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Sigma Mirror-Ultratelephoto 500mm f/4
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PostPosted: Thu Apr 14, 2011 5:38 pm    Post subject: Sigma Mirror-Ultratelephoto 500mm f/4 Reply with quote

I just got this interesting lens. I knew beforehand that it could suffer from defects and sure enough, there's debris and a haze inside. But that did not prevent me from using it.

Disclaimer: because it is hazy I have increased the contrast.

Interesting is the original lens cap which can also act as a f/5.6 diaphragm Smile

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Crop from the above photo:


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PostPosted: Thu Apr 14, 2011 5:53 pm    Post subject: Reply with quote

Apart from the sharpness that does not seem to be extreme, is it actually usable ? I mean, a 500/4 refractor gives a very thin dof, but a miror should give a thinner one, according to my experience with mirors.


PostPosted: Thu Apr 14, 2011 5:54 pm    Post subject: Reply with quote

Huge beast! And the first results seem promising.


PostPosted: Thu Apr 14, 2011 6:05 pm    Post subject: Reply with quote

CarbonR wrote:
Apart from the sharpness that does not seem to be extreme, is it actually usable ? I mean, a 500/4 refractor gives a very thin dof, but a miror should give a thinner one, according to my experience with mirors.


Probably the sharpness is also influenced by the fact that the interior is all but clean. In fact I expected much worse results! And is it really true that the DOF of a mirror lens is thinner than that from a 500mm f/4 telephoto?

Orio wrote:
Huge beast! And the first results seem promising.


Thank you! It's huge indeed, but fortunately not that heavy.

I forgot to add that I also got the matching "f=1000mm 1:8 attachment". That's what is engraved on it.


PostPosted: Thu Apr 14, 2011 6:59 pm    Post subject: Reply with quote

WOW Peter, what a monster lens Shocked ......first results seems not so bad at all.....but I thought you were not a "miror lens guy " Very Happy .....


PostPosted: Thu Apr 14, 2011 7:02 pm    Post subject: Reply with quote

pich900 wrote:
WOW Peter, what a monster lens Shocked ......first results seems not so bad at all.....but I thought you were not a "miror lens guy " Very Happy .....


Indeed, now my words are being used against me Laughing

But how could I resist this one, being cheaper than a 55mm f/1.8 SMC Takumar?


PostPosted: Thu Jun 09, 2011 11:44 am    Post subject: Reply with quote

Hi Peter

I have two of those and I expect neither is really as good as your example!

They are not identical, one has a pull out extender at the rear, I am not sure why but unless I pull that out I cannot get it to focus. The extender looks like what is on your lens. That one came to me from the estate of a scientist who worked in an observatory so it is quite possible he modified it some how.

The other lens was used by a wildlife photographer and shows signs of much use, but nothing I would call abuse. I could not reach the focus ring with my Pentax camera mounted so I made a disk to increase the diameter of the focus ring which made a world of difference. I have that leather lens cap cum stop down mask, I have even used it a few times.

I like mine as although huge to carry provided I can get something to lean against I can use them hand held without going to extremes of shutter speed.


PostPosted: Thu Jun 09, 2011 11:50 am    Post subject: Reply with quote

Hello and welcome, John!

I don't own the lens anymore; I sold it to a long lenses geek (for the same money as I have bought it for). He opened it up and cleaned it, and found out that there was some sort of coating defect in the front group. Apparently those old Sigmas are not really well built.

Do you have any shots to share?


PostPosted: Thu Jun 09, 2011 7:23 pm    Post subject: Reply with quote


I tried one out on this wild animal from down the road, Pentax *ist DS ISO 400 1/4000 hand held, f=500mm F1:4, distance about 35 metres.


PostPosted: Thu Jun 09, 2011 9:54 pm    Post subject: Reply with quote

Result is lot better what I did expect , from an inexpensive ultra fast 500mm mirror lens more than nice. How is it perform to long distance ?


PostPosted: Thu Jun 09, 2011 11:31 pm    Post subject: Reply with quote

SO here's a potentially dumb question:

If the lens cap can act as an f5.6 diaphragm, can you make make additional diaphragms to stop it down further and increase the DoF?


PostPosted: Tue Aug 14, 2012 10:13 pm    Post subject: Reply with quote

Huge lens ! But results are not so promising... Sad

So light blur on details...


PostPosted: Tue Aug 14, 2012 10:28 pm    Post subject: Reply with quote

David wrote:
SO here's a potentially dumb question:

If the lens cap can act as an f5.6 diaphragm, can you make make additional diaphragms to stop it down further and increase the DoF?


I guess that should work I mean, on a "normal" lens you do just that, close the aperture, there is nothing else happening with the lens so I guess it makes perfect sense to assume that.

These samples are nice and I guess it makes no sense to make a truly awfull 500mm lens, budget or not this is a very specific tool only bought for using in very particular situations and so it is targeted at a niche market.


PostPosted: Fri Jul 05, 2013 10:50 am    Post subject: Reply with quote

David wrote:
SO here's a potentially dumb question:

If the lens cap can act as an f5.6 diaphragm, can you make make additional diaphragms to stop it down further and increase the DoF?


Sure you can stop it down by using smaller diameter diaphragms, it's something regularly done i.e. on hobby telescopes, to image for example the moon which may have too much light intensity compared to other sky objects.

What you cannot alter much (reduce) thou is the ring bokeh, because the central light ostruction cannot be decreased in size.

leodp


PostPosted: Fri Jul 05, 2013 11:07 am    Post subject: Reply with quote

John Hill wrote:
I tried one out on this wild animal from down the road, Pentax *ist DS ISO 400 1/4000 hand held, f=500mm F1:4, distance about 35 metres.


John, the cat does not look so sharp. How did you image it?
This lens is almost a telescope: if you do not give it time to adapt to temperature changes (i.e. when you are taking the lens from home to a sunny place outside) I suspect that the resolution is going to be pretty low, not reflecting the real performance achievable.

It would be nice to see a comparison of a shot taken immediately upon going on field and after the lens has settled 1 hour or so.

Leo


PostPosted: Thu Sep 05, 2013 10:17 am    Post subject: Reply with quote

leodp wrote:
John Hill wrote:
I tried one out on this wild animal from down the road, Pentax *ist DS ISO 400 1/4000 hand held, f=500mm F1:4, distance about 35 metres.


John, the cat does not look so sharp. How did you image it?
This lens is almost a telescope: if you do not give it time to adapt to temperature changes (i.e. when you are taking the lens from home to a sunny place outside) I suspect that the resolution is going to be pretty low, not reflecting the real performance achievable.

It would be nice to see a comparison of a shot taken immediately upon going on field and after the lens has settled 1 hour or so.

Leo


Leo, as far as I recall that is full frame with no processing at all.


PostPosted: Thu Sep 05, 2013 10:18 am    Post subject: Reply with quote

leodp wrote:
John Hill wrote:
I tried one out on this wild animal from down the road, Pentax *ist DS ISO 400 1/4000 hand held, f=500mm F1:4, distance about 35 metres.


John, the cat does not look so sharp. How did you image it?
This lens is almost a telescope: if you do not give it time to adapt to temperature changes (i.e. when you are taking the lens from home to a sunny place outside) I suspect that the resolution is going to be pretty low, not reflecting the real performance achievable.

It would be nice to see a comparison of a shot taken immediately upon going on field and after the lens has settled 1 hour or so.

Leo


Leo, as far as I recall that is full frame with no processing at all.


PostPosted: Thu Sep 05, 2013 10:18 am    Post subject: Reply with quote

leodp wrote:
John Hill wrote:
I tried one out on this wild animal from down the road, Pentax *ist DS ISO 400 1/4000 hand held, f=500mm F1:4, distance about 35 metres.


John, the cat does not look so sharp. How did you image it?
This lens is almost a telescope: if you do not give it time to adapt to temperature changes (i.e. when you are taking the lens from home to a sunny place outside) I suspect that the resolution is going to be pretty low, not reflecting the real performance achievable.

It would be nice to see a comparison of a shot taken immediately upon going on field and after the lens has settled 1 hour or so.

Leo


Leo, as far as I recall that is full frame with no processing at all.


PostPosted: Thu Sep 05, 2013 10:20 am    Post subject: Reply with quote

leodp wrote:
John Hill wrote:
I tried one out on this wild animal from down the road, Pentax *ist DS ISO 400 1/4000 hand held, f=500mm F1:4, distance about 35 metres.


John, the cat does not look so sharp. How did you image it?
This lens is almost a telescope: if you do not give it time to adapt to temperature changes (i.e. when you are taking the lens from home to a sunny place outside) I suspect that the resolution is going to be pretty low, not reflecting the real performance achievable.

It would be nice to see a comparison of a shot taken immediately upon going on field and after the lens has settled 1 hour or so.

Leo


Leo, as far as I recall that is full frame with no processing at all.