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11-26-2017, 09:25 AM   #1
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Using the DA* 300 on a K-1

Having used full frame leses extensively on an aps-c camera in the past I thought I understood the "crop factor," at least somewhat, but apparently I don't. I'm considering purchasing a DA* 300 for use on my K-1 because of the stellar reviews in the lens review section of PF. But in further reading I found the following two quotes that confuse me.

In the PF Pentax K Mount Lens Series Explained page it states:

"Exceptions: The following three lenses officially cover the 24 x 36mm full-frame format: smc Pentax-DA* 200mm F2.8, smc Pentax-DA* 300mm F4, and HD Pentax-DA 560mm F5.6."

And I have read similar info elsewhere.

But on Ricoh Imaging's website info on the DA* 300 is the following comment:

"the smc PENTAX-D★ 300mm F4 ED[IF] SDM is a uni-focal super-telephoto lens with a focal length equivalent to 460mm in the 35mm format"

That seems backward to me.

To keep the question as simple as possible, if I put a DA* 300 on my K-1 what image will I see on the lcd screen - will it be the same as with a DFA 300 or will it be larger or smaller.

Also, if anyone has experience with the DA* 300 and any of Pentax's other star 300s I would be interested in your comparisons of the relative IQ of the different models, especially of sharpness.

Thanks for any help in clearing up my confusion!

11-26-2017, 09:40 AM   #2
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The 460mm equivalent is if you use it on aps-c. Essentially on the full frame it presents a wider image in the viewfinder.

I use mine on the K1. It is not very long, but is a nice light package. The lens is very nice. I tend to shoot longer, 500mm or shorter for scenery. It makes a very nice long close in lens for flowers and insects. I was very close to the sheep below.

Here are a couple examples.




11-26-2017, 09:40 AM   #3
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QuoteOriginally posted by wanderer2 Quote



To keep the question as simple as possible, if I put a DA* 300 on my K-1 what image will I see on the lcd screen - will it be the same as with a DFA 300 or will it be larger or smaller.

Also, if anyone has experience with the DA* 300 and any of Pentax's other star 300s I would be interested in your comparisons of the relative IQ of the different models, especially of sharpness.

Thanks for any help in clearing up my confusion!
Simple answer: you'll see the same size of picture on the LCD. 300mm FL is 300mm FL.
I can't comment on the IQ comparison from own experience, though.
From what I have read I would assume that both are excellent.
11-26-2017, 10:17 AM - 1 Like   #4
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Forget you ever heard about crop factor, it does nothing but confuse. As has been said a 300mm lens is a 300mm lens whatever format you use it on.

The DA* 300 is great on the K1.

11-26-2017, 10:21 AM   #5
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The DA*300 is excellent on the K-1, it behaves like any other 300mm lens, as you would expect.
I've not had mine too long but some shots from a trip to the French Alps and the British F1 Grand Prix earlier in the year




















11-26-2017, 10:43 AM   #6
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If the DA 300 only covered apsc (which it doesn't) then the viewfinder or lcd of your k-1 would show a central image that looked like that of a D FA at 300mm but the outside borders would be shaded or black and the sharpness in those areas outside the center might suffer (In Full Frame mode. In crop mode this would look different on the LCD since the outside borders would be chopped off - but as the post below me states - there would be no difference if you used a 300mm DA or a 300 D FA in crop mode - they would appear the same.). The central portion would appear the same. The way I try to describe it is to imagine you are in a room looking through a 16x24 inch window at a distant mountain chain. When you stand far from the window all you can see is what's directly visible through that opening. Now imagine that you have an identical room next to it with a 24x36 inch window that looks on the same scene. You would see more of the scene but the size of the things shown would not have changed. Only your perspective of what the scene looked like would differ. This is why we tend to use shorter lenses at the same distance to get the same perspective on crop bodies vs full frame. Don't get hung up on it. Just understand that when switching between formats the way a focal length appears is related to the size of the sensor not something special about the lens.

Last edited by UncleVanya; 11-26-2017 at 01:00 PM.
11-26-2017, 10:48 AM   #7
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QuoteOriginally posted by wanderer2 Quote
if I put a DA* 300 on my K-1 what image will I see on the lcd screen
In full frame mode the image you will see on the lcd screen will be the same as any other 300 mm lens would be.

In crop mode the image you see on the lcd screen (either in LV mode or after capture) will be bigger. But it will be the same size as any other 300mm lens in crop mode on the K1.

Does this mean you get extra "reach" in crop mode? No you do not. You simply get an image that was captured with less pixels (15mp versus 36mp) that is made larger because by its nature it has a narrower field of view. It will have less resolution, although still outstanding image quality.

You already have a K1. Switch to different modes and you will see the difference.
11-26-2017, 02:29 PM   #8
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QuoteOriginally posted by pschlute Quote
Does this mean you get extra "reach" in crop mode? No you do not. You simply get an image that was captured with less pixels (15mp versus 36mp) that is made larger because by its nature it has a narrower field of view. It will have less resolution, although still outstanding image quality.
That is true, but putting it on a K-3, with 24 Mpx (vs 15 for the K-1 crop mode), would give a bit more reach.

---------- Post added 11-26-17 at 02:38 PM ----------

Crop factor is a property of the camera/sensor, and is used to compare lens+camera combinations. You can’t really use it to just compare lenses on the same body. K-3 + DA-300 is 460 equivalent. K-1 + DA-300 is 300 equivalent. K-3 + FA-300 is 460 equivalent. K-1 + FA-300 is 300 equivalent.

11-26-2017, 03:32 PM - 1 Like   #9
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The “extra reach” in your examples is a product of the higher density pixel pitch of the k3 versus the k1. Nothing at all to do with crop sensor size.

I realise you understand this but we are now two decades into mass market digital SLR cameras and the crop factor confusion is as high as ever.

I personally think your description of the K3 having extra reach due to its pixel pitch is confusing to a newcomer to digital cameras. I started digitally with a Pentax *ist DS , 6 MP. When I used the DA*300 mm on that camera it was a 300 mm lens. It is nonsense to suggest that it is a 1200 mm equivalent lens if it is now mounted on a K3.

Discuss increased resolution of higher pixel count sensors by all means but don’t drag the lens focal length into the equation
11-26-2017, 04:11 PM - 1 Like   #10
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QuoteOriginally posted by wanderer2 Quote
To keep the question as simple as possible, if I put a DA* 300 on my K-1 what image will I see on the lcd screen - will it be the same as with a DFA 300 or will it be larger or smaller.
Mate, as has been mentioned already, 300mm is 300mm, don't worry about the 460mm field of view. When I first got my K-1 and put the DA*300/4 on, the camera defaulted to crop mode. To fix that I changed the crop setting to 'FF'. The only change you could see through the viewfinder is the crop square disappeared. Everything else stayed the same except now the full sensor was being used when the DA*300 was mounted.

I wouldn't be worrying about it too much as the DA*300 is a great lens to put on the K-1. I have used it with the K-1 at a motocross event, then before I went back for the next one I picked up the 150-450 so I have these two lenses to compare and the resolution achievable from both is really good. You can check both of them out here: Action, Sports, Motorsports & Events | Flickr (NOTE: The biggest variation was the DA*300 was used in overcast conditions and the 150-450 in sunny conditions).

So my recommendation is to set your K-1 to FF mode (camera settings, page 2 option 3) and start enjoying a smart decision to pick up the DA*300. I still have mine.

Tas
11-26-2017, 06:30 PM   #11
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Thanks very much to all of you for the explanations and clarifications. The comment on the Ricoh website, "focal length equivalent to 460mm in the 35mm format," really confused me (it's just plain wrong isn't it?). Since I had already ordered a used DA* 300 when I read that I became alarmed because I do not want a 460 mm lens. I also greatly appreciate the photos - the sharpness is terrific. Being a Formula 1 fan I thought the photo of Ricciardo in the Red Bull car was really good - it isn't easy to catch those cars so clearly with the speeds they go.

Thanks again. I feel much better about the purchase now.


Read more at: Using the DA* 300 on a K-1 - PentaxForums.com
11-26-2017, 06:43 PM   #12
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QuoteOriginally posted by wanderer2 Quote
Thanks very much to all of you for the explanations and clarifications. The comment on the Ricoh website, "focal length equivalent to 460mm in the 35mm format," really confused me (it's just plain wrong isn't it?).
Yeah, mostly.

Camera companies should know better, but they frequently use that language.

The field of view on APS-C is like 460mm on 35m, not focal length.
11-26-2017, 09:59 PM   #13
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Have fun with that combination. The low light capabilities are amazing.
11-26-2017, 11:03 PM   #14
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Is the crop mode on the K-1 1.6? if not why is Ricoh using Canon math to give their bad information? Shouldn't it be 450mm equivalent not 460mm? And yes I get that it is a bit of an illusion.
11-27-2017, 12:07 AM - 1 Like   #15
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It is a wonderful lens, on crop or full frame. I can not recommend it highly enough.

On the K-1, it gives a similar field of view (and depth of field wide open) as the DA*200 does on a crop body.
On a crop body, it gives a similar field of view (and depth of field wide open) as a 450/5.6 lens would on the K-1. Hence the statement from Ricoh.

Simple really
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