Sigma 600mm Mirror Lens - Has anyone used one?

[Steve Smith]

I acquired a Sigma 600mm mirror lens this weekend. I don't know if I will give it much use but it looks like a fun thing to own. Has anyone else got such a thing or has used one in the past?

It comes with a set of rear mount filters and is currently fitted with a clear 'filter'. I recall reading that it needs a clear piece of glass in the filter position if no other filter is being used in order to maintain focus. Is this correct?


Steve.

 

[pentaxuser]

Steve, a great find. 600mm is pretty powerful and the "cats" are as I understand it much lighter and smaller than a comparable 600mm conventional lens. In my albeit sparse reading about "cats" I cannot ever recall seeing a N.B. in any book reminding potential users to ensure that a clear filter was fitted.

Fine if you have one but hopefully it's not required. If it is then I wonder what the optical science is that means one is essential?

pentaxuser

 

[flash26c]

I own one for a Nikon. Haven't used it much but it did it's job when I did. Shallow DOF and not much light getting thru to focus unless it's bright out. I heard the same about the filter. Never tryed without.

 

[Steve Smith]

This one is f8. The viewfinder seems bright enough to focus in decent daylight.

The instruction booklet suggests that it can be used hand held but I think I would prefer a tripod.


Steve.

 

[Alan Johnson]

I have one in OM fit, but it came without any filters.It has not seen much use but produced an interesting result when used to photograph a boat in that the reflections off the waves were unusual.
Since you have the filter it can be used but I am encouraged by the following that having no filter should still be OK, except the focus is changed:
http://photo.net/classic-cameras-forum/00YBg4

 

[narsuitus]

I do not have the Sigma 600mm mirror lens but I do have a 1000mm mirror lens and a 500mm lens that require a filter in the filter slot for it to focus correctly. The way I understand it is if a filter is not in place, the infinity focus will be off. For example:

1. If you manually focus on an object that is at an infinite distance, the distance scale on the lens will not be lined up with the infinity marking.

2. If you rotate the focus ring to the infinity position and point your camera toward a star cluster, the star cluster, which should be in focus, will actually be out of focus.

However, using the lens without the filter in place has no affect on the image quality.

http://www.flickr.com/photos/11336821@N00/7798937038/

 

[lxdude]

I have a 500mm/f8 Tamron SP with matched 2X converter.

I really enjoy it. It's light and compact, and produces sharp images with good contrast.

Negatives of mirror lenses are: the "donut" look to out of focus highlights and busy/double line bokeh in backgrounds with distinct detail, caused by the secondary mirror's position in the light path; lower contrast due to having an obstruction in the light path; generally smaller maximum aperture; a fixed aperture opening which means no way to increase DoF, plus difficulty getting precise exposure setting with all-mechanical cameras unless in-between shutter speeds can be set as on the Nikon F2.
Positives include compactness and light weight (except the Vivitar Solid Cat, which is mostly a solid piece of glass); close focusing (mine goes to 1:3, and 1:1.5 with the 2X), which makes for some intriguing "nearly-macro" shots; less magnification of camera vibration due to short length and ability to attach the camera to the tripod directly. (Mine also has a tripod collar- I've used both setups and haven't seen a difference. But the lens is only about 3.75 inches long at infinity anyway, excluding the the hood). Finally, cost. A high quality regular telephoto will cost more than a comparable quality mirror lens.

The Tamron is said to be one of the best of the mirror lenses, and I certainly find sharpness and contrast to be good. I don't know how your Sigma stacks up.

I avoid the donut and double-line look by careful selection of background and/or foreground. The narrow depth of field is a plus in this, as extremely out-of-focus images in a background tend to blur to near non-definition. A very bright out-of-focus highlight, however, will be larger though dimmer the more it is out of focus, and can present problems. A uniformly lit out-of-focus area will not show the donut effect. I have also had success with uniformly mottled light/dark backgrounds looking good. Placing a subject against a uniform sky, stretch of calm water or area in shadow also works well.

I bought my lens mostly for shots of very distant objects at infinity, excluding closer objects, and for those shots foreground/background issues are eliminated. Also at long distances, issues of contrast and resolution compared to top-notch regular telephotos are less important. Subject contrast is usually reduced anyway, so a little lower contrast still looks natural. Same with resolution at those distances- atmospherics usually affect resolution anyway.

I don't mind the slowness- f/8@500mm, f/16@1000mm with the 2X. Depth of field is so shallow even at those apertures, and I'm (usually) not hand-holding anyway.


Always use one of the filters. The filter is part of the optical formula so it is important that it be used.

 

[cowanw]

What lxdude said, except that I was under the impression that DOF at f8 was what it was at f8. I don't think the mirror lens has less depth of field, than any other lens, but that the transitions may appear more abrupt. After all 500mm on 35 mm film has 6 inch of DOF at 30 feet. Mine is fitted to a Contax mount and I leave it on Aperture Priority and use appropriately fast film. A shutter speed of 1/500 or faster and you are good to go, handheld or bean bag.

 

[rmolson]

Had one as I remeber there is no adjustment for changing the f/stop.But what threw me for awhile was the fuzziness caused,by heat waves in the summer. You definatley can see that with a 500mm lens

 

[lxdude]

Thanks for bringing up those points, Bill.

Yes, you're right about DoF being the same.
My comments on DoF were subjective. To clarify: For me, the Dof is usually a good tradeoff at f/8- enough for fairly close work, but shallow enough to lose distracting backgrounds pretty easily. I would seldom want less for the shots I make at short range though, f/5.6 being about 4.3 inches at 30 ft., and the extra stop meaning a large increase in size and weight. So the larger aperture lenses aren't that useful to me, and the smaller maximum aperture is not a deficit.

You're right about hand-holding too. I've also hand-held, and it's certainly doable. I used to take pictures at air shows a lot, and the cat was great for that. It's a breeze to pivot holding it, as what weight it has is held close in. 400 ISO Provia and go. Pushing it, or using 400 ISO negative film's latitude would allow a higher shutter speed, though I just used Provia 400 at rated speed. It seemed easier for me to get a hand-held shot of a moving object than a stationary one. I used a monopod sometimes, but I usually ended up just hand-holding with good results. A bean bag on top of the car worked great, too.
I seldom shoot non-stationary objects these days, so I use a tripod to get maximum resolution. I might use it handheld again though, so I amended my post.

 

[Ralph Javins]

Good morning, Steve Smith;

Yes, I have and I have used the SIGMA MIRROR-TELEPHOTO 1:8 f=600mm lens with my Minolta cameras. While it also has filter threads on the front for 95mm diameter filters, at the back of the lens just inside the camera mount is the place where the 30.5mm filters will go, and, yes, for best results, there should be a filter screwed into that location. The optical design of the lens does intend for that filter to be in place, and that is why the "neutral filter" or "clear filter" is provided. You can also substitute a Skylight or UV or other similar clear filter that will screw into that location. In the tests of lenses where such a filter is included in the optical formula, usually there has been a slight degradation of the lens resolution quality when the filter was not included.

One odd quirk was noted by the MODERN PHOTOGRAPHY people when they tested the original Tamron Type 107B 300mm f:2.8 SP LD IF regular telephoto lens (not a mirror lens). It actually worked better without the filter screwed into the back filter holder. It seems that the original design of the 107B lens did not include the filter at that location, but it was added later as the production run began. In the following later versions, the Type 60B and the Type 360 lenses, they did rework the formula and the design to include the filter in the back filter holder location, and those do work better with the filter screwed in place.

With any of the long telephoto lenses, when you get to 500mm and longer, you will see many things about our air that may be a surprise. There is a refractive index to the air itself, and air that moves around, or is affected by differential heating by the sunlight on different surfaces under the optical path that the lens can see, will also produce different densities and movement of that air, and things will really dance around. The afternoon usually is the worst for this. If you can take a photograph with a very long lens in the early morning before things start to warm up and the winds are calm or very light, you will be happier with what the air does to your photographs.

And, there are mirror lenses here from 250mm out to 1900mm in focal length.

 

[Steve Smith]

Thanks for everyone's responses. I tried the lens with and without the clear 'filter' and leaving it out does shift infinity focus slightly.

I assume it is included so that a scene can be composed and focused then the clear filter swapped for a colour filter without any focus shift. I wouldn't want to focus this thing with the red filter in place effectively making this lens f22 as far as light transmission is concerned or with the neutral density filter fitted.


Steve.

 

[removed-user-1]

I've owned the Sigma 600mm f/8 mirror lens (got it for $50!), as well as Sigma's 500mm f/7.2 "normal" (non-mirror) telephoto (which I sold many years ago, sadly). Used them both on Nikons. The 600mm behaved just like any other mirror lens I've used, but it did seem sharper than some cheap 500mm mirror lenses. I did use it on a tripod exclusively. I liked the 500mm f/7.2 Sigma better, if only because I found the lack of an aperture control on the mirror lens limiting. I sold the mirror lens and am now looking for another long tele. Wish I hadn't sold the 500mm - it seems to be hard to find.