Sharper Imagon Examples

[Frank Petronio]

I'm semi-interested in Imagons, likely because I found a deal on one... how sharp can you make an Imagon while still being wide open? I am not a fan of the extreme softness I see on some of the photos - does anyone have any examples?

I don't mean stuff shot at f/32, I mean wide open or f/8-11 range but with the least severe disc (which one is that by the way?)

I'm hoping it is almost "normal" looking ;-p

Thanks

[BrianShaw]

I'm not intimately familiar with Imagon but selected a Fujinon for the same reasons you enquire about. It was always my impression that it was easier to get sharp soft-focus with Fujinon rather than Imagon. For the Fujinon "wide open" is quite different depending upon which disc is in place. With a red disk wide open is actually rather stopped down, but the effect is a rather sharp soft.

I look forward to reading more knowledgable replies though.

[Bob Salomon]

With the Imagons up to 250mm in Copal shutter 3 disks are supplied, with the 300mm in Copal 2 disks are supplied. In all cases the disk with the smallest center hole will be the sharpest and with all of that disk's outside holes closed the Imagon is very sharp.

The softest and most halation will always be with no disk. The disk with the largest center hole will will be next softest with all outside holes open. With the outside holes closed it will become a litlle sharper with a little less halation. The next disk also gets progressively less soft with progressively less halation depending on if the outside holes are open or closed.

Since the Imagon effect is strongly influenced by lighting ratios and the character of the light the Imagon is normally used at a strong ratio of about 5:1 and with strong spectrals since that is what halos.

So, with the largest disk or wide open an Imaagaon will be at its softest. With the smallest disk with the outside holes closed the Imagon will be at the smallest H number and will be at its sharpest. Exactly the opposite of what you are asking for. A 200 or 250mm in Copal is an H 5.8 lens. The largest disk is H5.8 to 7.7. The 300mm in Copal is a H 6.8 lens and the largest disk is H 7.7 to 9.5.

[Ed Bray]

Thanks Bob, I will try it out this weekend.

Silly question maybe, but if I half close the holes in the middle disk would that give an intermediate value say for the middle disk circa f8.6?

[Mark Woods]

I own a 200mm & 300mm Imagon. I use them wide open most often and really enjoy the softness. The 200mm is supposed to be used for 6x9, but it covers my 8x10 and give a beautiful image. Using the most open disk considerably increases the sharpness. Bob's analysis is very accurate. Frank, with the widest open disk, the F/Stop is F/6.3 for the 300mm and F/5.7 for the 200mm. They're a single element lens and neither of mine are coated. The example is a scan from an 11x14 print made from an 8x10 neg with the 200mm Imagon. Have fun with it.

[Ed Bray]

With the Imagons up to 250mm in Copal shutter 3 disks are supplied, with the 300mm in Copal 2 disks are supplied. In all cases the disk with the smallest center hole will be the sharpest and with all of that disk's outside holes closed the Imagon is very sharp.

The softest and most halation will always be with no disk. The disk with the largest center hole will will be next softest with all outside holes open. With the outside holes closed it will become a litlle sharper with a little less halation. The next disk also gets progressively less soft with progressively less halation depending on if the outside holes are open or closed.

Since the Imagon effect is strongly influenced by lighting ratios and the character of the light the Imagon is normally used at a strong ratio of about 5:1 and with strong spectrals since that is what halos.

So, with the largest disk or wide open an Imaagaon will be at its softest. With the smallest disk with the outside holes closed the Imagon will be at the smallest H number and will be at its sharpest. Exactly the opposite of what you are asking for. A 200 or 250mm in Copal is an H 5.8 lens. The largest disk is H5.8 to 7.7. The 300mm in Copal is a H 6.8 lens and the largest disk is H 7.7 to 9.5.

I own a 200mm & 300mm Imagon. I use them wide open most often and really enjoy the softness. The 200mm is supposed to be used for 6x9, but it covers my 8x10 and give a beautiful image. Using the most open disk considerably increases the sharpness. Bob's analysis is very accurate. Frank, with the widest open disk, the F/Stop is F/6.3 for the 300mm and F/5.7 for the 200mm. They're a single element lens and neither of mine are coated. The example is a scan from an 11x14 print made from an 8x10 neg with the 200mm Imagon. Have fun with it.

I have a 200mm Imagon, I have not actually used it yet but it is currently in the Synchro Compur shutter of my 300mm Symmar-S. I understood that the greater softness was produced by using the most open aperture along with the peripheral holes also open, is this not the case? as the statements in red above seem to contradict the one in green.

If I do not use the supplied disks but were to use the diaphragm in the shutter, would this give a sharper result?

[Bob Salomon]

I have a 200mm Imagon, I have not actually used it yet but it is currently in the Synchro Compur shutter of my 300mm Symmar-S. I understood that the greater softness was produced by using the most open aperture along with the peripheral holes also open, is this not the case? as the statements in red above seem to contradict the one in green.

If I do not use the supplied disks but were to use the diaphragm in the shutter, would this give a sharper result?

You can use the Imagon without a disk and that will be the softest and have the most halation. The H value with no disk on the 200mm is 5.8.
If you use the disk marked 5.8 to 7.7 with all the outside holes open you will also have an H value of 5.8 but there will be less softness and less halation then there was with no disk.

If you use that disk with all the outside holes closed the H value is 7.7 and the lens will become a bit sharper and have less halation again. If you use the middle disk with all the holes open you will also be at an H value of 7.7 but you again will be a bit sharper and a bit less halation again.

Some of the classic Imagon portrait shooters like Monte Zucker and Tibor Horvath shot with the second disk (7.7 to 9.5) with the outside holes fully open.

You should never use the aperture in the shutter if you want the effect of the Imagon. When you use the aperture in the shutter you block the peripheral rays and lose the classic Imagon look and feel.

[Mark Sawyer]

You can use the Imagon without a disk and that will be the softest and have the most halation. The H value with no disk on the 200mm is 5.8. If you use the disk marked 5.8 to 7.7 with all the outside holes open you will also have an H value of 5.8 but there will be less softness and less halation then there was with no disk.

Bob, is the H-value equivalent to the F/stop ratio in figuring the exposure? My Imagons are about f/4.8 without a disc, and there's no way a lens can be the same vlue (h-5.8) both with and without the disc.

A couple of old examples, wide open from a 300mm Imagon on 8x10:



And from a 360mm Imagon with the holes open (This is as soft as the Imagon gets using the softest disc):



The Imagon can be used to lovely effect with either a conventional aperture or the discs. Slightly different effects, but I like them both.

[Bob Salomon]

MarK, With the first disk fully open and no disk the lens is H5.8. With the first disk fully closed and the second disk fully open it is 7.7 and with the second disk fully closed and the last disk fully open it is 9.5.

These are H numbers not F stops but generally they correspond to the nearest F stop so: 5.6, 8.0 and almost f11.

[Brian C. Miller]

I'm semi-interested in Imagons, likely because I found a deal on one... how sharp can you make an Imagon while still being wide open?

Frank, you can make a "zone plate" for yourself and experiment with it without buying a thing. The Fuji SF and the Imagon both use zone plates, and you can make one yourself. Just take some black paper, and cut some holes in it. For a f/5.6 lens, the center hole would be at the f/11 size, and punch out holes at the f/8 size. Sandwich it inside the lens, and see what you get.