[danmdan]

Staff note: This post may contain affiliate links, which means Pentax Forums may earn a small commission if a visitor clicks through and makes a purchase. If you would like to support the forum directly, you may also make a donation here.

---

I haven't tried this myself, but I expect that a m42-to-K adapter between the lens and your OEM K-to-Q is all that you would need.

I did a quick search on eBay and found a whole bunch of them:

m42 k-mount in "Camera Lens Adapters, Mounts, and Tubes" | eBay

You can get M42 to Pentax Q in one adapter - available on flea-Bay for a modest amount !

[Phenix jc]

Hi,
Here's a Quick & Dirty test of 3 300mm :

Nikon 300mm 4.5 AI (not Ais)

Nikon 300mm 4.5 IFED

Tamron 60-300 3.8-5.4 23A

Camera : Q7, so 1380mm 24x36 here
higher speed 1/500e, lower speed 1/50e
Distance : 50m ?
Handheld on a Bean bag with IS (SR) on
Model : Michel.

Caution :
1/ It's made Q&D
2/ Samples may vary

So, this is what I think :

a/ Wide open - f5.6 range :
1/ Tamron 23A
Very good for a zoom (well known) ; But w.o. means f5.4 and the colors seem a little weird
2/ AI
I knew it was a good sample (this lens doesn't belong to me)
3/ IFED
...Bad sample ?

b/ f8 - f11 range :
1/ IFED
Best IQ overall IMHO
2/ Tamron 23A
3/ AI

[pleo]

as for the colours of the Tamron:
I noticed the same with the SP 3.5/70-210 ... which therefore had to got.
(the Sigma mf 3.5-4.5/70-210 APO was simply better)

Sharpness of the Tamron lenses is really good.
The colours of the shorter Tamron adaptall lenses is different though.
I don't have any explanation for that but simply found it out on practice.

[robota]

Hello,
Sorry for the newb questions in this thread; do I need to start a new one?
Posting here because I am interested in the topic and the 300mm Nikon lens Phenix jc is using is one I'm interested in. I just bought the original Q and am awaiting it's arrival. I loved the concept of it's compactness, lens interchangeability, telephoto with it's crop factor, and build quality all in one package.

I would like to try to photograph the eclipse.

My concern is that there's a review online:
Works but you loose infinity focusByMgBirderon January 4, 2013
I bought this adapter to use a Nikon 300mm f4.5 ED IF lens on the Pentax Q, it does work as intended but it looses infinity focus, i would estimate that anything past 60 meters will no longer be in focus, so the adapter works for close to medium ranges, no problem if you shoot macro but a deal breaker if you shoot landscapes or such.

The Fotodiox adapter description states:
Infinity Focus Allowed

The K&F Concept adapter description states:
Please note: Infinity focus position：the position of the infinity mark 【∞】of the telephoto lens or super telephoto lens is shifted slightly to the positive side to enable focus adjustment even when focus shift is caused due to temperature changes.The shift range is denoted by an L-shaped line, Be sure to check the focus through the viewfinder even when you shoot at infinity.


Should I go for a cheap 100-400 Promaster or old 400mm m42 instead? Issues with focus/ adapter too?

Please advise.

Thank you!

[vonBaloney]

There is no reason for any full-frame or APS-C lens adapted for the Q to lose infinity focus You lose infinity by having the lens farther away than it is supposed to be from the sensor plane, so going from Nikon(FF or APS-C) to Pentax(FF o rAPS-C) that's a problem because there is not enough room for the adapter, but going to the tiny sensor Q with short registration distance there is plenty of room so any proper adapter should be calibrated for infinity.

So, either that is one crappy adapter, or that reviewer is simply wrong, or that reviewer's lens is screwy and it doesn't focus to infinity at all. Fotodiox makes cheap adapters, but that NOT cheap -- really should work for infinity...

[reh321]

Hello,
Sorry for the newb questions in this thread; do I need to start a new one?
Posting here because I am interested in the topic and the 300mm Nikon lens Phenix jc is using is one I'm interested in. I just bought the original Q and am awaiting it's arrival. I loved the concept of it's compactness, lens interchangeability, telephoto with it's crop factor, and build quality all in one package.

I would like to try to photograph the eclipse.

My concern is that there's a review online:
Works but you loose infinity focusByMgBirderon January 4, 2013
I bought this adapter to use a Nikon 300mm f4.5 ED IF lens on the Pentax Q, it does work as intended but it looses infinity focus, i would estimate that anything past 60 meters will no longer be in focus, so the adapter works for close to medium ranges, no problem if you shoot macro but a deal breaker if you shoot landscapes or such.

The Fotodiox adapter description states:
Infinity Focus Allowed

The K&F Concept adapter description states:
Please note: Infinity focus position：the position of the infinity mark 【∞】of the telephoto lens or super telephoto lens is shifted slightly to the positive side to enable focus adjustment even when focus shift is caused due to temperature changes.The shift range is denoted by an L-shaped line, Be sure to check the focus through the viewfinder even when you shoot at infinity.


Should I go for a cheap 100-400 Promaster or old 400mm m42 instead? Issues with focus/ adapter too?

Please advise.

Thank you!

I know nothing about adapting Nikon lenses, so I'm afraid I cannot help you there.

I tried five different 300mm max K-mount lenses.
Then I did some backyard testing with a paper target, and ranked them as follows

5. Super Takumar 300mm

4. Ricoh 75-300mm

3. Tamron AdaptAll 60-300mm

2. Pentax 55-300mm

1. Sigma 70-300mm APO

All five of the lenses seemed to give me good focus at the distances where I photograph birds; I've never tried anything further than that. I should mention that 1,2 were very close, as were 3,4. Based on this testing, the Sigma APO lens + Pentax adapter now resides in my birding bag, and the Pentax lens in my K-30 bag.

I think the general conclusion would be that modern lenses seem to work better than the old-timers.

[barondla]

Hello robota. Welcome to the Q and Q community. If I am reading your post correctly the 1st adapter that can't achieve infinity focus is useless for the eclipse.

I have a Fotodiox Pentax K to Q adapter. It focuses to infinity fine. Imagine their Nikon adapter also works correctly.

The K&F Concept adapter seems to have fudged infinity slightly in the opposite direction of the 1st adapter to absolutely guarantee a lens can reach infinity. This is not a bad thing. Even big telephoto lenses, made by the camera company, usually focus past infinity. Why? Because the optics of the lens changes depending on temperature. This is why you should never set a focusing ring to infinity and assume it is correct. Always look thru the viewfinder or at the lcd monitor.

Changing lenses will not fix an incorrectly made adapter. Unless the lens focuses far enough past infinity to make up for the adapter's failing. Lenses have to be at a precise distance from the sensor to focus at infinity.

The 300mm Nikkor should be great. Hurry and get adapter #2 or 3 before the eclipse.
Thanks,
barondla

Has anyone here actually used a 300mm mirror lens with a Q?
They have the advantage of no CA and are much lighter than standard lenses.

The ultimate issue for any adopted lens, though, is how it resolves, does it resolve down to the tiny pixels on a Q's sensor, and you need to actually take some pictures to have much information on that.

I've adapted a Rokinon 300mm f6.3 to a PK mount, then to the Q7 with a cheap adapter :

IMGP5617 by Skinny Manny

Image quality at a distance is limited by atmosphere and the diffraction on the Q sensor:

IMGP3465 by Skinny Manny

The chainlink fence in the background is 1500 feet away. Notice the shallow depth of field. A 300mm mirror is hard to do on a Q, even with a tripod. The Rokinon is about $240, not exactly cheap (I got mine used for $60), I think you would do better with the Tamron

[Phenix jc]

@Robota,<br />
Don't hesitate to take any Nikon F adapter, there is plenty room to reach infinity, adapters are standardized now, so don't worry.<br />
<br />
Don't hesitate to use the 300mm IFED stopped down to f8-f11 (despite the theorical diffraction pb) to get the best of that lens, which is then at an &quot;aceptable&quot; level according to modern criteria.<br />
<br />
I've to share some results with the 400/5.6 IFED (not enough time)<br />
<br />
@reh321<br />
Modern lenses do work better because they're simply better, especially regular tele lens. (But you know that). The small sensor is very demanding.<br />
That's why (some) cine lens are also so good with the Q.<br />
<br />
@cipher<br />
AFAIK this 300/6.3 mirror lens is VG on mFT ; you should get good results on the Q, it's on my wish list.<br />
I've used a bunch of 500mm mirror lens intensively. IQ isn't as good as with a refractor, but sometimes, surprising. As we know, the best lens is the one we've with you : it's not given to every body to do hill walking with 2500mm in your pocket!<br />
(P900 though...)<br />
I've shared some results with the Nikon 500mm mirror here (many other lens to share, not enough time)

Re: Rokinon 300mm mirror. I've used it on my K-01 and my K-30, its OK, but definitely gives a different "look" than a regular lens. I get a little more resolution with the Q7, but with diffraction at f6.3 it is about a wash. Brightness at the corners falls off considerably on the APS-C bodies, but not a factor on the Qs.

Note: Rokinon doesn't offer this for the PK mount. You can sometimes find these cheap, most mounts have a cheap Q adapter available.

I think the ultimate Q long tele would be the SMC Pentax-A* 300mm F2.8 ED [IF], not exactly cheap!

[reh321]

OK, here is another extreme case. My wife and I saw this osprey while we were walking yesterday. The county park built an osprey nesting platform on top of a very tall pole, then put a substantial "no people" zone around it, so we could see it, but only in the distance. I took this picture @300mm, then tried to get a better angle, but he left and didn't return in the half hour we were willing to wait. This is a half-crop of the original image; combine that doubling with the "magnification" from using the Q-7, and the "35mm equiv" focal length is something like 2760mm. Yes, his head is slightly out of the DOF, noise is not good, and detail is less than I would prefer, but it is still an amazing picture from a system that cost me under $1000 {this was shot using Sigma 7-300 APO lens @ f/8 attached via Pentax adapter ... my backyard testing shows this lens/camera combination works best f/8-f/11}

[robota]

Thank you everyone for the awesome/helpful input! I did get email updates so was able to see the responses. Sorry for not replying sooner and bumping this thread.

Adapter(s) work perfectly fine and pretty happy with my first time attempt/ amateur astrophotography of the eclipse shots with the PentaxQ and Nikon 300mm. Fun stuff!

[Piotrek K]

Well, little bit off-topic but I just tested my new SMC-M 75 - 150/4 on the Q. For me 150 mm FL is a limit for a Q-use without tripod and this lens makes great small package Q-wise ). I found it really good at 150/5.6 - have to try it on birds!

[reh321]

I've been using a third-party adapter, but I don't think that would affect CA & sharpness comparisons between lenses.

I tried several older lenses, and every one showed noticeable CA - the only one I've used that hasn't shown noticeable CA is a new
Sigma 70-300mm f/4-5.6 APO DG Macro Autofocus
which is $179 at B&H. Unlike most newer lenses, this lens has an aperture ring, which gives you direct control over that; guys here have recommended not going any narrower than f/5.6, because small sensors like a Q-sensor start having diffraction issues much earlier than larger sensors. The real issue with adapted lenses is sharpness - you need a lot more resolution for a small 12MP sensor than for a larger one, and I've not yet found an inexpensive lens that provides as much sharpness as guys who are willing to spend more money have been able to get.

Today, my wife and I went to a county park where a pair of Bald Eagles have been nesting in recent years. The authorities (*) have it carefully arranged, with a path from the back leading up to a small shelter quite some distance from the nest, so the presence of people won't cause the eagles to abandon their nest {and the fledglings in it}. My K-30 + DA 55-300mm lens wasn't up to this task, but I had brought my Q-7 and the Sigma 70-300 with me. I backed it off to more like 240mm, and still used my monopod, because I wanted to show the massive nest in its entirety; when I looked at these images on my computer screen, I discover that I had also caught the "eagle cam", at the very top center of this image.

(*) the path starts in the park, but the nest and viewing shelter seem to be on property belonging to an environmental research arm of Notre Dame University.

[2old4toys]

Hi, as you have both, how does the DA 55-300mm lens adapted on a Q-7 compare with the Sigma 70-300 APO optical performance?
Thanks in advance.