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05-02-2015, 02:11 PM   #16
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Art at Brussels Airport with 18 mm lens. Self made (thin) washer-aperture stopping the lens to about f5.6. This is maybe not the best solution, but it works (and I also do not have acces reinforcing rings).




05-02-2015, 07:57 PM - 1 Like   #17
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QuoteOriginally posted by GUB Quote
Pentax 110 70mm on the original Q stopped down to about f4.5 with a blackened ringbinder reinforcing ring stuck to the rear element mount.
Although not blazingly sharp I think the 70mm on the Q has the makings of a great surreptitious portrait setup.
I had it pointed out to me on another thread that my dog portrait was a little soft.
I was about to blame my tools then I thought it would be interesting to tripod mount and turn SR off to max the potential of the lens.
My dog is very patient so I was able to use a 2 sec delay effectively.
In the image in the original post the centre of focus may be back just a little but most of the softness is probably from handholding and/or SR not doing its job.
The interesting thing in these new images is the wide open image is as sharp as the stopped down one.
Maybe the faster shutter speed has paid dividends over stopping down.
I have always felt that this 70mm doesn't improve much with the iris added.
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05-03-2015, 02:26 AM   #18
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Very usefull information for all 110 lenses fans, thanks GUB!
05-03-2015, 09:39 AM   #19
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QuoteOriginally posted by GUB Quote
I had it pointed out to me on another thread that my dog portrait was a little soft.
I was about to blame my tools then I thought it would be interesting to tripod mount and turn SR off to max the potential of the lens.
My dog is very patient so I was able to use a 2 sec delay effectively.
In the image in the original post the centre of focus may be back just a little but most of the softness is probably from handholding and/or SR not doing its job.
The interesting thing in these new images is the wide open image is as sharp as the stopped down one.
Maybe the faster shutter speed has paid dividends over stopping down.
I have always felt that this 70mm doesn't improve much with the iris added.
I doubt if this was a case of the SR not doing its job. I have taken hand-held pictures as slow as 1/6 and the pictures were as sharp as I could expect them to be. However, my experience has been that it is hard to maintain an exact distance from the subject when hand-holding the camera, so I sometimes use a monopod so to make it easier for me to take the picture at the same distance as the one I had been at when manually focusing.

05-03-2015, 02:09 PM   #20
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QuoteOriginally posted by reh321 Quote
I doubt if this was a case of the SR not doing its job. I have taken hand-held pictures as slow as 1/6 and the pictures were as sharp as I could expect them to be. However, my experience has been that it is hard to maintain an exact distance from the subject when hand-holding the camera, so I sometimes use a monopod so to make it easier for me to take the picture at the same distance as the one I had been at when manually focusing.
All agreed but the plane of focus can be seen through the back ear and the dogs ruff (this is the first image on page 1) and I don't think that focussed area is as sharp as the later images. That really leaves motion blur as the issue.
Remember we are resolving hairs here so the slightest tremble of the Dog could be an issue and is not going to be solved by SR (or a tripod). I think that often happens with small birds.
For reference shutter speeds were 1/50 on the first image then 1/125 and 1/250. I am sorry there is no exif -- it is a gimp issue.
05-03-2015, 06:39 PM   #21
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QuoteOriginally posted by GUB Quote
All agreed but the plane of focus can be seen through the back ear and the dogs ruff (this is the first image on page 1) and I don't think that focussed area is as sharp as the later images. That really leaves motion blur as the issue.
Remember we are resolving hairs here so the slightest tremble of the Dog could be an issue and is not going to be solved by SR (or a tripod). I think that often happens with small birds.
For reference shutter speeds were 1/50 on the first image then 1/125 and 1/250. I am sorry there is no exif -- it is a gimp issue.
What ISO setting are you using? When I've had sharpness issues, others here have encouraged me to push the ISO as high as 800, feeling that you lose less from pushing ISO to 800 than you gain from getting shutter speeds up to around 1/800.
05-03-2015, 08:32 PM   #22
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QuoteOriginally posted by reh321 Quote
What ISO setting are you using? When I've had sharpness issues, others here have encouraged me to push the ISO as high as 800, feeling that you lose less from pushing ISO to 800 than you gain from getting shutter speeds up to around 1/800.
ISO 125 on the original Q.
If I had realized it was such a slow exposure (1/50) I would have stepped it out to ISO 400.
But the original Q is not too tolerant of stepping up ISO.
That is one of the secrets of photography isn't it -- finding the correct balance of parameters to get the right outcome.
05-04-2015, 08:16 AM   #23
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QuoteOriginally posted by GUB Quote
ISO 125 on the original Q.
If I had realized it was such a slow exposure (1/50) I would have stepped it out to ISO 400.
But the original Q is not too tolerant of stepping up ISO.
That is one of the secrets of photography isn't it -- finding the correct balance of parameters to get the right outcome.
Yes, it takes time to understand a particular camera.
I've been reluctant to push my Q7 to 800, but others here have encouraged me to try it. I don't know how far you can push the Q before serious issues arise.

I've always taken more pictures of moving things than of landscapes, so I've always been more aware of shutter speed than of aperture; I guess understanding aperture is one of my growing edges.


Last edited by reh321; 05-04-2015 at 08:18 AM. Reason: complete thought
05-04-2015, 02:06 PM   #24
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QuoteOriginally posted by reh321 Quote
Yes, it takes time to understand a particular camera.
I've been reluctant to push my Q7 to 800, but others here have encouraged me to try it. I don't know how far you can push the Q before serious issues arise.

I've always taken more pictures of moving things than of landscapes, so I've always been more aware of shutter speed than of aperture; I guess understanding aperture is one of my growing edges.
Don't be afraid to push the ISO, I use iso 800 on a regular basis, it is often a matter of getting an image or not. Just don't underexpose or you will get some noise in the shadows, like here:



The following are a bit better:






The first one is with the 01lens and the others with the 06 lens, all ISO 800
05-04-2015, 02:19 PM   #25
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Step down rings - stop down on 70 mm lens?

Sometimes step down rings can act as a front aperture (like on preset lenses). I'm using step down rings mainly as a small hoods on my SLR lenses, but in some cases they also stop them down nicely and without vigneting (which may be handy sometimes for M series lenses).

I'm wondering if something like this could be possible for 70 mm lens on the Q? This one takes 49 mm filters, so there are really many different rings available (and they are really cheap). Then it should be possible to "change" the aperture without glueing anything to the lens end or inserting the discs in the adapter. Unfortunately I'm still trying to get this lens cheap without success to check this in practice.

This could also work maybe for 50 mm lens with some DIY work (some step down rings for 37 mm are available form China, but some work is needed to adapt them as the lens uses 37,5 mm filters).
05-04-2015, 03:09 PM - 1 Like   #26
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QuoteOriginally posted by Piotrek K Quote
Sometimes step down rings can act as a front aperture (like on preset lenses). I'm using step down rings mainly as a small hoods on my SLR lenses, but in some cases they also stop them down nicely and without vigneting (which may be handy sometimes for M series lenses).

I'm wondering if something like this could be possible for 70 mm lens on the Q? This one takes 49 mm filters, so there are really many different rings available (and they are really cheap). Then it should be possible to "change" the aperture without glueing anything to the lens end or inserting the discs in the adapter. Unfortunately I'm still trying to get this lens cheap without success to check this in practice.

This could also work maybe for 50 mm lens with some DIY work (some step down rings for 37 mm are available form China, but some work is needed to adapt them as the lens uses 37,5 mm filters).
Good thinking. With the added of cutting out any extra light onto the front glass.
So I had a quick play -- had a home built m42 - 49mm lens reversing ring.
This put the iris about 25mm in front of the glass but no visible vignetting.
Internal diameter of the iris -- 32mm
Diameter of the front lens about 42mm.
That should be about a 1 stop stop down.
Camera on tripod exposure to manual.
No perceptible change in exposure or image sharpness.
I am figuring that the lens does not use all of the front glass -- naturally stopped down by internal construction.
So you are going to need an iris considerably small than 32mm out front if I have got this right.
And if you are thinking that an iris 25mm away front the glass will cause vignetting rather than stopping the lens down then think again.
If you hold a pen 100mm in front of the lens when it is set to infinity the pen is all but invisible.
05-05-2015, 05:52 AM   #27
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Anyway, even if it would be not possible to stop down 110 lenses with step down rings for the Q the information that GUB posted above is really useful. I was using step down rings when adapting my Pentax M 135 on the Q (also quite "aggressive" I use step down ring to 28 mm plus the hood). This might be also the option for shading "bigger" 110 lenses (at least).
05-05-2015, 12:58 PM   #28
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QuoteOriginally posted by Piotrek K Quote
Anyway, even if it would be not possible to stop down 110 lenses with step down rings for the Q the information that GUB posted above is really useful. I was using step down rings when adapting my Pentax M 135 on the Q (also quite "aggressive" I use step down ring to 28 mm plus the hood). This might be also the option for shading "bigger" 110 lenses (at least).
Yeah, even if that outer rim of glass is not being used it still has the ability to scatter stray light through the lens.
Given that the f number is arrived at with the formula -- focal length / diameter of aperture -- so a 70mm f 2.8 lens requires a 25mm aperture. (That is theoretical and actual size depends on where the iris is placed.)
But I think it is reasonable logic to extend that in this situation the 70mm 2.8 requires 25mm of that front glass.
And one stop down would be with a 18mm mask.
05-05-2015, 02:23 PM   #29
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Many ways to make smaller front aperture effect.

#33
05-10-2015, 02:57 AM - 1 Like   #30
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I did a bit more testing on this front aperture disc idea of Piotek K and placed it on the adapted lens thread.
https://www.pentaxforums.com/forums/136-pentax-q/209474-adapted-lenses-tested...ml#post3248962
It confirms what I suspected -- that the lens only uses about 25mm of the front glass.
And stopping the 70 down does not gain much sharpness.
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