600mm f/4 Redux

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Steve (and others),

I'm giving serious thought to purchasing the 600mm f/4, primerily for wildlife work. I've read all the online comments, but there are still some unanswered questions.

The lens does not have a fully automatic diaphram. How is the manual diaphram implemented? Is there a pre-set lever. How does it work with the meter on the 67II?

Does it come with a lens shade, and if so how does it fit? Built in? Can't tell from the pics in the brochure.

The lens appears to have a rotating collar mount. Is that correct?

The focusing mount looks as if it's rack & pinion. How is this implemented? How easy is it to use, or how difficult.

Finally, I would enjoy hearing from anyone that has field experience with this lens. I'm well aware of how big and heavy it is, and have extensive experience with 400mm lenses in 35mm, but I'm enjoying the image quality with the Pentax so much I want to see if expanding its use to include wildlife as well as landscape is viable.

Thanks!

Michael

www.luminous-landscape.com

-- Michael Reichmann (mreichmann@home.com), December 12, 2001

Answers

The diaphragm is operated via a ring and it is slower to use than the auto diaphragm lenses but not by much. As far as how it meters with the 67II; I don't own the 67II but I'm sure there is no problem with metering. The built in shade fits tight but will bind on occasion so it is best to turn it a bit when moving. There is no rotating collar on the tripod mount as with other teles but the 600 can accommodate vertical shots by loosening the body and rotating to vertical. The geared focusing is easy to use and is fairly quick compared to helical systems. But, trying to use the DOF scale with this focus system is almost useless, especially if you put in a rear filter which changes the focus points at all distances. Using the DOF scale successfully can be done however. Hand holding this lens for subjects above you(birds) can be a challenge, as the focusing section is sometimes pulled out by the weight of the body. This will change your focus and cause much anger. But, for more normal shooting, the focus system does OK. For wildlife, this lens is limited to animals larger than a dove. Even with tubes, one can't get close enough to get a full frame on smaller subjects. It is great for the Elk, Deer, Moose, Owls, etc. I have put my Pentax KX on it for 12x magnifications using the K-Mount adapter. Handy for birds that won't let you get close. Landscapes are limited with the 600, but I have done many sunsets and some lightning with mine. Try to avoid using two tripods by keeping the shutter speed either slower than 1/2 sec or faster than 1/60. Never shoot the 600 at f/4. Even though it is corrected for three colors, at the time it was designed, Fluorite could not be grown in crystals 6 inches across and therefore conventional glass had to be used. Spherochromatism and fringing are the result. At f/6.7 to f/45 the fringing is not a problem. A 600 ED is overdue but will be expensive.

-- Steve Rasmussen (srasmuss@flash.net), December 13, 2001.

Michael, the outer bay collar allows you to rotate the body and lock in to a vertical position due to the notches machined into the lens' mounting face. The body will click into place once it passes over the notch. Once this happens, just retighten the collar. I've never used a Wimberly. I said limited landscapes because of its weight, DOF scale, the need to use two tripods occasionally, rear filter annoyances and the high magnification of this lens. Limited, yes---- impossible?, no. At f/4 the 600 is poor (3) as far as fringing is concerned. The shots will not be publishable, even in low contrast lighting. Spherical aberration has been well corrected as can be seen by the cross section in that there is obvious lens bending of various elements. The change in focus of various colors at different lens zones is another matter(spherochromatism). The mid aperture performance of this lens is really good and easily comparable to other lenses in the line(almost as sharp as the 75mm). The contrast is excellent and better than the 300mm.

-- Steve Rasmussen (srasmuss@flash.net), December 14, 2001.

Michael, one last point. You can rotate the body to shoot vertical. You don't have to remove the camera to do this. Just loosen the collar, turn the body 'til it clicks and tighten the collar.

-- Steve Rasmussen (srasmuss@flash.net), December 14, 2001.

Steve,

Thanks for the clarifications. Just a few more if you don't mind.

You wrote, "the 600 can accommodate vertical shots by loosening the body and rotating to vertical." I assume that this is because the 600mm uses the outer bayonette. I've never seen how this works. Is it a breach lock with a collar? A bit of an explanation of how this mount works would be really useful.

I'm planning on using the 600mm with a Wimberly mount, which I use in 35mm with super-teles when shooting wildlife. Any experience doing this?

You also say "Landscapes are limited with the 600". Can you elaborate? I do a lot of landscape work with a 300mm Tele-Xenar and 2X on my Rollei 6008. Why should it be a problem with the Pentax 600mm?

"...keeping the shutter speed either slower than 1/2 sec or faster than 1/60." I assume that this is due to shutter bounce. If so, I'm well aware of this even using the 300mm IF with too light a tripod.

I'm aware that there is some spherical aberation with this lens. "At f/6.7 to f/45 the fringing is not a problem." But, sometimes f/4 will be needed, especially with wildlife. How bad is the fringing? I know that quantifying something subjective like this is tough, but would you say it's 1-dreadful, 2-nasty, 3-poor, 4- annoying, 5-slightly visable?

Finally, how would you rate the lens when a solid tripod is used along with proper technique and mid-aperture? Are contrast and sharpness on a par with other top long lenses?

Thanks for your feedback. Since Pentax Canada doesn't have one of these for me to see and certainly no dealer has one, it's very tough to decide beforehand if this lens is going to be a net contributor to my work or an expensive dog that'll end up on E-bay next year.

Regards,

Michael

www.luminous-landscape.com

-- Michael Reichmann (mreichman@home.com), December 14, 2001.


I've had a 600 for about 4 years. The mount is a straight bayonet engagement (no rotation) that is locked down with a threaded collar after engagement. It will engage the camera either landscape or portrait (lens stays upright with R&P focus on bottom). Basically, if you want to change you take the camera off, turn it 90 degrees and put it back on.

Fringing at f/4 varies from 1 to 3 on your scale. Variance depends on the level of contrast in the image. In areas of an image where black meets white it can be very bad with a distinct red line in the white area. It quickly disappears as the lens is stopped down.

Contrast and sharpness are excellent. It is the most difficult lens I've owned to produce acceptable images. Your prior experience should help you. I find it VERY unforgiving of mediocre technique. But......when it works, it is truly wonderful. One just doesn't tend to 'accidently' produce good images with it.

-- Patrick Drennon (sierraengineering@att.net), December 14, 2001.



Thank you Steve & Patrick,

I now have the information I need to decide on a purchase. I'm feeling in an irrational mood right now and so I'm sorely tempted. If I still feel this way on Monday I'll order one. Or, maybe I'll sober up.

Michael

-- Michael Reichmann (mreichmann@home.com), December 14, 2001.


I have now purchased and done some preliminary tests with the Pentax 600mm f/4. It's quite a lens, and capable of producing excellent results with proper technique.

My write up can now be found at http://www.luminous- landscape.com/600mm.htm

Michael

-- Michael Reichmann (mreichmann@rogers.com), December 29, 2001.


Anyone concerned about the chromatic aberration problem with the 600mm f/4, or any other long lens for that matter, should have a look at my review of a software solution to the problem.

It can be found at http://www.luminous-landscape.com/chromatic.htm

Michael

-- Michael Reichmann (mreichmann@home.com), January 03, 2002.


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