Sigma 600mm Mirror Lens
Posted 28/08/2026 - 11:50
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Sorry but the AI artifacts are rather too visible for my tastes.
Posted 28/08/2026 - 12:13
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Yes, there are artifacts, the birds look to be rather over-sharpened to my eyes. However, a good first attempt. As a long focal length, manual focus lens with small aperture, focusing the Sigma 600mm is inevitably going to be tricky. In that situation, there is something to be said for taking several shots with slightly different focus then choosing the best - or even focus stacking if the subject hasn't moved between shots. Were you using a tripod? With a 600mm lens, your hands would need to be a lot steadier than mine to get really good hand-held shots. As you say, a lot more practice is needed - but of course that's the case with most of the worthwhile things in life .
Steve
Steve
Posted 28/08/2026 - 15:05
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Good results all the same though, does Topaz provide an adjustable slider or method to control the sharpening? I would like to think so, you could lower the amount perhaps to prevent the "artifacts" ?? In Rawtherapee it does allow some control BTW.
Posted 28/08/2026 - 15:25
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MikeInDevon wrote:
Sorry but the AI artifacts are rather too visible for my tastes.
Yes I know they are pretty bad but if you saw the original out of focus images, you probably would have binned them
Sorry but the AI artifacts are rather too visible for my tastes.
Posted 28/08/2026 - 15:28
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MikeInDevon wrote:
Sorry but the AI artifacts are rather too visible for my tastes.
Yes I know they are pretty bad but if you saw the original out of focus images, you probably would have binned them Sorry but the AI artifacts are rather too visible for my tastes.
Lubbyman wrote:
Yes, there are artifacts, the birds look to be rather over-sharpened to my eyes. However, a good first attempt. As a long focal length, manual focus lens with small aperture, focusing the Sigma 600mm is inevitably going to be tricky. In that situation, there is something to be said for taking several shots with slightly different focus then choosing the best - or even focus stacking if the subject hasn't moved between shots. Were you using a tripod? With a 600mm lens, your hands would need to be a lot steadier than mine to get really good hand-held shots. As you say, a lot more practice is needed - but of course that's the case with most of the worthwhile things in life .
Yes being MF it was tricky to use because the smallest movement of the focus ring made a huge difference. I did use a monopod but I think in future I should use a tripod but it was a fun exercise anyway
Steve
Yes, there are artifacts, the birds look to be rather over-sharpened to my eyes. However, a good first attempt. As a long focal length, manual focus lens with small aperture, focusing the Sigma 600mm is inevitably going to be tricky. In that situation, there is something to be said for taking several shots with slightly different focus then choosing the best - or even focus stacking if the subject hasn't moved between shots. Were you using a tripod? With a 600mm lens, your hands would need to be a lot steadier than mine to get really good hand-held shots. As you say, a lot more practice is needed - but of course that's the case with most of the worthwhile things in life .
Yes being MF it was tricky to use because the smallest movement of the focus ring made a huge difference. I did use a monopod but I think in future I should use a tripod but it was a fun exercise anyway
Steve
Posted 28/08/2026 - 15:31
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loadoftripe wrote:
Good results all the same though, does Topaz provide an adjustable slider or method to control the sharpening? I would like to think so, you could lower the amount perhaps to prevent the "artifacts" ?? In Rawtherapee it does allow some control BTW.
Yes Topaz has so many different settings both for sharpening and focus, it's another learning curve there too but I am amazed at what the software can do.
Good results all the same though, does Topaz provide an adjustable slider or method to control the sharpening? I would like to think so, you could lower the amount perhaps to prevent the "artifacts" ?? In Rawtherapee it does allow some control BTW.
Posted 28/08/2026 - 15:31
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Having had experience of a 500mm mirror lens many years ago, as well as the MF issue, your shutter speeds going to need to be pretty high.
With the fixed aperture prob F8 I guesstimate you'll need 1/1250 sec for any chance of a sharp image in reasonable light.
Increasing the iso much above 800 / 1000 will have its own issues as well.
With the fixed aperture prob F8 I guesstimate you'll need 1/1250 sec for any chance of a sharp image in reasonable light.
Increasing the iso much above 800 / 1000 will have its own issues as well.
Chris
www.chrismillsphotography.co.uk
" A Hangover is something that occupies the Head you neglected to use the night before".
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K1 - Sigma 85mm F1.4, Pentax DFA 150 -450 F4.5 / 5.6, Pentax DFA* 24 - 70 F2.8
Samyang 14mm F2.8, Pentax DFA* 70-200 F2.8, Pentax A 50mm F1.2
K3iii + K3ii + K5iis converted to IR, Sigma 17 - 70 F2.8, Pentax 55 - 300 F4.5 / F5.6 PLM
www.chrismillsphotography.co.uk
" A Hangover is something that occupies the Head you neglected to use the night before".
-------------------------------------------------------------
K1 - Sigma 85mm F1.4, Pentax DFA 150 -450 F4.5 / 5.6, Pentax DFA* 24 - 70 F2.8
Samyang 14mm F2.8, Pentax DFA* 70-200 F2.8, Pentax A 50mm F1.2
K3iii + K3ii + K5iis converted to IR, Sigma 17 - 70 F2.8, Pentax 55 - 300 F4.5 / F5.6 PLM
Posted 28/08/2026 - 15:53
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They look good for a first attempt and practice will improve things too. Would catch-in-focus work in this situation. It may help to improve the success rate.
Out of interest, does Topaz remove the doughnut highlights that you would normally get with a cat lens? They dont seem to be present here.
Out of interest, does Topaz remove the doughnut highlights that you would normally get with a cat lens? They dont seem to be present here.
Posted 28/08/2026 - 19:12
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smc wrote:
Out of interest, does Topaz remove the doughnut highlights that you would normally get with a cat lens? They dont seem to be present here.
Doughnuts are there. Look at the full size version of the 2nd heron shot, right hand side. The rough look of some of the OOF areas may well be due to Incipient doughnuts (how's that for inventing a new technical term?? ). Out of interest, does Topaz remove the doughnut highlights that you would normally get with a cat lens? They dont seem to be present here.
Steve
Posted 28/08/2026 - 21:05
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Another 'sharpening' trick with Topaz is to process the full size job then resize it to a much smaller format. Then sharpen it again. This is indeed a 'trick' and once you've done it you can't process it any further!
On the other hand, don't give up on the mirror lens. This was shot with the Pentax 400 - 600 zoom mirror at 420mm, hand held
.
On the other hand, don't give up on the mirror lens. This was shot with the Pentax 400 - 600 zoom mirror at 420mm, hand held
.
Posted 28/08/2026 - 22:01
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WiltshireBorn wrote:
But worth persevering with!
MikeInDevon wrote:
Sorry but the AI artifacts are rather too visible for my tastes.
Yes I know they are pretty bad but if you saw the original out of focus images, you probably would have binned them Sorry but the AI artifacts are rather too visible for my tastes.
Posted 29/08/2026 - 14:30
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Hi
I regularly use my Pentax 40-600 reflex zoom. Most shots at 400 mm are fine, but at 600 mm a monopod or tripod are essential. Also, as Chrism8 has already said, a shutter speed in excess of 1000th is a must, not to mention good light. Good luck
Michael
I regularly use my Pentax 40-600 reflex zoom. Most shots at 400 mm are fine, but at 600 mm a monopod or tripod are essential. Also, as Chrism8 has already said, a shutter speed in excess of 1000th is a must, not to mention good light. Good luck
Michael
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