600mm f/4 Redux

Steve (and others),

<p>

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.

<p>

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?

<p>

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.

<p>

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

<p>

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

<p>

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.

<p>

Thanks!

<p>

Michael

<p>

www.luminous-landscape.com

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,

<p>

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

<p>

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.

<p>

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?

<p>

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?

<p>

"...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.

<p>

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?

<p>

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?

<p>

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.

<p>

Regards,

<p>

Michael

<p>

www.luminous-landscape.com

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.

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.

<p>

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.

<p>

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.

Thank you Steve & Patrick,

<p>

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.

<p>

Michael

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.

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.

<p>

My write up can now be found at http://www.luminous-

landscape.com/600mm.htm

<p>

Michael

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.

<p>

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

<p>

Michael