Adapters for other camera lenses to Canon Body.

Jasp05 (Aaron) · #1 08-12-2016, 02:44 PM

Hi guys,

I was recently lent an old Pentax K1000D (or something like that

) with a longer zoom lens than what I have on my Canon 1200d.

I found you can buy an adapter online to suit K-mount pentax lens to canon body.

Are there pitfalls to these adapters? I mean its only $13 for the adapter so I've bought one to try.

But I would like to know if there are any issues I might run into with these adapters? (Light leaks, sloppy fitment?).

Also I've found a few cheap pentax lenses, (like a 50mm F2 for $15) but want to know if this going to be a worthwhile experiment. I'm only new to photography but these seem like cheap lenses but hopefully good enough to play around and learn with before dropping real money on better lenses.

If you guys have any experience with these adapters or similar pentax lenses, I'd love to hear your thoughts.

doppler (Rick) · #2 08-12-2016, 11:07 PM

Hi Aaron, old pentax pk mount lenses (on a canon 1100d) are all that I use for my wide field astro pics. I have bought a couple of these adaptors from different suppliers both of reasonable quality. There are a few issues that are easy to overcome. The first is focus, you need to use live view to focus, try focusing in the daytime with the eyepiece view finder and you will see what I mean (when you review the pic you just took). The second is CA, bright stars will become bloated and red or blue, all you need to do is stop the lens down a few stops. Because of the design of the lens diaphragm you will get star spikes on the brighter stars. You can make a lens cap to stop down the aperture to reduce the spikes. Here's a couple of pics taken with a 135mm Ricoh f2.8 lens.

WynneP (Peter) · #3 10-12-2016, 06:43 PM

Aaron,

A while ago I bought a Canon DSLR for astrophotography, with just the standard 18-55mm zoom lens. Whilst this was OK for general nightscape shots, I wondered if there was some way to use various Olympus/Zuiko lenses I had from a 40 year old SLR, which were optically superior, eg F1.4.

From internet searches, I sourced adaptors from the US, which cost less than $30 posted and work fine. Of course, they are only mechanical adaptors and you can't use the automatic electronic functions of the EOS, such as auto-focus, auto-exposure, etc. But for astro work you focus manually and set the f-stop and exposure manually, so this is not a problem. I understand you can pay a lot more (>$100) and get adaptors which adapt mechanically and electronically, if you wanted to use the DSLR for full automatic daylight photography. The ones I got were "Fotodiox" brand, which have been trouble free. Worth a try! And will save a lot of money, compared to buying equivalent Canon lenses.

MortonH · #4 12-12-2016, 12:10 PM

I have a few of these. The cheaper ones can be a bit loose. Fotodiox are good but more expensive.

Jasp05 (Aaron) · #5 13-12-2016, 11:32 AM

Thanks for the reply's guys.

I finally got my adapter but couldn't really try it out as its been very cloudy here for the past week and will be for another few days.

However I took some pics inside with it and the photos were very dark. I did end up realising that the aperture is operated with a lever and my camera has no way of adjusting this.

The lens does not have an aperture adjustment ring on the outside either. So I resorted to some blutac against the lever to hold it open.

Now my question is this. The lens is 18-200mm f3.5 - 6.3. If I hold the aperture wide open and zoom the lens to 200mm. What is the f# it will be operating at? is it going to be f3.5?

I'm assuming the lens was manually adjusting the f # when you adjusted the zoom on the proper pentax body.

I know trial and error is going to be required to find what works, but is the above basically whats happening if I open the aperture fully and use max zoom?

JA · #6 13-12-2016, 11:59 AM

Quote:

Originally Posted by Jasp05

Now my question is this. The lens is 18-200mm f3.5 - 6.3. If I hold the aperture wide open and zoom the lens to 200mm. What is the f# it will be operating at? is it going to be f3.5?

Hi Jasp,

This is a variable aperture lens and typical of very large zoom ratio lenses (11x in the case of your 18-200), the lens will be f3.5@18mm and f6.3@200mm and ascending f numbers in between these extremes, as indicated in the lens marking.

Best
JA

Jasp05 (Aaron) · #7 13-12-2016, 12:24 PM

Hi Ja,

Sorry If I wasn't clear on what I had done in my previous post. Hopefully this clears it up a bit.

When I manually zoom the lens the aperture is not adjusting inside. Checked it by doing it off the camera body. And I know the canon body can't adjust the aperture as it has no way of interacting with the lever which controls the aperture.

This is a pentax lens adapted to a canon dslr. So if I have manually set the aperture to wide open. (got it stuck there with blutac atm). And I zoom the lens, I've also checked that the aperture is not changing in the lens. (It remains wide open). Have I effectively got the lens operating at 200mm f3.5?

JA · #8 13-12-2016, 01:01 PM

Quote:

Originally Posted by Jasp05

Hi Ja,

Sorry If I wasn't clear on what I had done in my previous post. Hopefully this clears it up a bit.

When I manually zoom the lens the aperture is not adjusting inside. Checked it by doing it off the camera body. And I know the canon body can't adjust the aperture as it has no way of interacting with the lever which controls the aperture.

This is a pentax lens adapted to a canon dslr. So if I have manually set the aperture to wide open. (got it stuck there with blutac atm). And I zoom the lens, I've also checked that the aperture is not changing in the lens. (It remains wide open). Have I effectively got the lens operating at 200mm f3.5?

Hi Jasp,
I understood that you were holding the iris open with blutak on the lever. Is it a Pentax lens or Pentax mount lens by Sigma/Tamron ? Can you post a link to it online? Almost certainly not f3.5

Best
JA

Jasp05 (Aaron) · #9 13-12-2016, 01:17 PM

Hi JA,

it is a Sigma Lens for Pentax body.

https://www.photovideodirect.com.au/...eD0aApfZ8P8HAQ

It is an older lens.

JA · #10 13-12-2016, 05:26 PM

I thought it would be the Sigma and I found some data on it at DPreview

Here is a relevant part of the review on dpreview focal length V aperture data (scroll to bottom of page):

https://www.dpreview.com/reviews/sig...5-6p3-os-n15/2

As discussed earlier - It is f6.3 at 200mm. If you were thinking that using the blutak to hold the lens iris open will allow you to achieve a larger aperture, it won't. For that sort of lens (high ratio wide/tele zoom)it will be f6.3 at maximum opening, governed by design constraints (physical lens and iris sizes) inside the lens.

If you want a fast 200mm lens for Canon, there are some Full-frame f/2 and f/2.8 alternatives from others as well as Canon, although the Canon lenses are many times more expensive.

Best
JA

Jasp05 (Aaron) · #11 13-12-2016, 06:39 PM

Sorry JA. You will have to excuse my stubbornness here.

Does that iris have any function in the lens then? Or is it used in wide open position at each focal length to give the specified f#?

And then it will allow adjustments to increase the f# by closing the iris?

Just so i understand this properly for the future. As you can probably tell this is all new to me.

Actually after rereading your post i think that you were saying exactly what i mentioned above.

JA · #12 13-12-2016, 07:38 PM

Quote:

Originally Posted by Jasp05

Sorry JA. You will have to excuse my stubbornness here.

Does that iris have any function in the lens then? Or is it used in wide open position at each focal length to give the specified f#?

And then it will allow adjustments to increase the f# by closing the iris?

Just so i understand this properly for the future. As you can probably tell this is all new to me.

Actually after rereading your post i think that you were saying exactly what i mentioned above.

Hi Jasp,

The lens you have, like most now-days, does not have a manually controlled iris, i.e: there is no aperture control ring for you to turn on the outside of the lens when mounted to the camera. The purpose of the lever at the back of the lens is so that THE CAMERA can control the aperture (opening) of the iris, and thereby control light on to the sensor in accordance with whatever has been metered or set.

Your lens is f6.3 @200mm @ maximum opening. The manufacturer is not purposely limiting the opening to produce a lower performance lens

Anyway the best way to convince yourself is to put the lens set at 200mm on a PENTAX body (go to a camera shop and try) and electronically control the lens iris to set it at f/6.3 (hold down the depth of field preview button- hopefully it has one) and observe the iris opening diameter (you should be able to see this from the front of the lens) compared with how wide it opens manually by pushing the lever on the back of the lens whilst viewing the iris from the from the front of the lens as before. I venture it will open no larger than you are able to open in manually (with or without the blutak

).

Best
JA

Jasp05 (Aaron) · #13 13-12-2016, 08:00 PM

Yeah im on the same page with you now.

Thanks for the help though. Much appreciated.