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Forum: Pentax SLR Lens Discussion 02-20-2013, 03:55 PM  
Input On The Samyang/Rokinon/Vivitar 85mm f/1.4
Posted By sunglint
Replies: 12
Views: 2,203
I'm using this lens (the vivitar, only because of a good deal) on a K-01 and have been very impressed. I posted three shots in this thread that demonstrate how well it works with this camera. These mostly look like very well lit shots, but the gym was quite dim. In fact the amplification that the K-01 does in live view allowed me to take shots where I wouldn't have been able to focus with a non-live view camera, and focus peaking helped a great deal. Add the scaling ISO and it works great. You might add a A50/1.7 to get a slightly wider view, that 85 comes out to a 127.5 which will keep you a good distance from the action. The third photo, the girl with the silly hat, was done standing about 10-15 feet away. At parties I've been using my 16-45. I havent been happy with the speed/ISO tradeoff, Id love to get the 17-50(?) 2.8 but it's a bit pricey for me. But in the party setting I find a zoom with a wide end very nice, and great for capturing the scenes and people. That makes me wonder if the 85 is too long. I took my 50 1.7 and the 16-45 to a recent show (mini maker faire) and found the 50 too close, that 75 effective gets a small part of a booth. The 16-45 while lower IQ (lens IQ and higher ISO due to it's speed) was great for the close-quarters work. So the 85 is a great lens, but maybe not for this use.
Forum: Pentax K-01 01-02-2013, 02:59 PM  
Converting K-01 to IR-only camera.
Posted By sunglint
Replies: 23
Views: 7,402
I've tested my 720 filter on my K-01 and the liveview amped up enough for me to compose and focus, but it's still very dim and you may want a hood. The images in this thread were focused via live view on a bright sunny day and werent too dificult. I tried the R72 again over the holidays on an overcast day and could barely see what I was doing, but the focus peaking stood out and let me know where the plane of focus was.
I also noticed that the resolution of the images was quite poor, even though it was an A50/1.7, which I assume is due to using the red channel only, so 1/3 of the resolution, but I may be wrong.
Forum: Pentax SLR Lens Discussion 12-19-2012, 11:28 PM  
Lens Testing Procedures?
Posted By sunglint
Replies: 5
Views: 1,318
I just picked up a K-01, and am interested in testing my various old and newly purchased lenses.
One test it for basic sharpness. I found a printable lens test chart (just search, there are tons) and printed it out. I mounted it in an old paper display sleeve to keep it flat, and put a glass frameless frame below it to use dry-erase markers to indicate the lens.


This is a reduced resolution example, just to show what I mean. I do this wide open, fully closed, and a couple stops in the middle. You could certainly burn the bytes to do every stop. I left some background to demonstrate bokeh and eventually DOF.
A similar test would use a large grid (like a good paper cutting mat) shot filling the frame to indicate distortion.

Another good test would be to get a tape measure and run it along a fence. Put your white board in the middle, focus there and start adjusting the aperture. This should readily indicate the DOF at each stop. This is an example of what we're trying to accomplish, but without the technical stuff:

Copyright All rights reserved by Pete A. McLeod

A good still life with bright colors and interesting textures in repeatable lighting can illustrate color saturation, maybe with highlights to check for PF or CA. Something like DPReview does for their reviews.

There are setups you can buy but it should be easy enough to make all this stuff.
Forum: Pentax K-01 12-19-2012, 06:26 PM  
Messin' with the Rokinon 85mm f/1.4
Posted By sunglint
Replies: 13
Views: 2,892
As mentioned by robtcorl, this lens does not have a macro mode. Here are some purely technical shots:



This is at F1.4. It was just beyond minimum focus, at 107cm from the front of the lens. That's just about an 8 1/2 x 11 in view. Here's the Picasa link so you can zoom in some. As you can see it is quite sharp, this pic doesnt demonstrate the IQ, (the other posted photos do,) but you can get an idea of how close it can get, and that it is very sharp, even wide open.

I also tried a #1 Pentax extension tube:

This is handheld, F1.4, Picasa Link. This is the shortest extension tube.
This is a really nice lens.
Forum: Pentax SLR Lens Discussion 12-17-2012, 03:16 PM  
New Here Please help choose my first Lense for K-01
Posted By sunglint
Replies: 17
Views: 2,564
Well to start you have a great prime in the XS40. Most of the zooms will struggle to equal that quality, unless you spend some serious bucks.
The lens database is a great resource. Start by looking at the lens tables, balancing the rating, the number of reviews and the cost. You may be surprised at some of the lenses that come out on top. Some of the Russian lenses have great ratings for the price. The Voigtlanders are superior primes and sometimes reasonably priced. In a longer lens at a good price the 90 -105mm macros tend to be very sharp, and add the wonderful world of closeup. I just picked up a Samyang 85mm 1.4 (the Vivitar version) and absolutely love it; not a real telephoto, but great IQ and the speed makes it usable handheld. Manual focus is very easy with this camera, so don't ignore used lenses, aperture linking is more important (lenses with an "A" setting,) and even then more for convenience.
Given the crop factor and that you dont have anything but the 40XS, look at a 100mm macro, which will give an effective 150mm. For a wide try for low 20s although the 28mms are easy to find at a good price. Saving up for a better lens is worth it, glass can far outlive the camera, I'm on my 3rd Pentax body and it just gets better.
Forum: Pentax K-01 12-15-2012, 09:09 PM  
K-01 peaking works in near darkness !
Posted By sunglint
Replies: 13
Views: 2,509
I just got a Vivitar version of the Samyang 85mm f1.4 and found myself able to focus and take shots I could never do with my film camera. I always had split center focus screens, and one half goes dark in dim light. This shot was taken in very dim light, handheld:

It looks like a fully lit day shot, and is much brighter than the real scene, Like the OP I'm pleasantly surprised at how much easier this makes low-light photography.
What I dont see people talk about is how the gain changes on the screen. I didnt think I was using an old M lens right, because Id change the aperture but it looked the same on the screen. I finally played with the DOF preview and realized what it was doing. This camera (and the other new mirrorless cameras) is going to make old fast primes all popular again.
Forum: Pentax SLR Lens Discussion 12-15-2012, 01:35 AM  
A-50mm 1.7 vs M-50mm 1.7
Posted By sunglint
Replies: 34
Views: 5,413
Sorry, you're right. I'm probably remembering my old nikon F, the lenses that didnt index were similar. What kind of meterless film cameras? I keep eyeing the Bersas...
Forum: Pentax SLR Lens Discussion 12-14-2012, 01:48 PM  
A-50mm 1.7 vs M-50mm 1.7
Posted By sunglint
Replies: 34
Views: 5,413
Coming from the film world I prefer wide-open metering and composure. Since it takes an A or newer to link the aperture I try to go with those where possible. I have a 50 M 1.4 and will use it for night handheld stuff where it's going to stay open, but find my 50 A 1.7 to be much easier and quite sharp. With an A and up you can change the aperture via your controls, so no need to play with the ring at all. I strongly dislike trying to compose stopped down, hated that on my old Nikon too. For the price I would consider an FA 1.7, not ridiculously expensive and lets you have the autofocus.
Forum: Pentax SLR Lens Discussion 12-14-2012, 12:50 PM  
Using Film SLR Lens Filters On DSLR Lenses
Posted By sunglint
Replies: 19
Views: 3,160
This is not correct. A linear Polarizer (usually a type PL) is a glass element that rotates on a glassless base, rotated to block the reflections from a certain direction. The OPs old polarizer would be this kind. You put it on the camera and rotate it to get the desired effect. I tried my old PL filter with my K-01 and it had a very real difference, I made this post in the K-01 forum to demonstrate both polarizer and IR filters. Of the two at the top, you can see that the exposure barely changed, but the effect of rotating the filter was significant. I did not attempt to autofocus, I was using an MF lens anyways.

I haven't used a Circular Polarizer (type CPL) yet but just ordered one so will find out.

As mentioned most of the old filters will be compensating, i.e. fluorescent lights, yellow for contrast with B/W film, etc. If you shoot in RAW then you can adjust all this afterwards, or do a manual white balance at the time. Protecting the front element is still a good idea.
Forum: Pentax K-01 12-13-2012, 02:32 PM  
Messin' with the Rokinon 85mm f/1.4
Posted By sunglint
Replies: 13
Views: 2,892
I too just got one of these lenses, receiving my Vivitar yesterday. I took it to the rock gym last night and got the following:

ISO 6400 1/40 f1.4


ISO6400 1/60 f2.0


ISO6400 1/60 f2.0

While not super hi rez, what's amazing about these shots is that they are all handheld. The first one was in quite a dim lighting environment. This lens paired with the wonderful low-light capabilities of the K-01 lets me do things I couldn't even do with a film camera. At $300 this lens is a great choice for this camera!
Forum: Pentax K-01 12-07-2012, 04:17 PM  
IR and Polarizer filter tests
Posted By sunglint
Replies: 4
Views: 2,051
Hi! I just picked up a yellow brick from Adorama, and decided to do some tests with old school filters.

I started with the K-01 on a tripod and an old PENTAX-A 50mm F1.7 lens. I set the camera to manual, to ISO 100, and to F7.1 for a little sharpness.
Then I put an old school linear polarizing filter on it. Here are two shots at different filter rotations:



The one on the left was at 1/10 and the one on the right at 1/8, very close in exposure. You can see through the dirty glass better, and some of the leaves have more color due to no sunlight reflection. I hope this means that it is ok to use this filter on this camera.


Then I went crazy and tried an R72 Infrared filter:



The one on the left is at ISO 100 and a 30 second exposure, the one on the right at ISO 3200, f1.7 and 1/20. Lots more noise on the right but almost handholdable. Having live view made the focus shift trivial.

I used Raw Therapee Portable for processing, and copied the processing settings to ensure similar croping and such. I fiddled with channels to get the IR shots from bright red to this, and didnt work very hard on the second one.
Overall I'm very pleased with the camera, I'm able to use my old lenses and filters and get very nice results.
Forum: Pentax SLR Lens Discussion 02-27-2008, 07:51 PM  
lens option : 16-45mm or 28-75mm tamron? 35 mm f2 or 50mm f1.4?
Posted By sunglint
Replies: 15
Views: 5,403
I hit NYC recently and found the 16-45 during the day and an old 50 1.4 at night was great. Add an A 70-210 and you've spent little for some awesome lenses, and it'll be up to you to take the photos. I also love my 50 2.8 macro, is very nice.
Forum: Pentax SLR Lens Discussion 02-27-2008, 07:32 PM  
Wide-angle lens to replace K10D kit lens
Posted By sunglint
Replies: 20
Views: 5,525
The Pentax 16-45 is a wonderful lens, you wont put the kit lens back on your camera. That said, the Sigma 17-70 is also very highly regarded, and gives you better range. I wandered NYC recently with the 16-45 in the day and a K 50 1.4 at night and did great. If you get the 16-45 used you might have enough to get an M 80-200 to round it out.
Forum: Photographic Technique 02-11-2008, 09:40 PM  
Swapping the focus screen on the K100D ...
Posted By sunglint
Replies: 28
Views: 9,276
THANK YOU DENI! I got my chinese screen in last weekend, and waited, which had no instructions. You pics were invaluable! And focussing both manual and auto are spot on. Also, if you move the camera slightly right/left with respect to your eye you can compensate for one side darkening, but only to a point.
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