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05-28-2023, 06:17 PM - 1 Like   #19501
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Viewing Prints

QuoteOriginally posted by Kiwizinho Quote
I think it's all to do with the standard for print publications ie glossy magazines. Take a nice round figure 254dpi which happens to be exactly 10dpmm. A lot of artists would struggle to paint consistent detail at 0.1mm, but most people are quite happy with art that has considerably larger detail than that. Obviously with paintings the brush strokes are irregular whereas with a digital image pixels are square or rectangular so are likely to be a bit more obvious at a large size.
I just found an academic article on spacial resolution, and apparently under ideal circumstances, human angular resolution is equivalent to about 355lpi at 25cm, but that is at 25cm, and the further away from the subject, the lower it gets, with a better measure, 60 line pairs per degree; apparently at 1km that equates to 30cm minimum resolvable detail.
If I've done my calculations right, at 1m viewing distance, perfect 20:20 vision should be able to resolve about 87lpi, so probably anything over 100lpi printed should look acceptable to most people on a wall unless they're breathing on it.
Another thing to think of is that the gerneal viewing distance is 1.5 x the diagonal of that you're viewing. So an 8 x 10 print with a diagonal of 12.8 inches should (???) be viewed at about 19 inches from the print. A 1m x 2m print on a wall would be viewed at 3.35m from the print. A billboard at 6m x 3m is viewed at 10m.

This makes sense when you look at the resolution of large billboards, especially the electronic ones, and observe just how large the individual pixels are but when viewed at a reasonable viewing distance (greater than or equal to 1.5 x the diagonal) that there is no notable pixilation.

Regards

Chris

05-28-2023, 11:34 PM   #19502
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QuoteOriginally posted by Kiwizinho Quote
apparently under ideal circumstances, human angular resolution is equivalent to about 355lpi at 25cm, but that is at 25cm, and the further away from the subject, the lower it gets
This is the very principle Apple used when arriving at their 'retina display' resolutions. On the phones they started around 325 ppi if I remember correctly, but have since gone over 400. Yet the same 'retina' label on Macs refers to, for example, 218 ppi on my 27" display, which of course I view at a greater distance than my phone.

QuoteOriginally posted by Arpe Quote
For me, with sports, more pixels means cropping ability, extra zoom if you will. That's always handy.
That's a great reason to have higher megapixel counts on the sensor (within reason), but the discussion is about the ppi of the final output for printing. The more you crop in, the smaller the print size you are limited to for a given threshold ppi 'required' for a good print.
05-29-2023, 06:39 PM - 4 Likes   #19503
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Yeah -- my first 1000mm lens! Handheld shot of my silly Magnolia flowering now while old season leaves still adorn the tree.
Sometimes you have to take a gamble on the wording - paid off in this situation! Mirrors are so damn hard to use I don't blame someone for thinking it was faulty.
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05-29-2023, 06:47 PM   #19504
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QuoteOriginally posted by GUB Quote
eah -- my first 1000mm lens! Handheld shot of my silly Magnolia flowering now while old season leaves still adorn the tree.
Sometimes you have to take a gamble on the wording - paid off in this situation! Mirrors are so damn hard to use I don't blame someone for thinking it was faulty.
Congrats on the acquisition GUB, well done

It is nice to know that such an interesting lens will get some care, attention and use.

05-29-2023, 06:57 PM - 1 Like   #19505
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QuoteOriginally posted by NZ_Ross Quote
Congrats on the acquisition GUB, well done

It is nice to know that such an interesting lens will get some care, attention and use.
And at 2.3Kg I will get some exercise using it.!
05-30-2023, 02:20 AM - 1 Like   #19506
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QuoteOriginally posted by GUB Quote
Mirrors are so damn hard to use I don't blame someone for thinking it was faulty.
Your results look perfectly acceptable.

That's a real monster focal length.

QuoteOriginally posted by GUB Quote
And at 2.3Kg I will get some exercise using it.!
I suspect if it wasn't a mirror lens it would weigh even more.
05-30-2023, 04:38 AM - 1 Like   #19507
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QuoteOriginally posted by Kiwizinho Quote
I suspect if it wasn't a mirror lens it would weigh even more.
I am not sure about that! it still has a couple of thick elements up front that has to conform to f11. (1000 / 11 > 90mm). Then a couple of lightweight mirrors to fold the light. And then fine tuning out a few elements at the rear. And because there isn't a heck of a lot of focusing in before the mirror then the focusing helicoid has to be pretty well the diameter of the front. But it is certainly more compact.
It also has two filter wheels at the rear - one b&w filters for film and the other neutral density filters. A rather sophisticated monster.

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05-30-2023, 06:23 PM   #19508
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QuoteOriginally posted by GUB Quote
Yeah -- my first 1000mm lens! Handheld shot of my silly Magnolia flowering now while old season leaves still adorn the tree.
Sometimes you have to take a gamble on the wording - paid off in this situation! Mirrors are so damn hard to use I don't blame someone for thinking it was faulty.
Gub, what a wonderful lens and at such a great price. Mine cost me much more this $115. Great photo too! And handheld! It's not easy to hand hold this lens.

Regards

Chris
05-30-2023, 07:12 PM   #19509
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QuoteOriginally posted by GUB Quote
Yeah -- my first 1000mm lens! Handheld shot of my silly Magnolia flowering now while old season leaves still adorn the tree.
Sometimes you have to take a gamble on the wording - paid off in this situation! Mirrors are so damn hard to use I don't blame someone for thinking it was faulty.
Wow! That's a nice buy. Interesting lens and good shot!
05-30-2023, 08:38 PM - 1 Like   #19510
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QuoteOriginally posted by MarkJerling Quote
Annie and I have just returned from Otago where we did the Central Otago Rail Trail from Clyde to Middlemarch.
Fantastic trip. We used a company shebikeshebikes for bike hire, shuttles and accommodation and they did a superb job at a very fair price. I highly recommend them should you decide to do such a jaunt.

Here's a few photos.
Thanks for sharing, Mark. I think the Pentax-F 35-70mm is a proper stack-o-primes. When I put it on my Pentax, the images it rendered just looked very, very modern. Nowadays, they can be had for peanuts. Possessed AF is the right term for its AF.


QuoteOriginally posted by zkarj Quote
I just recently saw a comment in another forum from a lady who frequently prints large and that was "I don't know why people keep asking for 300ppi when 240 will do."
I know there is a Kiwi Pentaxian from Waikato with an old Pentax DSLR (K-30, maybe?) who gets his photos on magazines many times, but I am not sure if he's on this forum.

I believe that 300DPI is just the suggestion for optimised printing, meaning they want photos that are optimised for 300DPI and it's up to the publishers to scale them down. Many of the modern mirrorless ones don't really scale properly with 300DPI, even those with higher MPs. Some photographers scale their digital pixels to to make sure that nothing will overlap. Oftentimes, when printed, a DPI will have to cater for a couple of pixels and overlaps will render the whole image rather muddy but not pixelated. It's hard to explain here but can be demonstrated easily in-person.

Prints are still my final products/image and Pentax printing is a different story. The satisfaction is way up there and I print at 300DPI.


QuoteOriginally posted by seventhdr Quote
Another thing to think of is that the gerneal viewing distance is 1.5 x the diagonal of that you're viewing. So an 8 x 10 print with a diagonal of 12.8 inches should (???) be viewed at about 19 inches from the print. A 1m x 2m print on a wall would be viewed at 3.35m from the print. A billboard at 6m x 3m is viewed at 10m.

This makes sense when you look at the resolution of large billboards, especially the electronic ones, and observe just how large the individual pixels are but when viewed at a reasonable viewing distance (greater than or equal to 1.5 x the diagonal) that there is no notable pixilation.

Regards

Chris
This is good info, Chris. That's why it's important to ask the person/shooter what the final product medium is.



QuoteOriginally posted by GUB Quote
Yeah -- my first 1000mm lens! Handheld shot of my silly Magnolia flowering now while old season leaves still adorn the tree.
Sometimes you have to take a gamble on the wording - paid off in this situation! Mirrors are so damn hard to use I don't blame someone for thinking it was faulty.
I saw this on TM. Congrats on the purchase. Shooting one of these is always a different experience.
05-30-2023, 11:23 PM   #19511
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QuoteOriginally posted by Iron Quote
I think the Pentax-F 35-70mm is a proper stack-o-primes.
I need to give mine more outings. I do like the results when I use it, but I just spend too much time on my 55-300 aiming at things far away.
06-01-2023, 03:44 AM - 1 Like   #19512
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QuoteOriginally posted by Iron Quote
Thanks for sharing, Mark. I think the Pentax-F 35-70mm is a proper stack-o-primes. When I put it on my Pentax, the images it rendered just looked very, very modern. Nowadays, they can be had for peanuts. Possessed AF is the right term for its AF.
Thank you.
I like it because it produces good images from such a small lens - which makes it a great "walk around" lens. I have two good ones, one which is pretty much pristine.
There can be some vignetting at the 35mm end, but it's minor.
06-01-2023, 11:51 PM - 1 Like   #19513
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QuoteOriginally posted by MarkJerling Quote
I like it because it produces good images from such a small lens - which makes it a great "walk around" lens. I have two good ones, one which is pretty much pristine.
There can be some vignetting at the 35mm end, but it's minor.
My FA 24-90 also fits that role. Very nice lens image wise at f8. 355g so light enough and gives a very nice focal range for a "walk around" lens.
06-04-2023, 04:41 PM - 1 Like   #19514
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QuoteOriginally posted by zkarj Quote
I need to give mine more outings. I do like the results when I use it, but I just spend too much time on my 55-300 aiming at things far away.
I can understand why. The PLM is a different game. I came from primarily mirrorless and when learned about the PLM, saying that it's got a fast AF is an understatement. That may be the reason why I see some Pentaxians overseas using the 16-50mm PLM as a daily.

The 35-70mm is just a good stack-o-primes. I treat it as having three different lenses in one, 35mm, 70mm and 70mm Macro. I don't use the 50mm that much on APS-C.

QuoteOriginally posted by MarkJerling Quote
Thank you.
I like it because it produces good images from such a small lens - which makes it a great "walk around" lens. I have two good ones, one which is pretty much pristine.
There can be some vignetting at the 35mm end, but it's minor.
Yes, the vignetting is present at that end on FF.

I like the 35mm F3.5 end of that lens. It makes me flag-off getting a 35mm prime.... for now.

QuoteOriginally posted by NZ_Ross Quote
My FA 24-90 also fits that role. Very nice lens image wise at f8. 355g so light enough and gives a very nice focal range for a "walk around" lens.
Good to know. I will look at that, too. Cheers.

Last edited by Iron; 06-04-2023 at 04:55 PM. Reason: Consolidated my answers...
06-19-2023, 11:49 PM - 2 Likes   #19515
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Many years ago I designed and printed (using an inkjet) some cards that gave my zkarj.co.nz web site address. The intent was when I met someone 'in the field' while photographing aircraft, if they showed an interest in my photos, I could hand them a card. I can't remember how many I handed out, but I know it would have been more if I had managed to always keep some in my wallet! Anyway, I hadn't remembered for ages and decided it was time for a refresh, so I designed a new set and had them properly printed by Zazzle.

Wouldn't you know it, but since I've had the new ones in my wallet, I have not even met another photographer, let alone an interested bystander, so they got no use. However, on a road trip up to Rotorua late last week, I stopped by Taupo Airport to see if I could see anything interesting. I did, and I managed to hand over the very first card, with a rather cool outcome...

A Trip North – ZK-ARJ

Last week I also designed and have ordered cards for my bird photo site, too.
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