Mamiya Lens Coating Question.

[snegron]

I noticed that my shots taken with with my RB67, 90mm 3.8C lens, are sharp but they seem to lack color saturation. In other words, they appear bland, as if they were shot with a lens with no coating. The film was Porta 160VC. I also used a Mamiya 645 with a newer 80mm lens (same film) to compare the results. The images shot with my 645 appeared to have more vibrant colors than those shot with my RB.

Could this mean that the lens coating on my 90mm lens has faded? If so, what can I do to correct this? I'm sure I can get great saturated colors if I use a polorizing filter, but I really don't want to have to loose a stop especially when having to shoot in low light situations. Would a multicoated UV filter help? Can the lens be recoated? Would I be better off getting a new lens? I don't have this problem with any of my other lenses for my 645's (I only have this one lens for my RB). Is this what the images from the RB are supposed to look like?

 

[PHOTOTONE]

Coatings don't fade. If your lens is clear and clean it is performing as good as it can. Look thru it at a light bulb, and move the lens around and see if you see any internal haze? If so, this can reduce contrast, and can be professionally cleaned. The 645 lens line is newer and may be designed with more contrast in mind. It is not a coating thing, in my opinion. Adding a multi-coated filter to any lens will not "improve" the lens. A polarizing filter can be used at times to add contrast, by darkening skies, and eliminating reflections on things. I have had and use an RB-67 for almost 30 years now, with the 90, as well as the 50 and 180. I have never felt a lack of contrast in my work with this camera system.

All lenses can be recoated, but normally it is only the front surface of the front element that gets worn, so the cost is moderate...but if you are considering recoating every element in the lens, you are better off just purchasing another good used lens. The lowest cost coating service is Arax in the Ukraine, and he charges about $30 per element, and if your 90 has the average 5 or 6 elements then the cost will be about $200 including shipping. You will have to take the lens apart and just send him the glass elements. he does no disassembly. So you see, you could probably buy another 90mm lens for the same or possibly less.

 

[snegron]

Thanks for the info! Looking at the images shot with the RB, there doesn't appear to be a lack of contrast. The images just seem to lack those vibrant colors seen in images shot with other lenses. The lens appears to be clear of haze, event the front and rear elements have that "purple-ish" reflection that looks like a coated surface.

The images resemble shots taken with a camera from the 1950's; very sharp but dull colors.

 

[Nick Zentena]

Are you comparing the same shots? Or shots taken at different times?

How about a hood? Can't hurt and relatively small price for what it gives.

 

[snegron]

Are you comparing the same shots? Or shots taken at different times?

How about a hood? Can't hurt and relatively small price for what it gives.

Same shots, same times, hood was attatched to lenses on both the RB and the 645. The film was all from the same box as well. I'm going to go out and shoot something today with both cameras and post the images here by the end of next week (hopefully, given developing and scanning times).

 

[MattKing]

There are a lot of variables here that could affect the results.

If you are comparing prints, are you doing the printing, or is it a lab?

In either case, the different formats may mean that different enlarging lenses are being used. If they are machine prints, it may be that different machines are being used. If they are printed by hand at a lab, there may be different operators.

If you are scanning from negative, a whole bunch of variables could be different, based on the differing negative sizes.

Have you tried moderate contrast transparency film (e.g. Ektachrome E100G), viewed on a light box, with a loupe? If you get the rolls processed together, you are much more likely to be able to determine whether it is the camera or lens that is the source of the differences.

Matt

Are you comparing prints? If so, are the prints made in the s

 

[Werner B.]

I shoot with an RZ and a PRO TL. The 645 images are definitely higher in contrast and saturation. The RZ lenses are more neutral than the 645. This may be because of their intended uses. 645 for weddings and RZ/RB for studio. Your lense may be a little flat, there is no way of telling without seeing the proofs. With the RZ I tend to use punchier films. The portra VC is a good choice. If the shots look flat on their own(not beside the 645) Then I would try and borrow or rent a lense to check for a difference.

 

[John Koehrer]

or slight overexposure by a shutter that may be a tad bit slow?

 

[keithwms]

I agree with John ^^^ why not just slightly adjust your exposure. A half-stop change in how you rate the film can have noticeable effects in terms of saturation.

Dumb question just in case! Are you adjusting your RB exposure for bellows factor?

 

[snegron]

I agree with John ^^^ why not just slightly adjust your exposure. A half-stop change in how you rate the film can have noticeable effects in terms of saturation.

Dumb question just in case! Are you adjusting your RB exposure for bellows factor?

Bellows factor?

 

[Nick Zentena]

I don't know about the RB but I guess it's like the RZ. Look at the side of the camera. When you are focussed it'll indicated an exposure compensation factor. If you are always focused at infinitiy or are using a metering prism then it doesn't matter. But if you are using a hand held meter and focussing closely it might.

 

[keithwms]

Nick is right, it's similar to the RZ. On my RB, on the right hand side, you will find a multicoloured chart that tells you the bellows compensation factor for each focal length lens and focusing distance. You'll see 0, +0.5, +1.0. Those are the exposure corrections you need to add, otherwise you'll underexpose. For example +1.0 means add one stop, so you could open up the aperture by one f/stop or double the exposure time... your choice.

You can learn how to use the chart with a little practice. My overall recommendation is to get yourself a polaroid back to practice and to make trial exposures for critical shots. Or just use a PD metering prism finder.

This could definitely be the source of your colour saturation problems. Colour print film would tend to blah pastel without this exposure compensation. And slide film would tend to be too saturated.

 

[snegron]

I have the metered prism on my RB (my RB weighs 7 pounds with it attatched). I don't think it's an exposure problem, all the images are properly exposed. They just look dull and colorless. I was going to post some samples but the lab screwed up my negatives. I will reshoot another experiment next week (I'll use a different lab as well) and post the results here.