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10-23-2018, 07:39 AM   #1111
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QuoteOriginally posted by GUB Quote
This K series mirror zoom is about f12 at 600mm so we are into diffraction country well and truly. Still I think I am still ahead of using it on the K1 and cropping it but that comparison would be a good test one day. Saved in raw and pped to the best of my abilities. No cropping.
Neat lens entry GUB. Can't be easy to shoot with on a Q. You achieved better results than I expected. Good job.
Curious how this lens performs on the K1 uncropped? Would you rate it decent or better?
Thanks,
barondla

10-23-2018, 12:53 PM - 1 Like   #1112
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Yes hell to focus. The slight vibration of your hand touching the focus ring kills the focus peaking. I had hopes for it on the Q for astro work but I think the diffraction issues of f12 make it unusable. A good example of this is Apertority's post on this thread (post #1028)
Adapted lenses tested on the Q : the reference thread - Page 73 - PentaxForums.com.

That was on the QS1 so my smaller sensor on the Q original would be even worse.

The 400-600 mirror is my "go to" if I need reach on my K1. Nearest alternatives are a Tamron 500 and a Samyang 500 mirror both of which are left in the dust. The nearest contender in the Refractors is my K series 400mm 5.6 which feels totally unwieldly in comparison and I feel trails in IQ. Here is a shot taken yesterday with the 400 - 600 @ 400mm 1/125sec hand held on the K1. As you can see a very usable lens.
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Last edited by GUB; 10-23-2018 at 01:04 PM.
10-23-2018, 01:51 PM   #1113
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QuoteOriginally posted by GUB Quote
Yes hell to focus. The slight vibration of your hand touching the focus ring kills the focus peaking. I had hopes for it on the Q for astro work but I think the diffraction issues of f12 make it unusable. A good example of this is Apertority's post on this thread (post #1028)
Adapted lenses tested on the Q : the reference thread - Page 73 - PentaxForums.com.

That was on the QS1 so my smaller sensor on the Q original would be even worse.

The 400-600 mirror is my "go to" if I need reach on my K1. Nearest alternatives are a Tamron 500 and a Samyang 500 mirror both of which are left in the dust. The nearest contender in the Refractors is my K series 400mm 5.6 which feels totally unwieldly in comparison and I feel trails in IQ. Here is a shot taken yesterday with the 400 - 600 @ 400mm 1/125sec hand held on the K1. As you can see a very usable lens.
Looks very good. The mirror avoids the color fringing plaguing many older teles, including my Pentax 400 f5.6.
Will keep my eye out for one of these.
Thanks for sharing,
barondla
03-18-2019, 04:47 PM - 1 Like   #1114
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Tamron 6.5mm f1.8 c mount lens:



This is really only a 5 megapixel lens (if that) and while it does cover the Q7 sensor, it is somewhat soft in the center and very soft at the edges with lots of fringing and a fair amount of distortion (click through for magnified view.) No focusing either.

Its images gives the effect of a Kodak Instamatic camera, especially when shot square (as above.)

It might find some use as a moody video lens.


Last edited by Cipher; 03-25-2019 at 09:04 AM. Reason: typo
04-16-2019, 03:24 AM - 3 Likes   #1115
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Canon New FD 500mm f/4.5 L

We've had some nice spring weather recently and yesterday afternoon I went out to get a moonshot with the Q10 and the 80's oldie Canon New FD 500mm f/4.5 L. The birds were chirping in the trees nearby and a few stayed put for just long enough so I could get a few shots of them as well! I'm not a very good birder, but would guess it's a European Greenfinch and a Fieldfare (Thrush).

Shots wide-open at f/4.5. The bird images were taken some distance away and are heavy crops. The moon was of course also far away but is uncropped as it just barely fits into the image at 500mm

EDIT: Added a blackbird shot at f/5.6 as well. It kept singing, seemingly unbothered by my presence, so I was able to get the focus just right.

Lens notes:
- Impressive sharpness at f/4.5 - the images turned out quite nice IMHO regardless of the demanding small sensor
- Impressive control of CA - a tiny amount was present but could be mostly mitigated in the raw editor
- Not easy to nail focus due to 1) shallow depth of field wide-open, and 2) EVF shake when touching the lens. Sturdy support + an IR remote + a red dot sight for finding the subject is recommended!
- Colors are a bit flat - dial up vibrance and contrast!

All in all - it's not a particularly easy lens to use at 2810mm eq. focal length, but I think it can work well e.g. for photographing (still) wildlife in good light if the subjects are far away and you can't get closer.
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Last edited by eMH; 04-21-2019 at 12:28 AM.
04-17-2019, 01:43 AM   #1116
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QuoteOriginally posted by eMH Quote
We've had some nice spring weather recently and yesterday afternoon I went out to get a moonshot with the Q10 and the 80's oldie Canon New FD 500mm f/4.5 L. The birds were chirping in the trees nearby and a few stayed put for just long enough so I could get a few shots of them as well! I'm not a very good birder, but would guess it's a European Greenfinch and a Fieldfare (Thrush).

Shots wide-open at f/4.5. The bird images were taken some distance away and are heavy crops. The moon was of course also far away but is uncropped as it just barely fits into the image at 500mm

Lens notes:
- Impressive sharpness at f/4.5 - the images turned out quite nice IMHO regardless of the demanding small sensor
- Impressive control of CA - a tiny amount was present but could be mostly mitigated in the raw editor
- Not easy to nail focus due to 1) shallow depth of field wide-open, and 2) EVF shake when touching the lens. Sturdy support + an IR remote + a red dot sight for finding the subject is recommended!
- Colors are a bit flat - dial up vibrance and contrast!

All in all - it's not a particularly easy lens to use at 2810mm eq. focal length, but I think it can work well e.g. for photographing (still) wildlife in good light if the subjects are far away and you can't get closer.
Impressive images eMH! Especially from a lens from the 80's. This should allow wildlife images that are almost impossible to capture any other way.
Thanks for sharing,
barondla
04-19-2019, 08:44 AM   #1117
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That's pretty good eMH!


(500mm F/4.5 should look absolutely gigantic when mounted on your Q10, or is it your Q10 that is mounted on the lens )
04-21-2019, 02:09 AM - 1 Like   #1118
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Thanks barondla and kwb!

With this one it's indeed the case of lens holding the camera. Most definitely to be used on a good tripod with the Q, and a gimbal also helps a lot.

I have adapted the nFD 500mm f/4.5 L on other mirrorless cameras with great results, but have to say I was pleasantly surprised by the output of this combo. The Q really pushes legacy lenses with regards to sharpness and detail - many old lenses' sweet spot is around f/8, which is well into diffraction territory on the Q. This is not the case with this lens. It's sharp wide open and with good enough control of purple fringing that it can produce great results on the Q - if you are willing to work with the weight and size, price, extremely long equivalent focal length, and also face the reality of atmospheric effects.

Makes one curious about trying a good 300mm f/2.8 it would enable photography in lower light. Ah well...

04-22-2019, 01:02 PM   #1119
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QuoteOriginally posted by eMH Quote
Thanks barondla and kwb!

With this one it's indeed the case of lens holding the camera. Most definitely to be used on a good tripod with the Q, and a gimbal also helps a lot.

I have adapted the nFD 500mm f/4.5 L on other mirrorless cameras with great results, but have to say I was pleasantly surprised by the output of this combo. The Q really pushes legacy lenses with regards to sharpness and detail - many old lenses' sweet spot is around f/8, which is well into diffraction territory on the Q. This is not the case with this lens. It's sharp wide open and with good enough control of purple fringing that it can produce great results on the Q - if you are willing to work with the weight and size, price, extremely long equivalent focal length, and also face the reality of atmospheric effects.

Makes one curious about trying a good 300mm f/2.8 it would enable photography in lower light. Ah well...
All that is needed is a telecompressor to reduce focal length and add speed.
Thanks,
barondla
04-23-2019, 05:37 PM   #1120
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QuoteOriginally posted by eMH Quote
The Q really pushes legacy lenses with regards to sharpness and detail - many old lenses' sweet spot is around f/8, which is well into diffraction territory on the Q.
Several years ago when I performed backyard testing of lenses at 300mm on my Q-7, my Sigma 70-300 performed best at f/8.
04-23-2019, 05:57 PM   #1121
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QuoteOriginally posted by reh321 Quote
Several years ago when I performed backyard testing of lenses at 300mm on my Q-7, my Sigma 70-300 performed best at f/8.
I use the A* 600/5.6 at f/11 and it still looks good. Plus software is getting better and better at reversing diffraction blur.
04-24-2019, 10:45 AM   #1122
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Why do I get the feeling I should have chosen my wording a bit more carefully

QuoteOriginally posted by vonBaloney Quote
I use the A* 600/5.6 at f/11 and it still looks good. Plus software is getting better and better at reversing diffraction blur.
It's of course dumb to try to generalize when there are many variables in play. Regarding diffraction, I had in mind the tests of some of the native Q lenses at e.g. ephotozine.com or opticallimits.com, where MTF generally peaks around f/2.8-f/4 and drops thereafter. These results, while I think they tell something about diffraction of the Q sensor, also reflect the performance (and possibly the smaller image circle?) of the Q lenses - and thus may not generalize to all non-native lenses, which you and reh321 pointed out. My understanding is that, as long as lens sharpness increases more than the sensor-imposed diffraction limits it, you can stop down and get sharper results. And of course, sharpness is not the full story either, as this does not account for depth of field / aberration control / what is "sharp enough", and so on - YMMV. So, of course you should test out your lenses with the Q at different apertures and see what works for you.

Thanks vonBaloney for the tip! You are right in that softness caused by diffraction can be better mitigated nowadays - I did a search and found this thread and tried out the settings in RawTherapee - I had dismissed the RL deconvolution setting before, but now that I tried it I will look into it more. Cheers!
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