Lens decisions -Pentax 35 f2, 50 f1.4 or 40 f2.8

Hi there
I’m considering extending my lens collection to include a good prime as a walkabout lens and also for doing some portraits. My preference for portraits is usually of the head or from the waist up so I don’t think I need to have too wide a lens (I like the photo to be in close to the subject’s face). I would also like to use the lens in fairly low light conditions such as indoors in the evening and at dusk so I have tried to narrow my choice to reasonably fast lenses.

My question is which lens do people recommend for these purposes?

I have read a fair bit and every lens has its detractors and its fans and I thought I would see what the forum’s experience with these lens is. For example I have seen some people say that the 40 is very sharp wide open and that its speed is better than what one would expect for a f2.8 lens, is this a general consensus?

I currently have a Pentax A50 f1.7 but I really struggle to achieve focus with it indoors and I miss so many shots trying to focus it (despite a fair bit of practising!). I usually use the Tamron 28-70 f2.8 as my walkaround lens but it is pretty chunky and not so great for street photography or trying to get candid snaps of friends.

Any thoughts and opinions are welcome.

Thanks,

Ross

The 50mm is a short telephoto lens on digital, so not really ideal as an all round proposition. The 18-55mm is far better for that.

If you want a prime, the 35mm is the new "standard" lens, and that should be about right for what you seem to have in mind. At one time a similar lens was supplied as standard with almost every film camera, but that was the 50mm because the frame size was larger.

The FA43 suits me. My second choice would be 35mm.

Agree that the FA43 is useful for this type of shot (upper body portraits) and this is what I use mine for. It's pricey though.

I haven't used the DA40 but I would have thought this would achieve the same effect as the focal length is similar.

I find 50mm a bit long for indoor shots. A 35mm wouldn't cause that problem but it may be a bit wide for what you have in mind. You can always crop but you might as well get the focal length correct in the first place, right?

One idea would be to review the shots you have taken with your Tamron and see what common focal lenghts you use. That might help you narrow down the range.

Whilst I know it's not on your list, I'd suggest the Sigma 30/1.4 as it would fit your needs quite well.

It's fast, a useful focal length for a walkabout prime (slightly long 'normal') and an excellent portrait lens.

I think you mean a slightly "short" normal - in 35mm terms it is a 45mm lens.

Whilst I understand that the Sigma is an excellent lens, I should think that it is a bit wide for most portraits, and would therefore second the suggestions of a 40mm or the 43mm if the budget will stretch. If it won't, then the 1:2.4 35mm is going very cheap at the moment.

G

If you care about weight/size get a 40mm if you care about money get the 35mm 2.4 . For whatever it's worth I like the pictures out of the 40mm more but I wish it had a faster aperture. Ideally I'd have a Nikon 35mm 1.8 sized like a 40mm DA. I can keep on dreaming

the 35mm f/2.4 is very contrasty so not very flattering for female portraits, but I do like the portraits from it. The FA50mm is very good, but with the new 50mm 1.7 being launched this year I would wait and get that & the 35mm f/2.4.

Link below to my 35mm portraits..

Portraits on 35mm

Is the 40 suitable for use indoors or is it a bit slow?

It is pretty blinking good wide open so as long as your AF is accurate, should be good. Does self portraits too !
Pete

It is a bit slow, I'd much rather have something like 1.8, I can counteract that because the K-5 is fantastic on ISO 1600 even 3200 with some noise reduction post processing. With the GX20 you might need a bit more care.

The 35mm f2.4 is outstanding value. I love it. If you find manual focussing your A 50/1.7 difficult, you could add the upcoming DA 50/1.8 later this year (when it is released). The 35mm is very cheap, and I am sure the new 50mm will be too. I imagine the pair will end up costing less than a DA40mm Ltd and certainly a lot less than an FA43mm, albeit they are made of plastic whereas the Ltd lenses are beautifully crafted in metal.

My experience is I love my 35mm (albeit the older FA f2 not the DA f.2.4 so can't comment on that) & sold my 50 once I'd had the 35 for a while as it just never got used.

+1

I think that the 35/2.4 would be a good start, since it is cheap and optically rather good.

As you have the excellent Tamron 28-75 already and a 50/1.7, you could use them try out the various recommendations here in terms of speed and focal length.

To see what suits your needs best in terms of the focal length, try fixing the Tamron (using some insulating tape or one of those silicone charity bracelets to hold the zoom ring in place) at 30, 35, 40 and 43mm and using it as you would envisage using your new prime.

In terms of speed, you could use your A50/1.7 to see what aperture you need to get correctly exposed shots under the low light conditions you would like to use the new prime. Nailing the focus under these condtions isn't really important (except, possibly, for showing up camera shake, but then you may already have an idea of the lowest shutter speed you can get away with from past experience).

You could also use EXIF analysis tools to do data mining on the photos you have taken to date to find out what focal lengths you use most frequently with the Tamron zoom.

It is possible that this will show that you want a lens that doesn't exist, but it might help inform your choice. When I did it, it showed that I'd like something around 40mm and f/1.8, for example - I got the FA43 and really like it for portraits.

It depends on how you define 'normal'. I tend to use the geometric definition of 43mm (or 28/29mm on APS-C), as opposed to 50mm, so without wishing to get bogged down in the semantics, I think that we're both correct in our respective assertions!

When I was looking for a good 'walkabout' lens when shooting film (I was after a moderate-wide to standard length), I had the M 40/2.8 pancake & 50/1.7 and considered the 35/2. It's a difficult choice if you are only going to carry one lens (it will often be the wrong one for effect you're after). Even if you bought them all, you might still struggle to decide which to take with you.

I like primes of this length as they are 'sort-of' convenient to carry in pockets (especially the pancake) and not having the bulk of a zoom on the camera makes it feel far more portable. I agree that the 35/2.4 would be a good start and using this with your existing 50mm (at least initially) will give you coverage at both ends (and 35 is almost 40 anyway).

For portraits, the 50/1.7 (or better still a 1.4) is probably going to be the best option.

My favourite setup for a while was a Super-A, Motordrive-A & 40mm pancake.