meters you used for calibration, hence

minimising the effect of the pivot point error.

Hi Frederica,

 

The postcard picture you are looking for is on an island called La Digue, at a place called

Source d'Argent on the west coast, not far from where the boat will drop you . La Digue is

tiny, and all the photogenic places are along its western coastline, so you can basically

visit all the places on foot in a few hours. It is also ok to shoot at around 10am, the

colours will be very bright then. If you don't want to stay overnight in La Digue, you can

easily go for day trips from Praslin island. Praslin deserves at least a few days. Anse Lazio

beach on the north is a must. Also Vallée de Mai is impressive with its unique coco de mer

trees. If you are lucky, you might catch a glimpse of the Seychelles Black Parrot which lives

there, and nowhere else on earth! On Praslin I am sure that you can arrange for a taxi to

drive you around. On Mahé, the places you should not miss are Belle Ombre, Beau Vallon

beach, Port Glaud, Anse Royale, and Cascade. And there will be a lot of interesting things

in between!!! Keep in mind that Praslin and La Digue beaches are more spectacular than

Mahé. If you like seabirds, you could arrange a visit to some of the sanctuaries on Cousin

island, and Aride island. Both are accessible from Praslin.

Enjoy your trip, and please show us some pictures when you are back!

What the B&H description mean is that if you have the GL402, you can use the RA 402 with

the PRO, you don't need to buy the RA 401 instead. But you definitely need either the RA 401

or RA 402 to make the electrical connection between the grip and camera body.

If you bought the GL 401 left hand grip new, then the RA401 adapter should have been

included. If not, then just do a search for mamiya ra 401, and you will find different sources

where you could buy it from. You obviously need to connect the grip to the body if you want

to use the grip trigger switch.

With the camera set to AE/AEL mode, what happens when you close down the lens via the

aperture ring? What happens when you set the film speed dial to a low iso setting? What

happens when you put your hand in front of the meter window? Have you opened the curtain?

Have you tried cleaning the lens contacts with a pencil eraser? Make sure that the contacts

are clean on the camera side also.

If a regular grad nd filter is flipped to try and reproduce the effect of a reverse grad, then

some of the image forming rays will pass through the filter, the rest won't. This will produce

a dark line across the image at the filter boundary. For sunrise and sunset shots, a three stop

filter might be more appropriate than a two stop.

I cannot tell you where to buy, but I can only tell you who my favorite dealers are, in no order

of preference: Megapearls in Japan who have been supplying me the new Fuji Velvia 50 since

April or May this year, Robert White in England, B&H in NYC, Freestyle in California, and

Calumet in the Midwest. All are professional, reliable, and a pleasure to do business with. I

always choose the Post Office as my carrier for shipping into Canada, and I never had any

issue with X-rays. If I had to worry about film damage in transit, it would be more to do

about heat on a sunny summer day, while the film is the delivery truck. But again, this is a

non issue.

I shot a roll of 120 recently, bought from Megapearls in Japan. The stuff is great, but I still

feel that Velvia 100 is a touch smoother, and ever so slightly less saturated than the new 50.

I also tried pushing Velvia 100 by 1 stop, (shot at iso 200) and the results are amazing. No

grain, no noticable increase in contrast and still great saturation. With Velvia 100 and new 50

I am sitting in film heaven!!!

You don't need the full Gimbal support for that lens, the Sidekick at a fraction of the price will

do just fine, and will make a world of a difference compared to using just a ball head. The

beauty of the Sidekick is that you can buy it later when you have the funds, but make sure

that it will mate to the ball head you choose now. I use the Sidekick with a 600mm F5.6, and I

must admit that it is the best photo accessory I ever bought so far, in terms of price vs

usefulness.

Hi Pete,

 

I checked my 300mm ULD, and the IR index looks to be at exactly the same place as the dot shown in your picture.

 

Benoit Sauzier

Well, although my Mamiya 7II instruction booklet states on page 33 that filter compensation in AE or manual mode can be accomplished using the exposure compensation dial, it does not work in practice. Here is a quick test I just performed on my camera loaded with film: I set the multiple exposure button to Multi, kept the lens cap on, set the aperture dial to f22, set the speed dial to 1/2 second, and kept the compensation dial to zero, just to make sure I could hear the 1/2 second sound interval of the shutter opening and closing. I then set the compensation dial to +2, so I should have heard two clicks at a two second interval? Except that I still had the 1/2 second shutter click interval... No change! Same thing when setting the comp dial to -2, no change in shutter click interval.

 

If the camera is not loaded, the experiment can be performed with the back open, lens cap removed, and aperture set to the maximum for better visibility of the shutter opening and closing.

 

So as far as I am concerned, the exposure compensation dial has no effect when the camera is in manual mode, regardless of what is stated in the instruction booklet.