Questions about Fujinon W 250/6.7 lens

[benrains]

This is aimed at those of you who currently own this lens and use it for 8x10 work.

Recently I was fortunate enough to pick up a clean example of this lens, but its sharpness isn't quite up to my expectations and experience with other Fujinon lenses. For a few years I've had and used a newer 250/6.3 variant of the same lens for my 4x5 work, and I've even shot successfully with it on my 8x10 as long as I don't use any movements. Given the favorable reputation of the 250/6.7, with it's larger image circle, it seemed like a no-brainer to go that route.

But when I compare the image on the ground glass of the 250/6.7 with that of the 250/6.3, the 6.3 is much much sharper than that of the 6.7 lens with the aperture opened wide. And though the 6.7 is improves when I stop down to f/22, toward the outer edges of the ground glass the image still looks a slightly "mushy" when I compare it to my 6.3 lens at the same aperture. I'm not sure if this is normal--because it is a slightly early design of the lens--or whether I've just got a not so great example of the lens. Physically the lens is in very good condition; there's no separation or any sort of damage to the glass or metal element casings.

Still, I've got sort of a nagging uneasy feeling about the rear element that I can't quite shake. All the single coated Fujinon lenses have seen have a sort of warm bronze color to their coating. The front element of this 250/6.7 is that way, but the coating on the rear element of this lens is blue in color in some of the reflections. (Which I know is common in other manufacturers single coated lenses, I just haven't seen it myself in Fujinons) I'm wondering whether those of you with the same lens can let me know the color of the rear element coatings on your 250/6.7. I'm also curious to know the outer diameter of the rear element on your lens--mine is 56mm. I'm trying to rule out the possibility of the rear element being mismatched. (See the attached image for reference.)

Thanks for any help or suggestions you can offer.

[Gem Singer]

From your description, it appears that you have a mismatch.

Images from that lens should be sharp as a tack.

It's not unusual for a former owner to switch rear elements, either purposely, or accidentally.

[CatSplat]

Is there a serial number or other text engraved on the rear cell?

[benrains]

CatSplat, the rear cell doesn't have any markings on it, but a similar vintage Fujinon-W 210/5.6 of mine is also that way. I think that's normal for the older lenses because all of the identifying markings, including the serial number, are engraved around in the metal of the front face of the lens (vs the newer lenses which have the markings around the outer front element barrel and a serial number around the outer rear element barrel.)

Gem, thanks for the comment. In this case I've no reason to believe the seller purposefully switched the elements, rather he had the lens and hadn't used it himself to know there was possibly a problem with it. He fully refunded my purchase without any hassles and I'll be returning the lens today. I have no complaints. It's just one of those things that goes with the territory when you're buying used equipment.

[EdWorkman]

rear OD 2.5x25.4=65.5mmm
Measured with a ruler with 1/16" divisions, but that's enough to confirm "not 56mm"
And the serial is 250509, bought from Midwest almost 7 years ago

[EdWorkman]

And sorry I was inspecific about the serial #- it appears on the front element only- nada on the back one

[Steve Goldstein]

Mine takes a 64mm rear cap.

[James E Galvin]

I also have one of these lenses with (probably) a mismatched rear cell. It is JUST possible that we could trade rear cells and fix both. I'll send you measurements Monday to see if there is a chance.

[Kevin Crisp]

The one I had couldn't have been sharper, something is probably wrong. This isn't typical.

[Oren Grad]

At this point it sounds like probably a mismatched rear cell. But with apologies for asking the obvious, and just in case - are you sure both the front and rear cells are screwed in all the way so that there's no problem with the spacing of the elements?